Three new 2-(2-phenylethyl)chromone derivatives from agarwood of Aquilaria crassna Pierre ex Lecomte (Thymelaeaceae) in Laos

Abstract In our ongoing effort to study the metabolites from agarwood of Aquilaria crassna Pierre ex Lecomte (Thymelaeaceae) produced in Laos, three new 2-(2-phenylethyl)chromone derivatives ( 1 − 3 ) were isolated. Their structures were elucidated by comprehensive spectroscopic analyses, predominantly by 1D and 2D NMR spectroscopic methods, and by comparison with the reported data. Compound 2 exhibited tyrosinase inhibitory activity with IC 50 value of 172.6 ± 1.7 μM (kojic acid as the positive control, 46.1 ± 1.3 μM) and its inhibition mode was clarified by molecular modelling study. None of the isolates showed significant cytotoxicity towards tested cancer cell lines.