Rose Bengal Free Acid

Summary

Rose Bengal Free Acid (CHEMBL1208422) is an approved small-molecule fluorochrome targeting KCNJ4; indicated across 8 conditions including cutaneous melanoma and melanoma.

At a glance

• Status: Approved (max clinical phase 4)
• Modality: Small molecule
• Targets: 1 (KCNJ4)
• Indications: 8 conditions
• Clinical trials: 5
• Chemistry: 973.7 Da · C20H4Cl4I4O5

Identifiers

Drug identity and classification

Field	Value
ChEMBL ID	CHEMBL1208422
Name	Rose Bengal Free Acid
Type	Small molecule
Max phase	4
FDA approved	no
PubChem CID	25474
ChEBI	CHEBI:87202
Molecular formula	C20H4Cl4I4O5
Molecular weight	973.7
InChIKey	VDNLFJGJEQUWRB-UHFFFAOYSA-N

SMILES: C1=C2C(=C3C=C(C(=O)C(=C3OC2=C(C(=C1I)O)I)I)I)C4=C(C(=C(C(=C4Cl)Cl)Cl)Cl)C(=O)O

IUPAC name: 2,3,4,5-tetrachloro-6-(3-hydroxy-2,4,5,7-tetraiodo-6-oxoxanthen-9-yl)benzoic acid

ChEBI definition: A xanthene dye that is fluorescein bearing bromine substituents at positions 2’, 4’, 5’ and 7’ (on the xanthene ring) and iodine substituents at position 2, 3, 4, and 5 (on the phenyl ring). The dipotassium salt is the biological stain ‘rose bengal’.

Pharmacological roles (ChEBI): fluorochrome.

Also known as: NSC-10463, Rose bengal, Rose bengal free acid, SID29215482, SID29215483, SID174006187, ROSE BENGAL FREE ACID, Rose Bengal, ROSE BENGAL SODIUM

Parent form; salt/anhydrous children: CHEMBL594741, CHEMBL2359093, CHEMBL3989461, CHEMBL3989792

Patent coverage: 264 distinct patent families (476 SureChEMBL compound mentions), from 2 matched compound structure(s). One matched structure accounts for 375 (79%) of the total. Mentions count patents naming the compound (not distinct inventions), so promiscuous / reference molecules inflate the mention figure — families are the dedup metric.

Targets

Targets

Primary targets (GtoPdb curated mechanism): the Cancer dependency column is the DepMap CRISPR fitness signal (% of screened cell lines dependent on the target).

Gene	Target	Action	pAffinity	Cancer dependency	UniProt
KCNJ4	Kir2.3	Antagonist		4.4%	P48050

Broader ChEMBL bioactivity targets: 18 (assay-derived). Sample: Tyrosyl-DNA phosphodiesterase 1, Microtubule-associated protein tau, Nuclear receptor ROR-gamma, Prelamin-A/C, ATP-dependent DNA helicase Q1, RecQ-like DNA helicase BLM, Inositol monophosphatase 1, 4’-phosphopantetheinyl transferase ffp, Ferritin light chain, 15-hydroxyprostaglandin dehydrogenase [NAD(+)].

Bioactivity

ChEMBL activities: 14 potent at pChembl ≥ 5 of 34 total. Top 30 by potency (10 = 0.1 nM, 6 = 1 µM):

