The Monascus metabolite monascin against TNF-α-induced insulin resistance via suppressing PPAR-γ phosphorylation in C2C12 myotubes

Microbial pigments: Sources, current status, future challenges in cosmetics and therapeutic applications

Color serves as the initial attraction and offers a pleasing aspect. While synthetic colorants have been popular for many years, their adverse environmental and health effects cannot be overlooked. This necessitates the search for natural colorants, especially microbial colorants, which have proven and more effective. Pigment-producing microorganisms offer substantial benefits. Natural colors improve product marketability and bestow additional benefits, including antioxidant, antiaging, anticancer, antiviral, antimicrobial, and antitumor properties. This review covers the various types of microbial pigments, the methods to enhance their production, and their cosmetic and therapeutic applications. We also address the challenges faced during the commercial production of microbial pigments and propose potential solutions.

Monascin and ankaflavin-Biosynthesis from Monascus purpureus, production methods, pharmacological properties: A review

Monascus purpureus copiously yields beneficial secondary metabolites , including Monascus pigments, which are broadly used as food additives, as a nitrite substitute in meat products, and as a colorant in the food industry. Monascus yellow pigments (monascin and ankaflavin) have shown potential antidiabetic, antibacterial, anti-inflammatory, antidepressant, antibiotic, anticancer, and antiobesity activities. Cosmetic and textile industries are other areas where it has established its potential as a dye. This paper reviews the production methods of Monascus yellow pigments, biosynthesis of Monascus pigments from M. purpureus, factors affecting yellow pigment production during fermentation, and the pharmacological properties of monascin and ankaflavin.

The biological activity and application of Monascus pigments: a mini review

Monascus pigments (MPs), as secondary metabolites of Monascus, are microbial pigments which have been used for thousands of years. MPs are widely used in food industry as food pigments and preservatives, which have the stability of light resistance, high temperature resistance and acid-base change resistance. In addition, the antioxidant, antibacterial, antiviral and anti-tumor biological activities of MPs have also attracted people’s attention. Moreover, Due to the presence of citrinin, the safety of MPs still needs to be discussed and explored. In this paper, the production, biological activity, application in various fields and methods of detection and reduction of citrinin of MPs were reviewed, which provide new insights into the study and safe application related to human different diseases, medicines or health care products with MPs as active substances.

Thermal stability of natural pigments produced by Monascus purpureus in submerged fermentation

The major aim of the current study was to assess thermal stability of red pigments produced by Monascus purpureus ATCC 16362/PTCC 5303 in submerged fermentation. Natural pigments were produced by Monascus purpureus using stirred tank bioreactor. Stability of Monascus purpureus pigments was assessed under various temperature (50.2-97.8°C), salt (0%-2.5%), and pH (4.3-7.7) values. Thermal degradation constant and half-life value of the red Monascus purpureus pigments were analyzed using response surface methodology followed by a first-order kinetic reaction. Results of this study showed that pH, temperature, and salt content could affect red color stability of Monascus purpureus. The pigment showed various stabilities in various thermal conditions (temperature, salt, and pH). At high temperatures, degradation constant of the red pigments increased with decreasing pH, revealing that the Monascus red pigment was destroyed at lower pH values and salt could affect stability of the red pigments at lower temperatures.

Extract of white sweet potato tuber against TNF-α-induced insulin resistance by activating the PI3K/Akt pathway in C2C12 myotubes

BACKGROUND

White sweet potato (WSP; Ipomoea batatas L. Simon No. 1) has many potential beneficial effects on metabolic control and diabetes-related insulin resistance. The improvement of insulin resistance by WSP tuber extracts on glucose uptake were not investigated in C2C12 myoblast cells.

RESULTS

WSP tuberous ethanol extract (WSP-E) was partitioned with ethyl-acetate and water to obtain ethyl-acetate layer (WSP-EA) and water layer (WSP-EW). The WSP-EA shows the highest total phenolic contents and highest antioxidant activity by Folin-Ciocalteu and (2,2-diphenyl-1-picryl-hydrazyl-hydrate, DPPH) assay, respectively. After low concentration horse serum on differentiation inducement of C2C12 myoblasts into mature myotubes, the cells were treated with TNF-α to induce insulin resistance. WSP-EA and WSP-EW extracts increased the uptake of fluorescence glucose analogue (2-[N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl) amino]-2-deoxy-D-glucose, 2-NBDG) in a dose-dependent manner as examined by flow cytometry. The WSP-EA enhanced glucose uptake by activation of phosphorylation of IR (pIR), IRS-1 (pIRS-1) and Akt (pAkt) involved in PI3K (phosphatidylinositol 3-kinase)/protein kinase B (Akt) pathway, also upregulated glucose transporter 4 (GLUT4) expression in myotubes.

