Dimerumic acid protected oxidative stress-induced cytotoxicity in isolated rat hepatocytes

Transcriptional Differences Guided Discovery and Genetic Identification of Coprogen and Dimerumic Acid Siderophores in Metarhizium robertsii

Siderophores are small molecular iron chelators and participate in the multiple cellular processes in fungi. In this study, biosynthesis gene clusters of coprogens and dimerumic acids were identified by transcriptional level differences of genes related to iron deficiency conditions in Metarhizium robertsii. This leads to the characterization of new coprogen metachelin C (1) and five known siderophores metachelin A (2), metachelin A-CE (3), metachelin B (4), dimerumic acid 11-mannoside (5), and dimerumic acid (6). The structure of metachelin C (1) was elucidated by NMR spectroscopy and HR-ESI-MS analysis. Genetic deletions of mrsidA, and mrsidD abolished the production of compounds 1–6 that implied their involvement in the biosynthesis of coprogen and dimerumic acid. Interestingly, NRPS gene mrsidD is responsible for biosynthesis of both coprogen and dimerumic acid, thus we proposed plausible biosynthetic pathways for the synthesis of coprogen and dimerumic acid siderophores. Therefore, our study provides the genetic basis for understanding the biosynthetic pathway of coprogen and dimerumic acid in Metarhizium robertsii.

Structural Diversity and Biological Activities of the Cyclodipeptides from Fungi

Cyclodipeptides, called 2,5-diketopiperazines (2,5-DKPs), are obtained by the condensation of two amino acids. Fungi have been considered to be a rich source of novel and bioactive cyclodipeptides. This review highlights the occurrence, structures and biological activities of the fungal cyclodipeptides with the literature covered up to July 2017. A total of 635 fungal cyclodipeptides belonging to the groups of tryptophan-proline, tryptophan-tryptophan, tryptophan-Xaa, proline-Xaa, non-tryptophan-non-proline, and thio-analogs have been discussed and reviewed. They were mainly isolated from the genera of Aspergillus and Penicillium. More and more cyclodipeptides have been isolated from marine-derived and plant endophytic fungi. Some of them were screened to have cytotoxic, phytotoxic, antimicrobial, insecticidal, vasodilator, radical scavenging, antioxidant, brine shrimp lethal, antiviral, nematicidal, antituberculosis, and enzyme-inhibitory activities to show their potential applications in agriculture, medicinal, and food industry.

2,5-diketopiperazines in food and beverages: Taste and bioactivity

2,5-Diketopiperazines (2,5-DKPs) have been found to occur in a wide range of food and beverages, and display an array of chemesthetic effects (bitter, astringent, metallic, and umami) that can contribute to the taste of a variety of foods. These smallest cyclic peptides also occur as natural products and have been found to display a variety of bioactivities from antibacterial, antifungal, to anthroprotective effects and have the potential to be used in the development of new functional foods. An overview of the synthesis of these small chiral molecules and their molecular properties is presented. The occurrence, taste, and bioactivity of all simple naturally occurring 2,5-DKPs to date have been reviewed and those found in food from yeasts, fungi, and bacteria that have been used in food preparation or contamination, as well as metabolites of sweeteners and antibiotics added to food are also reviewed.

Dimerumic Acid and Deferricoprogen Activate Ak Mouse Strain Thymoma/Heme Oxygenase-1 Pathways and Prevent Apoptotic Cell Death in 6-Hydroxydopamine-Induced SH-SY5Y Cells

Parkinson's disease (PD) is a neurodegenerative disorder, which can be modeled using the neurotoxin 6-hydroxydopamine (6-OHDA) to generate oxidative stress. Here, we studied the effects of the antioxidants deferricoprogen (DFC) and dimerumic acid (DMA), produced by rice fermented with Monascus purpureus NTU 568, on 6-OHDA-induced apoptosis in SH-SY5Y cells and their potential protective mechanisms. DMA and DFC inhibited 6-OHDA-induced apoptosis and cellular reactive oxygen species (ROS) in SH-SY5Y human neuroblastoma cells. Molecular analysis demonstrated associated upregulation of the Ak mouse strain thymoma (Akt), heme oxygenase-1 (HO-1), and signal-regulated kinase (ERK) pathways along with inhibited phosphorylation of c-Jun N-terminal kinase (JNK) and p38 pathways and altered homodimeric glycoprotein, N-methyl-d-aspartate (NMDA) receptor, and immunoglobulin Fc receptor gene expression. These results suggested that the neuroprotection elicited by DMA and DFC against 6-OHDA-induced neurotoxicity was associated with the Akt, MAPK, and HO-1 pathways via regulating the gene expression of NMDA receptor, homodimeric glycoprotein, and immunoglobulin Fc receptor.

