LC-MS guided identification of dimeric 2-(2-phenylethyl)chromones and sesquiterpene-2-(2-phenylethyl)chromone conjugates from agarwood of Aquilaria crassna and their cytotoxicity

Four previously unreported dimeric 2-(2-phenylethyl)chromones (1-4a) and three unprecedented sesquiterpene-2-(2-phenylethyl)chromone conjugates (5-7), comprising a sesquiterpenoid and a 5,6,7,8-tetrahydroxy-2-(2-phenylethyl)-5,6,7,8 -tetrahydro-4H-chromone moiety, as well as three known dimeric 2-(2-phenylethyl)chromones (4b, 8a, 8b) were identified from agarwood originating from Aquilaria crassna in Cambodia by LC-MS guided separation. Their structures were elucidated by extensive NMR techniques, HRESIMS and CD. All compounds were evaluated for their cytotoxicity against four human cancer cell lines. Compounds 6, 7, 8a, 8b displayed a range of cytotoxic activities with IC50 values in the rang 10.93-49.0 μM.