New methoxylated aryltetrahydronaphthalene lignans and a norlignan from Aglaia cordata

Four novel lignans, aglacins E–H (1–4), were isolated and identified from the methanolic extract of the stem bark of Aglaia cordata collected in Indonesia. All of these metabolites contain two unusual contiguous trimethoxylated phenyl systems. While two of these compounds (1 and 2) are aryltetralin cyclic ether lignans, a third lignan (3) exhibits an unusual formyl group whereas compound (4) is a rare norlignan. The structures of all compounds were elucidated by interpretation of 1D and 2D NMR, as well as by low- and high-resolution EIMS. The absolute configurations of aglacins E and F (1 and 2) were determined by the modified Mosherʹs method.