Russula rosacea, a mycorrhizal fungus, has been used for edible and medicinal purposes. This study was conducted to evaluate the in vitro antioxidant, anti-hyperglycemic, anti-cholinesterase, and nitric oxide inhibitory effects of the fruiting bodies from R. rosacea extracted with methanol, and hot water. The 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activities of the methanol and hot water extracts (2.0 mg/ml) of R. rosacea were comparable with BHT, the positive control. The chelating effects of the mushroom and hot water extracts were significantly higher than that of BHT. The reducing power of methanol and hot water extract (6 mg/ml) were significantly lower than that of BHT. Seven phenolic compounds were detected from acetonitrile and hydrochloric acid solvent extract of the mushroom. alpha-amylase and alpha-glucosidase inhibitory activities of methanol and hot water extracts were lower than that of acarbose, the positive control. The acetylcholinesterase and butyrylcholinesterase inhibitory effects were moderate compared with galanthamine, the standard drug. Nitric oxide (NO) production in lipopolysaccharide (LPS) induced RAW 264.7 cells were inhibited significantly by the mushroom extracts in a concentration dependent manner. Therefore, we demonstrated that fruiting bodies of R. rosacea possess in vitro antioxidant, anti-hyperglycemic, anti-cholinesterase, and NO production inhibitory activities. The experimental results suggest that the fruiting bodies of R. rosacea are good natural antioxidant, anti-hyperglycemic, anti-cholinesterase, and anti-inflammatory sources.

After a mixed carbohydrate diet, inhibition of α-amylase and α-glucosidase involved in the digestion and absorption of carbohydrates can significantly decrease the postprandial increase of blood glucose level. In the course of screening these useful enzyme inhibitors, we selected five kinds of bean, using an in-vitro enzyme inhibition assay method. To evaluate the effect of germination process on the functionality of the bean, we investigated the inhibitory activities of the water extracts of non-germinated bean and germinated bean against α-amylase and α-glucosidase, relevant to postprandial hyperglycemia. We also investigated the oxygen radical absorbance capacity(ORAC), total phenolics content, and postprandial blood glucose lowering effect in rats(Sprague-Dawley rat model). Most germinated beans showed significantly higher α-glucosidase inhibitory activity, compared with non-germinated beans. Among germinated beans, Glycine max had the highest α-glucosidase inhibitory activity(53.3%). The water extract of germinated Phaseolus vulgaris L. had the highest α-amylase inhibitory activity(95.1%), followed by Glycine max(58.7%), and Glycine max L. Merr(54.1%). Furthermore, the five germinated beans also showed high antioxidant activities in ORAC assay. Results suggested that the germination process may improve and enhance the anti-hyperglycemia potential and antioxidant activity of the bean.

The inhibitory activities of a water extract of Sanghwang mushroom(Phellinus linteusau)(SWE) against α-glucosidases were evaluated in this study. Inhibiting these enzymes involved in the absorption of disaccharides significantly decreases the postprandial increase in blood glucose level after a mixed carbohydrate diet. Oxygen radical absorbance capacity and 1, 1-diphenyl-2-picryl hydrazyl scavenging activities of the SWE were evaluated to investigate the antioxidant activity of the SWE associated with complications of long-term diabetes. Furthermore, the postprandial blood glucose lowering effect of SWE was compared to a known type 2 diabetes drug(Acarbose®) in a Sprague-Dawley rat model. SWE significantly reduced the blood glucose increase after sucrose loading. These results suggest that SWE, which has high α-glucosidase inhibitory activity and high antioxidant activities, has the potential to contribute to a useful dietary strategy for controlling postprandial hyperglycemia.

Inhibition of α-glucosidasesinvolved in the digestion and absorption of carbohydrates can decrease the postprandial increase of blood glucose level after a mixed carbohydrate diet. Therefore, we investigated the changes in α-glucosidase inhibitory activity of wheat during germination process. We also investigated total phenolics and oxygen radical absorbance capacity (ORAC) during germination process of wheat. Wheat was germinated for 0, 12, 24 and 48 hrs and results showed that both phenolic contents and α-glucosidase inhibitory activities increased with germination time. More specifically, total phenolic content increased from (293mg/100g-F.W.) at 0 hrs germination to a high (4,082mg/100g-F.W.) achieved after 48 hrs germination. Additionally, alpha-glucosidase inhibitory activity was dramatically increased from a low 10% inhibition at 0 hrs germination to a high 60% inhibitory activity observed at 48 hrs. These results suggest that wheat, depending on the germination time, has the potential to contribute as a dietary supplement for controlling hyperglycemia and oxidative stress-linked diabetes complications. It may due to the natural response of plant seed to overcome the biotic/abiotic stress from environment during germination period.