Polyphenolic Profiles and Antioxidant Activities of Smilax glabra Roxb. and S. china L.

Smilax glabra Roxb. and S. china L. are widely consumed by Chinese as functional foods and in folk medicine for their medicinal properties. The present study by liquid chromatography-electrospray ionization-mass spectrometry revealed that the major polyphenolics in S. china were astilbin, isoastilbin, engelitin, isoengelitin and resveratrol, which were similar to those in S. glabra, however the total and individual concentrations in general were higher in S. china L. except isoanstilbin. The total phenolic content (TPC) of S. china was nearly twice as high as that of S. glabra. Extract of S. china also showed significantly stronger antioxidant activities as measured by the DPPH and ABTS methods (3 and 8 fold, respectively). The strong antioxidant activities of S. china and S. glabra extracts and the individual flavones isolated from these two Smilax species suggest that the flavones are the major antioxidant components. Higher TPC and stronger antioxidant activities of S. china L. extract also suggest the existence of additional polyphenolic antioxidants, such as resveratrol. The present finding helps further development of S. china L. based functional foods and herbal supplements.