Composition of phenolic compounds and antioxidant attributes estimated with in vitro and biochemical models for Cyclea gracillima Diels

Cyclea gracillima Diels is a Taiwanese native medicinal herb. However, there is almost no relevant report for its functional activity in the past. In this study, antioxidant attributes of the ethanol and hot water extracts for the herb were measured with in vitro models: scavenging 2, 2-diphenyl-1-(2, 4, 6-trinitrophenyl) hydrazyl radicals, Trolox equivalent antioxidant capacity, reducing power and chelating ferrous ion as well as biochemical models: inhibition of human low density lipoprotein oxidation, inhibition of human erythrocyte hemolysis and scavenging oxygen radicals in human blood. Composition and content of flavonoids and phenolic acids in these extracts were analyzed as well. Results showed that these extracts with high polyphenol levels presented remarkable antioxidant effects in all assays, especially for the ethanol extract. Six phenolic acids (the major ones: ferulic acid, sinapic acid and syringic acid) and 12 flavonoids (the major ones: narigenin, myricetin, naringin and apigenin) could be determined in these extracts.