CONCLUSIONS

WSP-EA enhanced the glucose uptake in C2C12 myotubes through upregulating the PI3K/Akt pathway. The in vitro data reveal that WSP tuber extracts has potential applications to improve insulin resistance in diabetes.

[Doctor, Do You Know Red Yeast Rice?]

Doctor, Do You Know Red Yeast Rice? Abstract. We present cases of patients with high total cholesterol who wanted to use an alternative therapy for lowering cholesterol. An improvement in the lipid profile was found in all patients, and all tolerated the product made from red rice yeast very well. No side effects were observed. The patients who take red fermented rice consciously choose an alternative agent in the field of phytotherapy because they already have to take several conventional medicines and are no longer willing to use an additional drug of this kind. Another reason is that they no longer want to put up with the side effects they suffered from when using a common lipid-lowering drug.

Impact of Red Yeast Rice on Metabolic Diseases: A Review of Possible Mechanisms of Action

Metabolic diseases constitute a major public health burden and are linked with high morbidity and mortality. They comprise atherosclerosis dyslipidemia, diabetes, hypertension, and obesity. However, there is no single drug that can simultaneously treat multiple diseases with complex underlying mechanisms. Therefore, it is necessary to identify a class of adjuvant drugs that block the development of metabolic diseases from a preventive perspective. Red yeast rice is a food fermentation product widely used to promote blood circulation and remove blood stasis. Modern pharmacology has shown that red yeast rice exerts potential protective effects on the liver, pancreas, blood vessels, and intestines. Therefore, this study was carried out to analyze and summarize the effect of red yeast rice on several metabolic diseases and the mechanisms of action involved. It was found that red yeast rice may be beneficial in the prevention and treatment of metabolic diseases.

Therapeutic potential of PPARγ natural agonists in liver diseases

Peroxisome proliferator‐activated receptor gamma (PPARγ) is a vital subtype of the PPAR family. The biological functions are complex and diverse. PPARγ plays a significant role in protecting the liver from inflammation, oxidation, fibrosis, fatty liver and tumours. Natural products are a promising pool for drug discovery, and enormous research effort has been invested in exploring the PPARγ‐activating potential of natural products. In this manuscript, we will review the research progress of PPARγ agonists from natural products in recent years and probe into the application potential and prospects of PPARγ natural agonists in the therapy of various liver diseases, including inflammation, hepatic fibrosis, non‐alcoholic fatty liver and liver cancer.

Multifaceted Applications of Microbial Pigments: Current Knowledge, Challenges and Future Directions for Public Health Implications

Microbial oddities such as versatile pigments are gaining more attention in current research due to their widely perceived applications as natural food colorants, textiles, antimicrobial activities, and cytotoxic activities. This indicates that the future generation will depend on microbial pigments over synthetic colorants for sustainable livelihood. Although several reviews have detailed the comprehensive applications of microbial pigments extensively, knowledge on several aspects of pigmented microbes is apparently missing and not properly reviewed anywhere. Thus, this review has been made to provide overall knowledge on biodiversity, distribution, pathogenicity, and ecological and industrial applications of microbial pigments as well as their challenges and future directions for food, industrial, and biomedical applications. Meticulously, this compendious review treatise on the pigments from bacteria, fungi, yeasts, and microalgae includes reports from the 1970s to 2018. A total of 261 pigment compounds produced by about 500 different microbial species are included, and their bioactive nature is described.

The Effect of Sea Buckthorn (Hippophae rhamnoides L.) Seed Oil on UV-Induced Changes in Lipid Metabolism of Human Skin Cells

