Novel cucurbitane triterpenoids and anti-cholinesterase activities of constituents from Momordica charantia L

The C-19 epimers of 5beta,19-epoxycucurbita-6,23(E),25(26)-triene-3f,19-diol (1) and 5/,19-epoxy-25-methoxycucurbita-6,23-diene-3beta,19-diol (2) along with (19R,23E)-5beta,19-epoxy-19-methoxycucurbita-6,23,25-trien-3beta-ol (3), (23E)-5beta,19-epoxycucurbita-6,23-diene-3beta,25-diol (4), ligballinol (5), charantin (6) and momordicoside K(7) were isolated from the green fruits of Momordica charantia. The (S)-epimers of 1 and 2 are the first reports in nature. The acetyl- and butyryl-cholinesterase inhibitory activities of the isolated compounds were evaluated, and 5 showed the highest activity of these compounds against butyrylcholinesterase (IC50 = 32.20 microM) with a reversible and non-competitive inhibition mode.