monascin and Diabetes-Mellitus

Edible fungi of the Monascus species have been used as traditional Chinese medicine in eastern Asia for several centuries. Monascus-fermented products possess a number of functional secondary metabolites, including the anti-inflammatory pigments monascin and ankaflavin. Monascin has been shown to prevent or ameliorate several conditions, including hypercholesterolemia, hyperlipidemia, diabetes, and obesity. Recently, monascin has been shown to improve hyperglycemia, attenuate oxidative stress, inhibit insulin resistance, and suppress inflammatory cytokine production. In our recent study, we have found that monascin is a peroxisome proliferator-activated receptor-gamma (PPARgamma) agonist. The PPARgamma agonist activity had been investigated and its exerted benefits are inhibition of inflammation in methylglyoxal (MG)-treated rats, prevention of pancreas impairment causing advanced glycation endproducts (AGEs), promotion of insulin expression in vivo and in vitro, and attenuated carboxymethyllysine (CML)-induced hepatic stellate cell (HSC) activation in the past several years. Moreover, our studies also demonstrated that monascin also activated nuclear factor-erythroid 2-related factor 2 (Nrf2) in pancreatic RIN-m5F cell line thereby invading methylglyoxal induced pancreas dysfunction. In this review, we focus on the chemo-preventive properties of monascin against metabolic syndrome through PPARgamma and Nrf2 pathways.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Diabetes Mellitus; Flavins; Glycation End Products, Advanced; Heterocyclic Compounds, 3-Ring; Humans; Hypoglycemic Agents; Insulin; Liver; Monascus; NF-E2-Related Factor 2; Pancreas; PPAR gamma; Rats

Monascin (MS) is a yellow compound isolated from Monascus-fermented products that has pancreatic protective, anti-inflammatory, anti-oxidative, and hypolipidemic activity. We recently found that MS also acts as a peroxisome proliferator-activated receptor-gamma (PPARγ) agonist, thereby promoting insulin sensitivity in C2C12 cells. However, the attenuation of hyperglycemia by MS treatment in vivo remains uncertain. In the present study, both MS and pioglitazone significantly down-regulated blood glucose and hyperinsulinemia in fructose-rich diet (FRD)-induced C57BL/6 mice (8 weeks). In addition, inhibitions of inflammatory factor production, serum dyslipidemia, and hepatic fatty acid accumulation by MS and pioglitazone were attenuated by GW9662 (PPARγ antagonist). These results were mediated by MS-suppressing FRD-elevated lipogenic transcription factors, including sterol regulatory element-binding protein-1c (SREBP-1c), carbohydrate response element-binding protein (ChREBP), PPARγ coactivator-1α (PGC-1α), and PPARγ coactivator-1β (PGC-1β). Taken together, de novo lipogenesis results in hyperlipidemia and hyperglycemia by fructose induction thereby leading to diabetes development; we found that MS may inhibit lipogenesis in FRD-induced mice. These findings suggest that MS acts as an antidiabetic agent and thus may have therapeutic potential for prevention of diabetes.

Topics: Animals; Diabetes Mellitus; Down-Regulation; Dyslipidemias; Female; Fructose; Heterocyclic Compounds, 3-Ring; Humans; Lipogenesis; Male; Mice; Mice, Inbred C57BL; Monascus; Plant Extracts; PPAR gamma; Sterol Regulatory Element Binding Protein 1

Several lines of evidence have implicated high levels of advanced glycation endproducts (AGEs) in diabetes. Pancreas impairment caused by AGEs has been found in recent studies. Monascin (MS) and monacolin K (MK) are active compounds identified from Monascus-fermented products, which have been reported to inhibit inflammation and improve insulin resistance. In order to confirm the protective effects of MS and MK on pancreatic function, BALB/c mice were treated with AGEs via intraperitoneal injection for 22 weeks to induce hyperglycemia, and the pancreas-protecting mechanism of MS and MK from AGE-induced damage was investigated. We found that the expression of pancreatic and duodenal homeobox-1 (PDX-1) and glucose transporter 2 (GLUT2) was recovered by MS or MK administration to AGE-treated mice. In addition, MS strongly improved performance in the oral glucose tolerance test (OGTT) and the insulin tolerance test (ITT), suggesting that MS sensitized to insulin in AGE-treated mice. Both MS and MK elevated pancreatic insulin expression when compared to the AGE-treated group, suggesting that MS and MK attenuated AGE-induced pancreatic dysfunction. Histopathology studies showed that intraperitoneal injection of AGEs did not result in pancreas damage. These findings confirm that the potential mechanism of AGEs on pancreatic dysfunction involves the induction of inflammation and the suppression of PDX-1 and GLUT2 expression. Taken together, MS and MK may be developed as an anti-diabetic agent in the future.

Topics: Animals; Diabetes Mellitus; Female; Fermentation; Glucose Tolerance Test; Glycation End Products, Advanced; Heterocyclic Compounds, 3-Ring; Humans; Hyperglycemia; Hypoglycemic Agents; Insulin; Insulin Resistance; Lovastatin; Male; Mice; Mice, Inbred BALB C; Monascus; Oryza; Pancreas