Two New Norlignans and a New Lignanamide from Peperomia tetraphylla

Two new cyclobutane-type norlignans, methyl rel- (1R, 2S, 3S) -2- (7-methoxy-1, 3-benzodioxol-5-yl) -3- (2, 4, 5-trimethoxyphenyl) cyclobutanecarboxylate (1), and methyl rel- (1R, 2R, 3S) -2- (7-methoxy-1, 3-benzodioxol-5-yl) -3- (2, 4, 5-trimethoxyphenyl) cyclobutanecarboxylate (2), and a new lignanamide, 3-hydroxy-N-2- (4-hydroxyphenyl) ethyl-α-4- (2-N-[2- (4-hydroxyphenyl) ethylcarbamoylethenyl) -3-methoxyphenoxy]-4-methoxycinnamamide 4, 8″-ether (3), along with five known amides, 4-8, were obtained from the whole plant of Peperomia tetraphylla. Their structures were elucidated mainly by the analysis of NMR and MS data. The new compounds 1-3 and the known compound 4 were tested for their cytotoxic activities against the HepG2 (human hepatocarcinoma), A549 (human lung cancer), and HeLa (human cervical cancer) cell lines. Compound 4 showed significant cytotoxicity against HepG2 cell lines with an IC (50) value of 9. 4 ± 1. 0 μM.