Diarylheptanoids from the Rhizomes of Curcuma kwangsiensis

Twelve new diarylheptanoids and six known compounds were isolated from rhizomes of Curcuma kwangsiensis. Structures of the new compounds were elucidated by spectroscopic and chemical methods as (3S)- and (3R)-1,7-bis(4-hydroxyphenyl)-(6E)-6-hepten-3-ol (1a and 1b), (3S)- and (3R)-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-(6E)-6-hepten-3-ol (2a and 2b), (3S)- and (3R)-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)heptan-3-ol (3a and 3b), (3R)-1-(3,4-dihydroxyphenyl)-7-phenyl-(6E)-6-hepten-3-ol (4b), (3S)- and (3R)-3-acetoxy-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-(6E)-6-heptene (5a and 5b), (3S)- and (3R)-3-acetoxy-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)heptanes (6a and 6b), and (E)-1,7-bis(4-hydroxyphenyl)-6-hepten-3-one (7). The absolute configurations were determined using the modified Mosher's method. Separation of the enantiomeric mixtures (1a and 1b, 2a and 2b, 3a and 3b, 4a and 4b, 5a and 5b, 6a and 6b) was achieved on a chiral column using acetonitrile-water mixtures as eluents. The S enantiomers exhibited negative specific optical rotations in MeOH, and the R enantiomers were positive. Inhibitory effects of the compounds on nitric oxide production in lipopolysaccaride-activated macrophages were evaluated.