Study On Flavonoids Extraction, Separation From Lotus Leaf And Its Antioxidant

Lotus leaf is a sort of crude plant material for medicine and food. Flavonoids have health functions, such as antioxidation, fighting against senium, curing cardiovascular diseases, reducing blood fat and so on. In this paper, the extraction, separation, purification and structural identfication of flavonoids from lotus leaf were studied; Meanwhile the biological antioxidant of ethanol extraction of lotus leaf were researched.The main results of this paper were obtained as follows:1. Three methods(natural airing, roast, low temperature freeze-drying) were made on fresh lotus leaf ,the result showed:the colour of lotus leaf drying by low temperature was aqua,flavor was faint scent, taste was purity. The effect(colour, flavor, taste and content of flavonoids) drying by roast was subaltern. The effect drying by natural airing was the worst.2. The four key factors, which affect the extraction ratio of flavonoids from lotus leaf, were reviewed by single factor test, the optimal process conditions were obtained as follows: ethanol concentration 70%, extracting temperature 80℃, ratio of solid to liquid 1:30, extracting duration 2h; Under this conditions, lotus leaves were extracted three times, the most content of flavonoids were come out, which reached 36.19 mg/g.3. The ethanol extraction of lotus leaf were isolated and purified respectively by there different methods, the separating effect of high speed counter current chromatogram was the best,the effect of sephadex LH-20 gelcolumn chromatogram was subaltern , the effect of silicagel column chromatogram was the worst.With analyzing of thin layer chromatogram and color reaction,high pure flavonoid compounds were obtained from ethanol extraction of lotus leaf by high speed counter current chromatogram.4. Results with qualitative identify revealed that the ethanol extraction of lotus leaf mostly had flavonoid compounds,the content of alkaloid was few. It showed that the main functional(antioxidant)component of the ethanol extraction of lotus leaf were flavonoid compounds.The ethanol extraction of lotus leaf had obvious antioxidant activities, of which provide theory base of health functions of lotus leaf.5. The antioxidant activities of lotus leaf ethanol extraction were investigated. Results revealed that the ethanol extraction of lotus leaf had obvious antioxidant activities;could remarkable delaying autooxidation of lard. The antioxidant activities of lotus leaf ethanol extraction were increasing with extraction concentration improving.