# IDO2 > Gene · canonical: https://sugi.bio/atlas/gene/IDO2/ > Atlas v1.12.2 · generated 2026-10-13T13:32:47+00:00 ## Summary **IDO2** (indoleamine 2,3-dioxygenase 2, HGNC:27269) is a protein-coding gene on chromosome 8p11.21, encoding **Indoleamine 2,3-dioxygenase 2** (Q6ZQW0). Catalyzes the first and rate limiting step of the catabolism of the essential amino acid tryptophan along the kynurenine pathway. Along with the enzymes encoded by the INDO (MIM 147435) and TDO2 (MIM 191070) genes, the enzyme encoded by the INDOL1 gene metabolizes tryptophan in the kynurenine pathway (Ball et al., 2007 [PubMed 17499941]). *Source: [NCBI Gene 169355](https://www.ncbi.nlm.nih.gov/gene/169355) — RefSeq curated summary.* **At a glance** - **GWAS associations:** 2 - **Clinical variants (ClinVar):** 78 total — 1 pathogenic - **GTEx eGene:** eQTL in 7 tissues, sQTL in 3 (q < 0.05) - **ChEMBL bioactivity:** 2 clinical-phase molecules tested; no curated mechanism-of-action drug - **Constraint (gnomAD):** pLI 0.00 (LoF-tolerant), LOEUF 1.26 (unconstrained) - **MANE Select transcript:** `NM_194294` - **Interaction hub:** 1,788 STRING partners (top 10% of genes corpus-wide) - **Notable:** 78 clinical variants but no curated precision-oncology (CIViC) evidence yet ## Identifiers ### Gene identifiers | Field | Value | | --- | --- | | HGNC ID | HGNC:27269 | | Approved symbol | IDO2 | | Name | indoleamine 2,3-dioxygenase 2 | | Location | 8p11.21 | | Locus type | gene with protein product | | Status | Approved | | Ensembl gene | ENSG00000188676 | | Ensembl biotype | protein_coding | | OMIM | 612129 | | Entrez | 169355 | ## Gene structure ### Transcript identifiers **Ensembl transcripts: 11** — 5 nonsense_mediated_decay, 4 protein_coding, 1 protein_coding_CDS_not_defined, 1 retained_intron **MANE Select:** `ENST00000502986` **Transcript support level (Ensembl TSL; 1 = fully mRNA-supported):** TSL 2: 2, TSL 5: 1 `ENST00000502986`, `ENST00000343295`, `ENST00000418094`, `ENST00000868807`, `ENST00000976281`, `ENST00000976282`, `ENST00000976283`, `ENST00000976284`, `ENST00000976285`, `ENST00000976286`, `ENST00001119374` **RefSeq mRNA: 2** — MANE Select: `NM_194294` `NM_001395206`, `NM_194294` **CCDS:** `CCDS6114` #### Canonical transcript exons `ENST00000502986` — 11 exons | Exon | Start | End | | --- | --- | --- | | ENSE00001504807 | 40005327 | 40005378 | | ENSE00001650066 | 39985508 | 39985522 | | ENSE00003513766 | 40015247 | 40016392 | | ENSE00003529992 | 39982652 | 39982770 | | ENSE00003565788 | 39989721 | 39989838 | | ENSE00003599615 | 39949149 | 39949264 | | ENSE00003621714 | 39979067 | 39979186 | | ENSE00003664855 | 39963608 | 39963703 | | ENSE00003664905 | 39987871 | 39987970 | | ENSE00003671451 | 40013565 | 40013713 | | ENSE00003964382 | 39934651 | 39935218 | ### Expression profiles **Bgee:** expression breadth **broad**, 80 present calls, max score 80.38. **FANTOM5 (CAGE):** breadth **tissue_specific**, TPM avg 0.0638 / max 28.0212, expressed in 12 samples. **Highest expression (Bgee):** lobe of liver, liver, male germ line stem cell (sensu Vertebrata) in testis, placenta, lobe of thyroid gland. #### Genetic regulation across tissues (GTEx eQTL / sQTL) IDO2 is an **eGene** in GTEx v10 — its expression is genetically regulated (eQTL) in **7** tissues and its splicing (sQTL) in **3** (q < 0.05). Strongest associations first; slope = normalized effect of the lead variant's alternative allele. 10 significant tissue × QTL associations: | Tissue | QTL | q-value | Slope | Lead variant | | --- | --- | --- | --- | --- | | Thyroid | sqtl | 7.2e-21 | +0.59 | 8:40000640:T:TGTTTGTTTGTTTTGA | | Liver | sqtl | 4.5e-09 | -0.70 | 8:40002154:A:G | | Lung | eqtl | 1.6e-08 | +0.92 | 8:39944149:A:G | | Skin Not Sun Exposed Suprapubic | eqtl | 2.3e-07 | +0.29 | 8:39945608:A:C | | Testis | sqtl | 1.2e-06 | -0.50 | 8:39995775:A:G | | Thyroid | eqtl | 1.1e-05 | -0.19 | 8:39943919:G:A | | Testis | eqtl | 7.8e-04 | -0.11 | 8:39991921:T:C | | Adipose Visceral Omentum | eqtl | 1.3e-03 | -0.26 | 8:39942486:C:A | | Skin Sun Exposed Lower leg | eqtl | 4.4e-03 | -0.21 | 8:39938290:C:CTATCTA | | Small Intestine Terminal Ileum | eqtl | 3.3e-02 | +0.49 | 8:40874481:A:G | #### FANTOM5 promoters 5 alternative TSS: | Promoter ID | TPM avg | Samples expressed | | --- | --- | --- | | 88594 | 0.0280 | 6 | | 88606 | 0.0134 | 5 | | 88595 | 0.0107 | 2 | | 88605 | 0.0081 | 1 | | 88596 | 0.0037 | 3 | #### Top tissues by expression showing 100 of 218 tissues by Bgee expression score (0-100, higher = more expressed): | Tissue | Anatomy ID | Expression score | Quality | | --- | --- | --- | --- | | right lobe of liver | UBERON:0001114 | 80.38 | gold quality | | liver | UBERON:0002107 | 74.35 | gold quality | | male germ line stem cell (sensu Vertebrata) in testis | CL:0000089 ∩ UBERON:0000473 | 73.04 | gold quality | | placenta | UBERON:0001987 | 71.04 | gold quality | | left lobe of thyroid gland | UBERON:0001120 | 68.50 | gold quality | | right lobe of thyroid gland | UBERON:0001119 | 68.48 | gold quality | | thyroid gland | UBERON:0002046 | 66.61 | gold quality | | vermiform appendix | UBERON:0001154 | 64.15 | gold quality | | sperm | CL:0000019 | 62.09 | silver quality | | primordial germ cell in gonad | CL:0000670 ∩ UBERON:0000991 | 62.08 | gold quality | | endometrium | UBERON:0001295 | 61.11 | gold quality | | lymph node | UBERON:0000029 | 61.04 | gold quality | | right testis | UBERON:0004534 | 60.81 | gold quality | | left testis | UBERON:0004533 | 60.63 | gold quality | | testis | UBERON:0000473 | 59.04 | gold quality | | caecum | UBERON:0001153 | 58.94 | gold quality | | skin of hip | UBERON:0001554 | 54.93 | gold quality | | gall bladder | UBERON:0002110 | 53.55 | gold quality | | spleen | UBERON:0002106 | 53.41 | gold quality | | rectum | UBERON:0001052 | 53.40 | gold quality | | buccal mucosa cell | CL:0002336 | 53.01 | gold quality | | mucosa of transverse colon | UBERON:0004991 | 52.48 | gold quality | | upper leg skin | UBERON:0004262 | 50.64 | silver quality | | sural nerve | UBERON:0015488 | 50.26 | gold quality | | bone marrow cell | CL:0002092 | 50.20 | gold quality | | colonic epithelium | UBERON:0000397 | 50.18 | gold quality | | tonsil | UBERON:0002372 | 50.09 | gold quality | | monocyte | CL:0000576 | 48.92 | silver quality | | small intestine Peyer's patch | UBERON:0003454 | 48.48 | gold quality | | skin of abdomen | UBERON:0001416 | 48.32 | gold quality | | small intestine | UBERON:0002108 | 47.95 | gold quality | | uterus | UBERON:0000995 | 47.92 | gold quality | | leukocyte | CL:0000738 | 47.89 | silver quality | | skin of leg | UBERON:0001511 | 47.89 | gold quality | | zone of skin | UBERON:0000014 | 47.26 | gold quality | | upper lobe of left lung | UBERON:0008952 | 46.51 | gold quality | | upper lobe of lung | UBERON:0008948 | 46.21 | gold quality | | granulocyte | CL:0000094 | 46.20 | silver quality | | duodenum | UBERON:0002114 | 46.02 | gold quality | | lung | UBERON:0002048 | 44.45 | gold quality | | bone marrow | UBERON:0002371 | 44.04 | gold quality | | right lung | UBERON:0002167 | 43.81 | gold quality | | skeletal muscle tissue of rectus abdominis | UBERON:0004511 | 43.37 | gold quality | | female reproductive system | UBERON:0000474 | 42.71 | gold quality | | secondary oocyte | CL:0000655 | 42.57 | gold quality | | kidney | UBERON:0002113 | 41.99 | silver quality | | adult mammalian kidney | UBERON:0000082 | 41.93 | gold quality | | vastus lateralis | UBERON:0001379 | 41.41 | gold quality | | quadriceps femoris | UBERON:0001377 | 41.37 | gold