Production and Characterization of Anti-Inflammatory Monascus Pigment Derivatives

Purified Monascus Pigments: Biological Activities and Mechanisms of Action

Monascus pigments having yellow, orange, and red colors are widely studied for their potential beneficial properties. Many different biological activities have been reported regarding Monascus pigments and their derivatives, but the usual method is to test complex extracts from the mycelium of the fungus or from a fungus-fermented substrate. However, this review is mainly concerned with the biological activities of purified Monascus pigments. Both yellow (ankaflavin, monascin) and red (rubropunctamine, monascorubramine) Monascus pigments are proven antioxidants if used in concentrations of 10 μg/mL or higher. Antimicrobial activity against Gram-positive and Gram-negative bacteria and fungi has been observed with all Monascus pigments. However, the best antimicrobials are red Monascus pigments, and their amino acid derivatives (l-cysteine derivatives have MIC 4 μg/mL against Enterococcus faecalis). Yellow monaphilones and orange monaphilols seem to have the highest anti-inflammatory activity (IC50 1.7 μM of monaphilol D) and, together with red Monascus pigment derivatives, have mild antiobesity and antidiabetic activities. Further, monascin and ankaflavin in daily doses of 0.5 and 0.08 mg, respectively, lowered serum blood levels of low-density lipoprotein cholesterol complexes in rats on a high-fat diet. Orange Monascus pigments, rubropunctatin and monaphilols A and C, exhibit cytotoxic and antitumor activities (IC50 8-10 μM).

A Comprehensive Investigation of Lipid Profile During the Solid-State Fermentation of Rice by Monascus purpureus

Red yeast rice is a nutraceutical fermented product used worldwide for the symptomatic relief of dyslipidemia and cardiovascular disease. However, the fermentation-induced lipid transformation from rice to red yeast rice remains unclear. Herein, an ultra-high performance liquid chromatography coupled with hybrid quadrupole-orbitrap mass spectrometry method was developed for the comprehensive lipid analysis during fermentation. A total of 246 lipids fall in 21 subclasses were annotated in rice and red yeast rice, including 37 lysophospholipids, 14 phospholipids, 29 diglycerides, 114 triglycerides and fatty acid (15 species), ceramide (12 species), hexosylceramide (3 species), sitosterol ester (2 species), monogalactosyldiacylglycerol (2 species), digalactosyldiacylglycerol (2 species), monogalactosylmonoacylglycerol (8 species), digalactosylmonoacylglycerol (5 species), coenzyme Q (1 species), acyl hexosyl campesterol ester (1 species), and acylcarnitine (1 species). Results showed that lipid profiles changed, and new lipid species emerged. Notably, 18 medium- and long-chain triacylglycerols and triacylglycerols with short-chains were tentatively identified. These triacylglycerols also show the effects of body fat accumulation reduction, and hypolipidemic and hypoglycemic activities. Furthermore, lipid species that were profoundly changed were quantified, and the dynamic changes were investigated. This study clarified the molecular species and compositional changes in fermented rice from lipid aspect.

Coordinated Synthesis of Pigments Differing in Side Chain Length in Monascus purpureus and Investigation of Pigments and Citrinin Relation

The Monascus fungi have traditionally been used in Asia for food coloring. Unfortunately, the most well-known species, Monascus purpureus, very often produce mycotoxin citrinin in addition to pigments, which poses a significant problem for the use of pigments in foods. There is a step in pigment biosynthesis where a side chain of five or seven carbons is attached to the tetraketide, the product of polyketide synthase, resulting in the formation of pigments in pairs. Further, it is still unclear whether pigment and citrinin biosyntheses are related or independent. Therefore, this study is focused on the relationship between pigment and citrinin production and pigment analogues that differ in side chain length, all evaluated by the Spearman correlation test. To generate sufficient data, Monascus purpureus DBM 4360 was cultivated with different carbon and nitrogen sources and under osmotic stress induced by glucose and/or sodium chloride. The study reveals a very strong correlation between the production of five- and seven-carbon side chain pigments under all culture conditions tested for all three groups, yellow, orange, and red pigments. The correlation between pigments and citrinin depended on the group assessed and ranged from fair to very strong. While the coordinated synthesis of pigment analogues in pairs has been clearly confirmed, the relationship between pigment and citrinin production was unfortunately neither confirmed nor refuted and must be the subject of further research.

Monascus pigment-protected bone marrow-derived stem cells for heart failure treatment

Mesenchymal stem cells (MSCs) have demonstrated significant therapeutic potential in heart failure (HF) treatment. However, their clinical application is impeded by low retention rate and low cellular activity of MSCs caused by high inflammatory and reactive oxygen species (ROS) microenvironment. In this study, monascus pigment (MP) nanoparticle (PPM) was proposed for improving adverse microenvironment and assisting in transplantation of bone marrow-derived MSCs (BMSCs). Meanwhile, in order to load PPM and reduce the mechanical damage of BMSCs, injectable hydrogels based on Schiff base cross-linking were prepared. The PPM displays ROS-scavenging and macrophage phenotype-regulating capabilities, significantly enhancing BMSCs survival and activity in HF microenvironment. This hydrogel demonstrates superior biocompatibility, injectability, and tissue adhesion. With the synergistic effects of injectable, adhesive hydrogel and the microenvironment-modulating properties of MP, cardiac function was effectively improved in the pericardial sac of rats. Our results offer insights into advancing BMSCs-based HF therapies and their clinical applications.

