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

Alternative lipid lowering strategies: State-of-the-art review of red yeast rice

Red yeast rice (RYR) is an entirely natural product that originates from the fermentation of white rice (Oryza sativa) with a yeast, mainly Monascus Purpureus, and has been part of traditional Chinese medicine and diet since ancient times. It has generated great interest in recent years in the context of cardiovascular (CV) prevention due to its ability to inhibit endogenous cholesterol production, helping to achieve and maintain optimal plasma lipid concentrations. This review aims to make an extensive 360-degree assessment and summary of the whole currently available scientific evidence about RYR, starting with its biochemical composition, passing through a historical reconstruction of all the studies that have evaluated its efficacy and safety in cholesterol-lowering action, with a focus on CV outcomes, and ultimately addressing its other relevant clinical effects. We also discuss its possible therapeutic role, alone or in combination with other nutraceuticals, in different clinical scenarios, taking into account the positions of major scientific documents on the issue, and describe the articulate legal controversies that have characterized the regulation of its use up to the present day. RYR preparations have been proven safe and effective in improving lipid profile, with a potential role in reducing cardiovascular risk. They can be considered as additional supportive agents in the armamentarium of lipid-modifying therapies.

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 Age-Related Macular Degeneration (AMD)-Preventing Mechanism of Natural Products

Age-related macular degeneration (AMD) is related to central visual loss in elderly people and, based on the increment in the percentage of the aging population, the number of people suffering from AMD could increase. AMD is initiated by retinal pigment epithelium (RPE) cell death, finally leading to neovascularization in the macula lutea. AMD is an uncurable disease, but the symptom can be suppressed. The current therapy of AMD can be classified into four types: device-based treatment, anti-inflammatory drug treatment, anti-vascular endothelial growth factor treatment, and natural product treatment. All these therapies have adverse effects, however early AMD therapy used with products has several advantages, as it can prevent RPE cell apoptosis in safe doses. Cell death (apoptosis) is caused by various factors, such as oxidative stress, inflammation, carbonyl stress, and a deficiency in essential components for cells, and RPE cell death is related to oxidative stress, inflammation, and carbonyl stress. Some natural products have anti-oxidative effects, anti-inflammation effects, and/or anti-carbonylation effects. The AMD preventive mechanism of natural products varies, with some natural products activating one or more anti-apoptotic pathways, such as the Nrf2/HO-1 anti-oxidative pathway, the anti-inflammasome pathway, and the anti-carbonyl pathway. As AMD drug candidates from natural products effectively inhibit RPE cell death, they have the potential to be developed as drugs for preventing early (dry) AMD.

Different types of components obtained from Monascus purpureus with neuroprotective and anti-inflammatory potentials

The mold Monascus has been used as a natural food coloring agent and food additive for more than 1000 years in Asian countries. In Chinese herbology, it was also used for easing digestion and antiseptic effects. Through a thorough investigation of a citrinin-free strain: M. purpureus BCRC 38110, four azaphilones, three benzenoids, one benzofuranone, one 5',6'-dihydrospiro[isochromane-1,2'-pyran]-4'(3'H)-one derivative, two steroids, and six tetralones have been successfully identified. Among them, monapyridine A (1), monatetralones A-E (2-6), and monabenzofuranone (7) were first reported. Their structures were characterized by 1D and 2D NMR, UV, IR, and HRESIMS analyses. With a series of bioactivity screening, monascuspirolide B (14) and ergosterol peroxide (16) exhibited concentration-dependent attenuation of the paclitaxel-induced neurite damage of mouse dorsal root ganglion neurons. The interleukin (IL)-1β-induced release of inflammatory cytokines IL-8 and tumor necrosis factor (TNF)-α in human chondrosarcoma cells was inhibited by monapurpureusone (8) and monascuspirolide B (14). Altogether, M. purpureus BCRC 38110 possessed potentials as natural therapeutics against inflammatory osteoarthritis and paclitaxel-induced neurotoxicity.

