Study of antioxidant properties of green tea extract

introduction Oxidation processes are among the chief reasons behind the deterioration of product life and quality during storage and application. It should be emphasized that oxidation is not only responsible for quality deterioration of products but also affect human organism, triggering a number of illnesses and increasing the rate of aging. In order to eliminate or reduce the oxidation rates, the food, pharmaceutical and cosmetic industries use antioxidants. Those agents capture the free radicals and bind them in low reactive, stable systems. On the one hand, the presence of antioxidants in cosmetics ensures the stability of the substance (by protecting the unsaturated ingredients from oxidation), on the other hand, antioxidants as active substances reduce the rate of aging of skin. The most widely used antioxidants in the cosmetic industry are: vitamin C, vitamin E, Q10 coenzyme, gallic acid and its esters, ferulic acid, lipoic acid, butylated hydroxytoluene (BHT) and polyphenoland flavonoid-rich plant extracts. The plants from which antioxidant-rich extracts are obtained include i.a. soy, grape seeds, lady’s milk, citrus fruits, rosemary, Gingko biloba and green tea. Tea is a plant of the Theaceae family – Camellia Sinensis (common tea). The tea plant is an evergreen shrub with small white petals and woody seedpods [1]. The green tea originates from China. Green tea was first mentioned in 3rd Century B.C., recalling a Chinese medic who recommended it to his patients for improving concentration and wit. until 3rd Century B.C. the green tea brew was used solely for medical purposes. Within the next Centuries the popularity of green tea increased, as its taste and therapeutic values came to be appreciated. The herbal material are tea leaves which, depending on the processing method, give the following types of tea: green, red or black. Green tea undergoes the least processing. It is not subjected to fermentation and, compared to other types, contains the most active complexes, including: flavonols (rutine, quercetin, kaempferol), catechin tannins, proanthocyanidines, xanthins (caffeine, theobromine, theophylline), theanine (aminoacid), phenolic acids (caffeic, gallic, chlorogenic), microelements (manganese, fluorides, aluminium), B and C vitamins, and essential oils [2, 3]. The antioxidant properties of flavonoids are widely known. The polyphenols in green tea belong to various classes of compounds, including: catechines, flavonols, flavones, their glucosides and phenolic acids [3÷10]. The polyphenol complexes content in dry mass is 20÷30% [2]. Due to high content of antioxidants, green tea functions as dietary supplement and ingredient in care cosmetics, shampoos, sweet waters, masks and anti-aging emulsions [4, 9]. The study investigated the impact of the conditions of green tea leaves extraction on the effectiveness of antioxidant properties. Three types of green tea extracts were obtained: ethanolic, glycolic, hydrous, as well as alcoholic and glycolic macerates. Aside from the effectiveness of active compounds extraction, the solvent selection was also conditional upon its safety in terms of application of liquid green tea extracts as cosmetic raw materials. Next, the rutine content in the obtained products was assayed and the effectiveness of the products antioxidant properties was assessed. The investigation of antioxidant capabilities was conducted on the basis of a colorimetric reaction with thiocyanate, tracking the oxidation process of linolic acid [1]. The changes were monitored using UV-vis spectrophotometer. experimental study In order to obtain extracts with maximum active substances content, two extraction methods were applied: continuous in Soxhlet extractor and maceration. Using the continuous method, three types of extracts were obtained: hydrous, ethanolic and glycolic extracts. Using maceration, two types of macerates were obtained: glycolic and ethanolic. The raw material for both extractions originated from the same source – Herbapol Lublin S.A. After initial mincing in a porcelain crucible, the dried green tea leaves were placed in an extraction thimble and then in Soxhlet extractor. First, the material underwent preliminary processing through extracting the raw material with the mixture of chloroform and petroleum ether (1:1) in order to remove chlorophyll and hydrophobic substances. The preliminary extraction was continued for 2 hours. After separating the eluent and drying the plant material, the proper extraction process was initiated. As solvents were used in the following order: ethanol 96% (POCH Gliwice), propylene glycol (POCH Gliwice), distilled water, in constant mass ratio of solvent to raw material (Tab. 1). table 1 characteristics of extraction process