Ultrafiltration LC-ESI-MSn screening of MMP-2 inhibitors from selected Chinese medicinal herbs Smilax glabra Roxb., Smilax china L. and Saposhnikovia divaricata (Turcz.) Schischk as potential functional food ingredients

• Ultrafiltration LC-DAD-ESI-MS is a relatively new method in functional foods and nutraceuticals research.
• First report on MMP-2 inhibition of Smilax glabra Roxb., Smilax china L. and Saposhnikovia divaricata (Turcz.) Schischk.
• The major bioactives are not the same as the major components.
• Method was validated by conventional enzyme assay.
• Method can be applied to other enzyme inhibitors in foods.

In vitro Matrix metalloproteases-2 (MMP-2) inhibition assay and ultrafiltration liquid chromatography coupled to electrospray ionization tandem mass spectrometry (ultrafiltration LC-ESI-MSn) were combined to screen MMP-2 inhibitors from three Chinese medicinal herbs, Smilax glabra Roxb., Smilax china L. and Saposhnikovia divaricata (Turcz.) Schischk as potential functional food ingredients. Results showed that extracts of two Smilax species and the three major components resveratrol, engelitin and asibinn, and extract of S. divaricata and its major component 4′-O-β-D-glucosyl-5-O-methylvisamminol and three other chromones were strong MMP-2 inhibitors. Resveratrol and 4′-O-β-D-glucosyl-5-O-methylvisamminol had the highest binding affinity to MMP-2 and were the main contributors to the MMP-2 activity of Smilax and Saposhnikovia extracts, respectively. The present results further suggest that ultrafiltration LC-ESI-MSn is a valid, selective and effective method, and can be used to screen MMP-2 inhibitors from other plants such as grapes that contain resveratrol as functional foods and nutraceuticals.