Lipids and proteins of skin cells are the most exposed to harmful ultraviolet (UV) radiation contained in sunlight. There is a growing need for natural compounds that will protect these sensitive molecules from damage, without harmful side effects. The aim of this study was to investigate the effect of sea buckthorn seed oil on the redox balance and lipid metabolism in UV irradiated cells formed different skin layers to examine whether it had a protective effect. Human keratinocytes and fibroblasts were subjected to UVA (ultraviolet type A; 30 J/cm² and 20 J/cm²) or UVB (ultraviolet type B; 60 mJ/cm² and 200 mJ/cm², respectively) radiation and treated with sea buckthorn seed oil (500 ng/mL), and the redox activity was estimated by reactive oxygen species (ROS) generation and enzymatic/non-enzymatic antioxidants activity/level (using electron spin resonance (ESR), high-performance liquid chromatography (HPLC), and spectrophotometry). Lipid metabolism was measured by the level of fatty acids, lipid peroxidation products, endocannabinoids and phospholipase A2 activity (GC/MS (gas chromatography/mass spectrometry), LC/MS (liquid chromatography/mass spectrometry), and spectrophotometry). Also, transcription factor Nrf2 (nuclear erythroid 2-related factor) and its activators/inhibitors, peroxisome proliferator-activated receptors (PPAR) and cannabinoid receptor levels were measured (Western blot). Sea buckthorn oil partially prevents UV-induced ROS generation and enhances the level of non-enzymatic antioxidants such as glutathione (GSH), thioredoxin (Trx) and vitamins E and A. Moreover, it stimulates the activity of Nrf2 leading to enhanced antioxidant enzyme activity. As a result, decreases in lipid peroxidation products (4-hydroxynonenal, 8-isoprostaglandin) and increases in the endocannabinoid receptor levels were observed. Moreover, sea buckthorn oil treatment enhanced the level of phospholipid and free fatty acids, while simultaneously decreasing the cannabinoid receptor expression in UV irradiated keratinocytes and fibroblasts. The main differences in sea buckthorn oil on various skin cell types was observed in the case of PPARs-in keratinocytes following UV radiation PPAR expression was decreased by sea buckthorn oil treatment, while in fibroblasts the reverse effect was observed, indicating an anti-inflammatory effect. With these results, sea buckthorn seed oil exhibited prevention of UV-induced disturbances in redox balance as well as lipid metabolism in skin fibroblasts and keratinocytes, which indicates it is a promising natural compound in skin photo-protection.

DHA increases adiponectin expression more effectively than EPA at relative low concentrations by regulating PPARγ and its phosphorylation at Ser273 in 3T3-L1 adipocytes

BACKGROUND

Enhancing circulating adiponectin is considered as a potential approach for the prevention and treatment of non-communicable diseases (NCDs). Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were reported to increase adiponectin by previous studies using a mixture of them. However, their individual effects on adiponectin and the underlying mechanisms are still unclear. In the present study, we observed and compared the individual effect of DHA and EPA on adiponectin in 3T3-L1 adipocytes, and further tested whether DHA or EPA regulated adiponectin by peroxisome proliferator-activated receptor γ (PPARγ) and its phosphorylation at Ser273 to provide a plausible explanation for their distinct actions.

METHODS

Firstly, 3T3-L1 adipocytes were treated with different doses of DHA or EPA for 24 h. Secondly, 3T3-L1 adipocytes were treated with DHA or EPA in the presence or absence of GW9662. Thirdly, 3T3-L1 adipocytes were pretreated with DHA or EPA for 24 h, followed by being respectively co-incubated with tumor necrosis factor α (TNF-α) or roscovitine for another 2 h. Bovine serum albumin treatment served as the control. After treatments, cellular and secreted adiponectin, cellular PPARγ and its phosphorylation at Ser273 were determined.

RESULTS

Compared with the control, DHA increased cellular and secreted adiponectin at 50 and 100 μmol/L, while EPA increased them at 100 and 200 μmol/L. Adiponectin expressions in DHA treated groups were significantly higher than those in EPA treated groups at 50 and 100 μmol/L. Both DHA and EPA enhanced PPARγ expression, but DHA was more effective. GW9662 blocked DHA- and EPA-induced increases in PPARγ as well as adiponectin. Remarkably, an opposite regulation of PPARγ phosphorylation was detected after fatty acids treatment: DHA inhibited it but EPA stimulated it. TNF-α blocked DHA-induced decrease in PPARγ phosphorylation, which eventually led to a decrease in adiponectin. Roscovitine blocked EPA-induced increase in PPARγ phosphorylation, but the corresponding increase in adiponectin was non-significant.

CONCLUSION

DHA compared with EPA led to a greater increase in cellular and secreted adiponectin at relative low concentrations by increasing PPARγ expression and inhibiting its phosphorylation at Ser273. DHA may be more beneficial than EPA in reducing risks of NCDs.

The effect of monascin on hematoma clearance and edema after intracerebral hemorrhage in rats

BACKGROUND AND PURPOSE

Intracerebral hemorrhage (ICH) is a particularly devastating form of stroke with high mortality and morbidity. Hematomas are the primary cause of neurologic deficits associated with ICH. The products of hematoma are recognized as neurotoxins and the main contributors to edema formation and tissue damage after ICH. Finding a means to efficiently promote absorption of hematoma is a novel clinical challenge for ICH. Peroxisome proliferator-activated receptor gamma (PPARγ) and nuclear factor erythroid 2-related factor 2 (Nrf2), had been shown that, can take potential roles in the endogenous hematoma clearance. However, monascin, a novel natural Nrf2 activator with PPARγ agonist, has not been reported to play a role in ICH. This study was designed to evaluate the effect of monascin on neurological deficits, hematoma clearance and edema extinction in a model of ICH in rats.

