Evaluation of lignans from Heliopsis helianthoides var. scabra for their potential antimetastatic effects in the brain.

Two new arylbenzofuran-type neolignans, 1"-dehydroegonol 3"-methyl ether (1) and egonol 3"-methyl ether (2), and four known lignan derivatives, namely, helioxanthin (3), (7E)-7,8-dehydroheliobuphthalmin (4), heliobuphthalmin (5), and 7-acetoxyhinokinin (6), were isolated from a chloroform-soluble partition of the methanol extract of the fresh roots of Heliopsis helianthoides var. scabra. These six compounds were evaluated in vitro in terms of their ability to inhibit the various steps involved in brain tumor metastasis formation. Compounds 3 and 4 inhibited the migration of both melanoma and brain endothelial cells, and 3 also reduced the adhesion of melanoma cells to the brain endothelium. Furthermore, 3 and 4 additionally enhanced the barrier function of the blood-brain barrier and the expression of the tight junction protein ZO-1 at the junctions of the endothelial cells. These findings suggest that 3 and 4 may have the potential to interfere with different steps of brain metastasis formation and to enhance the barrier function of cerebral endothelial cells.