Neuroprotective effects of dimerumic acid and deferricoprogen from Monascus purpureus NTU 568-fermented rice against 6-hydroxydopamine-induced oxidative stress and apoptosis in differentiated pheochromocytoma PC-12 cells

Context Oxidative stress plays a key role in neurodegenerative disorders, including Parkinson's disease (PD). Rice fermented with Monascus purpureus Went (Monascaceae) NTU 568 (red mould rice) was found to contain antioxidants, including dimerumic acid (DMA) and deferricoprogen (DFC). Objective The effects of DMA and DFC on 6-hydroxydopamine (6-OHDA)-induced cytotoxicity and potential protective mechanisms in differentiated PC-12 pheochromocytoma cells were investigated. Materials and methods DMA (0-60 μM) or DFC (0-10 μM) was co-treated with 6-OHDA (200 μM, 24 h exposure) in differentiated PC-12 cells. Cell viability and intercellular reactive oxygen species (ROS) were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and 2',7'-dichlorofluorescein-diacetate (DCFH-DA) assays, respectively. Cell apoptosis was determined by DNA fragmentation analysis and propidium iodide staining by flow cytometry. Western blot analysis was used to measure the levels of cell protein expression. Results DMA and DFC significantly increased cell viability to 72% and 81% in 6-OHDA-induced differentiated PC-12 cell cultures, respectively. Furthermore, DMA and DFC reduced 6-OHDA-induced formation of extracellular and intercellular ROS by 25% and 20%, respectively, and decreased NADPH oxidase-2 expression in differentiated PC-12 cells. DMA and DFC inhibited 6-OHDA-induced apoptosis and decreased activation of caspase-3 via regulation of Bcl-2-associated X protein (Bax) and Bcl-2 protein expression in differentiated PC-12 cells. Conclusion DMA and DFC may protect against 6-OHDA toxicity by inhibiting ROS formation and apoptosis. These results showed that the metabolites from M. purpureus NTU 568 fermentation were potential therapeutic agents for PD induced by oxidative damage and should be encouraged for further research.

The ameliorative effect of Monascus purpureus NTU 568-fermented rice extracts on 6-hydroxydopamine-induced neurotoxicity in SH-SY5Y cells and the rat model of Parkinson's disease

TheMonascus purpureusNTU 568-fermented rice extract contains antioxidants DMA and DFC, and it could reduce behavioral, neuronal, and biochemical characteristics in 6-OHDA-lesion rats.

In Vivo Hypocholesterolemic Effect of MARDI Fermented Red Yeast Rice Water Extract in High Cholesterol Diet Fed Mice

Fermented red yeast rice has been traditionally consumed as medication in Asian cuisine. This study aimed to determine the in vivo hypocholesterolemic and antioxidant effects of fermented red yeast rice water extract produced using Malaysian Agricultural Research and Development Institute (MARDI) Monascus purpureus strains in mice fed with high cholesterol diet. Absence of monacolin-k, lower level of γ-aminobutyric acid (GABA), higher content of total amino acids, and antioxidant activities were detected in MARDI fermented red yeast rice water extract (MFRYR). In vivo MFRYR treatment on hypercholesterolemic mice recorded similar lipid lowering effect as commercial red yeast rice extract (CRYR) as it helps to reduce the elevated serum liver enzyme and increased the antioxidant levels in liver. This effect was also associated with the upregulation of apolipoproteins-E and inhibition of Von Willebrand factor expression. In summary, MFRYR enriched in antioxidant and amino acid without monacolin-k showed similar hypocholesterolemic effect as CRYR that was rich in monacolin-k and GABA.

