Blepharocalyxins C-E, three new dimeric diarylheptanoids, and related compounds from the seeds of Alpinia blepharocalyx

Three novel diarylheptanoids, blepharocalyxins C-E (5-7), together with fou r new (1-4) and one known (8) diarylheptanoids bearing a tetrahydropyran ri ng were isolated from the residual fraction of an EtOH extract of the seeds of Alpinia blepharocalyx. The structures and the stereochemistry at the ch iral centers of the new diarylheptanoids were elucidated by spectroscopic t echniques including 20 NMR spectroscopy. Blepharocalyxins C-E (5-7) have a novel carbon framework and are dimeric diarylheptanoids consisting of two d iarylheptanoid units. Blepharocalyxin D (6) showed potent antiproliferative activity against murine colon 26-L5 carcinoma cells (ED50, 3.61 muM), whil e against human MT-1080 fibrosarcoma cells, blepharocalyxin E (7) showed po tent activity (ED50, 9.02 muM).