Pleiocarpumlignan A, a new dineolignan from Piper pleiocarpum Chang ex Tseng.

The investigation of chemical constituents from the whole plants Piper pleiocarpum Chang ex Tseng resulted in the isolation of one new dineolignan, pleiocarpumlignan A (1), along with one known benzoate derivative, trans-2,3-diacetoxy-1-[(benzoy1oxy)methyl]-cyclohexa-4,6-diene (2), and two known neolignans (3-4) as (±)-trans-dehydrodiisoeugenol (3), (7R,8R,3'S)-△^8'-3',6'-dihydro-3'-methoxy-3,4-methylenedioxy-6'-oxo-8,3',7,O,4'-lignan (4). Their structures were elucidated through extensive spectroscopic analyses including 1D, 2D NMR, HR-ESI-MS, and by comparison with the literature. All compounds (1-4) were firstly isolated from Piper pleiocarpum Chang ex Tseng. The ¹³C NMR spectra of 2 were completely assigned for the first time. Cytotoxic activities of these isolated compounds against five human cancer cell lines (including A-549, SMMC-7721, HL-60, MCF-7, and SW-480) were evaluated.