Anti-inflammatory neolignans from Piper kadsura.

Two new neolignans, piperkadsin A (1) and piperkadsin B (2), as well as 11 known neolignans, three known alkaloids, the highly oxygenated compound (+)-crotepoxide, and stigmasterol were isolated from the stems of Piper kadsura. The anti-inflammatory activities of these compounds were evaluated. Compounds 1, 2, futoquinol (3), piperlactam S (4), and N-p-coumaroyl tyramine (5) showed potent inhibition of PMA-induced ROS production in human polymorphonuclear neutrophils with IC(50) values 4.3 +/-1.0, 12.2 +/- 3.2, 13.1 +/- 5.3, 7.0 +/- 1.9, and 8.4 +/- 1.3 microM, respectively.