Anticoagulant flavonoid oligomers from the rhizomes of Alpinia platychilus.

Two pairs of enantiomers of flavonoid oligomers (1a and 1b, 2a and 2b) along with one known chalcone (3) were isolated from the rhizomes of Alpinia platychilus. Their structures were elucidated on the basis of spectroscopic data (MS and 1D/2D NMR). The absolute configurations of the flavonoid oligomers were established by their ECD spectra. Separation of the enantiomeric mixtures (1a and 1b, 2a and 2b) was achieved on a chiral column using hexane:isopropyl alcohol:ethanol (7:2:1) as eluents. The anticoagulant assay showed that 2a, 2b and 3 exhibited potent activities to prolong the prothrombin times (PT) and the thrombin times (TT).