Nutritional Composition, Antioxidant Capacity and Protective Activity against DNA Damage of Yaowang Tea (Potentilla glabra var. mandshurica) Endemic to Qinling Mountain

Objective: In order to provide evidence to scientific exploitation of Yaowang tea endemic to Qinling mountain, nutritional value, health benefits and their material basis of Yaowang tea were investigated. Methods: Chemical composition as well as nutrients and bioactive constituents profile of Yaowang tea was analyzed by high performance liquid chromatography and plasma emission spectroscopy, etc. Antioxidant activity was determined by free radical scavenging experiment, and protective effect on DNA damage was studied by agarose gel eletrophoresis. Results: Quercitrin, quercetin and gallic acid were determined in Yaowang tea, and their contents were 0.17%±0.00%, 0.29%±0.01% and 0.28%±0.01%, respectively. Content of essential amino acids was 65.65±1.97 mg/g. Contents of manganese, selenium and magnesium were 1.19±0.04, 0.43±0.02 and 2.80±0.05 mg/kg, respectively, while heavy metals (e.g., arsenic, cadmium, mercury, lead) did not exceed the national permissible limit. Yaowang tea extract exhibited the ability to scavenge DPPH and ABTS radicals with EC₅₀ values of 0.0704 and 0.3810 mg/mL, respectively. Protective activity of Yaowang tea extract against DNA damage was in dose-dependent manner. Protective effect of 1×10⁻² mg/mL Yaowang tea extract against DNA damage was higher than that of ascorbic acid. Conclusion: Yaowang tea contains several bioactive constituents, and it is safe in respect to heavy metals. Yaowang tea possesses in vitro antioxidant activity and protective effect against DNA damage.