METHODS

164 adult male Sprague-Dawley (SD) rats were randomly divided into sham; vehicle; monascin groups with low dosages (1mg/kg/day), middle dosages (5mg/kg/day) and high dosages (10mg/kg/day) respectively. Animals were euthanized at 1, 3 and 7days following neurological evaluation after surgery. We examined the effect of monascin on the brain water contents, blood brain barrier (BBB) permeability and hemoglobin levels, meanwhile reassessed the volume of hematoma and edema around the hematoma by Magnetic Resonance Imaging (MRI) in each group.

RESULTS

The high dosage of monascin significantly improved neurological deficits, reduced the volume of hematoma in 1-7days after ICH, decreased BBB permeability and edema formation in 1-3days following ICH.

CONCLUSION

Our study demonstrated that the high dosage of monascin played a neuroprotective role in ICH through reducing BBB permeability, edema and hematoma volume.

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.

Pigment fingerprint profile during extractive fermentation with Monascus anka GIM 3.592

BACKGROUND

Traditional submerged fermentation mainly accumulates intracellular orange pigments with absorption maxima at 470 nm, whereas extractive fermentation of Monascus spp. with Triton X-100 can promote the export of intracellular pigments to extracellular broth, mainly obtaining extracellular yellow pigments with absorption maxima at approximately 410 nm. In this study, a strain of Monascus (M. anka GIM 3.592) that produces high yields of pigments was employed to investigate the differences in pigment fingerprint profiles between submerged and extractive fermentations.

RESULTS

Using extractive fermentation with this high-yield strain, the extracellular pigments exhibited an absorption maximum at 430 nm, not 410 nm, as previously observed. By comparing the pigment fingerprint profiles between submerged and extractive fermentations, extractive fermentation was found to not only export intracellular pigments to the extracellular broth, but also to form four other yellow pigments (Y1-Y4) that accounted for a large proportion of the extracellular pigments and that were not produced in submerged fermentation. The yields of Y1-Y4 were closely related to the concentration and feeding time point of Triton X-100. Y1-Y4 presented identical UV-Vis spectra with absorption maxima at 430 nm and fluorescence spectra with absorption maxima (emission) at 565 nm. HPLC-MS and the spectral analysis showed that the four pigments (Y1-Y4) had not been previously reported. The results indicated that these pigments may rely on the bioconversion of orange pigments (rubropunctatin and monascorubrin).

CONCLUSIONS

Using extractive fermentation with M. anka led to a high yield of extracellular yellow pigments (AU_{410 nm} = 114), and the pigment fingerprint profile significantly differed compared to the results of traditional submerged fermentation. These results provide information and a detailed view of the composition and variation of pigments in extractive fermentation and could also contribute to characterizing pigment metabolism during extractive fermentation.

D-Xylose as a sugar complement regulates blood glucose levels by suppressing phosphoenolpyruvate carboxylase (PEPCK) in streptozotocin-nicotinamide-induced diabetic rats and by enhancing glucose uptake in vitro

BACKGROUND/OBJECTIVES

Type 2 diabetes (T2D) is more frequently diagnosed and is characterized by hyperglycemia and insulin resistance. D-Xylose, a sucrase inhibitor, may be useful as a functional sugar complement to inhibit increases in blood glucose levels. The objective of this study was to investigate the anti-diabetic effects of D-xylose both in vitro and stretpozotocin (STZ)-nicotinamide (NA)-induced models in vivo.

MATERIALS/METHODS

Wistar rats were divided into the following groups: (i) normal control; (ii) diabetic control; (iii) diabetic rats supplemented with a diet where 5% of the total sucrose content in the diet was replaced with D-xylose; and (iv) diabetic rats supplemented with a diet where 10% of the total sucrose content in the diet was replaced with D-xylose. These groups were maintained for two weeks. The effects of D-xylose on blood glucose levels were examined using oral glucose tolerance test, insulin secretion assays, histology of liver and pancreas tissues, and analysis of phosphoenolpyruvate carboxylase (PEPCK) expression in liver tissues of a STZ-NA-induced experimental rat model. Levels of glucose uptake and insulin secretion by differentiated C2C12 muscle cells and INS-1 pancreatic β-cells were analyzed.

RESULTS

In vivo, D-xylose supplementation significantly reduced fasting serum glucose levels (P < 0.05), it slightly reduced the area under the glucose curve, and increased insulin levels compared to the diabetic controls. D-Xylose supplementation enhanced the regeneration of pancreas tissue and improved the arrangement of hepatocytes compared to the diabetic controls. Lower levels of PEPCK were detected in the liver tissues of D-xylose-supplemented rats (P < 0.05). In vitro, both 2-NBDG uptake by C2C12 cells and insulin secretion by INS-1 cells were increased with D-xylose supplementation in a dose-dependent manner compared to treatment with glucose alone.