Suppression of dimerumic acid on hepatic fibrosis caused from carboxymethyl-lysine (CML) by attenuating oxidative stress depends on Nrf2 activation in hepatic stellate cells (HSCs)

Hyperglycemia facilitates the formation of advanced glycation end-products (AGEs) in type-2 diabetes. Evidence indicates that carboxymethyl-lysine (CML) is highly prevalent in diabetes, resulting in hepatic fibrosis. The current study was designed to evaluate the effects of dimerumic acid (DMA) identified from Monascus-fermented products on receptor for AGEs (RAGE) signal and hepatic stellate cells (HSCs) activation by CML treatment. We found that DMA (50 μM) eliminated collagen generation, mRNA expressions of α-smooth muscle actin (α-SMA), platelet-derived growth factor-β receptor (PDGF-βR), and procollagen 1a1 (proCol-1a1) in CML (100 μg/ml)-treated HSCs, and these effects were similar to allyl isothiocyanate (AITC; 50 μM). In addition, the suppression of α-SMA, PDGF-βR, proCol-1a1 by DMA were abolished while nuclear factor-erythroid 2-related factor 2 (Nrf2) silence in CML-treated HSCs. These findings suggested that DMA and AITC increased Nrf2 and glutamate-cysteine ligase (GCL) activities thereby inhibiting oxidative stress caused by CML and showing anti-fibrogentic effect in HSCs.

Dimerumic acid attenuates receptor for advanced glycation endproducts signal to inhibit inflammation and diabetes mediated by Nrf2 activation and promotes methylglyoxal metabolism into d-lactic acid

This study was designed to evaluate the effects of dimerumic acid (DMA) on receptor for advanced glycation endproducts (RAGE) signal activation and THP-1 monocyte inflammation treated with S100b, a specific ligand of RAGE. We found that DMA inhibited inflammatory cytokine production via upregulation of nuclear factor-erythroid 2-related factor 2 (Nrf2) and alleviated oxidative stress through attenuation of p47phox translocation to the membrane of S100b-treated THP-1 monocytes. We found that DMA activated Nrf2 mediated by the p38 kinase pathway in THP-1 monocytes. However, anti-inflammatory activity of DMA was attenuated by Nrf2 siRNA treatment. In an animal model, methylglyoxal (MG; 200mg/kg bw) was chosen to induce diabetes in Balb/C mice (6 weeks) in this work. The in vivo verification of anti-inflammation in peripheral blood mononuclear cells by DMA treatment was confirmed by tumor necrosis factor-α and interleukin-1β measurements. Oral glucose tolerance test, insulin tolerance test, hyperinsulinemia, and hyperglycemia were improved in MG-treated mice by DMA treatment and these effects were greater than those of silymarin and N-acetylcysteine. Furthermore, DMA increased hepatic glyoxalase mRNA and glutathione mediated by Nrf2 activation to metabolize MG into d-lactic acid, thereby reducing serum and hepatic AGE levels and suppressing inflammatory factor generation in MG-treated mice. However, DMA did not exert the antiglycation activity in MG-bovine serum albumin incubation. Taken together, the results indicate that DMA is a novel antioxidant and Nrf2 activator that lowers AGE levels and may prove to be an effective treatment for diabetes.

Reduction of serum lipids by the intake of the extract of garlic fermented with Monascus pilosus: a randomized, double-blind, placebo-controlled clinical trial

BACKGROUND & AIMS

A dietary supplement containing garlic fermented with Monascus pilosus (MGFE) may be useful to decrease the lipid concentrations in serum without serious adverse effects. The aim of the study was to assess whether MGFE decreases serum lipid contents in volunteers with mild hyperlipidemia in a randomized, double-blind, placebo-controlled, parallel-group trial.

METHODS

Healthy subjects (n = 55) with serum triglyceride concentrations of 120-200mg/dL were randomly assigned to take either MGFE or placebo capsules for 12 wk.

RESULTS

A borderline, but not significant effect, to decrease triglyceride concentrations in serum (approximately 15% reduction at maximum, P = 0.062, in time × treatment interaction effect) was observed by the MGFE intake for 12 wk. The decreased reading exhibited a significant difference at wk-8 between the MGFE and placebo groups (unpaired t test, P = 0.007). The total cholesterol (P = 0.003) and LDL cholesterol (P = 0.001) contents in the serum and the LDL/HDL ratio (P < 0.001) were significant in time × treatment interaction effects by the MGFE intake. However, no alteration in the body fat percentage and abdominal circumference was observed.

CONCLUSIONS

The intake of MGFE decreased triglyceride and cholesterol in serum with no appreciable adverse effects in normal to mildly hyperlipidemic individuals, suggesting that it may be effective to improve and prevent the metabolic syndrome. This clinical trial was registered with Clinicaltrials.gov as NCT00938249.

