Abstract:

Kunming male mice (about 6 weeks old, (20 ± 2) g) were used as experimental animals for measuring free radical scavenging activities and hypoglycemic effects of aqueous extracts of 4 species of edible fungi, including Pleurotus citrinopileatus, Stropharia rugoso-annulata, Pleurotus cornucopiae and Agrocybe aegerita. Meanwhile, active components in the aqueous extracts, including total flavonoids, total phenols and polysaccharides were quantified by spectrophotometric methods. Alloxaninduced diabetic mouse models were constructed by intraperitoneal injection and intragastrically administered with a dose of 400 mg/kg for continuously 28 d, using phenformin-treated mice (100 mg/kg) as positive group and normal mice as control group. Fasting blood glucose level was determined on the 0, 6th, 14th, 21st and 28th d, and glucose tolerance level was determined on the 28th d. After scarification, mice were subjected to blood sampling for assaying glycated hemoglobin and blood lipid levels. These aqueous extracts exhibited a total flavonoids content ranging 2.37－6.89 mg/g, a total phenols content ranging 2.5－4.96 mg/g and a polysaccharides content ranging 20.30－44.02 g/100 g. The EC50 values of Pleurotus citrinopileatus, Stropharia rugosoannulata, Pleurotus cornucopiae and Agrocybe aegerita extracts (PCTE, SRE, PCNE, AAE) were 0.32, 0.24, 0.36, 0.13 mg/ml for scavenging superoxide radicals, 2.36, 3.71, 2.60, 3.95 mg/ml for scavenging hydroxyl radicals, and 14.51, 15.32, 15.36, 11.20 mg/ml for scavenging DPPH radicals, respectively. The 28-day continuous administration of each of these aqueous extracts could result in a significant improvement in clinical symptoms of diabetes mellitus and a significant decrease in the levels of fasting blood sugar and glucose tolerance expressed as blood glucose area under the curve (P < 0.01). A decrease in blood glucose level of above 15% was observed in PCTE-, PCNE- and AAE-treated diabetic mice. In addition, GHB levels in blood serum came back normal. Furthermore, PCTE-, SRE-, PCNE- and AAE-treated diabetic mice exhibited normal levels of TC and HDL-C.

Key words: edible fungi extracts, free radical, antioxidant, diabetes mellitus, hypoglycemic effect