THE FIRST EVALUATION OF TYROSINASE AND ELASTASE INHIBITORY ACTIVITIES OF GRAYANANE-TYPE DITERPENOIDS ISOLATED FROM Rhododendron brachycarpum

DOI: 10.18173/2354-1059.2025-0041

Abstract

From the methanol extract of the aerial parts of Rhododendron brachycarpum, five grayanane-type diterpenoids were isolated. These grayananetype diterpenoids were elucidated by detailed analyses of NMR and MS data and identified as grayanoside B (1), rhodomoside A (2), piersformoside B (3), grayanotoxin III (4), and grayanotoxin I (5), based on comparison with previously reported spectral data. All compounds were evaluated for inhibitory activity against tyrosinase and elastase. The results revealed that the compounds 1-5 exhibited weak tyrosinase inhibitory activity, whereas compounds 1, 3, and 4 showed strong elastase inhibition, with inhibition rates of 71.78%, 71.11%, and 85.19%, respectively, at a concentration of 1mM. This study represents the first report of the anti-tyrosinase and anti-elastase activities of grayane-type diterpenoids isolated from R. brachycarpum.