Extraction of total flavonoids from Hibiscus manihot L.flower and their antioxidant activity in vitro

This test used solvent extraction of flavonoids from Hibiscus manihot L.flower by using response surface methodology to optimize the extraction conditions, and the antioxidant activity in vitro was evaluated by artificial free radicals in detail. The optimal extraction conditions were as follows: the volume fraction of ethanol 75%, ratio of liquid to solid 30 ∶ 1, extraction temperature 60 ℃, extraction time 2.5 h. Under this optimum conditions, the actual yield of flavonoids was 126.67 mg/g dry weight.The total flavonoids in Hibiscus manihot L.flower had a good scavenging effect on superoxide anion radical with a 50%inhibition concentration ( IC₅₀) of 207.1 μg/m L and which was better than that of ascorbic acid.The extracts also had a good scavenging effect on DPPH radical and hydroxyl radical with IC₅₀ of 37.5 μg/m L and 754.7 μg/m L respectively, which were a little lower than that of ascorbic acid.The extract also showed a certain reduction ability and it was 83% times as much as that of ascorbic acid.In general, total flavonoids from Hibiscus manihot L.flower had a high antioxidant activity.