New aporphine alkaloids and cytotoxic constituents from the root of Illigera luzonensis

Abstract

Illigera luzonensis Merr. (Hernandiaceae) is a scandent shrub distributed in Philippines, Ryukyus, and southern Taiwan [1]. Aporphine alkaloids, benzylisoquinoline alkaloids, lignans, and their derivatives are widely distributed in plants of the family Hernandiaceae [2], [3]. Many of these compounds exhibit various biological activities, such as cytotoxic, anti-platelet aggregation, vasorelaxing, antioxidant, and antiplasmodial activities [2], [3]. In our studies on the anti-cancer constituents of Formosan plants, many species have been screened for in vitro cytotoxic activity, and I. luzonensis has been found to be an active species. Five new aporphine alkaloids, (S)-N-butyrylcaaverine (1), (S)-N-propionylcaaverine (2), (S)-N-acetylcaaverine (3), (6aR,7R)-N-butyrylnorushinsunine (4), and (6aR,7R,E)-N-(but-2-enoyl)norushinsunine (5), and fifteen known compounds have been isolated and identified from the root of I. luzonensis. Among the isolates, (–)-yatein exhibited cytotoxicities, with IC50 values of 0.81, 0.20, and 0.59µg/mL, respectively, against DLD-1, CCRF-CEM, and HL-60 cell lines. (6aR,7R)-N-Butyrylnorushinsunine (4) exhibited cytotoxicities, with IC50 values of 5.45 and 3.66µg/mL, respectively, against DLD-1 and IMR-32 cell lines. In addition, N-phenethylcinnamamide exhibited cytotoxicities, with IC50 values of 6.84 and 5.79µg/mL, respectively, against DLD-1 and CCRF-CEM cell lines.