Dimeric sesquiterpenoid-4H-chromone derivatives from agarwood of Aquilaria crassna and their cytotoxicity.

Six previously undescribed uncommon ester-bonded dimeric compounds (aquilacrassnins A-F) containing a sesquiterpenoid and a 5,6,7,8-tetrahydroxy-2-(2-phenylethyl)-5,6,7,8-tetrahydro -4H-chromone units were isolated from the EtOAc extract of agarwood originating from Aquilaria crassna. Their structures were elucidated by spectroscopic (NMR, UV, IR, MS, and ECD) methods. All the compounds were tested for AChE inhibitory activity and cytotoxicity against K562, BEL-7402, SGC-7901, Hela, and A549 tumor cell lines. The results showed that aquilacrassnin A, B, and E exhibited weak cytotoxicity against the five tested cell lines, whereas all the compounds were inactive against AChE.