Four new bi-2-(2-phenylethyl)chromone derivatives of agarwood from Aquilaria crassna.

Four new bi-2-(2-phenylethyl)chromone derivatives, crassins A-D (1-4), were isolated from the EtOAc extract of agarwood originating from Aquilaria crassna. The structures including the absolute configurations of compounds were unambiguously elucidated by extensive spectroscopic methods (1D and 2D NMR, UV, ECD, IR, MS), and by comparison with the literature. The isolated compounds were tested for their acetylcholinesterase (AChE) and α-glucosidase inhibitory activities, as well as cytotoxic activities. All the compounds showed weak inhibitory activity against AChE, while compounds 3 and 4 also displayed weak cytotoxicity against human myeloid leukemia cell line (K562).