Bioassay-guided isolation and identification of anticancer and antioxidant compounds from Gynostemma pentaphyllum (Thunb.) Makino.

Gynostemma pentaphyllum (Thunb.) Makino is a medicinal and edible plant in China whose buds and leaves are used for making a popular kind of tea drink. The anticancer and antioxidant properties of the ethyl acetate (EA) and n -butanol ( n -Bu) fractions provide a basis for conducting experiments for isolation and identification of key compounds that may be responsible for the aforementioned properties of G. pentaphyllum . Four compounds were isolated from the two fractions using ODS packing column, silica gel column, polyamide column, Sephadex LH-20 gel column and HPLC. With the aid of 1 H, 13 C NMR and mass spectrometry, they were identified as 3,4-dihydroxy phenyl- O -β-d-glucoside, gypenoside XLVI, gypenoside L and ginsenoside Rd. 3,4-Dihydroxy phenyl- O -β-d-glucoside showed the strongest DPPH (97.23%) and ABTS (101.37%) scavenging effect and ferric ion reducing power (FRAP value 0.8846), which may be closely related to the hydrogen atoms of phenolic hydroxyls. Gypenoside L and ginsenoside Rd displayed the highest inhibition of tumor cell proliferation of A549 and MCF-7 cell lines, which had to do with the chemical structure of the compounds bearing glycosylated parts and free hydroxyls at the 20th or 21st carbon atom of dammarane-type saponin.