Rapid identification of α-glucosidase inhibitors from Dioscorea opposita Thunb peel extract by enzyme functionalized Fe3O4 magnetic nanoparticles coupled with HPLC-MS/MS.

Dioscorea opposita Thunb, commonly known as "yam" that has a long dietary therapy history for diabetes, is widely consumed as a botanical dietary supplement and widely cultivated in China. In this work, a method for rapid screening of α-glucosidase inhibitors from Dioscorea opposita Thunb peel extract was developed using α-glucosidase functionalized magnetic nanoparticles (αG-MNPs) as a solid phase extraction absorbent in combination with high performance liquid chromatography-mass spectrometry (HPLC-MS). Two α-glucosidase inhibitors were selectively extracted and identified as batatasin I and 2,4-dimethoxy-6,7-dihydroxyphenanthrene. Their α-glucosidase inhibitory activities (IC50 = 2.55 mM and 0.40 mM, respectively) were significantly higher than that of acarbose (as control). Taking advantage of the specificity in enzyme binding and the convenience of magnetic separation, this method has great potential for rapid and fast screening of α-glucosidase inhibitors from complex natural resources.