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Protein tyrosine phosphatase 1 B (PTP1B) is one of main causes involved in type 2 diabetes, it dephosphorylates insulin receptor substrate (IRS) and dysregulates insulin signaling pathway, thus inducing insulin resistance. Our previous work first reported that FYGL, a neutral hyperbranched proteoglycan ingredient extracted from Ganoderma lucidum, has hypoglycemic activity in vivo and inhibitory potency on PTP1B in vitro, but the underlying mechanism was still unclear. In this study, we sought to investigate effects of FYGL on insulin signaling pathway involved with PTP1B as the targeting point in hepatocytes. We found that FYGL inhibited overexpression of PTP1B in liver tissues of ob/ob mice and HepG2 cells, significantly improved the phosphorylation of IRS1 on tyrosine residues, activated phosphatidylinositol-3 kinase (PI3K)/protein kinase B (Akt) cascades and increased phosphorylation of glycogen synthesis kinase-3β (GSK3β), finally enhanced insulin-stimulated glycogen synthesis in HepG2 cells and decreased blood glucose in insulin resistance model mice. Our study clearly illustrated the hypoglycemic mechanism of a novel proteoglycan possibly used in type 2 diabetes management in vivo., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Presently, an efficient protein tyrosine phosphatase 1B (PTP1B) inhibitor, named FYGL-n, was isolated from Ganoderma Lucidum and characterized for its structure and bioactivity. Structure and chain conformation of FYGL-n based on both chemical and spectroscopic analysis showed that FYGL-n was a hyperbranched heteropolysaccharide bonded with protein via both serine and threonine residues by O-type glycoside, and showed a sphere observed by AFM. Specifically, monosaccharide composition indicated that FYGL-n consisted of D-arabinose, D-galactose, L-rhamnose and D-glucose in a mole ratio of 0.08:0.21:0.24:0.47, with a molecular mass of 72.9 kDa. The analysis of amino acids in FYGL-n indicated that there were 16 common amino acids, among which aspartic acid, glycine, serine, alanine, glutamic acid and threonine were the dominant components. Also it was demonstrated that FYGL-n could inhibit the PTP1B activity on a competitive mechanism in vitro., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Diabetic nephropathy (DN) is the major cause of morbidity among diabetic patients. Thus, antidiabetic drugs with protection potential in the kidneys would have a higher therapeutic value. The effects of a novel proteoglycan, named FYGL, isolated from G. lucidum fruiting bodies, on the kidney function were investigated systematically in present work. FYGL (250 mg/kg) not only dosedependently reduced the blood glucose concentration (23.5%, p<0.05), kidney/body weight ratio (23.6%, p<0.01), serum creatinine (33.1%, p<0.01), urea nitrogen (24.1%, p<0.01),urea acid contents (35.9%, p<0.01) and albuminuria (30.7%, p<0.01)of DN mice compared to the untreated DN mice but also increased the renal superoxide dismutase (75.3%, p<0.01), glutathione peroxidase (35.0%, p<0.01) and catalase activities (58.5%, p<0.01) compared to the untreated DN mice. The decreasing of renal malondialdehyde content (34.3%, p<0.01) and 8-hydroxy-2'-deoxyguanosine expression (2.5-fold, p<0.01) were also observed in FYGL-treated DN mice compared to the untreated DN mice, along with an amelioration of renal morphologic abnormalities. We conclude that FYGL confers protection against the renal functional and morphologic injuries by increasing activities of antioxidants and inhibiting accumulation of oxidation, suggesting a potential nutritional supplement for the prevention and therapy of DN., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Previously, we screened a proteoglycan for anti-hyperglycemic, named FYGL, from Ganoderma Lucidum. For further research of the antidiabetic mechanisms of FYGL in vivo, the glucose homeostasis, activities of insulin-sensitive enzymes, glucose transporter expression and pancreatic function were analyzed using db/db mice as diabetic models in the present work. FYGL not only lead to a reduction in glycated hemoglobin level, but also an increase in insulin and C-peptide level, whereas a decrease in glucagons level and showed a potential for the remediation of pancreatic islets. FYGL also increased the glucokinase activities, and simultaneously lowered the phosphoenol pyruvate carboxykinase activities, accompanied by a reduction in the expression of hepatic glucose transporter protein 2, while the expression of adipose and skeletal glucose transporter protein 4 was increased. Moreover, the antioxidant enzyme activities were also increased by FYGL treatment. Thus, FYGL was an effective antidiabetic agent by enhancing insulin secretion and decreasing hepatic glucose output along with increase of adipose and skeletal muscle glucose disposal in the late stage of diabetes. Furthermore, FYGL is beneficial against oxidative stress, thereby being helpful in preventing the diabetic complications.

Previously, we screened a proteoglycan for anti-hyperglycemic, named FYGL, from Ganoderma Lucidum. For further research of the antidiabetic mechanisms of FYGL in vivo, the glucose homeostasis, activities of insulin-sensitive enzymes, glucose transporter expression and pancreatic function were analyzed using db/db mice as diabetic models in the present work. FYGL not only lead to a reduction in glycated hemoglobin level, but also an increase in insulin and C-peptide level, whereas a decrease in glucagons level and showed a potential for the remediation of pancreatic islets. FYGL also increased the glucokinase activities, and simultaneously lowered the phosphoenol pyruvate carboxykinase activities, accompanied by a reduction in the expression of hepatic glucose transporter protein 2, while the expression of adipose and skeletal glucose transporter protein 4 was increased. Moreover, the antioxidant enzyme activities were also increased by FYGL treatment. Thus, FYGL was an effective antidiabetic agent by enhancing insulin secretion and decreasing hepatic glucose output along with increase of adipose and skeletal muscle glucose disposal in the late stage of diabetes. Furthermore, FYGL is beneficial against oxidative stress, thereby being helpful in preventing the diabetic complications. [ABSTRACT FROM AUTHOR]