| Abstract [eng] |
Evelina Petraitytė Master’s Thesis: Comparison of amounts of phenolic compounds and tannins in aqueous extracts of Ericaceae and Rosaceae plants obtained using different water extraction methods. The aim of the study: to determine and compare the total phenolic compounds and total tannins in aqueous extracts of leaves of some Ericaceae and Rosaceae plants growing in Lithuania, using different water extraction methods. Objectives: to determine the total phenolic compounds in aqueous extracts of blueberry, lingonberry, bearberry, heather, agrimony, wild strawberry, silverweed and lady's mantle leaves, regardless of the extraction method; to determine the total amount of tannins in aqueous extracts of leaves of the above Ericaceae and Rosaceae plants, irrespective of the extraction method; to compare the total amount of phenolic compounds and tannins in aqueous extracts of leaves of the above Ericaceae and Rosaceae plants obtained by the different extraction methods. Methods: moisture and dry matter content were determined by thermal drying in the plant material. The spectrophotometric method using Folin-Ciocalteu reagent was used to determine the total phenolic compounds. The tannin content was calculated by subtracting the amount of phenolic compounds remaining after binding of tannins to PVPP from the total phenolic content. Statistical analysis of the data was performed using STATISTICA® 10 and Microsoft Excel. Results and conclusions: of all the studied species, the Ericaceae species with the highest total phenolic content, regardless of the method of water extraction, was the common bearberry. The lowest levels of phenolic compounds in this family were found in the leaves of blueberry and in a mixture of leaves and flowers of heather. In the Rosaceae family, the highest amounts of phenolic compounds were found in the leaves of lady's mantle and agrimony, while the lowest amounts were found in the leaves of wild strawberry and silverweed. The highest tannin content, irrespective of the method of water extraction, was found in bearberry and the lowest in heather. Hot water extraction was the most efficient method for the extraction of phenolic compounds from Ericaceae species; maceration was the least efficient method, especially for bearberry. When the tannin contents of Ericaceae species were investigated, ultrasonic extraction was the most efficient for bearberry and lingonberry, boiling water extraction for blueberry and maceration for heather. It was not possible to identify a water extraction method that was effective in extracting phenolic compounds for all the Rosaceae species studied: boiling water extraction was the most effective method for extracting the leaves of the agrimony and the wild strawberry, while ultrasonic extraction was the most effective method for extracting the leaves of the silverweed and the lady's mantle. Maceration was the least effective in all species of this family. Maceration with water at room temperature overnight in the dark was the most effective method for extracting tannins from Rosaceae species, except for the agrimony, for which it was the least suitable. |