Comparative Study on the Antioxidant Activity of Monascus Yellow Pigments From Two Different Types of Hongqu-Functional Qu and Coloring Qu

This study is the first to investigate the difference in the composition of Monascus azaphilone pigments (MonAzPs) between functional Qu (FQ) and coloring Qu (CQ) and analyze their relationships with antioxidant activity. The composition of key active components and antioxidant activity of the ethanol extracts of FQ and CQ were analyzed by Uv-vis, HPLC, and chemical antioxidant tests. The composition of MonAzPs of the ethanol extracts was further analyzed by HPLC-MS. Seven Monascus yellow pigments (MYPs) with high abundance were successfully purified for the antioxidation evaluation in vitro and in the cell. Correlation analysis between the metabolites and the antioxidant activity of Hongqu indicated that MonAzPs might play an essential role in the antioxidant activity (r > 0.80). By contrast, the monacolin K (MK), polysaccharide, ergosterol, and γ-aminobutyric acid (GABA) were not significantly correlated with the antioxidant activity. Orthogonal partial least squares discriminant analysis (OPLS-DA) based on the composition of MonAzPs revealed that the abundance of MYPs is significantly different between FQ and CQ (P < 0.05 and VIP > 1.0). Seven MYPs (monasfluore A, monaphilone B, monascuspilion, monascin, monaphilone A, ankaflavin, and new yellow pigment) with high abundance were successfully purified for the antioxidation evaluation. Chemical antioxidant tests revealed that the antioxidant activities of monaphilone A, ankaflavin, and new yellow pigment only from CQ were significantly more potent than monasfluore A and monascuspilion only separated from FQ. The cellular antioxidant assay (CAA) showed that the new yellow pigment had the best antioxidant activity (quercetin equivalent 7.23 μM), followed by monasfluore A and monaphilone B, all of which were significantly better than monascin and ankaflavin, the two most frequently reported MYPs. Research on the structure-activity relationship demonstrated that alterations of the hydroxyl that occurred on C-3' or C-11 obviously affected the antioxidant activities of MYPs. Our findings provide evidence that MYPs may be the key active components for CQ to have a more potent antioxidant capacity than FQ. The alterations of the hydroxyl that occurred on C-3' or C-11 obviously affected the antioxidant activities of MYPs.

Investigations into Chemical Components from Monascus purpureus with Photoprotective and Anti-Melanogenic Activities

Monascus species are asexually or sexually reproduced homothallic fungi that can produce a red colorant, specifically the so-called red yeast rice or Anka, which is used as a food ingredient in Asia. Traditional experiences of using Monascus for treating indigestion, enhancing blood circulation, and health remedies motivate us to investigate and repurpose Monascus-fermented products. Here, two new 5H-cyclopenta[c]pyridine type azaphilones, 5S,6S-monaspurpyridine A (1) and 5R,6R-monaspurpyridine A (2), two new xanthonoids, monasxanthones A and B (3 and 4), one new naphthalenone, monasnaphthalenone (5), and one new azaphilone, monapurpurin (6), along with two known compounds were isolated from the 70% EtOH extract of a citrinin-free domesticated strain M. purpureus BCRC 38110. The phytochemical properties of the xanthonoid and naphthalenone components were first identified from Monascus sp. differently from the representative ingredients of polyketide-derived azaphilones. UVB-induced cell viability loss and reactive oxygen species (ROS) overproduction in human keratinocytes were attenuated by monascuspirolide B (7) and ergosterol peroxide (8), indicating their photoprotective potentials. Ergosterol peroxide (8) decreased the melanin contents and tyrosinase activities of mouse melanocytes, depending on the concentration, suggesting their anti-melanogenic effects. In conclusion, six new and two known compounds were isolated from M. purpureus BCRC 38110, and two of them exhibited dermal protective activities. The results revealed the novel potential of M. purpureus for developing natural cosmeceutics against skin photoaging.

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.

