Tyrosinase Inhibition Activity of Monoterpene Glucosides From Brugmansia arborea Flowers

Three monoterpene glucosides were isolated from the flowers of Brugmansia arborea L. using repeated silica gel and octadecyl SiO2 column chromatography. Based on spectroscopic data including 1d-NMR (1H, 13C, and distortionless enhancement by polarization transfer (DEPT)), 2D-NMR (gradient correlation spectroscopy (gCOSY), gradient heteronuclear single quantum coherence (gHSQC), and gradient heteronuclear multiple bond coherence (gHMBC)), Infrared Spectroscophy, and Mass Spectroscophy, the glucosides were identified as citronellol O- β-D-glucopyranoside (1), jasminoside N (2), and jasminoside P (3). The EtOAc ( Brugmansia arborea Flowers ethyl acetate fraction [BAFE]) and n-BuOH ( Brugmansia arborea Flowers n-butanol fraction [BAFB]) fractions showed high inhibition of tyrosinase activity (BAFE: IC50 = 68.0 and BAFB: IC50 = 59.3 μg/mL), and all isolated monoterpenes inhibited tyrosinase activity (1: IC50 = 156.5, 2: IC50 = 198.2, and 3: IC50 = 191.0 μM).