Influence of the leaf development phase on the accumulation of arbutin and other biologically active compounds in above-ground part of leather bergenia

Leather Bergenia (Bergenia crassifolia (L.) Fitsch) is one of the few plants that contain a significant amount of phenolic compounds in its leaves. The present research identified high content of gallotannins and tannins in Bergenia leaves. The maximum total content of gallotannins is found in green leaves - 29,49±0,32 %. Red leaves have the highest amount of tannins (24,1±0,03 %). The content of arbutin in leaves varied during seasonal development in the range from 10 to 18 % with a maximum accumulation in green leaves - 18,01±0,26 %. Throughout the growing season, a gradual decrease in arbutin is observed. By the end of the growing season, black leaves had a minimum arbutin value of 10.54 0.35%.Obviously, the arbutin content is higher in leaves during the mass flowering phase than in red and black leaves. It allows to determine the optimal time for harvesting arbutin-containing raw materials.