CYTOTOXIC AND ANTIBACTERIAL DIHYDROCHALCONES FROM PIPER ADUNCUM

Bioactivity-guided fractionation of a CH2Cl2 extract from the leaves o f Piper aduncum afforded three new dihydrochalcones, piperaduncins A [ 3], B [4], and C [5], as well as two known dihydrochalcones, 2',6'-dih ydroxy-4'-methoxydihydrochalcon [1] and 2',6',4-trihydroxy-4'-methoxyd ihydrochalcone [2] (asebogenin), together with sakuranetin, anodendroi c acid methyl ester, and the carotenoid lutein. The structures of the isolates were elucidated by spectroscopic methods, mainly 1D- and 2D n mr spectroscopy. The proposed stereochemistry for compound 4 was deduc ed by NOESY spectroscopy and the corresponding energy minimum was esta blished by molecular modelling calculations and translated into a 3D s tructure.