Enhanced insulin-hypoglycemic activity in rats consuming a specific glycoprotein extracted from maitake mushroom

SX-fraction: Promise for novel treatment of type 2 diabetes

SX-fraction (SXF) is a bioactive glycoprotein with anti-diabetic and hypoglycemic activities that have been documented in several reports. We have reviewed those studies herein and also explored the possible mechanism of its hypoglycemic activity. The early animal studies of SXF using diabetic mice showed the significant reduction in the three diabetic parameters, serum glucose, insulin, and triglyceride, suggesting its anti-diabetic activity. The limited clinical studies also showed that SXF led to the significant reduction in the fasting blood glucose levels of type 2 diabetic patients within 2 wk or a month, suggesting its hypoglycemic activity. To explore the hypoglycemic mechanism of SXF, its possible effects on the insulin signal transduction pathway was examined in vitro. Particularly, activities of insulin receptor, insulin receptor substrate 1, and protein kinase B, which are essential elements playing a key regulatory role in the signal pathway, were studied using skeletal muscle L6 cells. The status of these three parameters were examined under a high glucose (35 mmol/L) milieu with SXF and assessed using the enzyme-linked immunosorbent assay. Such studies revealed that all three parameters (insulin receptor, insulin receptor substrate 1, and protein kinase B) were inactivated by high glucose, indicating a disruption of the signal pathway. However, such an inactivation was reversed or re-activated by SXF to successfully carry out the sequential signaling events. In fact, a measurement of glucose uptake in cells showed that SXF did increase a glucose uptake while high glucose decreased it. Therefore, SXF has anti-diabetic and hypoglycemic activities through activation of the insulin signal pathway and appears to be a safe, natural agent for lowering the serum glucose levels in type 2 diabetic patents and improving their diabetic conditions.

Role of edible mushroom as a potent therapeutics for the diabetes and obesity

Diabetes and obesity are the most frequently found disease worldwide. Several factors are responsible for obesity, i.e., imbalance in energy expenditure, environmental factors, feeding habit, lifestyle, etc., which can also be responsible for type 2 diabetes mellitus. There are several synthetic drugs available to combat these diseases which have some side effects on sufferers. Therefore, people are shifting towards inexpensive, effective, widely available natural and herbal medicines. Edible mushrooms, which have been used from ancient time to cure these diseases, contain anti-oxidant, fibers, triterpenoids, alkaloid, and other phytochemicals. Comatin, β-glucan, Tremellastin, and Lentinan KS-2 are active chemicals of mushrooms which show great effect on diabetes mellitus and obesity by modulating either cellular function or biochemical pathways. Here, in this review, we have discussed the potential role of edible mushrooms and its biochemicals in control of diabetes and obesity. Using Bioinformatics, we can find the specific targets of theses biochemicals, so that these can be more effective.

CE–MS-based metabolomics reveals the metabolic profile of maitake mushroom (Grifola frondosa) strains with different cultivation characteristics

Maitake mushroom (Grifola frondosa [Dicks.] Gray) is generally cultured using the sawdust of broadleaf trees. The maitake strain Gf433 has high production efficiency, with high-quality of fruiting bodies even when 30% of the birch sawdust on the basal substrate is replaced with conifer sawdust. We performed metabolome analysis to investigate the effect of different cultivation components on the metabolism of Gf433 and Mori52 by performing CE–MS on their fruiting bodies in different cultivation conditions to quantify the levels of amino acids, organic acids, and phosphorylated organic acids. We found that amino acid and organic acid content in Gf433 were not affected by the kind of sawdust. However, Gf433 contained more organic acids and less amino acids than Mori52, and Gf433 also contained more chitin compared with Mori52. We believe that these differences in the metabolome contents of the two strains are related to the high production efficiency of Gf433.

Hypoglycemic effects of Grifola frondosa (Maitake) polysaccharides F2 and F3 through improvement of insulin resistance in diabetic rats

This study demonstrated the hypoglycemic effects of Grifola frondosa polysaccharides F2 and F3 through insulin sensitivity improvement in diabetic rats.

White vegetables: glycemia and satiety

The objective of this review is to discuss the effect of white vegetable consumption on glycemia, satiety, and food intake. White vegetables is a term used to refer to vegetables that are white or near white in color and include potatoes, cauliflowers, turnips, onions, parsnips, white corn, kohlrabi, and mushrooms (technically fungi but generally considered a vegetable). They vary greatly in their contribution to the energy and nutrient content of the diet and glycemia and satiety. As with other foods, the glycemic effect of many white vegetables has been measured. The results illustrate that interpretation of the semiquantitative comparative ratings of white vegetables as derived by the glycemic index must be context dependent. As illustrated by using the potato as an example, the glycemic index of white vegetables can be misleading if not interpreted in the context of the overall contribution that the white vegetable makes to the carbohydrate and nutrient composition of the diet and their functionality in satiety and metabolic control within usual meals. It is concluded that application of the glycemic index in isolation to judge the role of white vegetables in the diet and, specifically in the case of potato as consumed in ad libitum meals, has led to premature and possibly counterproductive dietary guidance.

Possible hypoglycemic action of SX-fraction targeting insulin signal transduction pathway

BACKGROUND

SX-fraction (SXF) is a bioactive glycoprotein with hypoglycemic activity that has been demonstrated in our pilot clinical study. However, how it would actually work in diabetic patients remains unclear. To explore such a mechanism, the effects of SXF on the insulin signal transduction pathway were investigated using skeletal muscle L6 cells in vitro.