Monascin accelerates anoikis in circulating tumor cells and prevents breast cancer metastasis

Anoikis resistance has been observed in various types of cancers in which anchorage-independent growth is a crucial step for cancer metastasis. Therefore, agents interfering with this specific cancer cell behavior may be integrated into novel antimetastatic strategies. Monascin (MS), a secondary metabolite found in Monascus species, is a known potent chemopreventive compound used for treating metabolic complications; however, the effect of MS on anoikis resistance has not been investigated. In this study, 4T1 breast cells were treated with MS under either suspension or adhesion conditions. The higher cytotoxicity of MS was more potent against suspended cells than against adherent cells. This selective cytotoxicity was due to the induction of anoikis, which was evidenced by changes in cell aggregation, caspase activity, and Annexin V/propidium iodide binding as well as the results of systemic metastasis in an animal model. Furthermore, MS inhibited E-cadherin and β-catenin expression in the cells; the treated cells formed spherical aggregates, which suggested that anchorage-independent growth was prevented by MS. These results provide new insights into the mechanisms underlying the growth-preventing effect of MS on cancer cells and indicate the potential ability of MS to suppress metastasis.

Natural constituents from food sources as therapeutic agents for obesity and metabolic diseases targeting adipose tissue inflammation

Adipose tissue, an endocrine and paracrine organ, plays critical roles in the regulation of whole-body metabolic homeostasis. Obesity is accompanied with a chronic low-grade inflammation status in adipose tissue, which disrupts its endocrine function and results in metabolic derangements, such as type 2 diabetes. Dietary bioactive components, such as flavonoids, polyphenols and unsaturated fatty acids from fruits and vegetables, have been widely revealed to alleviate both systemic and adipose tissue inflammation, and improve metabolic disorders. Remarkably, some dietary bioactive components mitigate the inflammatory response in adipocytes, macrophages, and other immune cells, and modulate the crosstalk between adipocytes and macrophages or other immune cells, in adipose tissue. Epidemiological and preclinical studies related to these substances have indicated beneficial effects on adipose tissue inflammation. The main purpose of this review is to provide a comprehensive and up-to-date state of knowledge on dietary components targeting adipose tissue inflammation and their underlying mechanisms. These natural products have great potential to be developed as functional food or lead compounds for treating and/or preventing metabolic disorders.

Transfigured Morphology and Ameliorated Production of Six Monascus Pigments by Acetate Species Supplementation in Monascus ruber M7

Monascus species have been used for the production of many industrially and medically important metabolites, most of which are polyketides produced by the action of polyketide synthases that use acetyl-CoA and malonyl-CoA as precursors, and some of them are derived from acetate. In this study the effects of acetic acid, and two kinds of acetates, sodium acetate and ammonium acetate at different concentrations (0.1%, 0.25% and 0.5%) on the morphologies, biomasses, and six major Monascus pigments (MPs) of M. ruber M7 were investigated when M7 strain was cultured on potato dextrose agar (PDA) at 28 °C for 4, 8, 12 days. The results showed that all of the added acetate species significantly affected eight above-mentioned parameters. In regard to morphologies, generally the colonies transformed from a big orange fleecy ones to a small compact reddish ones, or a tightly-packed orange ones without dispersed mycelia with the increase of additives concentration. About the biomass, addition of ammonium acetate at 0.1% increased the biomass of M. ruber M7. With respect to six MPs, all acetate species can enhance pigment production, and ammonium acetate has the most significant impacts. Production of monascin and ankaflavin had the highest increase of 11.7-fold and 14.2-fold in extracellular contents at the 8th day when 0.1% ammonium acetate was supplemented into PDA. Intracellular rubropunctatin and monascorubrin contents gained 9.6 and 6.46-fold at the 8th day, when 0.1% ammonium acetate was added into PDA. And the extracellular contents of rubropunctamine and monascorubramine were raised by 1865 and 4100-fold at the 4th day when M7 grew on PDA with 0.5% ammonium acetate.

