Lignans, such as 6“ - bromo - isoarboreol, 4-hydroxysesamin, 4,8-dihydroxysesamin, 1,4-dihydroxysesamin (gummadiol), 2-piperonyl-3-hydroxymethyl-4-(α-hydroxy-3,4-methylenedioxybenzyl)-4-hydroxytetrahydrofuran and the 4-O-glucoside of 4-epigummadiol, can be isolated from the heartwood of Gmelina arborea.