Vedecký časopis

Journal of Food and Nutrition Research
Online First Articles

Savic-Gajic, I. M. – Savic, I. M. – Nikolic, V. D.
Modeling and optimization of quercetin extraction and biological activity of quercetin-rich red onion skin extract from Southeastern Serbia

Ivana M. Savic-Gajic, Department of Organic-technological Sciences, Faculty of Technology, University of Nis, Bulevar oslobodjenja 124, 16000 Leskovac, Serbia. Tel.: +381 16 247 203; fax: +381 16 242 859, e-mail: vana.savic@yahoo.com

Received 27 June 2017; accepted 2 November 2017

Súhrn: Quercetin is a bioactive compound that has the beneficial effect to the human health because of its antioxidant, anti-inflammatory, antimicrobial, antiviral, antiallergic, cardioprotective, vasodilator and anticancer activity. Due to high content of quercetin in the red onion skin, the aim of paper was modeling 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, expressed as volume centimetres per gram) were varied to estimate their effect on the quercetin yield. The optimal extraction conditions were obtained for 47.3 min using 80% ethanol adjusted to pH 1.0 at the 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 flavonoid and polyphenol 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 antioxidant activity indicated that quercetin has the 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 the instrumental methods.

Kľúčové slová: central composite design; total flavonoid; total polyphenol; antioxidant activity