A comprehensive review of therapeutic targets that induce microglia/macrophage-mediated hematoma resolution after germinal matrix hemorrhage

Currently, there is no effective treatment for germinal matrix hemorrhage and intraventricular hemorrhage (GMH-IVH), a common and often fatal stroke subtype in premature infants. Secondary brain injury after GMH-IVH is known to involve blood clots that contribute to inflammation and neurological deficits. Furthermore, the subsequent blood clots disrupt normal cerebrospinal fluid circulation and absorption after GMH-IVH, contributing to posthemorrhagic hydrocephalus (PHH). Clinically, GMH-IVH severity is graded on a I to IV scale: Grade I is confined to the germinal matrix, grade II includes intraventricular hemorrhage, grade III includes intraventricular hemorrhage with extension into dilated ventricles, and grade IV includes intraventricular hemorrhage with extension into dilated ventricles as well as parenchymal hemorrhaging. GMH-IVH hematoma volume is the best prognostic indicator, where patients with higher grades have worsened outcomes. Various preclinical studies have shown that rapid hematoma resolution quickly ameliorates inflammation and improves neurological outcomes. Current experimental evidence identifies alternatively activated microglia as playing a pivotal role in hematoma clearance. In this review, we discuss the pathophysiology of GMH-IVH in the development of PHH, microglia/macrophage's role in the neonatal CNS, and established/potential therapeutic targets that enhance M2 microglia/macrophage phagocytosis of blood clots after GMH-IVH.

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.

Methylglyoxal in Metabolic Disorders: Facts, Myths, and Promises

Glucose and fructose metabolism originates the highly reactive byproduct methylglyoxal (MG), which is a strong precursor of advanced glycation end products (AGE). The MG has been implicated in classical diabetic complications such as retinopathy, nephropathy, and neuropathy, but has also been recently associated with cardiovascular diseases and central nervous system disorders such as cerebrovascular diseases and dementia. Recent studies even suggested its involvement in insulin resistance and beta-cell dysfunction, contributing to the early development of type 2 diabetes and creating a vicious circle between glycation and hyperglycemia. Despite several drugs and natural compounds have been identified in the last years in order to scavenge MG and inhibit AGE formation, we are still far from having an effective strategy to prevent MG-induced mechanisms. This review summarizes the endogenous and exogenous sources of MG, also addressing the current controversy about the importance of exogenous MG sources. The mechanisms by which MG changes cell behavior and its involvement in type 2 diabetes development and complications and the pathophysiological implication are also summarized. Particular emphasis will be given to pathophysiological relevance of studies using higher MG doses, which may have produced biased results. Finally, we also overview the current knowledge about detoxification strategies, including modulation of endogenous enzymatic systems and exogenous compounds able to inhibit MG effects on biological systems.

Ankaflavin and Monascin Induce Apoptosis in Activated Hepatic Stellate Cells through Suppression of the Akt/NF-κB/p38 Signaling Pathway

The increased proliferation of activated hepatic stellate cells (HSCs) is associated with hepatic fibrosis and excessive extracellular matrix (ECM)-protein production. We examined the inhibitory effects of the Monascus purpureus-fermented metabolites, ankaflavin and monascin (15 and 30 μM), on the Akt/nuclear factor (NF)-κB and p38 mitogen-activated protein kinase (MAPK) signaling pathways in HSC-T6 (activated hepatic stellate cell line). Ankaflavin and monascin (30 μM) induced apoptosis and significantly inhibited cell growth (cell viabilities: 80.2 ± 5.43% and 62.8 ± 8.20%, respectively, versus control cells; P < 0.05). Apoptosis and G1 phase arrest (G1 phase percentages: 76.1 ± 2.85% and 79.9 ± 1.80%, respectively, versus control cells 65.9 ± 4.94%; P < 0.05) correlated with increased p53 and p21 levels and caspase 3 activity and decreased cyclin D1 and Bcl-2-family protein levels (P < 0.05, all cases). The apoptotic effects of ankaflavin and monascin were HSC-T6-specific, suggesting their potential in treating liver fibrosis.

