New triterpenoid alkaloid cholinesterase inhibitors from Buxus hyrcana

Three new triterpenoid alkaloids, (+)-N-benzoylbuxahyrcanine [(20S)-3β-benzoylamino-20-dimethylaminobux-9(11)-ene-10α-ol] (1), (+)-N-tigloylbuxahyrcanine [(20S)-20-(dimethylamino)-3β-(2′-methyl-2′butenoylamino) bux-9(11)-en-10α-ol] (2), and (+)-N-isobutyroylbuxahyrcanine [(20S)-20-(dimethylamino)3β-(2′-methylpropanoyl)bux-9(11)- en-10α-ol] (3), have been isolated from the leaf extracts of Buxus hyrcana collected in Iran. Their structures were determined using spectroscopic methods. The structures of compounds 1 and 2 were unambiguously confirmed by single-crystal X-ray diffraction techniques. Compounds 1-3 were evaluated for their acetylcholinesterase and butyrylcholinesterase inhibitory activities, and compound 2 was found to be active against both enzymes.