Monacolin K and monascin attenuated pancreas impairment and hyperglycemia induced by advanced glycation endproducts in BALB/c mice

In Vitro, In Silico, and In Vivo Studies of Cardamine hirsuta Linn as a Potential Antidiabetic Agent in a Rat Model

Diabetes mellitus (T2DM) is a multifaceted metabolic disorder with no definite treatment. In silico characterization can help to explain the interaction between molecules and predict 3D structures. The aim of the present study was to evaluate the hypoglycemic activities of the hydro-methanolic extract of Cardamine hirsuta in a rat model. In vitro antioxidant and α-amylase inhibitory assays were evaluated in the present study. Phyto-constituents were quantified using RP-UHPLC-MS analysis. Molecular docking of compounds into the binding site of different molecular targets, i.e., tumor necrosis factor (TNF-α), glycogen synthase kinase 3 β (GSK-3β), and AKT, was carried out. Acute toxicity model, in vivo antidiabetic effect, and the influence on biochemical and oxidative stress parameters were also investigated. T2DM was induced in adult male rats by streptozotocin using a high-fat diet model. Three different doses (125, 250, and 500 mg/kg BW) were orally gavaged for 30 days. Mulberrofuran-M and quercetin3-(6″caffeoylsophoroside) have demonstrated remarkable binding affinity toward TNF-α and GSK-3β, respectively. 2,2-Diphenyl-1-picrylhydrazyl and α-amylase inhibition assay exhibited IC50 values of 75.96 and 73.66 μg/mL, respectively. In vivo findings exhibited that 500 mg/kg body weight (BW) dose of the extract significantly decreased the blood glucose level, improved biochemical parameters as well as oxidative stress by reduction of lipid peroxidation, and increased high-density lipoproteins. Moreover, activities of glutathione-s-transferase, reduced glutathione, superoxide dismutase were enhanced, and cellular architecture in the histopathological examination was restored in treatment groups. The present study affirmed the antidiabetic activities of mulberrofuran-M and quercetin3-(6″caffeoylsophoroside) present in the hydro-methanolic extract of C. hirsuta, possibly due to the reduction in oxidative stress and α-amylase inhibition.

Advanced Glycation End Products (AGEs) Inhibit Macrophage Efferocytosis of Apoptotic β Cells through Binding to the Receptor for AGEs

Pancreatic β cell apoptosis is important in the pathogenesis of type 2 diabetes mellitus (T2DM). Generally, apoptotic β cells are phagocytosed by macrophages in a process known as "efferocytosis." Efferocytosis is critical to the resolution of inflammation and is impaired in T2DM. Advanced glycation end products (AGEs), which are increased in T2DM, are known to suppress phagocytosis function in macrophages. In this study, we found that AGEs inhibited efferocytosis of apoptotic β cells by primary peritoneal macrophages in C57BL/6J mice or mouse macrophage cell line Raw264.7. Mechanistically, AGEs inhibit efferocytosis by blocking Ras-related C3 botulinum toxin substrate 1 activity and cytoskeletal rearrangement through receptor for advanced glycation end products/ras homolog family member A/Rho kinase signaling in macrophages. Furthermore, it was observed that AGEs decreased the secretion of anti-inflammatory factors and promoted the proinflammatory ones to modulate the inflammation function of efferocytosis. Taken together, our results indicate that AGEs inhibit efferocytosis through binding to receptor for advanced glycation end products and activating ras homolog family member A/Rho kinase signaling, thereby inhibiting the anti-inflammatory function of efferocytosis.

