Optimization of microwave-assisted extraction of phenolic compounds in Dendrobium formosum Roxb. ex Lindl. and glucose uptake activity

Phenolic compounds are active compounds in Dendrobium formosum Roxb. ex Lindl. that have antidiabetic and anti-obesity activities. To obtain a high extraction yield of phenolic compounds from D. formosum, optimization of microwave-assisted extraction (MAE) was developed in this study using response surface methodology. The optimal conditions for phenolic compound yield were using absolute ethanol as the solvent, 540 W of microwave power, 49.37 s of extraction time, a 22.67 mL/g solvent-to-feed ratio, and three extraction cycles. The yields of coelonin, erianthridin, moscatilin, lusianthridin, gigantol and batatasin III when extracted under optimal conditions were 0.38 ± 0.04, 0.40 ± 0.05, 1.45 ± 0.18, 0.14 ± 0.01, 0.47 ± 0.05 and 0.58 ± 0.06 mg/g dry weight, respectively, with errors of less than 4% deviation from the predicted values. Our results indicate that MAE can obtain a higher yield of phenolic compounds and have a greater effect on glucose uptake than those of other extraction methods. Therefore, MAE has high efficiency for extracting phenolic compounds from D. Fomosum, yielding extracts with a high amount of compounds that exhibit antidiabetic activity.