Chemical constituents from Betula schmidtii and their free radical scavenging, tyrosinase inhibitory, and neuroprotective activities

Abstract

The study was performed to identify bioactive constituents from the inner bark of Betula schmidtii. Seven compounds were isolated through silica gel and Sephadex LH‐20 column chromatography, and identified to be betulin (1), betulinic acid (2), β‐sitosterol (3), lupeol (4), kojic acid (5), 1,7‐bis‐(ρ‐hydroxyphenyl)‐(3,4‐dihydroxy)‐hepan‐5‐one (6), and platyphyllenone (7) using EI‐MS, 1D‐, and 2D‐NMR data. Compounds 5, 6, and 7 show antioxidant effect with IC50 values of 18.23 ± 1.08, 29.37 ± 1.42, and 40.14 ± 1.75 μM in DPPH free radical scavenging activity. Compounds 4 and 5 show an antioxidant effect with IC50 values of 28.21 ± 1.80 and 37.74 ± 1.02 μM in DCHF‐DA intracellular ROS generations. Compounds 5, 6, and 7 also exhibited mushroom tyrosinase inhibitory activity with IC50 values of 17.42 ± 1.08, 47.17 ± 1.92, and 26.64 ± 1.40 μM. Compound 1 showed cell viability of 24.50 ± 6.30 and 45.60 ± 3.10% at 10 and 25 μM, while compound 6 showed 11.20 ± 1.40% at 25 μM in glutamate‐induced damaged mouse neuronal cells.