Onoceranoid-type triterpenoids from Lansium domesticum.

A rare class of onoceranoid-type triterpenoids, represented by lamesticumin A (1), the ethanolysis product of lamesticumin A (2), lamesticumins B-F (3-7), lansic acid 3-ethyl ester (8), and ethyl lansiolate (9), along with four known analogues were isolated from the twigs of Lansium domesticum. Their structures were elucidated on the basis of extensive spectroscopic analysis, and the absolute configuration of C-21 in compound 7 was assigned by using Snatzke's method. Compounds 1-9 exhibited moderate antibacterial activity against Gram-positive bacteria.