Probl Hig Epidemiol 2018, 99(3): 245-251pl

The effect of a solvent on the antioxidant properties of green tea (Camellia sinensis L.) extracts

Anna Nowak ^1/, Anna Maciejewska ^2/, Wiktoria Duchnik ^1/, Katarzyna Florkowska ^1/, Adam Klimowicz ^1/

1/ Katedra i Zakład Chemii Kosmetycznej i Farmaceutycznej, Pomorski Uniwersytet Medyczny w Szczecinie
2/ absolwentka Kosmetologii, Pomorski Uniwersytet Medyczny w Szczecinie

Summary
Introduction. Green tea (Camellia sinensis L.) is one of the most popular beverages in the world. As a source of antioxidant properties it is used for prevention of cardiovascular; neoplastic, and neurodegenerative (e.g. Parkinson´s and Alzheimer´s) diseases. It also features antidiabetic, anti-aging and anti-inflammatory properties.
Aim. To assess the antioxidant activity of alcoholic and aqueous extracts of dried leaves of green tea.
Materials & methods. The raw material consisted of dried leaves of green tea purchased in a local hypermarket. Its antioxidant activity was determined by means of the DPPH, ABTS, and FRAP methods, while the total polyphenols content was tested by the Folin-Ciocalteu method. The extracts for analysis were subjected to ultrasound for 15, 30, and 60 minutes. The extraction solvents used were 70% (v/v) and 96% (v/v) ethanol, 70% (v/v) and 99.5% (v/v) methanol, and water. Also evaluated were the antioxidant activity and the total polyphenols content of the tea infusions, depending on the infusion time (5, 15, or 30 minutes) at temperatures of 80 and 100°C.
Results. The highest antioxidant activity, measured by the DPPH method, was observed in extracts prepared in concentrated methanol over a period of 30 minutes. In the case of the ABTS method, the highest antioxidant activity was found in the test samples in 70% (v/v) methanol extracted for a period of 60 minutes. The most effective green tea infusions, measured by the FRAP method, were those made as a result of infusion for 30 minutes at a temperature of 80°C. The highest total polyphenols content was observed in aqueous infusions extracted using an ultrasonic bath for 60 minutes.
Conclusion. Extracts from dry green tea leaves are characterized by high antioxidant activity, which suggests the possibility of using these plants as raw materials in the cosmetics and pharmaceutical industries.

Key words:  green tea, antioxidant activity, plant extracts