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| Names | |
|---|---|
| Other names sandaracopimaric acid | |
| Identifiers | |
| CAS Number | |
| ECHA InfoCard | 100.163.144 
|
| PubChem CID | |
| CompTox Dashboard (EPA) | |
| Properties | |
| Chemical formula | C20H30O2 |
| Molar mass | 302.45 g/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa).
 Y verify (what is ?)
Infobox references
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Isopimaric acid (IPA) is a toxin which acts as a large conductance Ca-activated K channel (BK channel) opener.
Source
IPA originates from many sorts of trees, especially conifers (Wilson et al. 1996).
Chemistry
IPA is one of the members of the resin acid group which is a tricyclic diterpene (Wilson et al. 1996). It has a condensed three-ring structure, one carboxyl-group and a (conjugated) double bond (Hwang, 1996).
Target
IPA acts on the large-conductance calcium activated K+ channels ( BK channels) (Kaczorowski et al. 1996, Imaizumi et al. 2002).
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)(Kaczorowski et al. 1996, Imaizumi et al. 2002). 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.
Therapeutic use
This toxin may be of value in the treatment of urinary bladder overactivity, stroke treatment and in problems with the hyperactivity of (vascular) smooth muscle cells (Imaizumi et al. 2002).
References
- Imaizumi Y, S. 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): 836-846 PMID 12237330
- C. M. J. Råbergh, H. L., J. E. Eriksson and B. Isomaa (1999). "The resin acids dehydroabietic acid and isopimaric acid release calcium from intracellular stores in rainbow trout hepatocytes." Aquatic Toxicology 46(1): 55-65
- Hwang, J. S. (1996). Modern solder technology for competitive electronics manufacturing Electronic packaging and interconnection series McGraw-Hill
- Kaczorowski GJ, K. H., Leonard RJ, McManus OB, Garcia ML (1996). "High-conductance calcium-activated potassium channels; structure, pharmacology, and function." Bioenergenetics and biomembranes 28(3): 255-267 PMID 8807400
- Rabergh, 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 hepatocytes from rainbow trout (Oncorhynchus mykiss)." Aquatic Toxicology 23(3): 169-180 DOI: 10.1016/0166-445X(92)90050-W
- Wilson AE, M. E., Mohn WW (1996). "Isolation and characterization of isopimaric acid-degrading bacteria from a sequencing batch reactor." Applied and Environmental Microbiology 62(9): 3146-3151 PMID 8795202