Miracle Fruit (Synsepalum dulcificum) Exhibits as a Novel Anti-Hyperuricaemia Agent

Miracle fruit (Synsepalum dulcificum) belongs to the Sapotaceae family. It can change flavors on taste buds, transforming acidic tastes to sweet. We evaluated various miracle fruit extracts, including water, butanol, ethyl acetate (EA), and hexane fractions, to determine its antioxidant effects. These extracts isolated from miracle fruit exerted potential for reduction of uric acid and inhibited xanthine oxidase activity in vitro and in monosodiumurate (MSU)-treated RAW264.7 macrophages. Moreover, we also found that the butanol extracts of miracle fruit attenuated oxonic acid potassium salt-induced hyperuricaemia in ICR mice by lowering serum uric acid levels and activating hepatic xanthine oxidase. These effects were equal to those of allopurinol, suggesting that the butanol extract of miracle fruit could be developed as a novel anti-hyperuricaemia agent or health food.

Effect of diet-derived advanced glycation end products on inflammation

Advanced glycation end products (AGEs) formed via the Maillard reaction during the thermal processing of food contributes to the flavor, color, and aroma of food. A proportion of food-derived AGEs and their precursors is intestinally absorbed and accumulates within cells and tissues. AGEs have been implicated in the pathogenesis of diabetes-related complications and several chronic diseases via interaction with the receptor for AGEs, which promotes the transcription of genes that control inflammation. The dicarbonyls, highly reactive intermediates of AGE formation, are also generated during food processing and may incite inflammatory responses through 1) the suppression of protective pathways, 2) the incretin axis, 3) the modulation of immune-mediated signaling, and 4) changes in gut microbiota profile and metabolite sensors. In animal models, restriction of dietary AGEs attenuates chronic low-grade inflammation, but current evidence from human studies is less clear. Here, the emerging relationship between excess dietary AGE consumption and inflammation is explored, the utility of dietary AGE restriction as a therapeutic strategy for the attenuation of chronic diseases is discussed, and possible avenues for future investigation are suggested.

Uremic Toxicity of Advanced Glycation End Products in CKD

Advanced glycation end products (AGEs), a heterogeneous group of compounds formed by nonenzymatic glycation reactions between reducing sugars and amino acids, lipids, or DNA, are formed not only in the presence of hyperglycemia, but also in diseases associated with high levels of oxidative stress, such as CKD. In chronic renal failure, higher circulating AGE levels result from increased formation and decreased renal clearance. Interactions between AGEs and their receptors, including advanced glycation end product-specific receptor (RAGE), trigger various intracellular events, such as oxidative stress and inflammation, leading to cardiovascular complications. Although patients with CKD have a higher burden of cardiovascular disease, the relationship between AGEs and cardiovascular disease in patients with CKD is not fully characterized. In this paper, we review the various deleterious effects of AGEs in CKD that lead to cardiovascular complications and the role of these AGEs in diabetic nephropathy. We also discuss potential pharmacologic approaches to circumvent these deleterious effects by reducing exogenous and endogenous sources of AGEs, increasing the breakdown of existing AGEs, or inhibiting AGE-induced inflammation. Finally, we speculate on preventive and therapeutic strategies that focus on the AGE-RAGE axis to prevent vascular complications in patients with CKD.

Resveratrol protects against methylglyoxal-induced hyperglycemia and pancreatic damage in vivo

Methylglyoxal (MG) has been found to cause inflammation and insulin resistance in vitro and in vivo in recent studies. Resveratrol has been proposed as an effective treatment that helps lower the risk of developing complications of diabetes. To study the significance of glycosylation-related stress on the pathology of diabetes, the effects of resveratrol were examined in a mouse model of diabetes induced by MG. Resveratrol was given via oral gavage in MG-treated mice, and diabetes-related tests and markers were assessed using biochemical and immunohistochemical analyses. Treatment with resveratrol markedly improved blood glucose level from the oral glucose tolerance test and promoted nuclear factor erythroid 2-related factor-2 (Nrf2) phosphorylation (p < 0.05) in the pancreas of MG-treated mice. However, these effects were abolished by retinoic acid, Nrf2 inhibitor, in resveratrol and retinoic acid-treated and MG-induced mice. These findings support that resveratrol may be useful in the treatment of type-2 diabetes by protecting against pancreatic cell dysfunction.

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.