quality | | superficial temporal artery | UBERON:0001614 | 41.33 | gold quality | | intestine | UBERON:0000160 | 41.26 | gold quality | | mucosa of paranasal sinus | UBERON:0005030 | 40.98 | gold quality | | smooth muscle tissue | UBERON:0001135 | 40.90 | gold quality | | urinary bladder | UBERON:0001255 | 40.85 | gold quality | | amniotic fluid | UBERON:0000173 | 40.69 | gold quality | | muscle tissue | UBERON:0002385 | 40.62 | gold quality | | jejunal mucosa | UBERON:0000399 | 40.59 | gold quality | | biceps brachii | UBERON:0001507 | 40.57 | gold quality | | epithelium of nasopharynx | UBERON:0001951 | 40.45 | gold quality | | myocardium | UBERON:0002349 | 40.45 | gold quality | | gingival epithelium | UBERON:0001949 | 40.43 | gold quality | | germinal epithelium of ovary | UBERON:0001304 | 40.33 | gold quality | | esophagus squamous epithelium | UBERON:0006920 | 40.29 | gold quality | | skeletal muscle tissue of biceps brachii | UBERON:0004502 | 40.27 | gold quality | | jejunum | UBERON:0002115 | 40.18 | gold quality | | cartilage tissue | UBERON:0002418 | 40.06 | gold quality | | oviduct epithelium | UBERON:0004804 | 40.03 | gold quality | | mammary duct | UBERON:0001765 | 39.98 | gold quality | | mucosa of sigmoid colon | UBERON:0004993 | 39.95 | gold quality | | skeletal muscle tissue | UBERON:0001134 | 39.89 | gold quality | | deltoid | UBERON:0001476 | 39.83 | gold quality | | saphenous vein | UBERON:0007318 | 39.83 | gold quality | | parotid gland | UBERON:0001831 | 39.81 | gold quality | | oocyte | CL:0000023 | 39.80 | gold quality | | urethra | UBERON:0000057 | 39.80 | gold quality | | heart right ventricle | UBERON:0002080 | 39.79 | gold quality | | left adrenal gland cortex | UBERON:0035825 | 39.78 | gold quality | | pericardium | UBERON:0002407 | 39.77 | gold quality | | layer of synovial tissue | UBERON:0007616 | 39.77 | gold quality | | endothelial cell | CL:0000115 | 39.75 | gold quality | | cortical plate | UBERON:0005343 | 39.75 | gold quality | | synovial joint | UBERON:0002217 | 39.70 | gold quality | | dorsal root ganglion | UBERON:0000044 | 39.68 | gold quality | | nipple | UBERON:0002030 | 39.68 | gold quality | | bronchial epithelial cell | CL:0002328 | 39.65 | gold quality | | decidua | UBERON:0002450 | 39.65 | gold quality | | penis | UBERON:0000989 | 39.64 | gold quality | | gingiva | UBERON:0001828 | 39.64 | gold quality | | bronchus | UBERON:0002185 | 39.64 | gold quality | | trigeminal ganglion | UBERON:0001675 | 39.63 | gold quality | | tendon of biceps brachii | UBERON:0008188 | 39.60 | gold quality | | inferior vagus X ganglion | UBERON:0005363 | 39.57 | gold quality | | superior surface of tongue | UBERON:0007371 | 39.56 | gold quality | | pylorus | UBERON:0001166 | 39.55 | gold quality | | renal medulla | UBERON:0000362 | 39.53 | gold quality | | pons | UBERON:0000988 | 39.51 | gold quality | | thymus | UBERON:0002370 | 39.50 | gold quality | | medulla oblongata | UBERON:0001896 | 39.48 | gold quality | | superior vestibular nucleus | UBERON:0007227 | 39.47 | gold quality | | cardia of stomach | UBERON:0001162 | 39.46 | gold quality | #### Single-cell (SCXA) Detected in 1 experiment(s), a significant marker in 1. | Experiment | Marker? | Max mean expression | | --- | --- | --- | | [E-ANND-3](https://www.ebi.ac.uk/gxa/sc/experiments/E-ANND-3) | yes | 5.04 | #### HPA expression RNA tissue specificity: **Group enriched** 38 HPA tissues / cells by nTPM: | Tissue / cell | Axis | nTPM | | --- | --- | --- | | Cerebellum | tissue | 10.8 | | Olfactory bulb | tissue | 10.7 | | Superior colliculi | tissue | 9.4 | | Spinal cord | tissue | 9.2 | | Cerebral cortex | tissue | 8.9 | | Insular cortex | tissue | 8.9 | | Amygdala | tissue | 8.6 | | Basal ganglia | tissue | 8.2 | | Retrosplenial cortex | tissue | 8.1 | | Retrosplenial and cingulate cortex | tissue | 7.9 | | Temporal cortex | tissue | 7.9 | | Hippocampal formation | tissue | 7.8 | | Entorhinal cortex | tissue | 7.8 | | Corpus callosum | tissue | 7.7 | | Ventral forebrain | tissue | 7.3 | | Prefrontal cortex | tissue | 7.2 | | Occipital cortex | tissue | 7.0 | | Motor cortex | tissue | 6.6 | | Putamen | tissue | 6.6 | | Periaqueductal gray | tissue | 6.5 | | Septum | tissue | 6.5 | | Somatosensory cortex | tissue | 6.2 | | Substantia nigra | tissue | 5.8 | | Medulla oblongata | tissue | 5.5 | | Hypothalamus | tissue | 5.5 | | Placenta | tissue | 5.2 | | Midbrain | tissue | 5.0 | | Thalamus | tissue | 4.3 | | Pons | tissue | 4.2 | | Liver | tissue | 3.1 | | Frontal cortex | tissue | 0.3 | | Caudate putamen | tissue | 0.3 | | Lymph node | tissue | 0.2 | | Kidney | tissue | 0.2 | | Duodenum | tissue | 0.1 | | Thymus | tissue | 0.1 | | Tonsil | tissue | 0.1 | | Appendix | tissue | 0.1 | **Brain sub-regions (HPA Brain Atlas):** detected in 8; highest nTPM — Dorsal spinal cord (9.2), White matter (7.7), Subiculum (7.2), Ventral spinal cord (6.7), Ventral hippocampus (6.5). ### Regulation **Is transcription factor: no** **Upstream regulators (CollecTRI, top):** PTMA #### miRNA regulators (miRDB) Targeting IDO2 by miRDB confidence (max_score; target_count = how many genes the miRNA targets in total — lower means more specific). showing 30 of 55 miRNAs: | miRNA | Max score | Avg score | miRNA target_count | | --- | --- | --- | --- | | HSA-MIR-4673 | 100.00 | 66.64 | 1490 | | HSA-MIR-3667-3P | 99.99 | 67.17 | 1636 | | HSA-MIR-4482-3P | 99.98 | 72.50 | 3147 | | HSA-MIR-5696 | 99.98 | 72.36 | 4487 | | HSA-MIR-4645-5P | 99.98 | 65.81 | 1284 | | HSA-MIR-548AN | 99.97 | 70.91 | 2817 | | HSA-MIR-3065-5P | 99.97 | 71.56 | 3281 | | HSA-MIR-507 | 99.97 | 70.11 | 1915 | | HSA-MIR-1250-3P | 99.96 | 70.04 | 4038 | | HSA-MIR-3658 | 99.96 | 73.87 | 4379 | | HSA-MIR-557 | 99.96 | 70.01 | 1640 | | HSA-MIR-3910 | 99.95 | 71.13 | 2227 | | HSA-MIR-548E-5P | 99.89 | 72.73 | 4486 | | HSA-MIR-4731-5P | 99.89 | 67.23 | 2537 | | HSA-MIR-153-5P | 99.89 | 73.86 | 6317 | | HSA-MIR-579-3P | 99.86 | 71.66 | 3628 | | HSA-MIR-4728-5P | 99.85 | 69.39 | 4718 | | HSA-MIR-664B-3P | 99.84 | 71.65 | 3590 | | HSA-MIR-4799-5P | 99.82 | 70.60 | 2663 | | HSA-MIR-6785-5P | 99.82 | 68.68 | 4428 | | HSA-MIR-4659A-3P | 99.80 | 72.62 | 4248 | | HSA-MIR-4659B-3P | 99.80 | 72.62 | 4248 | | HSA-MIR-4760-5P | 99.80 | 69.88 | 1619 | | HSA-MIR-149-3P | 99.72 | 68.22 | 3963 | | HSA-MIR-4699-3P | 99.71 | 70.15 | 3142 | | HSA-MIR-6883-5P | 99.69 | 68.05 | 3785 | | HSA-MIR-8061 | 99.63 | 69.44 | 1411 | | HSA-MIR-3942-3P | 99.57 | 69.03 | 2854 | | HSA-MIR-7159-5P | 99.53 | 72.12 | 2472 | | HSA-MIR-4441 | 99.49 | 66.56 | 3216 | ### Functional genomics **gnomAD constraint:** pLI 1.89e-05, LOEUF 1.26, missense Z -0.84 — population loss-of-function intolerance (pLI ≥ 0.9 = LoF-intolerant; lower LOEUF = more constrained). [gnomAD](https://gnomad.broadinstitute.org/) **Regional missense constraint (gnomAD RMC):** no regional variation along `ENST00000502986` — one region, missense o/e 1.11. ### Literature-anchored findings (GeneRIF, showing 37) - This article describes the evolutionary relationships between the INDO and INDOL1 genes. The INDOL1 protein has a distinct expression pattern compared to INDO and both have the ability to catabolise tryptophan. (PMID:17499941) - IDO2 encodes a novel IDO-related tryptophan catabolic enzyme that is preferentially inhibited by D-1-methyl-tryptophan (D-1MT). IDO2 may have a distinct role in immune tolerance. Two common human genetic polymorphisms ablate IDO2 enzyme activity. (PMID:17671174) - First study to report IDO2 expression in pancreatic ductal adenocarcinoma