Discovery of Lignans from the Herbs of Peperomia heyneana with Inhibitory Activities on BPH-1 Cells

Chemical investigation on the whole herb of <i>Peperomia heyneana</i> Miq. resulted in the isolation of six lignans, including two previously undescribed compounds, named peperomianan A and B (<b>1</b>-<b>2</b>), and four known compounds, 1,2-cyclobutanedicarboxylic acid (<b>3</b>), (+)-medioresinol (<b>4</b>), (+)-pinoresinol (<b>5</b>), and (+)-yangambin (<b>6</b>). Their structures were established by extensive spectroscopic analyses. The absolute configuration of compound <b>1</b> was determined by comparison of the experimental and calculated electronic circular dichroism (ECD) spectra. Subsequently, the effects of all isolates on BPH-1 cells were evaluated in vitro by MTT assay.