Collagenase inhibition by waterpepper (Polygonum hydropiper L.) sprout extract

Introduction: Collagenase plays an important role in the degradation of dermal matrix proteins leading to wrinkle formation. The objectives of this study were to evaluate the inhibitory effect of waterpepper (Polygonum hydropiper L.) sprout extract on the activity of collagenase and to identify the inhibitory compounds.Methods: Collagenase inhibitory activity was measured by spectrophotometric assay. Activityguided fractionation was performed using liquidliquid extraction of water and nbutanol and Diaion HP20 column chromatography, followed by highperformance liquid chromatography (HPLC) fraction collection.Results: A methanolic extract of waterpepper sprout inhibited collagenase activity in a concentrationdependent manner with an IC50 value of 156.7 μg/mL. Collagenase inhibitory activity (IC50 = 23.5 μg/mL) was found in 50% methanol eluate from the HP20 column chromatography of the nbutanol soluble fraction. The active compound (IC50 = 1.9 μg/mL) in the eluate was isolated by HPLC and identified as quercetin3Ogalactoside (hyperoside) from comparing retention time, UVVis absorption, and mass spectra with those of the standard. LineweaverBurk plots revealed that hyperoside was an uncompetitive inhibitor against collagenase. Hyperoside was also the most abundant flavonoid present in the methanolic extract.Conclusion: These results suggest that waterpepper sprouts could be beneficial as a natural source of collagenase inhibitor which might be used for the treatment of skin aging.