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Isopimaric acid

Names
IUPAC name (13S)-Pimara-7,15-dien-18-oic acid
Systematic IUPAC name (1R,4aR,4bS,7S,10aR)-7-Ethenyl-1,4a,7-trimethyl-1,2,3,4,4a,4b,5,6,7,8,10,10a-dodecahydrophenanthrene-1-carboxylic acid
Identifiers
CAS Number	5835-26-7
3D model (JSmol)	Interactive image
ChEBI	CHEBI:6039
ChEMBL	ChEMBL512164
ChemSpider	390596
ECHA InfoCard	100.163.144
KEGG	C09118
PubChem CID	442048
UNII	1E37K85HHK
CompTox Dashboard (EPA)	DTXSID9022233
InChI InChI=1S/C20H30O2/c1-5-18(2)12-9-15-14(13-18)7-8-16-19(15,3)10-6-11-20(16,4)17(21)22/h5,7,15-16H,1,6,8-13H2,2-4H3,(H,21,22)/t15-,16+,18-,19+,20+/m0/s1Key: MXYATHGRPJZBNA-KRFUXDQASA-N InChI=1/C20H30O2/c1-5-18(2)12-9-15-14(13-18)7-8-16-19(15,3)10-6-11-20(16,4)17(21)22/h5,7,15-16H,1,6,8-13H2,2-4H3,(H,21,22)/t15-,16+,18-,19+,20+/m0/s1Key: MXYATHGRPJZBNA-KRFUXDQABR
SMILES 12(C)(C(O)=O)CCC1(C)3()C(C(C=C)(C)CC3)=CC2
Properties
Chemical formula	C20H30O2
Molar mass	302.458 g·mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). N verify (what is  ?) Infobox references

Isopimaric acid (IPA) is a toxin which acts as a large conductance Ca-activated K channel (BK channel) opener.

Sources

IPA originates from many sorts of trees, especially conifers.

Chemistry

IPA is one of the members of the resin acid group and it is a tricyclic diterpene.

Target

IPA acts on the large-conductance calcium activated K+ channels (BK channels).

Mode of action

BK channels are formed by α subunits and accessory β subunits arranged in tetramers. The α subunit forms the ion conduction pore and the β subunit contributes to channel gating. IPA interaction with the BK channel enhances Ca and / or voltage sensitivity of the α subunit of BK channels without affecting the channel conductance. In this state BK channels can still be inhibited by one of their inhibitors, like charybdotoxin (CTX). Opening of the BK channel leads to an increased K-efflux which hyperpolarizes the resting membrane potential, reducing the excitability of the cell in which the BK-channel is expressed.

Toxicity

Studies on rainbow trout hepatocytes have shown that IPA increases intracellular calcium release, leading to a disturbance in the calcium homeostasis. This could be important in the possible toxicity of the toxin.

See also

• Pimaric acid

Notes

1. ^ Wilson, AE; Moore, ER; Mohn, WW (1996). "Isolation and characterization of isopimaric acid-degrading bacteria from a sequencing batch reactor". Applied and Environmental Microbiology. 62 (9): 3146–51. Bibcode:1996ApEnM..62.3146W. doi:10.1128/aem.62.9.3146-3151.1996. PMC 168108. PMID 8795202.
2. ^ Kaczorowski, GJ; Knaus, HG; Leonard, RJ; McManus, OB; Garcia, ML (1996). "High-conductance calcium-activated potassium channels; structure, pharmacology, and function". Journal of Bioenergetics and Biomembranes. 28 (3): 255–67. doi:10.1007/bf02110699. PMID 8807400. S2CID 25857254.
3. ^ Imaizumi, Y; Sakamoto, K; Yamada, A; Hotta, A; Ohya, S; Muraki, K; Uchiyama, M; Ohwada, T (2002). "Molecular basis of pimarane compounds as novel activators of large-conductance Ca(2+)-activated K(+) channel alpha-subunit". Molecular Pharmacology. 62 (4): 836–46. doi:10.1124/mol.62.4.836. PMID 12237330.

References

• Råbergh, Christina M.I.; Lilius, Henrik; Eriksson, John E.; Isomaa, Boris (1999). "The resin acids dehydroabietic acid and isopimaric acid release calcium from intracellular stores in rainbow trout hepatocytes". Aquatic Toxicology. 46 (1): 55–65. Bibcode:1999AqTox..46...55R. doi:10.1016/S0166-445X(98)00115-5.
• Råbergh, C.M.I.; Isomaa, B.; Eriksson, J.E. (1992). "The resin acids dehydroabietic acid and isopimaric acid inhibit bile acid uptake and perturb potassium transport in isolated hepatocvtes from rainbow trout (Oncorhynchus mykiss)". Aquatic Toxicology. 23 (3–4): 169–179. Bibcode:1992AqTox..23..169R. doi:10.1016/0166-445X(92)90050-W.

• Ion channel toxins
• Carboxylic acids
• Diterpenes
• Non-protein ion channel toxins
• Potassium channel openers
• Phenanthrenes
• Vinyl compounds