Secolignans with antiangiogenic activities from Peperomia dindygulensis.

Two new secolignans, peperomins G and H (1 and 2, resp.), were isolated from the whole plant of Peperomia dindygulensis, together with five known secolignans, peperomin A (3), peperomin E (4), peperomin B (5), 2,3-trans-2-methyl-3-{(3-hydroxy-4,5-dimethoxyphenyl)[5-methoxy-3,4-(methylenedioxy) phenyl]methyl}butyrolactone (6), 2,3-cis-2-(hydroxymethyl)-3-{bis[5-methoxy-3,4-(methylenedioxy) phenyl]methyl}butyrolactone (7). Their structures and configurations were elucidated by spectroscopic methods including 2D-NMR techniques. Antiangiogenic effects of all compounds were evaluated using human umbilical vein endothelial cells (HUVEC) proliferation and tube-formation tests, with compounds 4 and 5 being active in the bioassay. Compounds 4 and 5 induced obvious cell toxicity to HUVEC with IC(50) values of 1.64 +/- 0.19 and 8.44 +/- 0.4 mu m, respectively. Compounds 4 and 5 also exhibited significant HUVEC tube formation-inhibiting activity with IC(50) values of 3.13 +/- 0.09 and 6.24 +/- 0.12 mu m, respectively.