Optimization purification characterization of quercetin extracted from onion skin radish leaves and fenugreek stems

Abstract

Quercetin was isolated from crude extract of vegetable wastes like onion skin, radish leaves and fenugreek stems by three extraction methods such as Microwave Assisted Extraction, Soxhlet Extraction and Maceration with the help of three different Ethanol oncentrations (30 %, 60 % and 90 %). Phytochemical analysis such as total phenolic content (TPC), total lavonoid content (TFC) and antioxidant activity of crude extract was also conducted spectrophotometrically. Quantification of Quercetin in extracts was done by HPLC at 254 nm wavelength and purification by using column chromatography and thin layer chromatography. Microwave extraction exhibited higher extraction yield of 18.93 %, 35.33 % and 32.13 % for onion skin, radish leaves and fenugreek stems extract with 30% Ethanol respectively. TPC, TFC and antioxidant activity were also higher for microwave extraction than that of conventional extraction. The maximum TPC was found as 519.25, 177.5 and 149.75 mg GAE/g for onion skin, radish leaves and fenugreek stems extract with 90 % Ethanol respectively. Best results of TFC were 120.75, 55.09 and 43.46 mg QE/g for onion skin, radish leaves and fenugreek stems extract with 90 % Ethanol at 300W respectively. Free Radical Scavenging Activity (FRSA) of onion skin extract ranging from 42.22 to 84.68 for which minimum IC50 value of 37.75 µg/ml was recorded, FRSA of radish leaves extract ranging from 34.64 to 78.70 % for which IC50 value of 65.73 µg/ml was calculated and FRSA of fenugreek stems extract ranging from 37.6 to 77.99 % for which IC50 value of 63.01 µg/ml was calculated. Quercetin yield for onion skin extract, radish leave extract and fenugreek stem extract was higher for microwave extraction at 400 W with 90 % Ethanol i.e. 14.44, 3.44 and 0.54 µg/g respectively. Purified Quercetin from onion skin gave the higher yield (170 mg, 3.4 %) than radish leaves and fenugreek stems. Antioxidant activity of purified Quercetin was compared with Ascorbic acid, from the results it can be concluded tha