CONCLUSIONS

In this study, D-xylose exerted anti-diabetic effects in vivo by regulating blood glucose levels via regeneration of damaged pancreas and liver tissues and regulation of PEPCK, a key rate-limiting enzyme in the process of gluconeogenesis. In vitro, D-xylose induced the uptake of glucose by muscle cells and the secretion of insulin cells by β-cells. These mechanistic insights will facilitate the development of highly effective strategy for T2D.

A novel PPARgamma agonist monascin's potential application in diabetes prevention

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.

Ice plant (Mesembryanthemum crystallinum) improves hyperglycaemia and memory impairments in a Wistar rat model of streptozotocin-induced diabetes

BACKGROUND

Ice plant (Mesembryanthemum crystallinum) has been used as an anti-diabetic agent in Japan because it contains d-pinitol. The efficacy of ice plant in the regulation of blood glucose is unclear at present. Recently, memory impairment and development of Alzheimer's disease found in diabetic patients are thought to be caused by high blood glucose. The mechanism by which ice plant protects against the impairment of memory and learning abilities caused by high blood glucose remains unclear. The aim of this study was to evaluate the protection of ice plant water extracts (IPE) and D-pinitol against memory impairments in a Wistar rat model of streptozotocin (STZ)-induced diabetes. We hypothesised that IPE and D-pinitol could suppress blood glucose and elevate insulin sensitivity in these rats.

RESULTS

For memory evaluation, IPE and D-pinitol also improved the passive avoidance task and the working memory task. In addition, inhibition of acetylcholinesterase activity in hippocampus and cortex was found in this rat model administered IPE or D-pinitol. IPE and D-pinitol also markedly elevated superoxide dismutase activity against oxidative stress and reduced malondialdehyde production in hippocampus and cortex of the rats.

CONCLUSION

These findings indicated that IPE and D-pinitol possess beneficial effects for neural protection and memory ability in a rat model of diabetes.

Monascin attenuates oxidative stress-mediated lung inflammation via peroxisome proliferator-activated receptor-gamma (PPAR-γ) and nuclear factor-erythroid 2 related factor 2 (Nrf-2) modulation

We speculated that peroxisome proliferator-activated receptor (PPAR)-γ agonists may modulate the oxidative stress pathway to ameliorate the development of airway inflammation. The effect of Monascus-fermented metabolite monascin (MS) and rosiglitazone (Rosi) on oxidative stress-induced lung inflammation was evaluated. Luciferase assay and DNA binding activity assay were used to point out that MS may be a novel PPAR-γ agonist and nuclear factor-erythroid 2 related factor 2 (Nrf-2) activator. We used hydrogen peroxide (H2O2) to induce inflammation in lung epithelial cells. MS and Rosi prevented H2O2-induced ROS generation in A549 epithelial cells through PPAR-γ translocation, avoiding inflammatory mediator expression via inhibiting nuclear factor (NF)-κB translocation. The regulatory ability of MS was abolished by siRNA against PPAR-γ. MS also elevated antioxidant enzyme expression via Nrf-2 activation. Both PPAR-γ and Nrf-2 might have benefits against lung inflammation. MS regulated PPAR-γ and Nrf-2 to improve lung oxidative inflammation.

Red Mold Rice against Hepatic Inflammatory Damage in Zn-deficient Rats

The protective effect of red mold rice (RMR) against liver injury in rats fed with a Zn-deficient diet for 12 weeks was investigated in this study. Rats were orally administered RMR (151 mg/kg body weight or 755 mg/kg body weight; 1 × dose or 5 × dose, respectively) with or without Zn once a day for 4 consecutive weeks. The severity of liver damage was evaluated by measuring the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in Zn-deficient rats. RMR significantly inhibited the elevation of serum ALT levels by Zn-deficient induction. Hepatic antioxidase activity was also significantly increased in the RMR + Zn group (RZ), thereby suppressing the productions of reactive oxygen species (ROS) and proinflammatory cytokines in the liver of Zn-deficient rats. These findings suggested that RMR exerted hepatoprotective effects against Zn deficiency-induced liver inflammation.

