Abstract
Cashew nut shell liquid (CNSL) has been used in traditional medicine for the treatment of a wide variety of pathophysiological conditions. To further define the mechanism of CNSL action, we investigated the effect of cashew nut shell extract (CNSE) on two matrix metalloproteinases, MMP-2/gelatinase A and MMP-9/gelatinase B, which are known to have critical roles in several disease states. We observed that the major constituent of CNSE, anacardic acid, markedly inhibited the gelatinase activity of 3T3-L1 cells. Our gelatin zymography studies on these two secreted gelatinases, present in the conditioned media from 3T3-L1 cells, established that anacardic acid directly inhibited the catalytic activities of both MMP-2 and MMP-9. Our docking studies suggested that anacardic acid binds into the MMP-2/9 active site, with the carboxylate group of anacardic acid chelating the catalytic zinc ion and forming a hydrogen bond to a key catalytic glutamate side chain and the C15 aliphatic group being accommodated within the relatively large S1′ pocket of these gelatinases. In agreement with the docking results, our fluorescence-based studies on the recombinant MMP-2 catalytic core domain demonstrated that anacardic acid directly inhibits substrate peptide cleavage in a dose-dependent manner, with an IC50 of 11.11 μM. In addition, our gelatinase zymography and fluorescence data confirmed that the cardol-cardanol mixture, salicylic acid, and aspirin, all of which lack key functional groups present in anacardic acid, are much weaker MMP-2/MMP-9 inhibitors. Our results provide the first evidence for inhibition of gelatinase catalytic activity by anacardic acid, providing a novel template for drug discovery and a molecular mechanism potentially involved in CNSL therapeutic action.
Footnotes
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The online version of this article (available at http://molpharm.aspetjournals.org) contains supplemental material.
This work was supported in part by Amrita University Research, the National Institutes of Health National Cancer Institute [Grant CA92584]; the National Institutes of Heath National Institute of Arthritis and Musculoskeletal and Skin Diseases [Grant AR059968]; and the Council of Scientific and Industrial Research and University Grants Commission (junior research fellowships to A.O. and J.N., respectively).
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
ABBREVIATIONS:
- CNSL
- cashew nut shell liquid
- HAT
- histone acetyltransferase
- MMP
- matrix metalloproteinase
- PE
- petroleum ether
- CNSE
- cashew nut shell extract
- HPLC
- high-performance liquid chromatography
- DMSO
- dimethyl sulfoxide
- DMEM
- Dulbecco's modified Eagle's medium
- MTT
- 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide
- SA
- salicylic acid
- PDB
- Protein Data Bank
- Mca
- (7-methoxycoumarinyl) a cetyl
- Dap
- [3(2-dinitrophenyl 2,3-diaminopropionyl].
- Received March 29, 2012.
- Accepted June 28, 2012.
- Copyright © 2012 The American Society for Pharmacology and Experimental Therapeutics
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