Optimization of the Extraction Technology of Total Flavonoids and in Vitro Antioxidant Activity of Extract from Persimmon Leaves

Objective:To optimize the reflux extraction technology of the total flavonoids from persimmon leaves and evaluate the antioxidant activity of the extract.Methods:The best conditions of extracting total flavonoids from persimmon leaves by reflux extraction were screened by orthogonal and response surface method based on single factor experiments with the yield of total flavonoids as index.Meanwhile, the antioxidant capacity was measured by scavenging of DPPH·and hydroxyl free radical, with V_C as the control.Results:The results showed that optimal process obtained by orthogonal test were as follows:Ethanol concentration was 40%, extraction temperature was 50℃, ratio of raw material to liquid was 1:50 (g/mL) and extraction time was 120 min, the yield of total flavonoids was 18.11 mg/g. The results showed that optimal process obtained by response surface were ethanol concentration was 50%, extraction temperature was 50℃, ratio of raw material to liquid was 1:60 (g/mL) and extraction time was 120 min, the yield of total flavonoids was 18.21 mg/g, the total flavonoids content extracted by the response surface methodology was increased by 0.55% compared with orthogonal test.From an economic perspective, low ethanol concentration and low feed-liquid ratio could save cost and energy consumption, and the extraction rate of the two was almost the same. Therefore, it was more suitable for the extraction process of total flavonoids from persimmon leaves.Under the optimal extraction process of orthogonal test, IC₅₀ of total flavonoids from persimmon leaves to DPPH free radical, hydroxyl radical and uperoxide free radical were 8.0, 18.0, 76.0 μg/mL, respectively. The results of in vitro antioxidant test showed that the scavenging effects of total flavonoids extract from persimmon leaves to DPPH·and hydroxyl radical were better than that of vitamin C solution at the same concentration. And superoxide free radical was lower than that of ascorbic acid. Conclusion:The orthogonal method to optimize the extraction of persimmon leaf flavonoids technology was rational and feasible, economical and economical, it could be applied to industrial production, and the extract exhibited strong antioxidant activity.