Extraction, purification by macrospores resin and in vitro antioxidant activity of flavonoids from Moringa oliefera leaves

Abstract To promote extraction of flavonoids compounds from Moringa oliefera leaves (MOL) by ultrasound-assisted extraction, Box behken desing as a kind of response surface methodology was utilized. Moreover, five macrospores resins were used to investigate the kinetics of purification of flavonoids from the MOL extract. As results, the optimal conditions for maximizing flavonoids extraction were determined as follows: ratio of aqueous ethanol solution to material 52 mL/g, extraction time 43 min and extraction temperature 76 °C. Nevertheless, AB-8 resin was the suitable resin for purification of flavonoids with the following conditions: initial flavonoids concentration 20 mg/mL, eluting solvent 70% aqueous ethanol solution and 1.5 mL/min eluting flow rate. Moreover, five flavonoids (rutin, kaempferol acetyl glycoside, quercetin-3-glucoside, quercetin-3-acetyl-glucoside and kaempferol 3-glucoside) were identified by HPLC-ESI-MS. Regarding to antioxidant activity purified flavonoids, the results showed that the scavenging activity against 2,2-diphenyl-1-picrylhydrazyl free radicals was 85.99% at a concentration of 100 μg/mL, while the scavenging activity against 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) radicals was 84.72% at 50 μg/mL. The results suggest that the flavonoids from MOL can be used in the development of functional foods.