indicating that IDO2 genetic polymorphisms do not negate interferon-gamma-inducible protein expression. (PMID:19476837) - High activity of indoleamine 2,3 dioxygenase enzyme predicts disease severity and case fatality in bacteremic patients. (PMID:19487973) - The pro-apoptotic activity of indoleamine 2, 3-dioxygenase is responsible for its transcriptional regulation and the modulation of its pro-apoptotic activity during death receptor activation in melanoma cells. (PMID:19799997) - Tryptophan supplementation was able to completely restore hepatitis b virus replication in IFN-gamma- but not IFN-alpha-treated cells, which strongly argues that IDO is the primary mediator of IFN-gamma-elicited antiviral response in human hepatocytes. (PMID:21084489) - Data show that IDO2-specific T cells are cytotoxic effector cells that recognize and kill tumor cells. (PMID:21406395) - Purification and kinetic characterization of human indoleamine 2,3-dioxygenases 1 and 2 (IDO1 and IDO2) and discovery of selective IDO1 inhibitors. (PMID:21835273) - Indoleamine2,3-dioxygenase and tryptophanyl-tRNA synthetase may play critical roles in the immune pathogenesis of chronic kidney disease. (PMID:23651343) - The IDO2 is now known to catalyze the first and rate-limiting step in the catabolism of tryptophan along a relative newcomer to the kynurenine pathway field. (PMID:24105077) - IDO2 is expressed in both mDCs and plasmacytoid DCs and is not modulated by PGE2. IDO2 expression is constitutively, stably expressed in steady-state conditions and may contribute to the homeostatic tolerogenic capacity of DCs. (PMID:24391212) - Multiple-scattering (MS) analysis of EXAFS data on met-indoleamine 2,3-dioxygenase-2 (IDO2) and analysis of XANES have provided the first direct structural information about the axial donor ligands of the iron center for this recently discovered protein. (PMID:24858687) - Human indoleamine 2,3-dioxygenase-2 has substrate specificity and inhibition characteristics distinct from those of indoleamine 2,3-dioxygenase-1 (PMID:24875753) - These results demonstrate that IDO2 plays a novel role as a negative regulator of IDO1 by competing for heme-binding with IDO1. (PMID:25394548) - functional importance of IDO enzymes in human Crohn's disease (PMID:25541686) - High IDO2 expression is associated with cervical cancer. (PMID:27106797) - High IDO2 expression is associated with Colorectal Cancer. (PMID:27578919) - This study demonstrated that IDO2 rs10109853 and rs4503083 polymorphisms are not associated with MS risk, age at onset and disease progression in Italian MS patients. (PMID:28477703) - Data suggest a strong association between the Indoleamine-2,3-Dioxygenase-2 (IDO2) inactivating Y359Stop single nucleotide polymorphism and an increased risk of familial pancreatic cancers when compared with the control group. (PMID:29426021) - The results of this study provide genetic support for IDO2 as a contributing factor in PDAC development and argue that IDO2 genotype analysis has the immediate potential to influence the PDAC care decision-making process through stratification of those patients who stand to benefit from adjuvant radiotherapy (PMID:30266763) - IDO expression correlates with intra-tumoral neutrophils infiltration and prognosis in the hepatocellular carcinoma patients. (PMID:30843276) - Genetic Polymorphisms Affecting IDO1 or IDO2 Activity Differently Associate With Aspergillosis in Humans. (PMID:31134053) - Elevated expression of IDO2 is associated with Chemoresistance in breast cancer. (PMID:31844921) - Influence of Indoleamine-2,3-Dioxygenase and Its Metabolite Kynurenine on gammadelta T Cell Cytotoxicity against Ductal Pancreatic Adenocarcinoma Cells. (PMID:32384638) - Indoleamine 2,3-Dioxygenase 2 Immunohistochemical Expression in Resected Human Non-small Cell Lung Cancer: A Potential New Prognostic Tool. (PMID:32536910) - High PD-L1/IDO-2 and PD-L2/IDO-1 Co-Expression Levels Are Associated with Worse Overall Survival in Resected Non-Small Cell Lung Cancer Patients. (PMID:33671892) - Methylene blue and ascorbate interfere with the accurate determination of the kinetic properties of IDO2. (PMID:33686747) - IDO2 rs10109853 polymorphism affects the susceptibility to multiple myeloma. (PMID:33709342) - Investigating the Role of Indoleamine 2,3-Dioxygenase in Acute Myeloid Leukemia: A Systematic Review. (PMID:33777052) - Indoleamine 2,3-dioxygenase (IDO)-1 and IDO-2 activity and severe course of COVID-19. (PMID:34859884) - Single-nucleotide polymorphisms and activities of indoleamine 2,3-dioxygenase isoforms, IDO1 and IDO2, in tuberculosis patients. (PMID:35045867) - Heterozygote Advantage of the Type II Deiodinase Thr92Ala Polymorphism on Intrahospital Mortality of COVID-19. (PMID:35137147) - Indoleamine 2,3-dioxygenase 2 immunohistochemical expression in medullary thyroid carcinoma: implications in prognosis and immunomodulatory effects. (PMID:36319978) - Regulation of IDO2 by the Aryl Hydrocarbon Receptor (AhR) in Breast Cancer. (PMID:37408267) - Prolonged indoleamine 2,3-dioxygenase-2 activity and associated cellular stress in post-acute sequelae of SARS-CoV-2 infection. (PMID:37506544) - Membrane Localization and Phosphorylation of Indoleamine 2,3-Dioxygenase 2 (IDO2) in A549 Human Lung Adenocarcinoma Cells: First Steps in Exploring Its Signaling Function. (PMID:38003426) - Marked IDO2 expression and activity related to autophagy and apoptosis in brain tissue of fatal tuberculous meningitis. (PMID:38460493) ### Cross-species orthologs **2 orthologs** | Organism | Symbol | Gene ID | | --- | --- | --- | | mus_musculus | Ido2 | ENSMUSG00000031549 | | rattus_norvegicus | Ido2 | ENSRNOG00000025365 | #### Mouse-model phenotypes Observed phenotypes of the mouse ortholog ([MGI:2142489](https://www.informatics.jax.org/marker/MGI:2142489)) from MGI (Alliance of Genome Resources) — knockout/mutant phenotypes, ranked by annotation count. 6 distinct phenotype terms. | Mouse phenotype (MP) | Records | | --- | --- | | decreased susceptibility to type IV hypersensitivity reaction | 2 | | abnormal regulatory T cell physiology | 1 | | decreased tumor necrosis factor secretion | 1 | | decreased interferon-gamma secretion | 1 | | decreased interleukin-6 secretion | 1 | | abnormal chemokine secretion | 1 | #### Additional cross-species homologs Sequence homologs in species beyond Ensembl Compara's model organisms, by Diamond local protein alignment (% sequence identity; best hit per species). Lower-identity rows are more distant homologs. The matched accessions' gene symbols aren't in biobtree yet, so each row shows the UniProt accession. | Organism | UniProt | Identity | Method | | --- | --- | --- | --- | | Haliotis diversicolor | [Q01966](https://www.uniprot.org/uniprotkb/Q01966/entry) | 87.3% | Diamond | | Haliotis madaka | [P51537](https://www.uniprot.org/uniprotkb/P51537/entry) | 87.0% | Diamond | | Aspergillus terreus NIH2624 | [Q0CG33](https://www.uniprot.org/uniprotkb/Q0CG33/entry) | 54.4% | Diamond | | Aspergillus nanangensis | [A0A6G9KIF9](https://www.uniprot.org/uniprotkb/A0A6G9KIF9/entry) | 46.9% | Diamond | | Penicillium citrinum | [P0DUR8](https://www.uniprot.org/uniprotkb/P0DUR8/entry) | 46.9% | Diamond | | Fusarium equiseti | [A0A823AAW6](https://www.uniprot.org/uniprotkb/A0A823AAW6/entry) | 37.8% | Diamond | | Saccharomyces cerevisiae S288C | [P47125](https://www.uniprot.org/uniprotkb/P47125/entry) | 35.0% | Diamond | ### Genomic neighbors (locus context) Genes flanking this one on the chromosome (NCBI/Entrez gene neighborhood). Positional context only — some neighbors share regulatory elements (bidirectional promoters, antisense/overlapping transcripts), but chromosomal adjacency is not itself a functional relationship (see Interactions for that). | Symbol | Type | Entrez | | --- | --- | --- | | [LINC02866](/atlas/gene/LINC02866/) | ncRNA | 105379385 | | [IDO1](/atlas/gene/IDO1/) | protein-coding | 3620 | | [TCIM](/atlas/gene/TCIM/) | protein-coding | 56892 | | [SIRLNT](/atlas/gene/SIRLNT/) | ncRNA | 112543493 | | [ZMAT4](/atlas/gene/ZMAT4/) | protein-coding | 79698 | | [ADAM2](/atlas/gene/ADAM2/) | protein-coding | 2515 | | [ADAM18](/atlas/gene/ADAM18/) | protein-coding | 8749 | ## Protein ### Protein identifiers **Indoleamine 2,3-dioxygenase 2** — `Q6ZQW0` (reviewed: Q6ZQW0) **Alternative names:** Indoleamine 2,3-dioxygenase-like protein 1, Indoleamine-pyrrole 2,3-dioxygenase-like protein 1 **All UniProt accessions (1):** `Q6ZQW0` #### UniProt curated annotations — [full annotation on UniProt →](https://www.uniprot.org/uniprotkb/Q6ZQW0/entry) **Function.