Prenylflavonols from the leaves of Macaranga sampsonii.

Four novel prenylflavonols, macaranones A-D (1-4), were isolated from the leaves of Macaranga sampsonii. Their structures were elucidated on the basis of spectroscopic data. Macaranones C (3) and D (4) represent first two examples of flavonols having an unusual peltogynoid skeleton which is formed from a 2'-geranylflavonol by cyclization between 3-OH and C-1'' of the 2'-geranyl substituent of the flavonol. Compounds 1-4 were evaluated for the cytotoxicity against several human cancer cell lines.