METHODS

L6 cells were first differentiated to myotubes expressing several biochemical parameters that were examined in this study. Myotubes were exposed to a high concentration (35 mM) of glucose (Glc) alone or in combination with SXF or insulin for 24 hours. Possible effects of these agents on activities of insulin receptor (IR), IR substrate 1 (IRS-1), and Akt, which are key elements involved in the signal pathway, were assessed using enzyme-linked immunosorbent assay (ELISA). Any changes in Glc uptake were also determined.

RESULTS

High Glc indeed led to inactivation of IR, IRS-1, and subsequent Akt in myotubes, indicating an interruption of the signal pathway. However, such inactivation was reversed or reactivated by SXF, presumably aiding the occurrence of successive signaling events. Measurement of Glc uptake to assess the outcome of this signaling cascade showed that high Glc decreased Glc uptake (interfering with the signal pathway), but SXF was capable of overcoming such a suppressive effect, resulting in the increased Glc uptake. Insulin was used as a positive control in this study and all results were nearly compatible to those obtained from SXF.

CONCLUSION

The present study suggests that SXF may specifically target the insulin signal pathway, and, in particular, the IR and IRS-1 therein that trigger the subsequent signaling events. As a result, SXF could activate such an impaired signal pathway through high Glc or under a hyperglycemic milieu, thereby ultimately facilitating Glc uptake. This may then account for possible hypoglycemic action of SXF.

Hypoglycemic effects of Ganoderma lucidum polysaccharides in type 2 diabetic mice

Our aims were to investigate the hypoglycemic effects and mechanisms of action of Ganoderma lucidum polysaccharides (GLPs) administered for 7 days in type 2 diabetic mice. The mice were randomly divided into four groups (8 mice/group): normal control group, diabetic control group, low-dose GLP-treated diabetic group (50 mg/kg/d), and high-dose GLP-treated diabetic group (100 mg/kg/d). Diabetes was induced by streptozotocin injection and high-fat dietary feeding. At the end of the study, fasting serum glucose, insulin, body weight (BW) and epididymal white adipose tissue weight were measured. The hepatic mRNA levels of glycogen phosphorylase (GP), fructose-1,6-bisphosphatase (FBPase), phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) genes were determined by real-time polymerase chain reaction. Both doses of GLPs significantly decreased fasting serum glucose, insulin and epididymal fat/BW ratio compared with the diabetic control group (p < 0.05). The hepatic mRNA levels of GP, FBPase, PEPCK and G6Pase were significantly lower in both GLP-treated groups compared with the diabetic control group. Taken together, GLPs significantly decrease fasting serum glucose levels in type 2 diabetic mice in a dose-dependent manner. The decreases in fasting serum glucose levels may be associated with decreased mRNA expression levels of several key enzymes involved in gluconeogenesis and/or glycogenolysis.

Profiling of hepatic gene expression of mice fed with edible japanese mushrooms by DNA microarray analysis: comparison among Pleurotus ostreatus, Grifola frondosa, and Hypsizigus marmoreus

To compare and estimate the effects of dietary intake of three kinds of mushrooms (Pleurotus ostreatus, Grifola frondosa, and Hypsizigus marmoreus), mice were fed a diet containing 10-14% of each mushroom for 4 weeks. Triacylglycerol in the liver and plasma decreased and plasma cholesterol increased in the P. ostreatus-fed group compared with those in the control group. Cholesterol in the liver was lower in the G. frondosa-fed group than in the control group, but no changes were found in the H. marmoreus-fed group. DNA microarray analysis of the liver revealed differences of gene expression patterns among mushrooms. Ctp1a and Fabp families were upregulated in the P. ostreatus-fed group, which were considered to promote lipid transport and β-oxidation. In the G. frondosa-fed group, not only the gene involved in signal transduction of innate immunity via TLR3 and interferon but also virus resistance genes, such as Mx1, Rsad2, and Oas1, were upregulated.

Maitake mushroom (Grifola frondosa) extract induces ovulation in patients with polycystic ovary syndrome: a possible monotherapy and a combination therapy after failure with first-line clomiphene citrate

BACKGROUND

Insulin resistance is a prominent feature of polycystic ovary syndrome (PCOS), and insulin-sensitizing drugs are used to induce ovulation. Recently, it was reported that an extract from Maitake mushroom (Grifola frondosa) improves insulin resistance.

OBJECTIVES

The objective was to explore the effects of Maitake extract (SX-fraction: MSX) to induce ovulation in patients with PCOS in comparison with and in combination with clomiphene citrate (CC).

DESIGN

We conducted an open trial with 80 patients with PCOS at three clinics in Japan. Seventy-two (72) new patients were randomly assigned to receive MSX or CC monotherapy for up to 12 weeks. Eighteen (18) patients who did not respond to MSX or CC were subjected to combination therapy of MSX and CC for up to 16 weeks. Eight (8) patients with documented history of failure to CC received combination therapy from the beginning. Ovulation was assessed by ultrasonography.

RESULTS

Twenty-six (26) patients in the MSX group and 31 in the CC group were evaluated for ovulation. The ovulation rates for MSX and CC were as follows: 76.9% (20/26) and 93.5% (29/31), respectively by the patients (NS), and 41.7% (30/72) and 69.9% (58/83), respectively, by the cycles (p = 0.0006). In the combination therapy, 7 of 7 patients who failed in MSX monotherapy and 6 of 8 patients who failed in CC monotherapy showed ovulation.

CONCLUSIONS

The present study suggests that MSX alone may induce ovulation in PCOS patients and may be useful as an adjunct therapy for patients who failed first-line CC treatment.