Optimization of Quercetin Extraction from Green Tea (Camellia sinensis) Using Central Composite Design, and the Pharmacological Activity of the Extract

I. M. Savic, V. D. Nikolic, I. M. Savic-Gajic, L. B. Nikolic, K. Moder and M. Hopkins

Abstract
The aim of this paper was to optimize an extraction procedure of quercetin from green tea using central composite design. Extraction time, ethanol concentration, and solid to liquid ratio were selected as the independent variables, while quercetin yield was defined as a response. The impact of factors and their interactions on the quercetin yield was studied based on the results of ANOVA test. The extraction time of 58.5 min, ethanol concentration of 94.7 % (v/v), and solid to liquid ratio of 1:19.4 (m/v) were found as the optimal conditions. The experimental confirmation of the proposed optimal conditions indicated that there was a good agreement between the experimental and predicted values. In addition to quercetin, the presence of 17 bioactive compounds was confirmed in the green tea extract using mass spectrometry method. Antioxidant, antimicrobial and antitumor activity of the optimal extract was determined using DPPH assay, disk diffusion method, and MTT assay, respectively.

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Keywords
optimisation, quercetin extraction, green tea, central composite design, MS analysis