Screening potential α-glucosidase inhibitors from Anemarrhena asphodeloides using response surface methodology coupled with grey relational analysis

Objective: To screen potential alpha-glucosidase inhibitors from Anemarrhena asphodeloides. Methods: Response surface methodology employing Box-Behnken design was used to optimize conditions for the extraction of alpha-glucosidase inhibitory active compounds from A. asphodeloides. The powders (20.0 g) of A. asphodeloides were extracted under the optimized conditions. The extract was applied to a D-101 macroporous resin column. It was eluted with ethanol and water to give six fractions. Compounds from the active fraction were identified by UPLC-Q-TOF-MS. The structure-activity relationship was discussed based on grey relational analysis. Results: The optimum extraction conditions were as follows: ethanol concentration, 100%; extraction temperature, 51 degrees C; and solvent to solid ratio, 23 mL/g. It indicated that the active compounds were concentrated into 80% ethanol fraction. Twenty five steroid saponins from 80% ethanol fraction were identified by UPLC-Q-TOF-MS. Peaks 19 and 23 were tentatively identified as new structures. The predicted alpha-glucosidase inhibitory activities of the compounds were 7 > 2 > 1 > 22 > 23 > 3 > 9 > 21 > 24 > 4 > 13 > 8 > 14 > 16 > 17 > 25 > 6 > 19. Conclusion: The fraction eluted by 80% ethanol showed the best inhibitory activity. After analyzing the data of UPLC-Q-TOF-MS, 25 steroid saponins were tentatively identified in this fraction. (c) 2018 Tianjin Press of Chinese Herbal Medicines. Published by Elsevier B. V. All rights reserved.