Further New Gypenosides from Jiaogulan (Gynostemma pentaphyllum)

Jiaogulan (Gynostemma pentaphyllum) has been widely used as a herbal tea, dietary supplement, and vegetable in Asian countries. In this study, six new gypenosides (1-6) were isolated from the aerial parts of G. pentaphyllum. Their molecular structures were elucidated through spectroscopic analysis and acid hydrolysis. Gypenosides 1 and 2 represented the first example of a dammar-21-O- glucopyranoside without any unsaturated functional group and a dammar-3-O-glucopyranosyl-25-Oglucopyranoside without any cyclization in the side chain, respectively. In addition, gypenosides 5 and 6 exhibited the first example of a 24-hydroperoxy-19-oxo-dammarane triterpenoid and 19-oxo-dammar-21-O-glucopyranoside with a saturated side chain, respectively. Gypenoside 5 was found to possess protein tyrosine phosphatase 1B inhibitory activity, with an IC50 value of 8.2 +/- 0.9 mu M, and moderate cytotoxicity against human breast cancer cells MCF7, MCF7/ADR, and MDA-MB-231, with IC50 values ranging from 10.5 +/- 1.4 to 14.2 +/- 2.6 mu M. The outcome of the study provided crucial information regarding the structural diversity and health benefits of gypenosides.