Monoterpene lactones from the seeds of Nephelium lappaceum.

Dichloromethane extracts of the seeds of Nephelium lappaceum afforded two new diastereomeric monoterpene lactones, 1 and 2, and the known butenolide siphonodin (3), as well as kaempferol 3-O-beta-D-glucopyranoside-7-O-alpha-L-rhamnopyranoside. Compounds 1 and 2 represent a new monoterpene skeleton, and their structures were elucidated by extensive 1D and 2D NMR spectral data interpretation. Antimicrobial testing was carried out on 1 and 2 against a panel of bacteria and fungi.