Characterization of Total Phenolic Constituents from the Stems of Spatholobus suberectus Using LC-DAD-MSn and Their Inhibitory Effect on Human Neutrophil Elastase Activity

Spatholobus suberectus Dunn, belonging to the legume family (Fabaceae), has been used as a Traditional Chinese Medicine for the treatment of anemia, menoxenia and rheumatism . A limited number of studies report that various types of flavonoids are the main characteristic constituents of this herb. We have now found that S. suberectus contains about 2% phenolic components and characterized the major phenolic components as homogeneous B-type procyanidin conjugates using a liquid chromatography with diode-array detection-ESI mass spectrometry (LC-DAD/ESI-MS) method. This is the first report on occurrence of most B-type procyanidins in this herb. Moreover, the total phenolics extract was assayed for inhibitory activity on human neutrophil elastase and its IC 50 was found to be 1.33 μg/mL.