Anti-diabetic effects of astaxanthin on an STZ-induced diabetic model in rats

Type 2 diabetes mellitus (T2DM), which is characterized by insulin resistance and relative insulin insufficiency, has become the most common chronic metabolic disease threatening global health. The preferred therapies for T2DM include lifestyle interventions and the use of anti-diabetic drugs. However, considering their adverse reactions, it is important to find a low-toxicity and effective functional food or drug for diabetes prevention and treatment. Astaxanthin is a potent antioxidant carotenoid found in marine organisms has been reported to prevent diet-induced insulin resistance and hepatic steatosis. To investigate the anti-diabetic effects of astaxanthin, male Wistar rats were fed a high-energy diet for 4 weeks, followed by a low dose streptozotocin (STZ) injection to induce the diabetes model, and the rats were then fed an astaxanthin-containing diet for another 3 weeks. Astaxanthin significantly decreased blood glucose and total cholesterol (TC) levels, and increased blood levels of high density lipoprotein cholesterol (HDL-C) in STZ-induced diabetic rats in a dose dependent manner. These results were associated with increased expression of insulin sensitivity related genes (adiponectin, adipoR1, and adipoR2) in vivo, thereby attenuating STZ-induced diabetes. In addition, we also compared the anti-diabetic effects of astaxanthin and monacolin K, which has been reported to downregulate hyperlipidemia and hyperglycemia. The results revealed that astaxanthin and monacolin K showed similar anti-diabetic effects in STZ-induced diabetic rats. Therefore, astaxanthin may be developed as an anti-diabetic agent in the future.

Red yeast rice prevents chronic alcohol-induced liver disease by attenuating oxidative stress and inflammatory response in mice

Alcoholic liver disease (ALD) is characterized by dyslipidemia, hepatic steatosis, steatohepatitis, edema, necrosis, etc. Studies have reported that some dietary nutrition factors have beneficial effects in improving ALD. Red yeast rice (RYR), a traditional herbal supplement, has been confirmed to lower cholesterol mainly due to its component monacolin K. However, the effect of RYR on ALD has not been investigated. In this study, mice were supplemented with a daily oral gavage of 4 g/kg 50% ethanol for 8 weeks to induce a chronic ALD. RYR (150 mg kg^-1  day^-1 ) was supplied to ALD mice in treatment group. The results showed that RYR supplementation significantly attenuated hyperlipidemia, elevated circulating inflammatory cytokines, hepatic structural damage, and oxidative stress in mice supplemented with alcohol with no effects on body weight. Moreover, RYR significantly suppressed alcohol-induced hepatic NF-κB activation and apoptosis. Our results suggest that RYR is capable of preventing ALD mainly by attenuating hepatic oxidative stress and inflammatory response. PRACTICAL APPLICATIONS: RYR was known for cholesterol-lowering effect through its main component monacolin K. The current study revealed that RYR was capable of ameliorating ALD, which is characterized by profound dyslipidemia, hepatic steatosis, steatohepatitis, edema, etc. Our results indicated that the protective effect of RYR on ALD is largely achieved by regulating lipid metabolism, and closely related to the anti-inflammatory and antioxidant effects of RYR. This study provides research foundation for the development of RYR-related food or pharmaceutical products, especially targeting for ALD.

An antidiabetic nutraceutical combination of red yeast rice (Monascus purpureus), bitter gourd (Momordica charantia), and chromium alleviates dedifferentiation of pancreatic β cells in db/db mice

Antidiabetic properties of red yeast rice, bitter gourd, and chromium have gained scientific support. This study aimed to test whether a nutraceutical combination of these 3 materials prevented dedifferentiation of pancreatic β cells. Male db/db mice (8 weeks of age) were allocated into four groups (DB, DB/L, DB/M, and DB/H; n = 8-10) and fed a high-fat diet containing 0%, 0.2%, 0.4%, or 1% nutraceutical, respectively, whereas wild-type mice receiving a standard diet served as a healthy control (C; n = 10). The nutraceutical contained 10 mg/g monacolin K, 165 µg/g chromium, and 300 mg/g bitter gourd. After 8-weeks dietary treatment, diabetic syndromes (including hyperglycemia, hyperphagia, excessive drinking, polyuria, glucosuria, albuminuria, and glucose intolerance), were improved by the nutraceutical in a dose-dependent fashion. Decreased insulin and increased glucagon in serum and pancreatic islets in db/db mice were abolished in the DB/H group. Furthermore, supplementation curtailed dedifferentiation of β cells, as evidenced by decreasing the dedifferentiation marker (Aldh1a3) and increasing β-cell-enriched genes and transcription factors (Ins1, Ins2, FOXO1, and NKX6.1), as well as nuclear localization of NKX6.1 in pancreatic islets when compared to the DB group. We concluded that this nutraceutical, a combination of Monascus purpureus, Momordica charantia, and chromium, could be used as an adjunct for type 2 diabetes treatment and delay disease progression by sustaining β-cell function.

