Novel diarylheptanoids of Alpinia blepharocalyx

The seeds of Alpinia blepharocalyx K. Schum. (Zingiberaceae) is used in Chinese traditional medicine for the treatment of stomach disorders. From the ether fraction of a 95% ethanolic extract, which showed hepatoprotective and antiproliferative activities, we isolated 16 novel diarylheptanoids bearing a chalcone or a flavanone moiety [calyxins A-H; epicalyxins B-D, G, and H; 6-hydroxycalyxin F; and blepharocalyxins A and B] together with seven known compounds, while the residual fraction of the ethanolic extract gave 32 novel diarylheptanoids namely, calyxins A, E-G, and I-M; epicalyxins B, F, I-K, and M; deoxycalyxin A; blepharocalyxins C-E; neocalyxins A and B; (3S,5S)- and (3S,5R)-3-hydroxy-1-(4-hydroxyphenyl)-5-methoxy-7-phenyl-6E-heptene, (3S,5S)- and (3S,5R)-3-hydroxy-1-(4-hydroxyphenyl)-5-ethoxy-7-phenyl-6E-heptene, (3S)-3-methoxy-1,7-bis(4-hydroxyphenyl)-6E-hepten-5-one, 1,7-bis(4-hydroxyphenyl)-hepta-4E,6E-dien-3-one, (3S,7R)-5,6-dehydro-1,7-bis(4-hydroxy-phenyl)-4"-de-O-methyl-centrolobine, (3S,5S,6S,7R)-5,6-dihydroxy-1,7-bis(4-hydroxyphenyl)-4"-de-O-me-thylcentrolobine, (3S,5R,6S,7R)- and (3S,5S,6R,7R)-5,6-dihydroxy-1,7-bis(4-hydroxyphenyl)-4"-de-O-methyl-centrolobine, 1,2- dihydro-bis(de-O-methyl)curcumin, and (3S,7S)-5,6-dehydro-4"-de-O-methylcentrolobine, and one known diarylheptanoid [(3S,5S)-3,5-dihydroxy-1,7-bis(4-hydroxyphenyl)heptane] together with 12 other known phenolic compounds. Moreover, in vitro NO inhibitory and antiproliferative activities of the isolated compounds were also tested and the active constituents identified.