Interactions between thrombin and natural products of Millettia speciosa Champ. using capillary zone electrophoresis.

In Chinese medicine Suberect Spatholobus Stem is used to treat menoxenia, blood deficiency, numb paralyses, and so on. In folk, Millettia speciosa is often used as a substitute for Suberect Spatholobus Stem in some areas but it has not been reported whether M. speciosa is the eligible substitute for Suberect Spatholobus Stem or not till now. In this study, a capillary zone electrophoretic method was applied to determinate the interactions between natural products isolated from M. speciosa Champ. and thrombin for the first time. Both qualitative and quantitative characterizations of the molecule-enzyme binding were determined. Twenty ingredients were isolated from M. speciosa Champ. and the results showed that compared with positive and negative control, the compounds YT-1, YT-2, YT-3, YT-8, YT-9, YT-10, YT-11, YT-12, YT-14, YT-15, YT-16, and YT-20 interacted with thrombin while the other eight had no binding to thrombin. The binding constants of the interaction between compounds and thrombin were calculated by the Scatchard analysis formula. Because M. speciosa contains these compounds which have different levels of anticoagulant activity, it may be the eligible substitute for Suberect Spatholobus Stem.