In Vitro and In Vivo Antidiabetic Evaluation of Selected Culinary-Medicinal Mushrooms (Agaricomycetes)

Management of type 2 diabetes by delaying or preventing glucose absorption using natural products is gaing significant attention. Edible mushrooms are well documented for their nutritional and medicianal properties. This investigation was designed to evaluate the antidiabetic activity of aqueous extracts of selected culinary-medicinal mushrooms, namely, Pleurotus ostreatus, Calocybe indica, and Volvariella volvacea, using in vitro models (alpha-amylase inhibition assay, glucose uptake by yeast cells, and glucose adsorption capacity). The most active extract was subsequently examined in vivo using the oral starch tolerance test in mice. All prepared extracts showed dose-dependent inhibition of alpha-amylase and an increase in glucose transport across yeast cells. C. indica extract was the most active alpha-amylase inhibitor (half-maximal inhibitory concentration, 18.07 +/- 0.75 mg/mL) and exhibiteed maximum glucose uptake by yeast cells (77.53 +/- 0.97 % at 35 mg/mL). All extracts demostrated weak glucose adsorption ablilty. The uptake by yeast tests for C. indica paved the way for in vivo studies. C. indica extract (200 and 400 mg/kg) significantly (p < 0.05) reduced postprandial blood glucose peaks in mice challenged with starch. The extract (400 mg/kg) and acarbose normalized blood glucose levels at 180 minutes, when they were statistically similar to values in normal mice. Thus, it may be concluded that the antidiabetic effect of C. indica is mediated by inhibition of starch metabolism (alpha-amylase inhibition), increased glucose uptake by peripheral cells (promotion of glucose uptake by yeast cells), and mild entrapment (adsorption) of glucose. Hence, C. indica can be developed as antidiabetics drug after detailed pharmacological studies.