Monascin and ankaflavin act as natural AMPK activators with PPARα agonist activity to down-regulate nonalcoholic steatohepatitis in high-fat diet-fed C57BL/6 mice

Yellow pigments monascin (MS) and ankaflavin (AK) are secondary metabolites derived from Monascus-fermented products. The hypolipidemic and anti-inflammatory effects of MS and AK indicate that they have potential on preventing or curing nonalcoholic fatty liver disease (NAFLD). Oleic acid (OA) and high-fat diet were used to induce steatosis in FL83B hepatocytes and NAFLD in mice, respectively. We found that both MS and AK prevented fatty acid accumulation in hepatocytes by inhibiting fatty acid uptake, lipogenesis, and promoting fatty acid beta-oxidation mediated by activating peroxisome proliferator-activated receptor (PPAR)-α and AMP-activated kinase (AMPK). Furthermore, MS and AK significantly attenuated high-fat diet-induced elevation of total cholesterol (TC), triaceylglycerol (TG), free fatty acid (FFA), and low density lipoprotein-cholesterol (LDL-C) in plasma. MS and AK promoted AMPK phosphorylation, suppressed the steatosis-related mRNA expression and inflammatory cytokines secretion, as well as upregulated farnesoid X receptor (FXR), peroxisome proliferator-activated receptor gamma co-activator (PGC)-1α, and PPARα expression to induce fatty acid oxidation in the liver of mice. We provided evidence that MS and AK act as PPARα agonists to upregulate AMPK activity and attenuate NAFLD. MS and AK may be supplied in food supplements or developed as functional foods to reduce the risk of diabetes and obesity.

Inhibition of Th2 cytokine production in T cells by monascin via PPAR-γ activation

Yellow pigment monascin (MS) is a secondary metabolite isolated from Monascus -fermented products and has numerous physiological activities. However, the potential use of MS for immunomodulation remains unclear. We showed that MS and the synthetic peroxisome proliferator-activated receptor (PPAR)-γ ligand rosiglitazone (RG) significantly inhibited the production of Th2 cytokines, including IL-4, IL-5, and IL-13, in PMA/ionomycin-activated mouse EL-4 T cells. Moreover, we showed that this was due to cellular PPAR-γ translocation. These results indicate that MS and RG promote PPAR-γ-DNA interactions and suggest that the regulatory effects of MS and RG on Th2 cytokine production could be abolished with PPAR-γ antagonist treatment. MS and RG also suppressed Th2 transcription factor translocation (e.g., GATA-3 and nuclear factor of activated T cells) by preventing the phosphorylation of protein kinase C and signal transducer and activator of transcription 6.

Peroxisome proliferator-activated receptor-γ activators monascin and rosiglitazone attenuate carboxymethyllysine-induced fibrosis in hepatic stellate cells through regulating the oxidative stress pathway but independent of the receptor for advanced glycation end products signaling

Advanced glycation end products (AGEs) signaling through its receptors (RAGE) results in an increase in reactive oxygen species (ROS) and is thought to contribute to hepatic fibrosis via hyperglycemia. Carboxymethyllysine (CML) is a key AGE, with highly reactive dicarbonyl metabolites. We investigated the inhibitory effect of Monascus -fermented metabolite monascin and rosiglitazone on CML-induced RAGE signaling in hepatic stellate cells (HSCs) and its resulting antihepatic fibrosis activity. We found that monascin and rosiglitazone upregulated peroxisome proliferator-activated receptor-γ (PPAR-γ) to attenuate α-smooth muscle actin (SMA) and ROS generation in CML-treated HSCs in a RAGE activation-independent pathway. Therefore, monascin may delay or inhibit the progression of liver fibrosis through the activation of PPAR-γ and might prove to be a major antifibrotic mechanism to prevent liver disease.

Monascin and AITC attenuate methylglyoxal-induced PPARγ phosphorylation and degradation through inhibition of the oxidative stress/PKC pathway depending on Nrf2 activation

Abnormal cellular accumulation of the dicarbonyl metabolite methylglyoxal (MG) results in cell damage, inflammation, and oxidative stress. It is also associated with increased protein linkage to form advanced glycation end products (AGEs) or induce DNA strand breaks. The association between peroxisome proliferator-activated receptor-γ (PPARγ) and nuclear factor-erythroid 2-related factor 2 (Nrf2) is unclear. This study investigated Nrf2 activator protection against PPARγ phosphorylation and degradation to maintain pancreatic function. MG was used at a noncytotoxic concentration (200 μM) to induce protein kinase C (PKC) and PPARγ phosphorylation in pancreatic RINm5F cells. For in vivo studies, MG (60 mg/kg bw) was intraperitoneally (IP) injected into Balb/C mice for 28 d to induce pancreas damage, at which point we investigated the effect of monascin protection (PPARγ and Nrf2 activator), rosiglitazone (PPARγ activator), allyl isothiocyanate (AITC; Nrf2 activator), or N-acetylcysteine (NAC) on pancreatic function. The in vitro and in vivo results indicated that MG leads to marked PPARγ phosphorylation (serine 82); this effect led to reduction in pancreatic and duodenal homeobox-1 (PDX-1), glucokinase (GCK), and insulin expression. However, monascin and rosiglitazone may protect PPARγ degradation by elevating PDX-1, GCK, and as a result, insulin expression. Monascin and AITC can attenuate PKC activation to suppress PPARγ phosphorylation caused by oxidative stress through the Nrf2 pathway. Similarly, the N-acetylcysteine (NAC) antioxidant also improved oxidative stress and pancreatic function. This study examined whether MG caused impairment of PDX-1, GCK, and insulin through PPARγ phosphorylation and degradation. MG and AGE accumulation improved on Nrf2 activation, thereby protecting against pancreas damage. Taken together, PPARγ activation maintained pancreatic PDX-1, GCK, and insulin expression levels to regulate blood glucose levels.

