Modelling and optimization of quercetin extraction and biological activity of quercetin-rich red onion skin extract from Southeastern Serbia.

SAVIC-GAJIC, IVANA M.; SAVIC, IVAN M.; NIKOLIC, VESNA D.

Quercetin is a bioactive compound that has the beneficial effect on human health because of its antioxidant, antiinflammatory, antimicrobial, antiviral, antiallergic, cardioprotective, vasodilatatory and anticancer activity. Due to high content of quercetin in the red onion skin, the aim of this study was modelling and optimization of quercetin extraction using central composite design. The extraction time (5-60 min), ethanol concentration (5-100%) and liquid-to-solid ratio (10-80 cm3.g-1) were varied to estimate their effect on the yield of quercetin. The optimal extraction conditions were obtained for 47.3 min using 80% ethanol adjusted to pH 1.0 at a liquid-to-solid ratio of 63.9 cm3.g-1. In the extract obtained under these conditions, the quercetin content was found to be 28.5 g.kg-1 of the dry plant material, while the content of total flavonoids and polyphenols was found to be 30.1 g rutin equivalent per kilogram of the dried extract and 53.82 g gallic acid equivalent per kilogram of the dried extract, respectively. The studies of the antioxidant activity indicated that quercetin had a higher activity than the extract enriched with quercetin. Quercetin was also isolated from the extract by the liquid-liquid extraction technique and structurally characterized using instrumental methods.

QUERCETIN; ONIONS; ANTI-inflammatory agents; GALLIC acid; LIQUID-liquid extraction

Journal of Food & Nutrition Research, 2018, Vol 57, Issue 1, p15

1336-8672

Academic Journal