Monascus secondary metabolites monascin and ankaflavin inhibit activation of RBL-2H3 cells

Monascus-fermented products have been used as dietary food and traditional medicine due to their beneficial effects on circulation and digestive systems in Asia for thousands of years. Besides, monascin and ankaflavin, secondary metabolites from Monascus-fermented products, have proven anti-inflammatory and immunomodulatory effects. In previous research, monascin and ankaflavin ameliorated ovalbumin-induced airway allergic reaction often used as a type I allergy asthma model. Additionally, mast cells play critical roles in type I allergy. Therefore, RBL-2H3 cells were used as the mast cell model to determine whether the improving effects on asthma of monascin and ankaflavin came from influencing mast cells. PMA and ionomycin are common activators of mast cells because they stimulate the main signaling molecules during mast cell activation. Forty micromolar monascin and ankaflavin inhibited PMA/ionomycin-induced mast cell degranulation and TNF-α secretion through suppressing the phosphorylation of PKC and MAPK family ERK, JNK, and p38. Consequently, monascin and ankaflavin affected the activation of mast cells and may have the potential to improve type I allergy.

Compounds blocking methylglyoxal-induced protein modification and brain endothelial injury

BACKGROUND AND AIMS

Elevated levels of reactive carbonyl species such as methylglyoxal triggers carbonyl stress and activates a series of inflammatory responses leading to accelerated vascular damage. Carbonyl stress is implicated in conditions and diseases like aging, diabetes mellitus, Alzheimer's disease and cardiovascular diseases. Our aim was to examine the effects of methylglyoxal on human hCMEC/D3 brain endothelial cells and search for protective molecules to prevent endothelial damage.

METHODS

Methylglyoxal-induced modification of albumin was tested in a cell-free assay. Endothelial cell viability was monitored by impedance measurement in real-time. The following compounds were tested in cell-free and viability assays: β-alanine, all-trans-retinoic acid, aminoguanidine, ascorbic acid, L-carnosine, GW-3333, indapamide, piracetam, γ-tocopherol, U0126, verapamil. Barrier function of brain endothelial monolayers was characterized by permeability measurements and visualized by immunohistochemistry for β-catenin. mRNA expression level of 60 selected blood-brain barrier-related genes in hCMEC/D3 cells was investigated by a custom Taqman gene array.

RESULTS

Methylglyoxal treatment significantly elevated protein modification, exerted toxicity, reduced barrier integrity, increased permeability for markers FITC-dextran and albumin and caused higher production of reactive oxygen species in hCMEC/D3 endothelial cells. Changes in the mRNA expression of 30 genes coding tight junction proteins, transporters and enzymes were observed in methylglyoxal-treated hCMEC/D3 cells. From the tested 11 compounds only all-trans-retinoic acid, an antioxidant and antiglycation agent, U0126, a MAP/ERK kinase inhibitor and aminoguanidine attenuated methylglyoxal-induced damage in hCMEC/D3 cells.

CONCLUSIONS

All-trans-retinoic acid and inhibition of the MAP/ERK signaling pathway may be protective in carbonyl stress induced brain endothelial damage.

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.

Protective effects of vescalagin from pink wax apple [Syzygium samarangense (Blume) Merrill and Perry] fruit against methylglyoxal-induced inflammation and carbohydrate metabolic disorder in rats

The unbalance of glucose metabolism in humans may cause the excessive formation of methylglyoxal (MG), which can react with various biomolecules to form the precursor of advanced glycation end products (AGEs). Vescalagin (VES) is an ellagitannin that alleviates insulin resistance in cell study. Results showed that VES reduced the value of oral glucose tolerance test, cardiovascular risk index, AGEs, and tumor necrosis factor-α contents while increasing C-peptide and d-lactate contents significantly in rats orally administered MG and VES together. The preventive effect of VES on MG-induced inflammation and carbohydrate metabolic disorder in rats was thus proved. On the basis of the experiment data, a mechanism, which involves the increase in d-lactate to retard AGE formation and the decrease in cytokine release to prevent β-cell damage, is proposed to explain the bioactivities of VES in antiglycation and in the alleviation of MG-induced carbohydrate metabolic disorder in rats.

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.