Effects of monascin on anti-inflammation mediated by Nrf2 activation in advanced glycation end product-treated THP-1 monocytes and methylglyoxal-treated wistar rats

Hyperglycemia is associated with advanced glycation end products (AGEs). This study was designed to evaluate the inhibitory effects of monascin on receptor for advanced glycation end product (RAGE) signal and THP-1 monocyte inflammation after treatment with S100b, a specific ligand of RAGE. Monascin inhibited cytokine production by S100b-treated THP-1 monocytes via up-regulation of nuclear factor-erythroid 2-related factor-2 (Nrf2) and alleviated p47phox translocation to the membrane. Methylglyoxal (MG, 600 mg/kg bw) was used to induce diabetes in Wistar rats. Inhibitions of RAGE and p47phox by monascin were confirmed by peripheral blood mononuclear cells (PBMCs) of MG-induced rats. Silymarin (SM) was used as a positive control group. It was found that monascin promoted heme oxygenase-1 (HO-1) expression mediated by Nrf2. Suppressions of AGEs, tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-β) in serum of MG-induced rats were attenuated in the monascin administration group treated with retinoic acid (RA). RA treatment resulted in Nrf2 inactivation by increasing RA receptor-α (RARα) activity, suggesting that RA acts as an inhibitor of Nrf2. The results showed that monascin exerted anti-inflammatory and antioxidative effects mediated by Nrf2 to prevent the development of diseases such as type 2 diabetes caused by inflammation.

Ankaflavin, a novel Nrf-2 activator for attenuating allergic airway inflammation

The role of inflammation-induced oxidative stress in the pathogenesis and progression of chronic inflammatory airways diseases has received increasing attention in recent years. Nuclear factor-erythroid 2 related factor 2 (Nrf-2) is the primary transcription factor that regulates the expression of antioxidant and detoxifying enzymes. In this study, yellow pigment ankaflavin (AK), derived from Monascus-fermented products, elevated nuclear Nrf-2 protein translocation in both the A549 lung cell line and the lungs of ovalbumin (OVA)-challenged mice. Furthermore, AK increased the mRNA expression of antioxidant enzymes regulated by Nrf-2, leading to a reduction in allergen-driven airway inflammation, mucus cell hyperplasia, and eosinophilia in OVA-challenged mice. Additionally, AK prevented T-cell infiltration and Th2 cytokines including interleukin (IL)-4, IL-5, and IL-13 generation in bronchial alveolar lavage fluid. The adhesion molecules ICAM-1, VCAM-1, and eotaxin were substantially reduced by AK treatment. Importantly, the inhibitory effect of AK on adhesion molecule production and immune cell infiltration was abolished by Nrf-2 small interfering RNA. This is the first study to illustrate that AK acts as a novel Nrf-2 activator for modulating the oxidative stress pathway to improve the lung injury and ameliorate the development of airway inflammation.

Monascus pigments

Monascus pigments (MPs) as natural food colorants have been widely utilized in food industries in the world, especially in China and Japan. Moreover, MPs possess a range of biological activities, such as anti-mutagenic and anticancer properties, antimicrobial activities, potential anti-obesity activities, and so on. So, in the past two decades, more and more attention has been paid to MPs. Up to now, more than 50 MPs have been identified and studied. However, there have been some reviews about red fermented rice and the secondary metabolites produced by Monascus, but no monograph or review of MPs has been published. This review covers the categories and structures, biosynthetic pathway, production, properties, detection methods, functions, and molecular biology of MPs.

Resveratrol upregulates Nrf2 expression to attenuate methylglyoxal-induced insulin resistance in Hep G2 cells

