The composition of fatty and organic acids in quince leaves and fruits (Cydonia oblonga Mill.) of selection of M. M. Grishko National Botanical Garden of National Academy of Sciences of Ukraine sorts was determined by gas chromatography-mass spectrometry method. Six sorts of quince were examined: "Academichna", "Kashchenka N18", "Studenrka', "Oranzheva", 'Maria", "Darunok onuku". The presence of 36 fatty acids and 32 organic acids in leaves and fruits of the quince were identified and determined their content. Therefore, main acids are oxalic, citric, palmitic and linolenic acids in quince leaves and malic, palmitic and linoleic acids in quince fruits. The highest content of all acids were identified in the quince leaves of sort "Maria". Moreover, a quite high content of succinic acid in the quince leaves was detected.

To study an impact of auxiliary substances on gel containing extracts of quince leaves and grape seed meal, which is based on polymethylsiloxane. Pharmaco - technological and physicochemical methods. In this study, a spectrophotometric method is applied to determine an antioxidant activity of the gel. We examined an impact of auxiliary substances on the gel. According to the results of studies we chose auxiliary ingredients which improve not only gustatory quality but also technological parameters. Applying spectrometric analysis, we investigated an antioxidant activity of phytogel. The gel has a structure of rigid matrix, which is built through a process of condensation of methylsilanetriol and siloxane bonds between the silicon atoms, which makes it possible to maintain and stabilize active natural ingredients. The experiment proved that the extract of leaves of quince and grape seed meal have some antioxidant activity. But, upon the introduction of stevia extract as a coregent taste, the gel that contains quince leaf extract and grape seed meal increases the antioxidant activity. Phytogel has antioxidant activity of 84% relative to the reference sample, which suggests that the gel can resist the harmful effects of free radicals, which are constantly produced in the human organism It was confirmed that the addition of auxiliary substances into the gel with the extracts of quince leaves and grape seed meal based on polymethylsiloxane increases bioavailability and therapeutic efficiency, in particular, the antioxidant activity, of the gel. Stevia extract as an adjuvant in the phytogel, as gustatory corrector, increases the antioxidant activity of phyto pharmaceutical drugs.