ACAT inhibition of alkamides identified in the fruits of Piper nigrum

Alkamide (5) and five known alkamides were isolated from MeOH extracts of the fruits of Piper nigum. Their structures were elucidated as retrofractamide A, pipercide, piperchabamide D, pellitorin, dehydroretrofractamide C and dehydropipernonaline by spectroscopic analyses (1H, 13C NMR and ESI-MS). These compounds moderately inhibited cholesterol esterification of ACAT enzyme from rat liver and HepG2 cells.