Studies On Ultrasonic Extraction And Antioxidant Activities Of Flavonoids From Scutellaria Baicalensis Georgi

Scutellaria baicalensis Georgi is a traditional chinese medicine, and was listed in the first section of the 2005's edition of "Pharmacopoeia of the People's Republic of China". It has the functions of dispelling wind-heat to reduce fever and detoxifcating. The flavonoids from S. baicalensis which have important pharmacological and hygienical functions, are widely used in pharmacy. In this paper, we studied the extraction and antioxidant activities of flavonoids which were extracted from S. baicalensis. The main conclusions were showed as follow:1.The optimum extraction condition of flavonoids from S. baicalensis was obtained by single factor experiments. The result was as follows:solid to liquid ratio of 1:40(g:mL), ethanol concentration of 70%, ultrasonic time of 40 min, ultrasonic temperature of 60℃2.Response surface methodology was used to optimize the extraction processing of S. baicalensis flavonoids according to central composite design principle based on the single factor experimental results. Through screening of factors and levels, and the analysis of cross-interaction among factors, the optimal extraction conditions for S.baicalensis flavonoids were solid to liquid ratio of 1:50(g:mL), extraction temperature of 66℃, extraction time of 41 min, and alcohol concentration of 58%. The extraction rate of flavonoids was 2.25% under the optimal extraction conditions.3.The result of ultrasonic extraction of S.baicalensis flavonoids:The S. baicalensis power(200 g) were extracted under the condition [alcohol concentration of 58%,extraction temperature of 66℃,solid to liquid ratio of 1:50(g:mL) and extraction time of 41 min]. The primary extract was evaporated to dryness in vacuo. The crude ethanol extract was suspended in water and subjected to sequential liquid-liquid extraction with petroleum ether, chloroform, ethyl acetate and n-butanol. The results were crude ethanol extract 103.4 g, petroleum ether fraction 1.31 g, chloroform fraction 2.05 g, ethyl acetate fraction 2.5 g, n-butanol 14.5 g, and aqueous fraction 80.27 g.4.The antioxidant activities were evaluated by the ABTS+ and DPPH·scaveng-ing capacity. The antioxidant activity of ethyl acetate fraction was the highest which was almost the same as VE. The others were lower than the ethyl acetate fraction. The results of DPPH·scavenging were consistent with ABTS+ scavenging. It has been shown by experimentation that the antioxidant activity of ethyl acetate fraction was close to VE.