** Catalyzes the first and rate limiting step of the catabolism of the essential amino acid tryptophan along the kynurenine pathway. Involved in immune regulation. May not play a significant role in tryptophan-related tumoral resistance. **Tissue specificity.** Detected in liver, small intestine, spleen, placenta, thymus, lung, brain, kidney, and colon. Also expressed at low level in testis and thyroid. Not expressed in the majority of human tumor samples (>99%). **Activity regulation.** Activity is inhibited by D-1MT (1-methyl-D-tryptophan) and MTH-trp (methylthiohydantoin-DL-tryptophan) but not L-1MT (1-methyl-L-tryptophan). **Cofactor.** Binds 1 heme group per subunit. **Pathway.** Amino-acid degradation; L-tryptophan degradation via kynurenine pathway; L-kynurenine from L-tryptophan: step 1/2. **Polymorphism.** The variant Trp-248 (p.R248W) drastically reduces the enzymatic activity. The Del359-420 variant (p.Y359X) generates a truncated, enzymatically inactive protein. The high prevalence of these polymorphic alleles results in a non-functional IDO2 enzyme in up to 50% of Caucasians. **Miscellaneous.** IDO1 and IDO2 are 2 distinct enzymes which catalyze the same reaction. IDO2 affinity for tryptophan is much lower than that of IDO1. 50 % of Caucasians harbor polymorphisms which abolish IDO2 enzymatic activity. IDO2 is expressed in human tumors in an inactive form: tryptophan degradation is entirely provided by IDO1 in these cells. IDO2 may play a role as a negative regulator of IDO1 by competing for heme-binding with IDO1. Low efficiency IDO2 enzymes have been conserved throughout vertebrate evolution, whereas higher efficiency IDO1 enzymes are dispensable in many lower vertebrate lineages. IDO1 may have arisen by gene duplication of a more ancient proto-IDO gene before the divergence of marsupial and eutherian (placental) mammals. **Similarity.** Belongs to the indoleamine 2,3-dioxygenase family. #### Isoforms (2) | UniProt ID | Names | Canonical? | | --- | --- | --- | | Q6ZQW0-1 | 1 | yes | | Q6ZQW0-2 | 2 | | **RefSeq proteins (2):** `NP_001382135`, `NP_919270`* (*=MANE) #### Domains & families (InterPro) | ID | Name | Type | | --- | --- | --- | | IPR000898 | Indolamine_dOase | Family | | IPR037217 | Trp/Indoleamine_2_3_dOase-like | Homologous_superfamily | **Pfam:** `PF01231` #### Enzyme classification (BRENDA) - EC 1.13.11.11 — tryptophan 2,3-dioxygenase *(BRENDA: 16 organisms, 15 substrates, 146 inhibitors, 17 Km, 8 kcat entries)* - EC 1.13.11.52 — indoleamine 2,3-dioxygenase *(BRENDA: 49 organisms, 208 substrates, 831 inhibitors, 203 Km, 109 kcat entries)* #### Substrate kinetics (BRENDA) 23 substrates with measured Km, best-characterized 15. *Km ranges are aggregated across organisms/conditions.* | Substrate | Km (mM) | Measurements | | --- | --- | --- | | L-TRYPTOPHAN | 0.0007–62.4 | 96 | | D-TRYPTOPHAN | 0.0019–16 | 27 | | L-TRYPTOPHAN | 0.02–1.531 | 13 | | L-TRP | 0.02–133 | 12 | | 5-HYDROXY-L-TRYPTOPHAN | 0.017–0.68 | 10 | | O2 | 0.037–119 | 10 | | 5-FLUORO-DL-TRYPTOPHAN | 0.006–100 | 6 | | 5-METHYL-DL-TRYPTOPHAN | 0.088–1.57 | 6 | | 6-METHYL-DL-TRYPTOPHAN | 0.056–3.457 | 5 | | D-TRP | 0.3–5.2 | 5 | | 6-FLUORO-DL-TRYPTOPHAN | 0.186–186 | 4 | | 1-METHYL-L-TRYPTOPHAN | 0.062–0.696 | 3 | | 1-METHYL-D-TRYPTOPHAN | 0.66–0.747 | 2 | | 5-FLUORO-TRYPTOPHAN | 0.006–0.36 | 2 | | 5-METHOXY-DL-TRYPTOPHAN | 0.113–0.547 | 2 | #### Catalyzed reactions (Rhea) - L-tryptophan + O2 = N-formyl-L-kynurenine *(RHEA:24536)* **UniProt features (6 total):** splice variant 2, sequence variant 2, chain 1, binding site 1 ### Structure #### Experimental structures (PDB) 11 structures by resolution: | PDB | Title | Method | Resolution (Å) | | --- | --- | --- | --- | | 9UYY | Crystal structure of the indoleamine 2,3-dioxygenagse 2 (IDO2) complexed with L-Trp | X-RAY DIFFRACTION | 2.25 | | 9UZ1 | Crystal structure of the indoleamine 2,3-dioxygenagse 2 (IDO2) H143Y mutant complexed … | X-RAY DIFFRACTION | 2.35 | | 9UYZ | Crystal structure of the indoleamine 2,3-dioxygenagse 2 (IDO2) complexed with 5-HT | X-RAY DIFFRACTION | 2.45 | | 9UZ0 | Crystal structure of the indoleamine 2,3-dioxygenagse 2 (IDO2) as resting state | X-RAY DIFFRACTION | 2.45 | | 9UZ3 | Crystal structure of the indoleamine 2,3-dioxygenagse 2 (IDO2) complexed with D-Trp | X-RAY DIFFRACTION | 2.5 | | 9UZ4 | Crystal structure of the indoleamine 2,3-dioxygenagse 2 (IDO2) complexed with … | X-RAY DIFFRACTION | 2.5 | | 9UZ5 | Crystal structure of the indoleamine 2,3-dioxygenagse 2 (IDO2) complexed with … | X-RAY DIFFRACTION | 2.5 | | 21OO | Crystal structure of the indoleamine 2,3-dioxygenagse 2 (IDO2) H143Y mutant complexed … | X-RAY DIFFRACTION | 2.55 | | 9UZ2 | Crystal structure of the indoleamine 2,3-dioxygenagse 2 (IDO2) complexed with Cyanide ion | X-RAY DIFFRACTION | 2.55 | | 21OK | Crystal structure of the indoleamine 2,3-dioxygenagse 2 (IDO2) H143Y mutant complexed … | X-RAY DIFFRACTION | 2.6 | | 21OM | Crystal structure of the indoleamine 2,3-dioxygenagse 2 (IDO2) complexed with … | X-RAY DIFFRACTION | 2.68 | #### Predicted structure (AlphaFold) | Model | pLDDT | Fraction very-high | | --- | --- | --- | | AF-Q6ZQW0-F1 | 93.25 | 0.87 | ### Human Protein Atlas **Protein class:** Metabolic proteins, Predicted intracellular proteins **Protein evidence:** Evidence at protein level **Subcellular location (HPA, imaging):** cytosol **Antibody reliability (HPA):** IF approved ### Functional residue map Curated UniProt residues grouped by drug-discovery relevance — catalytic, ligand-binding, modification, and mutation-validated positions. *Source: UniProtKB sequence features.* #### Ligand- & substrate-binding residues (1) | Position | Role | | --- | --- | | 347 | heme | ## Function ### Pathways and Gene Ontology #### Reactome pathways **1 curated (TAS)** of 3; 0 disease pathways. Curated-first; evidence = TAS (manually curated) vs IEA (electronic inference). 