Determination of the quantitative composition and antioxidant activity of phenolic compounds and flavonoids in Ginkgo biloba L. leaves and medical products.

Object and methods: Extracts of gingko biloba leaves and medical preparations. Determination of total phenolic compounds and flavonoids was done by spectrophotometric method. Antioxidant activity was determined by spectrophotometric method using DPPH reagent. Aim: To evaluate the quantitative composition of phenolic compounds and flavonoids accumulated in ginkgo biloba leaves, collected in different places of Lithuania, and medical products registered in Lithuania and also to assess the antioxidant activity of the extracts using the spectrophotometric method. Objective: to determine the diversity of phenolic compounds and flavonoids in leaves of ginkgo biloba and medicinal preparations. To compare difference in the amount of compounds that could depend on the location of the collection. To evaluate quantity differences between gingko biloba leaves and medicinal preparations. To assess the antioxidant activity of the extracts. Conclusions: The maximum amount of phenolic compounds was determined in ginkgo biloba leaves grown in Kaunas Botanical Garden (16.03 GRE mg/g), as well as the maximum quantities of flavonoids (5.09 mg/g). The smallest amount of phenolic compounds obtained from the investigated leaves collected in Silute (8.99 GRE mg/g), also the lowest amount of flavonoids (2.30 RE mg/g). In test of ginkgo biloba medical products a maximum amount of phenol compounds was found in Tanakan 40 mg (30.07 GRE mg/g), but the highest amount of flavonoids was obtained with Bilobil 120 mg (6.22 mg/g) . The least amount of phenolic compounds was observed in Ginkobil 120 mg (19.52 GRE mg/g). The lowest levels of flavonoids were found in medical products of Gingium 120 mg (3.02 RE mg/g) and Ginkobil 120 mg (2.98 RE mg/g). The highest antioxidant activity was observed in leaves collected in the Kaunas Botanical Garden (82.95 μmol TE/g) and in Klaipeda Botanical Garden (81.66 μmol TE/g). In the medicinal products, the highest antioxidant activity was shown by Tanakan 40 mg (86.11 μmol TE/g) and Bilobil (84.47 μmol TE/g)