Pamoic acid

Pamoic acid^[1]^[2]

IUPAC name 4-[(3-Carboxy-2-hydroxynaphthalen-1-yl)methyl]-3-hydroxynaphthalene-2-carboxylic acid
Other names Embonic acid
Identifiers
CAS number	130-85-8^Y
PubChem	8546
ChemSpider	8228^Y
UNII	7RRQ8QZ38N^Y
EC number	204-998-0
MeSH	Pamoic+acid
ChEBI	CHEBI:50186
ChEMBL	CHEMBL177880^Y
RTECS number	QL2180000
Beilstein Reference	901319
Jmol-3D images	Image 1 Image 2
SMILES OC(=O)C1=CC2=CC=CC=C2C(CC2=C(O)C(=CC3=CC=CC=C23)C(O)=O)=C1O C1=CC=C2C(=C1)C=C(C(=C2CC3=C(C(=CC4=CC=CC=C43)C(=O)O)O)O)C(=O)O
InChI InChI=1S/C23H16O6/c24-20-16(14-7-3-1-5-12(14)9-18(20)22(26)27)11-17-15-8-4-2-6-13(15)10-19(21(17)25)23(28)29/h1-10,24-25H,11H2,(H,26,27)(H,28,29)^Y Key: WLJNZVDCPSBLRP-UHFFFAOYSA-N^Y
Properties
Molecular formula	C₂₃H₁₆O₆
Molar mass	388.37 g mol⁻¹
Exact mass	388.094688244 g mol^-1
Melting point	≥300 °C
log P	6.169
Acidity (pK_a)	2.675
Hazards
EU classification	Xi
R-phrases	R36/37/38
S-phrases	S26 S36
Main hazards	Causes skin irritation Causes serious eye irritation May cause respiratory irritation
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Pamoic acid, also called embonic acid, is a naphthoic acid derivative. Salts and esters of pamoic acid are known as pamoates or embonates. It can be prepared by the reaction of 2-hydroxy-3-naphthoic acid with formaldehyde. In pharmacology, the salt form of pamoic acid (pamoate ion) can be used as a counter ion of a drug compound to increase the solubility of the drug in water.^[3] The presence of multiple oxygen atoms enables significant hydrogen bonding to occur. Hydrogen bonds facilitate the dissolution of compounds in water.

It was demonstrated that pamoic acid has agonist activity for the orphan G protein-coupled receptor GPR35 by which it activates ERK and beta-arrestin2, and causes antinociceptive activity. Although (like other drug salts) it has been considered an inactive compound by the FDA, these recent data suggest that its use may be reexamined.

References

^ Merck Index, 12th Edition, 7136.
^ Zhao, P.; Sharir, H.; Kapur, A.; Cowan, A.; Geller, E. B.; Adler, M. W.; Seltzman, H. H.; Reggio, P. H. et al. (2010). "Targeting of the Orphan Receptor GPR35 by Pamoic Acid: A Potent Activator of Extracellular Signal-Regulated Kinase and -Arrestin2 with Antinociceptive Activity". Molecular Pharmacology 78 (4): 560–8. doi:10.1124/mol.110.066746. PMC 2981393. PMID 20826425. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2981393.
^ Saesmaa, T; Tötterman, AM (1990). "Dissolution studies on ampicillin embonate and amoxycillin embonate". Journal of pharmaceutical and biomedical analysis 8 (1): 61–5. PMID 2102266.

External links

Neubig, Richard R (2010). "Mind your salts: when the inactive constituent isn't". Molecular Pharmacology 78 (4): 558–9. doi:10.1124/mol.110.067645. PMID 20651116.