Composition of phenolic compounds and antioxidant attributes of Cyclea gracillima Diels extracts

Jau-Tien Lin ^a, Shih-Chuan Liu ^b, Li-Chun Kuo ^b, Deng-Jye Yang ^c,*

^a Department of Medical Applied Chemistry, Chung Shan Medical University, and Department of Medical Education, Chung Shan Medical University Hospital, 110, Section 1, Jianguo North Road, Taichung 40201, Taiwan

^b Department of Health Diet and Industry Management, Chung Shan Medical University, and Department of Nutrition, Chung Shan Medical University Hospital, 110, Section 1, Jianguo North Road, Taichung 40201, Taiwan

^c Department of Nutrition, China Medical University, 91, Hsueh-Shih Road, Taichung 40402, Taiwan

Cyclea gracillima Diels is a Taiwanese native medicinal herb. However, there are currently few relevant reports on its biochemical activity. In this study, the antioxidant attributes of the ethanol and hot water extracts of this herb were assayed using in vitro models, including the following: 2,2-diphenyl-1-(2,4,6-trinitrophenyl)-hydrazyl radical scavenging, Trolox equivalent antioxidant capacity, reducing power, and chelating ferrous ions. The following biochemical models were also assayed: inhibition of human low density lipoprotein oxidation, inhibition of human erythrocyte hemolysis, and scavenging oxygen radicals in human blood. The composition and content of flavonoids and phenolic acids in these extracts were also analyzed. The results showed that these extracts with high polyphenol levels presented remarkable antioxidant effects in all assays, especially when extracted with ethanol. Six phenolic acids (mainly ferulic acid, sinapic acid, and syringic acid) and 12 flavonoids (mainly narigenin, myricetin, naringin, and apigenin) were found in these extracts.