Theoretical and experimental investigation of the antioxidative activity of monascin

Monascin, a specific type of monascus pigments, exhibits many bioactivities. In this study, the antioxidative activity of monascin was investigated by theoretical and experimental methods. First, the antioxidant potential of six monascus pigments was predicted by density functional theory (DFT) and time-dependent density functional theory (TDDFT) at the B3LYP/6-31+G (d, p) level, and monascus yellow pigments were predicted to have strong antioxidant capacity, as they can transfer hydrogen to free radicals and accept electrons from radicals. Then, the free radical-scavenging capacity of monascin for 2,2-diphenyl-1-picrylhydrazyl (DPPH), superoxide, and hydroxyl radicals was experimentally validated by electron spin resonance (ESR) measurement. Monascin exhibited a quenching effect on DPPH, superoxide, and hydroxyl radicals in a dose-dependent manner. Specifically, the scavenging activity of monascin for DPPH, superoxide, and hydroxyl radicals was 97.5%, 59.5%, and 68.6%, respectively, when 0.1 mg mL-1 monascin was present. Our study provides theoretical evidence for the strong antioxidative activity of monascin and offers a simple and reliable strategy to determine the antioxidative activity.

Monascin ameliorate inflammation in the lipopolysaccharide-induced BV-2 microglial cells via suppressing the NF-κB/p65 pathway

Objectives

The pathophysiology of neurodegenerative diseases is complicated, in which inflammatory reactions play a vital role. Microglia cells activation, an essential process of neuroinflammation, can produce neurotoxic molecules and neurotrophic factors, which aggravate inflammation and neuronal injury. Monascin, a major component of red yeast rice, is an azaphilonoid pigment with potential anti-inflammatory effects; however, the effects in central nervous system have not been evaluated. Our goal in this project was to explore the therapeutic effect and the underlying mechanism of Monascin, which may be via anti-inflammatory action.

Materials and Methods

We used lipopolysaccharide to induce BV-2 microglial cells in order to form an inflammation model in vitro. The anti-inflammatory effects of Monascin were measured by enzyme-linked immunosorbent assay (ELISA), real time-polymerase chain reaction (RT-PCR), Western Blot and Immunofluorescent staining.

Results

Our data indicated that inflammatory cytokines including interleukin-1β (IL-1β), IL-6, tumor necrosis factor-alpha (TNF-α) and nitric oxide were suppressed by Monascin treatment. Furthermore, the related pro-inflammatory genes were inhibited consistent with the results of ELISA assay. Western blotting results showed that the phosphorylation of nuclear factor kappa B (NF-κB/p65) was reduced by Monascin treatment may be through suppressing the activation of IκB. Furthermore, immunofluorescence staining showed that the translocation of NF-κB/p65 to the cellular nuclear was blockaded after Monascin treatment.

Conclusion

Taken together, Monascin exerts anti-inflammatory effect and suppressed microglia activation, which suggested its potential therapeutic effect for inflammation-related diseases.

Inhibition of advanced glycation endproducts during fish sausage preparation by transglutaminase and chitosan oligosaccharides induced enzymatic glycosylation

A non-antioxidative method in which glycosylation induced by transglutaminase “replaced” glycation to inhibit the formation of AGEs in real foods.

Monascin inhibits IL-1β induced catabolism in mouse chondrocytes and ameliorates murine osteoarthritis

Osteoarthritis (OA) is an age-related degenerative disease and is the fourth major cause of disability, but there are no effective therapies because of its complex pathology and the side effects of the drugs.