3 pathways: | ID | Pathway | Evidence | | --- | --- | --- | | R-HSA-71240 | Tryptophan catabolism | curated | | R-HSA-1430728 | Metabolism | — | | R-HSA-71291 | Metabolism of amino acids and derivatives | — | **MSigDB gene sets: 113** (showing top): `GOBP_ALPHA_AMINO_ACID_METABOLIC_PROCESS`, `REACTOME_TRYPTOPHAN_CATABOLISM`, `GCAAGGA_MIR502`, `GOBP_ORGANOPHOSPHATE_METABOLIC_PROCESS`, `GOBP_NUCLEOSIDE_PHOSPHATE_BIOSYNTHETIC_PROCESS`, `GOBP_KETONE_METABOLIC_PROCESS`, `GOBP_ORGANOPHOSPHATE_BIOSYNTHETIC_PROCESS`, `GOBP_NADPLUS_METABOLIC_PROCESS`, `GOBP_NUCLEOBASE_CONTAINING_SMALL_MOLECULE_METABOLIC_PROCESS`, `SHETH_LIVER_CANCER_VS_TXNIP_LOSS_PAM4`, `GOBP_AROMATIC_AMINO_ACID_METABOLIC_PROCESS`, `ACEVEDO_LIVER_TUMOR_VS_NORMAL_ADJACENT_TISSUE_DN`, `GOBP_ORGANIC_ACID_CATABOLIC_PROCESS`, `GOBP_INDOLE_CONTAINING_COMPOUND_METABOLIC_PROCESS`, `GOBP_ORGANIC_ACID_METABOLIC_PROCESS` **GO Biological Process (3):** immune system process (GO:0002376), 'de novo' NAD+ biosynthetic process from L-tryptophan (GO:0034354), L-tryptophan catabolic process (GO:0006569) **GO Molecular Function (6):** L-tryptophan 2,3-dioxygenase activity (GO:0004833), heme binding (GO:0020037), indoleamine 2,3-dioxygenase activity (GO:0033754), metal ion binding (GO:0046872), oxidoreductase activity (GO:0016491), dioxygenase activity (GO:0051213) **GO Cellular Component (2):** cytoplasm (GO:0005737), cytosol (GO:0005829) #### Reactome top-level categories 2 top-level categories: | Category | Pathways | | --- | --- | | Metabolism of amino acids and derivatives | 1 | | Metabolism | 1 | #### GO top-level categories 17 GO namespaces: | Category | Terms | | --- | --- | | oxidoreductase activity, acting on single donors with incorporation of molecular oxygen, incorporation of two atoms of oxygen | 2 | | cellular anatomical structure | 2 | | biological_process | 1 | | aromatic amino acid metabolic process | 1 | | NAD+ biosynthetic process | 1 | | indole-containing compound metabolic process | 1 | | proteinogenic amino acid metabolic process | 1 | | amino acid catabolic process | 1 | | aromatic amino acid catabolic process | 1 | | indole-containing compound catabolic process | 1 | | proteinogenic amino acid catabolic process | 1 | | tetrapyrrole binding | 1 | | cation binding | 1 | | catalytic activity | 1 | | oxidoreductase activity | 1 | | intracellular anatomical structure | 1 | | cytoplasm | 1 | #### Experimentally-supported GO annotations GO terms backed by direct experimental evidence (ECO experimental codes) — 1 of 12 annotations. The rest are phylogenetic / computational / electronic (IEA). 1 experimentally-supported GO terms: | GO term | NS | Evidence | | --- | --- | --- | | [indoleamine 2,3-dioxygenase activity](https://amigo.geneontology.org/amigo/term/GO:0033754) | MF | direct assay | ### Protein interactions and networks #### STRING showing 15 of 1,788 interactions by confidence (×1000): | Protein A | Protein B | Partner UniProt | Score | | --- | --- | --- | --- | | IDO2 | TDO2 | P48775 | 953 | | IDO2 | IFNG | P01579 | 892 | | IDO2 | FOXP3 | Q9BZS1 | 829 | | IDO2 | CD4 | P01730 | 821 | | IDO2 | CTLA4 | P16410 | 820 | | IDO2 | TNFRSF18 | Q9Y5U5 | 807 | | IDO2 | TNFSF18 | Q9UNG2 | 803 | | IDO2 | CD80 | P33681 | 795 | | IDO2 | KYNU | Q16719 | 790 | | IDO2 | KMO | O15229 | 790 | | IDO2 | IL10 | P22301 | 776 | | IDO2 | TNF | P01375 | 771 | | IDO2 | CD274 | Q9NZQ7 | 754 | | IDO2 | IL2 | P01585 | 753 | | IDO2 | IL6 | P05231 | 747 | #### IntAct Human interaction partners of IDO2 in IntAct, one row per partner (best MIscore; records = supporting IntAct interaction records). 1 partners by confidence: | Partner | Interaction type | MIscore | Records | | --- | --- | --- | --- | | ATF1 | association | 0.350 | 1 | **BioGRID (16 interactions; top human partners by supporting records):** ATF1 (Affinity Capture-MS; 2 records), DPP8 (Affinity Capture-MS; 2 records), EME1 (Affinity Capture-MS; 2 records), KLF12 (Affinity Capture-MS; 2 records), NRN1 (Affinity Capture-MS; 2 records), BANP (Two-hybrid), ERICH5 (Affinity Capture-MS), FAM171A2 (Affinity Capture-MS), LZTS1 (Two-hybrid), SMARCA1 (Affinity Capture-MS), ULBP2 (Affinity Capture-MS) ## Disease & clinical ### Genetic variants **Variant evidence for IDO2:** [78 ClinVar records](#clinvar) (1 pathogenic / likely pathogenic); [2 GWAS associations](#gwas-assoc). Per-variant detail is on [Sugi Variant](https://sugi.bio/variant/gene/IDO2). #### ClinVar 78 variants total. Per-class counts are floors (≥ shown; pagination cap): | Classification | Count (floor) | | --- | --- | | Pathogenic | 1 | | Likely pathogenic | 0 | | Uncertain significance | 61 | | Likely benign | 4 | | Benign | 3 | #### Top pathogenic / likely-pathogenic (1) Showing all 1 pathogenic / likely-pathogenic ClinVar records, ranked by ClinVar review status (expert panel → multiple submitters → single submitter), then by number of submitting labs. | Variant ID | HGVS | Classification | Review | Submitters | | --- | --- | --- | --- | --- | | 4888407 | GRCh38/hg38 8p12-q11.1(chr8:35340961-46330497)x3 | Pathogenic | criteria provided, single submitter | 1 | #### Per-variant reference — Sugi Variant Explore IDO2's pathogenic and likely-pathogenic variants individually — each with its ClinVar classification and conditions, applied ACMG criteria (ClinGen expert panel, where curated), the calibrated in-silico predictors (AlphaMissense, REVEL, SaProt, conservation), gnomAD frequency, and the predictor-disagreement QC signal — on [Sugi Variant](https://sugi.bio/variant/gene/IDO2). #### SpliceAI Top 10 splice-impact sites by Δscore (adjacent positions with the same effect merged into one range; 29 predictions of 1,353): | Position(s) | Effect | Δscore | Sites | | --- | --- | --- | --- | | 8:39985477 | acceptor_gain | 1.0000 | | | 8:40013708 | donor_gain | 1.0000 | | | 8:40013714–40013715 | donor_loss | 1.0000 | 5 | | 8:40015245–40015246 | acceptor_loss | 1.0000 | 3 | | 8:39963601 | acceptor_gain | 0.9900 | | | 8:39989839–39989840 | donor_loss | 0.9900 | 6 | | 8:39991083 | donor_gain | 0.9900 | | | 8:40013563–40013564 | acceptor_loss | 0.9900 | 3 | | 8:40015245 | acceptor_loss | 0.9900 | 2 | | 8:39979187–39979188 | donor_loss | 0.9800 | 6 | #### AlphaMissense 411 missense substitutions predicted likely pathogenic (of 2,755 scored), across 142 residues. Top 20 hotspot residues, ranked by the number of likely-pathogenic substitutions (of those reachable by a single-nucleotide change), then by mean score: | Residue | Likely-pathogenic substitutions | Mean am_pathogenicity | Max am_pathogenicity | | --- | --- | --- | --- | | D291 | 8 | 0.883 | 0.924 | | E188 | 7 | 0.884 | 0.958 | | F40 | 7 | 0.878 | 0.981 | | F180 | 7 | 0.875 | 0.969 | | W56 | 7 | 0.823 | 0.956 | | W254 | 7 | 0.804 | 0.941 | | N150 | 7 | 0.792 | 0.938 | | W109 | 7 | 0.759 | 0.828 | | D145 | 7 | 0.728 | 0.774 | | H317 | 7 | 0.683 | 0.841 | | F243 | 6 | 0.828 | 0.932 | | F320 | 6 | 0.806 | 0.938 | | M313 | 6 | 0.775 | 0.835 | | Q283 | 6 | 0.764 | 0.925 | | H360 | 6 | 0.740 | 0.862 | | M309 | 6 | 0.720 | 0.806 | | S284 | 5 | 0.919 | 0.978 | | F305 | 5 | 0.872 | 0.943 | | F403 | 5 | 0.869 | 0.921 | | S280 | 5 | 0.868 | 0.967 | ### HPA cancer prognostics **RNA cancer specificity:** Not detected Human Protein Atlas survival analysis — favorable = higher expression predicts better survival. 1 prognostic cancer types: | Cancer | Prognostic | p-value | | --- | --- | --- | | Liver Hepatocellular Carcinoma (validation) | favorable | 0.000196 | ### Disease associations **OMIM:** gene `MIM:612129` | disease phenotypes: #### GWAS associations 2 associations: | Study | Trait | p-value | | --- | --- | --- | | GCST012310_22 | Schizophrenia x sex interaction | 2e-6 | | GCST012311_19 | Schizophrenia x sex interaction | 5e-6 | #### EFO canonical traits (from GWAS) 1 canonical traits: | EFO ID | Trait name | | --- | --- | | EFO:0008343 | sex interaction measurement | ## Drugs & pharmacology ### Drug and pharmacology data **Is drug target: yes** **ChEMBL targets (1):** CHEMBL3627587 (SINGLE PROTEIN) #### Molecules with ChEMBL bioactivity Phase ≥1, by development phase (incl. off-target/promiscuous compounds). Patent mentions across the top 20 by phase: **8,583** (via chembl_molecule>>patent_compound — counts attach to the compound, not the gene–compound relationship, so off-target/promiscuous molecules can dominate). 