Target	pChembl	Type	Value	Unit	Activity ID
LMNA	6.4	Potency	398.1	nM	CHEMBL_ACT_3653159
MEN1	6.15	Potency	707.9	nM	CHEMBL_ACT_3616424
MEN1	6.15	Potency	707.9	nM	CHEMBL_ACT_4589302
TDP1	6.1	Potency	794.3	nM	CHEMBL_ACT_3931797
MEN1	6.05	Potency	891.3	nM	CHEMBL_ACT_4591480
TDP1	5.9	Potency	1259	nM	CHEMBL_ACT_3931988
MAPT	5.8	Potency	1585	nM	CHEMBL_ACT_3963807
MEN1	5.55	Potency	2818	nM	CHEMBL_ACT_3634743
THRB	5.55	Potency	2818	nM	CHEMBL_ACT_4018043
MAPT	5.5	Potency	3162	nM	CHEMBL_ACT_4054136
THRB	5.4	Potency	3981	nM	CHEMBL_ACT_4018130
THRB	5.3	Potency	5012	nM	CHEMBL_ACT_3656471
THRB	5.2	Potency	6310	nM	CHEMBL_ACT_3656497
P51450	5	Potency	10000	nM	CHEMBL_ACT_4113494

Target pathways

Aggregated over 1 target gene(s): KCNJ4.

Top Reactome pathways

15 total, by targets touching each:

Pathway	Targets	Genes
Neurotransmitter receptors and postsynaptic signal transmission	1	KCNJ4
Transmission across Chemical Synapses	1	KCNJ4
Neuronal System	1	KCNJ4
Activation of G protein gated Potassium channels	1	KCNJ4
Classical Kir channels	1	KCNJ4
G protein gated Potassium channels	1	KCNJ4
Inwardly rectifying K+ channels	1	KCNJ4
Potassium Channels	1	KCNJ4
Muscle contraction	1	KCNJ4
Phase 4 - resting membrane potential	1	KCNJ4
Cardiac conduction	1	KCNJ4
GABA receptor activation	1	KCNJ4
GABA B receptor activation	1	KCNJ4
Activation of GABAB receptors	1	KCNJ4
Inhibition of voltage gated Ca2+ channels via Gbeta/gamma subunits	1	KCNJ4

Dominant GO biological processes

GO term	Targets
potassium ion transport	1
regulation of monoatomic ion transmembrane transport	1
potassium ion import across plasma membrane	1
monoatomic ion transport	1
monoatomic ion transmembrane transport	1

Indications & clinical

Indications

8 indications (0 at ChEMBL trial phase 4). Phase below is the highest clinical-trial phase recorded for this drug against each disease — not the molecule’s overall approval status (that is in the Summary).

Indication	Trial phase	MONDO	EFO
cutaneous melanoma	3	MONDO:0005012	EFO:0000389
melanoma	3	MONDO:0005105	EFO:0000756
nicotine dependence	3	MONDO:0008575	EFO:0003768
Acanthamoeba keratitis	3	MONDO:0005629	EFO:0007126
keratitis	3	MONDO:0003085	EFO:0009449
psoriasis	2	MONDO:0005083	EFO:0000676
neuroendocrine neoplasm	1	MONDO:0019496	EFO:1001901
breast neoplasm	1	MONDO:0021100	MONDO:0007254

Clinical trials

Total trials: 5.

Phase distribution

Phase	Trials
PHASE3	3
PHASE2	1
Not specified	1

Top trials by phase / activity

NCT	Phase	Status	Title
NCT06271772	PHASE3	ACTIVE_NOT_RECRUITING	Rose Bengal Electromagnetic Activation With Green Light for Infection Reduction II
NCT04837664	PHASE3	UNKNOWN	Curcumin; Rose Bengal; Denture Stomatitis
NCT05110001	PHASE3	COMPLETED	Rose Bengal Electromagnetic Activation With Green Light for Infection Reduction
NCT02322086	PHASE2	COMPLETED	A Phase 2 Study of Cellular and Immunologic Changes in the Skin of Subjects Receiving PH-10
NCT03031899	Not specified	COMPLETED	Comparison or Rose Bengal and Toluidine Blue Staining for Lesion Detection Efficacy

Clinical evidence (CIViC)

No CIViC predictive evidence (expected for non-precision-medicine drugs).

Pharmacology

Pharmacogenomics

No PharmGKB pharmacogenomic data curated for this drug.

Related molecules

Related molecules

No competitor molecules sharing a primary target (ChEMBL phase ≥2 or PubChem drug-class).