Alleviation of metabolic syndrome by monascin and ankaflavin: the perspective of Monascus functional foods

The metabolites of Monascus with multiple benefits are popular subjects for the development of functional foods. The yellow pigments, monascin and ankaflavin, which are the constituent metabolites of M. purpureus, M. pilosus and M. ruber, are becoming the focus of research on Monascus. Monascin and ankaflavin are azaphilone compounds with similar structures that exhibit multiple beneficial effects including anti-inflammation, anti-oxidation, anti-diabetes, immunomodulation, attenuation of Alzheimer's disease risk factor, and anti-tumorigenic effects. Monascin and ankaflavin not only possess pleiotropic bioactivities, but are also more potent than monacolin K in lowering lipid levels and have lower toxicity. Monascin and ankaflavin act as the activators of PPARγ agonist/Nrf-2 that subsequently ameliorate metabolic syndrome. Following the intensive exploration of Monascus bioactivities in recent years, the focus of research on Monascus-functional foods has shifted from whole fermented products/extracts to specific bioactive compounds. Therefore, the production of monascin and ankaflavin is an important topic with respect to Monascus-functional foods. Although several genomic studies have paved the way for understanding the production of secondary metabolites in Monascus, efforts are still required to effectively manipulate the biosynthesis of secondary metabolites with genetic engineering and/or culture techniques.

Monascin from Monascus-Fermented Products Reduces Oxidative Stress and Amyloid-β Toxicity via DAF-16/FOXO in Caenorhabditis elegans

Amyloid-β (Aβ)-induced oxidative stress and toxicity are leading risk factors for Alzheimer's disease (AD). Monascin (MS) is a novel compound proposed for antioxidative stress applications and is derived from an edible fungus secondary metabolite. This study assessed the effects of MS on oxidative stress, paralysis, Aβ accumulation, and lifespan in the nematode Caenorhabditis elegans and investigated its underlying mechanisms of action. The results showed that MS increased the survival of C. elegans under juglone-induced oxidative stress and attenuated endogenous levels of reactive oxygen species. Furthermore, MS induced a decline in Aβ-induced paralysis phenotype and Aβ deposits in the transgenic strains CL4176 and CL2006 of C. elegans, which expresses human muscle-specific Aβ1-42 in the cytoplasm of body wall muscle cells. In addition, mRNA levels of strain CL4176 of several antioxidant genes (sod-1, sod-2, sod-3, hsp16.2) and daf-16 were up-regulated by MS treatment when compared to the nontreated controls. Further evidence showed that MS treatment in C. elegans strains lacking DAF-16/FOXO did not affect paralysis or lifespan phenotypes. The findings indicate that MS reduces oxidative stress and Aβ toxicity via DAF-16 in C. elegans, suggesting that MS can be used for the prevention of AD-associated oxidative stress complications.

Scopoletin protects against methylglyoxal-induced hyperglycemia and insulin resistance mediated by suppression of advanced glycation endproducts (AGEs) generation and anti-glycation

Recently, several types of foods and drinks, including coffee, cream, and cake, have been found to result in high methylglyoxal (MG) levels in the plasma, thus causing both nutritional and health concerns. MG can be metabolized by phase-II enzymes in liver through the positive regulation of nuclear factor-erythroid 2-related factor 2 (Nrf2). In this study, we investigated the ability of scopoletin (SP) to protect against MG-induced hyperglycemia and insulin resistance. Recently, SP was shown to be a peroxisome proliferator-activated receptor-γ activator to elevate insulin sensitivity. We investigated the effects of oral administration of SP on the metabolic, biochemical, and molecular abnormalities characteristic of type 2 diabetes in MG-treated Wistar rats to understand the potential mechanism of scopoletin for diabetes protection. Our results suggested that SP activated Nrf2 by Ser40 phosphorylation, resulting in the metabolism of MG into d-lactic acid and the inhibition of AGEs generation, which reduced the accumulation of AGEs in the livers of MG-induced rats. In this manner, SP improved the results of the oral glucose tolerance test and dyslipidemia. Moreover, SP also increased the plasma translocation of glucose transporter-2 and promoted Akt phosphorylation caused by insulin treatment in MG-treated FL83B hepatocytes. In contrast, SP effectively suppressed protein tyrosine phosphatase 1B (PTP1B) expression, thereby alleviating insulin resistance. These findings suggest that SP acts as an anti-glycation and anti-diabetic agent, and thus has therapeutic potential for the prevention of diabetes.