2 molecules by phase: | Molecule | Name | Phase | Patents | | --- | --- | --- | --- | | CHEMBL3545369 | [EPACADOSTAT](/atlas/drug/epacadostat/) | 3 | 6,316 | | CHEMBL1475252 | TENATOPRAZOLE | 2 | 2,267 | **PharmGKB:** 1 entry (CPIC guideline: no) #### GtoPdb / IUPHAR curated pharmacology *(IUPHAR/BPS Guide to Pharmacology — expert-curated)* **Target class:** enzyme — *Dioxygenases* **Most potent curated ligand interactions (2 total), top 2:** | Ligand | Action | Affinity | Parameter | | --- | --- | --- | --- | | example 184 [WO2014186035] | Inhibition | 6.0 | pIC50 | | tryptanthrin 5i | Inhibition | 5.74 | pIC50 | #### Binding affinities (BindingDB) 137 measured of 210 human assays (210 total across all organisms); most potent 50 below. *Values come from heterogeneous assays and are not directly comparable.* | Ligand | Measure | Value | Patent | | --- | --- | --- | --- | | CHEMBL5091825 | IC50 | 2.2 nM | | | CHEMBL4514196 | IC50 | 10 nM | | | CHEMBL4791168 | IC50 | 13 nM | | | CHEMBL4588805 | IC50 | 20 nM | | | CHEMBL4437046 | IC50 | 20 nM | | | Methyl 3-chloro-6,12-dioxo-6,12-dihydroindolo[2,1-b]quinazoline-8-carboxylate | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | N-(3-Chloro-6,12-dioxo-6,12-dihydroindolo[2,1-b]quinazolin-8-yl)acetamide | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 3-Chloro-6,12-dioxo-6,12-dihydroindolo[2,1-b]quinazoline-8-carboxamide | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 1,3-Difluoro-8-nitroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 3-Fluoro-8-(methylsulfonyl)indolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 8-Fluoro-3-((4-methylpiperazin-1-yl)methyl)indolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 3-Amino-8-nitroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | tert-Butyl (8-nitro-6,12-dioxo-6,12-dihydroindolo[2,1-b]quinazolin-3-yl)carbamate | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 1,3-Dichloro-N-methyl-6,12-dioxo-6,12-dihydroindolo[2,1-b]quinazoline-8-carboxamide | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 1,3-Dichloro-6,12-dioxoindolo[2,1-b]quinazoline-8-carboxamide | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 1,3-Dichloro-N,N-dimethyl-6,12-dioxo-6,12-dihydroindolo[2,1-b]quinazoline-8-carboxamide | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 4-Bromo-6,12-dioxo-6,12-dihydroindolo[2,1-b]quinazoline-8-carbonitrile | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 8-(Benzylthio)-3-fluoroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 3-Fluoro-6,12-dioxo-6,12-dihydroindolo[2,1-b]quinazoline-8-sulfonamide | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 3-Fluoro-4-methyl-8-nitroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 3-Fluoro-6-hydroxy-12-oxo-5,5a,6,12-tetrahydroindolo[2,1-b]quinazoline-8-carbonitrile | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 1,3-Difluoro-6-hydroxy-8-nitro-5a,6-dihydroindolo[2,1-b]quinazolin-12(5H)-one | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 4-bromo-3-fluoro-8-nitroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 4-Chloro-8-nitroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 1-Chloro-8-nitroindolo[2,1-b]quinazolin-12(5H)-one | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 1-fluoro-4-methyl-8-nitroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 4-Fluoro-8-nitroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 4-Bromo-8-nitroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 4-Bromo-8-fluoroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 4-Bromo-2-fluoro-8-nitroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | Synthesis of 4-bromo-6,12-dioxo-6,12-dihydroindolo[2,1-b]quinazoline-8-carbonitrile | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 2-Fluoro-4-methyl-8-nitroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 1,3-Dichloro-8-nitroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 3-Methoxy-9-nitropyrido[3',4':4,5]pyrimido[1,2-a]indole-5,11-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 8-Nitroindolo[2,1-b]quinazolin-12(6H)-one | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 3-bromo-8-nitroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 3-fluoro-8-methylsulfonyl-6-nitroso-5H-indolo[2,1-b]quinazolin-12-one | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | N-(2-aminoethyl)-3-chloro-6-nitroso-12-oxo-5H-indolo[2,1-b]quinazoline-8-carboxamide | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | N-(3-chloro-6,12-dioxoindolo[2,1-b]quinazolin-8-yl)-3-(3-methyldiazirin-3-yl)propanamide | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 3-chloro-6,12-dioxoindolo[2,1-b]quinazoline-8-sulfonamide | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | tert-butyl N-[2-[(3-chloro-6,12-dioxoindolo[2,1-b]quinazoline-8-carbonyl)amino]ethyl]carbamate | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 8-benzylsulfanyl-3-chloroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 3-fluoro-12-oxo-6H-indolo[2,1-b]quinazoline-8-carboxamide | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | 3-fluoro-8-methylsulfonyl-6H-indolo[2,1-b]quinazolin-12-one | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | N-(1,3-dichloro-6,12-dioxoindolo[2,1-b]quinazolin-8-yl)methanesulfonamide | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | Synthesis of 8-fluoro-3-(1H-imidazol-4-yl)indolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | Synthesis of 3-(aminomethyl)-8-fluoroindolo[2,1-b]quinazoline-6,12-dione Hydrochloride Salt | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | Synthesis of benzyl (Z)-((8-fluoro-6-(methoxyimino)-12-oxo-6,12-dihydroindolo[2,1-b]quinazolin-3-yl)methyl)carbamate | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | Synthesis of (Z)—N-((8-fluoro-6-(methoxyimino)-12-oxo-6,12-dihydroindolo[2,1-b]quinazolin-3-yl)methyl)acetamide | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | | Synthesis of 1-(aminomethyl)-8-fluoroindolo[2,1-b]quinazoline-6,12-dione | IC50 | 20 nM | [US-20250171452](https://patents.google.com/patent/US20250171452): TRYPTANTHRIN DERIVATIVES AND USES THEREOF | #### ChEMBL bioactivities 59 potent at pChembl≥5 of 129 total, top 50 by pChembl (potency: 10 = 0.1 nM, 6 = 1 µM). | pChembl | Type | Value | Unit | Molecule | | --- | --- | --- | --- | --- | | 6.95 | IC50 | 112 | nM | [CHEMBL5219888](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5219888/) | | 6.87 | IC50 | 134 | nM | [CHEMBL5220224](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5220224/) | | 6.84 | IC50 | 144 | nM | [CHEMBL5091825](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5091825/) | | 6.55 | IC50 | 280 | nM | [CHEMBL4472697](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL4472697/) | | 6.51 | IC50 | 310 | nM | [CHEMBL4791168](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL4791168/) | | 6.44 | IC50 | 362 | nM | [CHEMBL5085580](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5085580/) | | 6.41 | IC50 | 387 | nM | [CHEMBL5221035](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5221035/) | | 6.35 | IC50 | 450 | nM | [CHEMBL432537](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL432537/) | | 6.35 | IC50 | 446 | nM | [CHEMBL432537](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL432537/) | | 6.31 | IC50 | 490 | nM | [CHEMBL4514196](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL4514196/) | | 6.24 | IC50 | 575 | nM | [CHEMBL5221037](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5221037/) | | 6.23 | IC50 | 590 | nM | [CHEMBL4436582](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL4436582/) | | 6.20 | IC50 | 630 | nM | [EPACADOSTAT](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL3545369/) | | 6.16 | IC50 | 689 | nM | [CHEMBL5082481](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5082481/) | | 6.15 | IC50 | 710 | nM | [EPACADOSTAT](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL3545369/) | | 6.14 | IC50 | 726 | nM | [CHEMBL5090441](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5090441/) | | 6.10 | IC50 | 794 | nM | [CHEMBL5092513](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5092513/) | | 6.08 | IC50 | 830 | nM | [CHEMBL5091241](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5091241/) | | 6.06 | IC50 | 865 | nM | [CHEMBL5091415](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5091415/) | | 6.03 | IC50 | 930 | nM | [CHEMBL5091243](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5091243/) | | 6.02 | IC50 | 958 | nM | [CHEMBL5093816](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5093816/) | | 6.02 | IC50 | 947 | nM | [CHEMBL5091590](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5091590/) | | 6.02 | IC50 | 958 | nM | [CHEMBL5084150](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5084150/) | | 6.01 | Ki | 970 | nM | [CHEMBL432537](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL432537/) | | 5.97 | IC50 | 1081 | nM | [CHEMBL5078912](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5078912/) | | 5.93 | IC50 | 1174 | nM | [CHEMBL5078101](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5078101/) | | 5.93 | IC50 | 1171 | nM | [CHEMBL5088729](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5088729/) | | 5.92 | IC50 | 1200 | nM | [CHEMBL1098875](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL1098875/) | | 5.91 | IC50 | 1230 | nM | [CHEMBL1098875](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL1098875/) | | 5.75 | IC50 | 1800 | nM | [CHEMBL432537](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL432537/) | | 5.75 | IC50 | 1800 | nM | [TENATOPRAZOLE](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL1475252/) | | 5.73 | IC50 | 1870 | nM | [CHEMBL432537](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL432537/) | | 5.73 | IC50 | 1874 | nM | [CHEMBL5084767](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL5084767/) | | 5.71 | Ki | 1960 | nM | [CHEMBL4436480](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL4436480/) | | 5.50 | IC50 | 3200 | nM | [CHEMBL72165](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL72165/) | | 5.49 | IC50 | 3220 | nM | [CHEMBL72165](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL72165/) | | 5.46 | Ki | 3500 | nM | [CHEMBL1098875](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL1098875/) | | 5.46 | Ki | 3510 | nM | [CHEMBL1098875](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL1098875/) | | 5.45 | IC50 | 3580 | nM | [CHEMBL4436480](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL4436480/) | | 5.42 | IC50 | 3810 | nM | [CHEMBL4452150](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL4452150/) | | 5.37 | Ki | 4320 | nM | [CHEMBL4452150](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL4452150/) | | 5.30 | IC50 | 5000 | nM | [TRYPTANTHRIN](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL306946/) | | 5.30 | IC50 | 5010 | nM | [TRYPTANTHRIN](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL306946/) | | 5.25 | Ki | 5600 | nM | [CHEMBL72165](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL72165/) | | 5.25 | Ki | 5620 | nM | [CHEMBL72165](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL72165/) | | 5.21 | Ki | 6110 | nM | [CHEMBL4577825](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL4577825/) | | 5.20 | Ki | 6320 | nM | [CHEMBL4437046](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL4437046/) | | 5.12 | IC50 | 7600 | nM | [CHEMBL1098875](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL1098875/) | | 5.12 | IC50 | 7680 | nM | [CHEMBL1098875](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL1098875/) | | 5.09 | IC50 | 8200 | nM | [CHEMBL3087009](https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL3087009/) | #### PubChem BioAssay actives 48 with measured affinity, of 277 total; 35 most potent distinct compounds. *Largely complementary to BindingDB; screening values are coarse (µM, 4 dp), so sub-nM hits tie at the floor.* | Compound | Assay | Type | Value | Unit | | --- | --- | --- | --- | --- | | N-[[1-[2-[[4-[N'-[(3-bromophenyl)methyl]-N-hydroxycarbamimidoyl]-1,2,5-oxadiazol-3-yl]amino]ethyl]triazol-4-yl]methyl]pyridine-2-carboxamide | [1916992](https://pubchem.ncbi.nlm.nih.gov/bioassay/1916992/): Inhibition of human IDO2 | ic50 | 0.1120 | uM | | N-[[1-[2-[[4-[N'-(3-bromo-4-fluorophenyl)-N-hydroxycarbamimidoyl]-1,2,5-oxadiazol-3-yl]amino]ethyl]triazol-4-yl]methyl]-1H-pyrrole-2-carboxamide | [1916992](https://pubchem.ncbi.nlm.nih.gov/bioassay/1916992/): Inhibition of human IDO2 | ic50 | 0.1340 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-(2-hydroxyethoxymethyl)triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 0.1440 | uM | | N'-(3-bromo-4-fluorophenyl)-4-[2-[[ethoxy(ethyl)phosphoryl]amino]ethylamino]-N-hydroxy-1,2,5-oxadiazole-3-carboximidamide | [1609232](https://pubchem.ncbi.nlm.nih.gov/bioassay/1609232/): Inhibition of N-terminal His-tagged human IDO2 expressed in Escherichia coli expression system | ic50 | 0.2800 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[3-[[methoxy(methyl)phosphoryl]amino]propylamino]-1,2,5-oxadiazole-3-carboximidamide | [1728731](https://pubchem.ncbi.nlm.nih.gov/bioassay/1728731/): Inhibition of N-terminal 6His-tagged recombinant human IDO2 (15 to 420 residues) expressed in Escherichia coli using L-Trp as substrate by UV absorbance method | ic50 | 0.3100 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-(1-hydroxyethyl)triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 0.3620 | uM | | N-[[1-[2-[[4-[N'-(3-bromo-4-fluorophenyl)-N-hydroxycarbamimidoyl]-1,2,5-oxadiazol-3-yl]amino]ethyl]triazol-4-yl]methyl]pyridine-2-carboxamide | [1916992](https://pubchem.ncbi.nlm.nih.gov/bioassay/1916992/): Inhibition of human IDO2 | ic50 | 0.3870 | uM | | 8-nitroindolo[2,1-b]quinazoline-6,12-dione | [1332708](https://pubchem.ncbi.nlm.nih.gov/bioassay/1332708/): Inhibition of recombinant human IDO2 expressed in human U87MG cells assessed as reduction in kynurenine formation using L-tryptophan as substrate after 6 hrs by spectrophotometry | ic50 | 0.4500 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[[methoxy(methyl)phosphoryl]amino]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1609232](https://pubchem.ncbi.nlm.nih.gov/bioassay/1609232/): Inhibition of N-terminal His-tagged human IDO2 expressed in Escherichia coli expression system | ic50 | 0.4900 | uM | | N-[[1-[2-[[4-[N'-(3-bromophenyl)-N-hydroxycarbamimidoyl]-1,2,5-oxadiazol-3-yl]amino]ethyl]triazol-4-yl]methyl]pyridine-2-carboxamide | [1916992](https://pubchem.ncbi.nlm.nih.gov/bioassay/1916992/): Inhibition of human IDO2 | ic50 | 0.5750 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[4-[[methoxy(methyl)phosphoryl]amino]butylamino]-1,2,5-oxadiazole-3-carboximidamide | [1609232](https://pubchem.ncbi.nlm.nih.gov/bioassay/1609232/): Inhibition of N-terminal His-tagged human IDO2 expressed in Escherichia coli expression