Oxidative stress can result in insulin resistance, a primary cause of type-2 diabetes. Methylglyoxal (MG), a highly reactive dicarbonyl metabolite generated during glucose metabolism, has also been confirmed to cause pancreatic injury and induce inflammation, thereby resulting in insulin resistance. Recently, resveratrol has been reported to exert antioxidant properties, protecting cells from the generation of reactive oxygen species (ROS). The aim of this study was to evaluate resveratrol activation of nuclear factor erythroid 2-related factor 2 (Nrf2) to attenuate MG-induced insulin resistance in Hep G2 cells. Therefore, the molecular signaling events affecting resveratrol-mediated heme oxygenase-1 (HO-1) and glyoxalase expression levels were further investigated in this study. Our findings indicated that resveratrol activated the extracellular signal-regulated kinase (ERK) pathway but not the p38 or c-Jun N-terminal kinase (JNK) pathways, subsequently leading to Nrf2 nuclear translocation and elevation of HO-1 and glyoxalase expression levels. Moreover, resveratrol significantly elevated glucose uptake and protected against MG-induced insulin resistance in Hep G2 cells. In contrast, depletion of Nrf2 by small interfering RNA (si-RNA) resulted in the abrogation of HO-1 and glyoxalase expression in the MG-treated resveratrol group in Hep G2 cells. Administration of an appropriate chemopreventive agent, such as resveratrol, may be an alternative strategy for protecting against MG-induced diabetes.

Fagopyrum tataricum (buckwheat) improved high-glucose-induced insulin resistance in mouse hepatocytes and diabetes in fructose-rich diet-induced mice

Fagopyrum tataricum (buckwheat) is used for the treatment of type 2 diabetes mellitus in Taiwan. This study was to evaluate the antihyperglycemic and anti-insulin resistance effects of 75% ethanol extracts of buckwheat (EEB) in FL83B hepatocytes by high-glucose (33 mM) induction and in C57BL/6 mice by fructose-rich diet (FRD; 60%) induction. The active compounds of EEB (100 μg/mL; 50 mg/kg bw), quercetin (6 μg/mL; 3 mg/kg bw), and rutin (23 μg/mL; 11.5 mg/kg bw) were also employed to treat FL83B hepatocytes and animal. Results indicated that EEB, rutin, and quercetin + rutin significantly improved 2-NBDG uptake via promoting Akt phosphorylation and preventing PPARγ degradation caused by high-glucose induction for 48 h in FL83B hepatocytes. We also found that EEB could elevate hepatic antioxidant enzymes activities to attenuate insulin resistance as well as its antioxidation caused by rutin and quercetin. Finally, EEB also inhibited increases in blood glucose and insulin levels of C57BL/6 mice induced by FRD.

Ankaflavin and monascin regulate endothelial adhesion molecules and endothelial NO synthase (eNOS) expression induced by tumor necrosis factor-α (TNF-α) in human umbilical vein endothelial cells (HUVECs)

Previous studies have established that red mold rice can regulate blood pressure in spontaneously hypertensive rats (SHR) and that Monascus -fermented products, including monacolin K, ankaflavin (AF), and monascin (MS), can inhibit expression of adhesion factors such as E-selectin and endothelin-1 to prevent human acute monocytic leukemia cell line THP-1 monocytes from adhering to human aortic endothelial cells. However, it remains unknown whether AF and MS act directly on human umbilical endothelial cells (HUVECs) to enhance nitric oxide (NO) synthesis through the stimulation of endothelial NO synthase (eNOS) expression. To address this knowledge gap, this study investigated whether AF and MS directly regulate NO synthesis and attenuate adhesion factor expression induced by treatment with tumor necrosis factor-α (TNF-α) in HUVECs. The results revealed that both AF and MS (20 μM) treatments promoted increases in eNOS expression and decreases in vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and endothelin-1 mRNA and protein expression resulting from 12 h of TNF-α treatment. These effects are attributed to the ability of AF and MS to inhibit extracellular signal-regulated protein kinase (ERK) phosphorylation and nuclear factor κB (NF-κB) translocation from the cytoplasm into the nucleus, thereby exerting antihypertensive activity.

Monascus-fermented metabolite monascin suppresses inflammation via PPAR-γ regulation and JNK inactivation in THP-1 monocytes

Fermentation products of the fungus Monascus offer valuable therapeutic benefits and have been used extensively for centuries in Asia. The aim of this study is to investigate the inhibitory effect of the Monascus-fermented metabolite monascin (MS) on the molecular mechanism of ovalbumin (OVA)-induced inflammation in the human THP-1 monocyte cell line. We found that 1, 5, and 25 μM of MS significantly attenuated several proinflammatory mediators, including inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression as well as nitric oxide (NO) and prostaglandin E(2) (PGE(2)) formation caused by OVA stimulation. Further, 5 and 25 μM of MS significantly reduced the generation of tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) at both the protein and mRNA levels. MS (5 and 25 μM) decreased OVA-induced phosphorylation of mitogen-activated protein kinase (MAPK) c-Jun NH(2)-terminal kinase (JNK), but not that of extracellular signal-regulated kinase (ERK) or p38 kinase. We used the peroxisome proliferator activated receptor-γ (PPAR-γ) antagonist GW9662 to show that MS inhibit JNK phosphorylation through increased expression of PPAR-γ. Thus, the metabolites from Monascus fermentation may serve as a dietary source of anti-inflammatory agents.