Investigation of phenolic compounds at the leaves and shoots Arctostaphylos spp. and their antioxidant and antityrosinase activities

Comparative phytochemical and pharmacological analysis of leaves and shoots of Arctostaphylos uva-ursi (L.) Spreng. and endemic of Transcaucasia and North Caucasia Arctostaphylos caucasica Lipsch. was carried out. Phenolic compounds in methanol extracts were investigated by HPLC-PDA-ESI-MS. Pharmacological investigation was carried out at the models of generation of superoxide, DPPH, hydroxyl and nitrosyl radicals. The antityrosinase properties were evaluated in the reaction of tyrosinase inhibition using L -tyrosine as a substrate. Five new compounds were identified in the shoots and leaves of A. uva-ursi: 4,6-di-О-galloylglucose; 2,3-di-О-galloylglucose; 1,4,6-tri-О-galloylglucose; 1,2,4,6-tetra-О-galloylglucose; tetra-О-galloylhexose. Thirty-five phenolic compounds and two saponins were identified for the first time in A. caucasica. Water-alcohol extract (70% ethanol) from A. caucasica had the highest antiradical activity. Water extracts from both species had antityrosinase activity and possessed comparable efficiency (IC₅₀ = 36.4 ± 1.2 µg/ml and IC₅₀ = 35,5 ± 2 µg/ml, respectively).