Characterization and Bioactive Potential of Secondary Metabolites Isolated from Piper sarmentosum Roxb.

Piper sarmentosum Roxb. (Piperaceae) is a traditional medicinal plant in South-East Asian countries. The chemical investigation of leaves from this species resulted in the isolation of three previously not described compounds, namely 4″-(3-hydroxy-3-methylglutaroyl)-2″- β -D-glucopyranosyl vitexin ( 1 ), kadukoside ( 2 ), and 6- O - trans-p- coumaroyl-D-glucono-1,4-lactone ( 3 ), together with 31 known compounds. Of these known compounds, 21 compounds were isolated for the first time from P. sarmentosum . The structures were established by 1D and 2D NMR techniques and HR-ESI-MS analyses. The compounds were evaluated for their anthelmintic ( Caenorhabditis elegans ), antifungal ( Botrytis cinerea , Septoria tritici and Phytophthora infestans ), antibacterial ( Aliivibrio fischeri ) and cytotoxic (PC-3 and HT-29 human cancer cells lines) activities. Methyl-3-(4-methoxyphenyl)propionate ( 8 ), isoasarone ( 12 ), and trans -asarone ( 15 ) demonstrated anthelmintic activity with IC 50 values between 0.9 and 2.04 mM. Kadukoside ( 2 ) was most active against S. tritici with IC 50 at 5.0 µM and also induced 94% inhibition of P. infestans growth at 125 µM. Trans -asarone ( 15 ), piperolactam A ( 23 ), and dehydroformouregine ( 24 ) displayed a dose-dependent effect against B. cinerea from 1.5 to 125 µM up to more than 80% inhibition. Paprazine ( 19 ), cepharadione A ( 21 ) and piperolactam A ( 23 ) inhibited bacterial growth by more than 85% at 100 µM. Only mild cytotoxic effects were observed.