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Our previous study demonstrated that the fruiting bodies of Cordyceps sinensis, a traditional Chinese medicine, attenuated diabetes-induced weight loss, polydipsia, and hyperglycemia in rats. In the present study, we further compared the anti-hyperglycemic activity of the fermented mycelia and broth of Cordyceps sinensis with that of the fruiting bodies. Male Wistar rats orally administered a placebo (STZ group), fruiting bodies (FB group, 1 g/day), fermented mycelia (MCS group, 1 g/day), fermented broth (BCS group, 1 g/day), or fermented mycelia plus broth (XCS group, 0.5 g/day of each) of Cordyceps sinensis (d1 to d28) were injected with nicotinamide (200 mg/kg) and streptozotocin (65 mg/kg) on d15. Rats fed with a placebo and injected with saline served as the control (CON) group. The amount of water and food consumption (d15 to d29), the 2-hour-postprandial blood glucose concentrations (d21 and d28), and the serum concentrations of fructosamine (d29) were significantly lower in the FB, MCS, BCS, and XCS groups than in the STZ group (one-way ANOVA, p < 0.05). The diabetic rats had significantly higher blood glucose concentrations as measured by the oral glucose tolerance test than the control rats; moreover, these changes were significantly reduced by ingesting the fruiting bodies, fermented mycelia and/or broth of Cordyceps sinensis. Our results revealed that the fermented mycelia and broth of Cordyceps sinensis have anti-hyperglycemic activities similar to those of the fruiting bodies. Therefore, the fermented products of Cordyceps sinensis could be developed as potential anti-diabetic agents or functional foods for persons with a high risk of diabetes mellitus.

Grifola frondosa, an edible fungus with a large fruiting body and overlapping caps, has been demonstrated to be a natural source of health-promoting substances, mainly due to its polysaccharides β-glucan. By using male Wistar rats injected with saline (normal rats) or nicotinamide plus streptozotocin (diabetic rats), we investigated the effects of an orally ingested placebo (CON and STZ groups), culture mycelium (CGM and SGM groups), broth (CGB and SGB groups), and mycelium plus broth (CGX and SGX groups) of Grifola frondosa on glycemic responses. During the experimental period (from day 0 to day 15), the STZ group had significantly lower body weight compared to the CON group (one-way ANOVA, p < 0.05). Moreover, the STZ group had significantly higher blood glucose concentrations at 2 hour-postprandial periods on days 0, 7, and 14 and in an oral glucose tolerance test (OGTT) on day 10, as well as significantly higher serum fructosamine and triglyceride on day 15 compared to the CON group. These diabetes-induced increases were significantly attenuated by administrations of mycelium and/or broth, i.e., the SGM, SGB, and SGX groups. The results of repeated-measures analysis and three-way ANOVA indicated that diabetes mellitus significantly increases, and mycelium administration significantly decreases postprandial blood glucose; diabetes mellitus significantly increases, and mycelium and broth administrations significantly decrease serum triglyceride, fructosamine, and blood glucose concentrations; moreover, in the area under the curve in OGTT, p < 0.05. Our results revealed that submerged-culture mycelia and broth of Grifola frondosa have bioactivities for improving glycemic responses.