Isolation and Characterization of Potential Acetylcholinesterase Inhibiting Peptides from Conus mustelinus Venom Extracts

Abstract

The neurotoxic effect of Conus peptides is usually attributed to its ability to interfere with the function of receptors and channels. The ability of conopeptides to inhibit acetylcholinesterase (AChE) has not been extensively evaluated; hence this study employed the use of Conus mustelinus venom to evaluate its inhibition of acetylcholinesterase. The crude venom extract and the purified peptides, designated as CMF1P1 (eluted at 20.916% B90), CMF1P2 (eluted at 21.461% B90), and CMF1P3 (eluted at 22.99% B90), were investigated through Ellman’s Spectrophotometric Method and Mus musculus (mice) bioassay for in vitro and in vivo inhibition of AChE activities. The crude venom extract exhibited significant AChE inhibition (p<0.05) both in vitro (55 to 63%) and in vivo (14.10%). Significant acetylcholinesterase inhibition (p<0.05) was also observed in vitro using 5 nmol (48.57% for CMF1P1, 34.28% for CMF1P2, and 43.92% for CMF1P3) and 10 nmol (45.35% for CMF1P1, 33.58% for CMF1P2, and 26.57% for CMF1P3) peptide. An attempt to estimate AChE activity in vivo, however, showed no evidence of AChE inhibition by any of the peptide fractions isolated. Only CMF1P2 was subjected to kinetic analysis and was found to exhibit competitive inhibition with Ki of 0.02267 mM. The study of AChE inhibitors can lead to understanding enzyme-targeting peptides that might be present in the venom of cone snails, and in the future may aid in the development of safer and more efficient drugs.