system | ic50 | 0.5900 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-(sulfamoylamino)ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [2032194](https://pubchem.ncbi.nlm.nih.gov/bioassay/2032194/): Inhibition of IDO2 (unknown origin) using D-Trp as substrate incubated for 1 hr | ic50 | 0.6300 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-(2-hydroxy-4-methylpentan-2-yl)triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 0.6890 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-(2-hydroxypropan-2-yl)triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 0.7260 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-(hydroxymethyl)triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 0.7940 | uM | | N'-(3-bromo-4-fluorophenyl)-4-[2-(4-butyltriazol-1-yl)ethylamino]-N-hydroxy-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 0.8300 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-(1-hydroxycyclohexyl)triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 0.8650 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-[1-(2-hydroxyethoxy)ethyl]triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 0.9300 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-(1-hydroxypropyl)triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 0.9470 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-(2-hydroxybutan-2-yl)triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 0.9580 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-(3-hydroxypropyl)triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 0.9580 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-(4-hydroxybutyl)triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 1.0810 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-[2-(2-hydroxyethoxy)propan-2-yl]triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 1.1710 | uM | | N'-(3-bromo-4-fluorophenyl)-N-hydroxy-4-[2-[4-(2-hydroxyethyl)triazol-1-yl]ethylamino]-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 1.1740 | uM | | 8-fluoroindolo[2,1-b]quinazoline-6,12-dione | [1332708](https://pubchem.ncbi.nlm.nih.gov/bioassay/1332708/): Inhibition of recombinant human IDO2 expressed in human U87MG cells assessed as reduction in kynurenine formation using L-tryptophan as substrate after 6 hrs by spectrophotometry | ic50 | 1.2000 | uM | | 5-methoxy-2-[(4-methoxy-3,5-dimethyl-2-pyridinyl)methylsulfinyl]-1H-imidazo[4,5-b]pyridine | [1917028](https://pubchem.ncbi.nlm.nih.gov/bioassay/1917028/): Inhibition of IDO2 (unknown origin) | ic50 | 1.8000 | uM | | N'-(3-bromo-4-fluorophenyl)-4-[2-(4-tert-butyltriazol-1-yl)ethylamino]-N-hydroxy-1,2,5-oxadiazole-3-carboximidamide | [1833933](https://pubchem.ncbi.nlm.nih.gov/bioassay/1833933/): Inhibition of IDO2 (unknown origin) assessed as reduction in kynurenine formation using L-tryptophan as substrate by methylene blue reagent based assay | ic50 | 1.8740 | uM | | 8-fluoro-2-(piperazin-1-ylmethyl)indolo[2,1-b]quinazoline-6,12-dione | [1558441](https://pubchem.ncbi.nlm.nih.gov/bioassay/1558441/): Uncompetitive inhibition of C-terminal His6-tagged human IDO2 (14 to 420 residues) expressed in Escherichia coli BL21 (DE3) assessed as inhibition constant using varying concentration of L-tryptophan as substrate by Dixon plot analysis | ki | 1.9600 | uM | | 8-bromoindolo[2,1-b]quinazoline-6,12-dione | [1332708](https://pubchem.ncbi.nlm.nih.gov/bioassay/1332708/): Inhibition of recombinant human IDO2 expressed in human U87MG cells assessed as reduction in kynurenine formation using L-tryptophan as substrate after 6 hrs by spectrophotometry | ic50 | 3.2000 | uM | | 2-[(dimethylamino)methyl]-8-fluoroindolo[2,1-b]quinazoline-6,12-dione | [1558435](https://pubchem.ncbi.nlm.nih.gov/bioassay/1558435/): Inhibition of human IDO2 transfected in human U87MG cells assessed as reduction in kynurenine production using L-tryptophan as substrate incubated with for 6 hrs | ic50 | 3.8100 | uM | | indolo[2,1-b]quinazoline-6,12-dione | [1332708](https://pubchem.ncbi.nlm.nih.gov/bioassay/1332708/): Inhibition of recombinant human IDO2 expressed in human U87MG cells assessed as reduction in kynurenine formation using L-tryptophan as substrate after 6 hrs by spectrophotometry | ic50 | 5.0000 | uM | | tert-butyl 4-[(8-fluoro-6,12-dioxoindolo[2,1-b]quinazolin-2-yl)methyl]piperazine-1-carboxylate | [1558441](https://pubchem.ncbi.nlm.nih.gov/bioassay/1558441/): Uncompetitive inhibition of C-terminal His6-tagged human IDO2 (14 to 420 residues) expressed in Escherichia coli BL21 (DE3) assessed as inhibition constant using varying concentration of L-tryptophan as substrate by Dixon plot analysis | ki | 6.1100 | uM | | 8-fluoro-2-[(4-methylpiperazin-1-yl)methyl]indolo[2,1-b]quinazoline-6,12-dione | [1558440](https://pubchem.ncbi.nlm.nih.gov/bioassay/1558440/): Mixed competitive inhibition of C-terminal His6-tagged human IDO2 (14 to 420 residues) expressed in Escherichia coli BL21 (DE3) assessed as inhibition constant using varying concentration of L-tryptophan as substrate by Dixon plot analysis | ki | 6.3200 | uM | | 2,8-difluoroindolo[2,1-b]quinazoline-6,12-dione | [1332708](https://pubchem.ncbi.nlm.nih.gov/bioassay/1332708/): Inhibition of recombinant human IDO2 expressed in human U87MG cells assessed as reduction in kynurenine formation using L-tryptophan as substrate after 6 hrs by spectrophotometry | ic50 | 8.2000 | uM | | 2-[(4-methylpiperazin-1-yl)methyl]indolo[2,1-b]quinazoline-6,12-dione | [1558442](https://pubchem.ncbi.nlm.nih.gov/bioassay/1558442/): Mixed uncompetitive inhibition of C-terminal His6-tagged human IDO2 (14 to 420 residues) expressed in Escherichia coli BL21 (DE3) assessed as inhibition constant using varying concentration of L-tryptophan as substrate by Dixon plot analysis | ki | 8.8500 | uM | #### CTD chemical–gene interactions 15 total (human), top 15 by PubMed support. | Chemical | Actions (top 5) | PubMed papers | | --- | --- | --- | | Benzo(a)pyrene | affects methylation | 2 | | Lipopolysaccharides | affects cotreatment, increases expression, affects response to substance | 2 | | Tetrachlorodibenzodioxin | decreases reaction, increases expression | 2 | | salinomycin | decreases expression | 1 | | S-(1,2-dichlorovinyl)cysteine | affects response to substance, increases expression, affects cotreatment | 1 | | indeno(1,2,3-cd)pyrene | increases expression | 1 | | 3'-methoxy-4'-nitroflavone | decreases reaction, increases expression | 1 | | abrine | increases expression | 1 | | CL 075 | increases expression | 1 | | (+)-JQ1 compound | decreases expression | 1 | | Poly I-C | increases expression | 1 | | Valproic Acid | increases methylation | 1 | | Antirheumatic Agents | decreases expression | 1 | | Okadaic Acid | decreases expression | 1 | | Permethrin | increases expression | 1 | #### ChEMBL screening assays 46 unique, capped per target: 46 binding Representative assays (with source publication via chembl_document): | Assay ID | Type | Description | Source paper | | --- | --- | --- | --- | | CHEMBL3630806 | Binding | Inhibition of human IDO2 | Challenges and Opportunities in the Discovery of New Therapeutics Targeting the Kynurenine Pathway. — \*J Med Chem\* | #### Clinical trials (associated diseases) Via MONDO — disease-level, not drug-specific. #### Predicted chemistry — Sugi Predict The predicted patent-compound landscape for IDO2 across ~30M SureChEMBL compounds — [explore on Sugi Predict](https://sugi.bio/predict/target/IDO2/). ## Related Atlas pages *No linked Atlas pages yet — the cross-entity mesh grows as the corpus expands.*