Sasa borealis extract exerts an antidiabetic effect via activation of the AMP-activated protein kinase

Leaf of Sasa borealis, a species of bamboo, has been reported to exhibit anti-hyperglycemic effect. However, its antidiabetic mechanism is not fully understood. In this study, we examined whether an extract of S. borealis activates AMP-activated protein kinase (AMPK) and exerts anti-hyperglycemic effects. Treatment with the S. borealis extract increased insulin signaling and phosphorylation of AMPK and stimulated the expression of its downstream targets, including PPARalpha, ACO, and CPT-1 in C2C12 cells and PPARalpha in HepG2 cells. However, inhibition of AMPK activation attenuated insulin signaling and prevented the stimulation of AMPK target genes. The S. borealis extract increased glucose uptake in C2C12 cells and suppressed expression of the gluconeogenic gene, PEPCK in HepG2 cells. The extract significantly reduced blood glucose and triglyceride levels in STZ-induced diabetic mice. The extract enhanced AMPK phosphorylation and increased Glut-4 expression in the skeletal muscle of the mice. These findings demonstrated that the S. borealis extract exerts its anti-hyperglycemic effect through activation of AMPK and enhancement of insulin signaling.

Effects of Sasa Borealis Leaf Extract on the Glucose Tolerance of Major Foods for Carbohydrate

Sasa borealis leaf has been known to have anti-diabetic properties. In this study, we tried to evaluate the effects of Sasa borealis leaf extract (SBE) on the inhibition of alpha-glucosidase activity and postprandial glycemic response following ingestion of four carbohydrate-rich foods; cooked rice, ramen (instant noodle), noodle, and bread. Fourteen healthy female adults consumed 50 g of glucose (control) or one of the four foods containing 50 g of available carbohydrate with or without 2,000 mg of SBE. The activity of alpha-glucosidase was inhibited dose-dependently by SBE. With SBE, blood glucose concentration at 15 min and the positive area under the curve (AUC) of postprandial glycemic response at 15 min and 30 min after consuming each of the four foods were reduced significantly. As the result, total positive AUC during 120 min was decreased in case of taking cooked rice or bread. Glycemic index and glycemic load of the four foods were declined from 13% to 23% with SBE. The results of this study suggest that SBE may be effective for postprandial glucose control by inhibiting alpha-glucosidase activity.

Sasa borealis leaves extract improves insulin resistance by modulating inflammatory cytokine secretion in high fat diet-induced obese C57/BL6J mice

Obesity is considered a mild inflammatory state, and the secretion of inflammation-related cytokines rises as adipose tissue expands. Inflammatory cytokines, including tumor necrosis factor-alpha (TNF-alpha), interlukin 6 (IL-6) and monocyte-chemoattractant protein 1 (MCP-1), are modulated by adipose tissue and known to play an important role in insulin resistance which is the common characteristics of obesity related disorders. In this study we analyzed the effects of Sasa borealis leaves extract on inflammatory cytokines and insulin resistance in diet induced obese C57/BL6J mice. The obese state was induced by a high fat diet for 20 weeks and then the mice were divided into two groups; obese control group (OBC, n = 7) and experimental group (OB-SBE, n = 7). The OBC group was fed a high fat diet and the OB-SBE group was fed a high fat diet containing 5% Sasa borealis leaves extract (SBE) for 12 weeks. We also used mice fed a standard diet as a normal control (NC, n = 7). The body weight and adipose tissue weight in the OB group were significantly higher than those in the NC group. The effects of the high fat diet were reduced by SBE treatments, and the body weight and adipose tissue deposition in the OB-SBE group were significantly decreased compared to the OBC group. The OBC group showed higher serum glucose and insulin levels which resulted in a significant increase of incremental area under the curve (IAUC) and HOMA-IR than the NC group. Also, serum leptin, TNF-alpha, and IL-6 levels were significantly higher in the OBC group than in the NC group. In contrast, the OB-SBE group showed a reversal in the metabolic defects, including a decrease in glucose, insulin, IAUC, HOMA-IR, TNF-alpha, IL-6 and leptin levels. These results suggest that BSE can suppress increased weight gain and/or fat deposition induced by a high fat diet and theses effects are accompanied by modulation of the inflammatory cytokines, TNF-alpha and IL-6 secretion resulting in improved insulin resistance.

The Effects of the Sasa Borealis Leaves Extract on Plasma Adiponectin, Resistin, C-Reactive Protein and Homocysteine Levels in High Fat Diet-Induced Obese C57/BL6J Mice

As obesity is known to be related to hyperlipidemia, diabetes and coronary heart disease, and other chronic diseases, many researches have focused on functional food materials showing anti-obesity activity. The adipokines secreted by adipose tissue, resistin and adiponectin are known to play an important role in the pathogenesis of chronic diseases directly. C-reactive protein and homocysteine are molecules regulated by adipose tissue indirectly also relate to the chronic diseases. This study was performed to study of the anti-obesity effects of Sasa borealis in diet-induced obese mice (C57/BL6J). The mice were divided into four group: NFD (Normal fat diet), HFD (High fat diet), BSE (High fat diet containing 5% of 70% ethanol extract of Sasa borealis leaves), BLW (High fat diet containing 5% of water extract of Sasa borealis leaves). The experimental diets were fed for 11 weeks. The final body weight of the mice in the groups of BSE and BLW groups were significantly lower than the HFD group. The effects of weight reduction were due to reduced body fat accumulation. The adiponectin levels are significantly decreased in HFD group compared than NFD group and increased taken by Sasa borealis containing diet. The resistin levels are not significantly different between experimental groups. The CRP and homocyteine levels are significantly higher in HFD group than NFD group and significantly decreased by Sasa borealis containing diet, especially BLW group. These results indicate that orally administered Sasa borealis not only has the effect of reducing the body weight and total fat weight, but preferable effect in adiponectin levels and related molecules as CRP and homocysteine. Therefore we expect the Sasa borealis may have an anti-obesity function and anti-metabolic syndrome effect in diet-induced obese mice.