Hepatoprotective and antioxidant effects of licorice extract against CCl₄-induced oxidative damage in rats

Licorice has been used in Chinese folk medicine for the treatment of various disorders. Licorice has the biological capabilities of detoxication, antioxidation, and antiinfection. In this study, we evaluated the antihepatotoxic effect of licorice aqueous extract (LE) on the carbon tetrachloride (CCl₄)-induced liver injury in a rat model. Hepatic damage, as reveled by histology and the increased activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) activities, and decreased levels of serum total protein (TP), albumin (Alb) and globulin (G) were induced in rats by an administration of CCl₄ at 3 mL/kg b.w. (1:1 in groundnut oil). Licorice extract significantly inhibited the elevated AST, ALP and ALT activities and the decreased TP, Alb and G levels caused by CCl₄ intoxication. It also enhanced liver super oxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), Glutathione S-transferase (GST) activities and glutathione (GSH) level, reduced malondialdehyde (MDA) level. Licorice extract still markedly reverses the increased liver hydroxyproline and serum TNF-α levels induced by CCl₄ intoxication. The data of this study support a chemopreventive potential of licorice extract against liver oxidative injury.

Inhibition of endothelial adhesion molecule expression by Monascus purpureus-fermented rice metabolites, monacolin K, ankaflavin, and monascin

BACKGROUND

Inflammation is an independent risk factor of cardiovascular diseases and is associated with endothelial dysfunction. Monascus purpureus-fermented rice, containing naturally occurring statins and various pigments, has lipid-modulating, anti-inflammatory and antioxidative effects.

RESULTS

The effects of monacolin K, ankaflavin and monascin, as metabolites from Monascus-fermented rice, on the expression of cell adhesion molecules (intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecular-1 (VCAM-1) and E-selectin) by tumor necrosis factor (TNF)-α-treated human aortic endothelial cells (HAECs) were investigated. Supplement of HAECs with these Monascus-fermented rice metabolites significantly suppressed cellular binding between the human monocytic cells U937 and TNF-α-stimulated HAECs. Immunoblot analysis showed that Monascus-fermented rice metabolites significantly attenuated TNF-α-induced VCAM-1 and E-selectin but not ICAM-1 protein expression. Gel shift assays showed that Monascus-fermented rice metabolites treatment reduced TNF-α-activated transcription factor nuclear factor (NF)-κB. Furthermore, Monascus-fermented rice metabolites also attenuated reactive oxygen species (ROS) generation in vitro and in TNF-α-treated HAECs. Supplement with an ROS scavenger N-acetylcysteine gave similar results as compared with Monascus-fermented rice metabolites.

CONCLUSION

Monascus-fermented rice metabolites reduced TNF-α-stimulated endothelial adhesiveness as well as downregulating intracellular ROS formation, NF-κB activation, and VCAM-1/E-selectin expression in HAECs, supporting the notion that the various metabolites from Monascus-fermented rice might have potential implications in clinical atherosclerosis disease.

Dimerumic acid inhibits SW620 cell invasion by attenuating H₂O₂-mediated MMP-7 expression via JNK/C-Jun and ERK/C-Fos activation in an AP-1-dependent manner

Reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂) in the tumor microenvironment play important roles in tumor invasion and metastasis. Recently, ROS have been reported to cause a significant increase in the production and expression of matrix metalloproteinase (MMP)-7, which is closely correlated with metastatic colorectal cancer. The present study was undertaken to evaluate the scavenging activity of dimerumic acid (DMA) for H₂O₂ isolated from Monascus-fermented rice to investigate the inhibitory effects of DMA on the invasive potential of SW620 human colon cancer cells, and to explore the mechanisms underlying both these phenomena. Our results showed that increased MMP-7 expression due to H₂O₂ exposure was mediated by activation of mitogen-activated protein kinases (MAPKs) such as Jun N-terminal kinase (JNK), extracellular-regulated kinase (ERK), and p38 kinase. DMA pretreatment suppressed activation of H₂O₂-mediated MAPK pathways and cell invasion. Moreover, H₂O₂-triggered MMP-7 production was demonstrated via JNK/c-Jun and ERK/c-Fos activation in an activating protein 1 (AP-1)-dependent manner. Taken together, these results suggest that DMA suppresses H₂O₂-induced cell invasion by inhibiting AP-1-mediated MMP-7 gene transcription via the JNK/c-Jun and ERK/c-Fos signaling pathways in SW620 human colon cancer cells. Our data suggest that DMA may be useful in minimizing the development of colorectal metastasis. In the future, DMA supplementation may be a beneficial antioxidant to enhance surgical outcomes.