Phospholipid biosynthesis regulation for improving pigment production by Monascus in response to ammonium chloride stress

In the actual industrial production process, the efficient biosynthesis and secretion of Monascus pigments (MPs) tend to take place under abiotic stresses, which often result in an imbalance of cell homeostasis. The present study aimed to thoroughly describe the changes in lipid profiles in Monascus purpureus by absolute quantitative lipidomics and tandem mass tag-based quantitative proteomics. The results showed that ammonium chloride stress (15 g/L) increased MP production while inhibiting ergosterol biosynthesis, leading to an imbalance in membrane lipid homeostasis in Monascus. In response to the imbalance of lipid homeostasis, the regulation mechanism of phospholipids in Monascus was implemented, including the inhibition of lysophospholipids production, maintenance of the ratio of PC/PE, and improvement of the biosynthesis of phosphatidylglycerol, phosphatidylserine, and cardiolipin with high saturated and long carbon chain fatty acids through the CDP-DG pathway rather than the Kennedy pathway. The inhibition of lysophospholipid biosynthesis was attributed to the upregulated expression of protein and its gene related to lysophospholipase NTE1, while maintenance of the PC/PE ratio was achieved by the upregulated expression of protein and its gene related to CTP: phosphoethanolamine cytidylyltransferase and phosphatidylethanolamine N-methyltransferase in the Kennedy pathway. These findings provide insights into the regulation mechanism of MP biosynthesis from new perspectives.IMPORTANCEMonascus is important in food microbiology as it produces natural colorants known as Monascus pigments (MPs). The industrial production of MPs has been achieved by liquid fermentation, in which the nitrogen source (especially ammonium chloride) is a key nutritional parameter. Previous studies have investigated the regulatory mechanisms of substance and energy metabolism, as well as the cross-protective mechanisms in Monascus in response to ammonium chloride stress. Our research in this work demonstrated that ammonium chloride stress also caused an imbalance of membrane lipid homeostasis in Monascus due to the inhibition of ergosterol biosynthesis. We found that the regulation mechanism of phospholipids in Monascus was implemented, including inhibition of lysophospholipids production, maintenance of the ratio of PC/PE, and improvement of biosynthesis of phosphatidylglycerol, phosphatidylserine, and cardiolipin with high saturated and long carbon chain fatty acids through the CDP-DG pathway. These findings further refine the regulatory mechanisms of MP production and secretion.

Lecithin/chitosan nanoparticle drug carrier improves anti-tumor efficacy of Monascus pigment rubropunctatin

Rubropunctatin, a metabolite isolated from the fungi of the genus Monascus, is a natural lead compound applied for the suppression of tumors with good anti-cancer activity. However, its poor aqueous solubility has limited its further clinical development and utilization. Lecithin and chitosan are excellently biocompatible and biodegradable natural materials, which have been approved by the FDA as drug carrier. Here, we report for the first time the construction of a lecithin/chitosan nanoparticle drug carrier of the Monascus pigment rubropunctatin by electrostatic self-assembly between lecithin and chitosan. The nanoparticles are near-spherical with a size 110-120 nm. They are soluble in water and possess excellent homogenization capacity and dispersibility. Our in vitro drug release assay showed a sustained release of rubropunctatin. CCK-8 assays revealed that lecithin/chitosan nanoparticles loaded with rubropunctatin (RCP-NPs) had significantly enhanced cytotoxicity against mouse mammary cancer 4T1 cells. The flow cytometry results revealed that RCP-NPs significantly boosted cellular uptake and apoptosis. The tumor-bearing mice models we developed indicated that RCP-NPs effectively inhibited tumor growth. Our present findings suggest that lecithin/chitosan nanoparticle drug carriers improve the anti-tumor effect of the Monascus pigment rubropunctatin.

Inhibition of cellulase activity by liquid hydrolysates from hydrothermally pretreated soybean straw

The one-pot biomass conversion process is a promising strategy to minimize potential product loss and reduce processing costs. However, this strategy has technical limitations due to the inhibitory effects of biomass components like lignin as well as the generated inhibitors (e.g., furans, phenols) during biomass processing. In this study, the inhibitory effects of liquid hydrolysates formed by hydrothermal pretreatment of soybean straw with either sodium hydroxide (NaOH) or hydrogen peroxide (H2O2) on cellulolytic enzyme activity were investigated. Hydrothermal pretreatment of soybean straw (10% w/v) was carried out with either sodium hydroxide (1% v/v) or hydrogen peroxide (1% v/v) at 121°C for 60 min to evaluate the effect of water-soluble inhibitors released from soybean pretreatment on cellulolytic enzyme activity. The fraction of cellulose in pretreated solids (1% w/v glucan) was enzymatically hydrolyzed for 72 h with 45 IU/g glucan (corresponding to 25 mg enzyme protein/g glucan) in the presence of either buffer or liquid hydrolysate generated from the pretreatments. Hydrolysis of NaOH and H2O2 pretreated solids resulted in 57% and 39% of glucose yields in buffer, respectively. In the presence of the liquid hydrolysates, NaOH and H2O2 pretreated biomass showed 20% and 30% glucose yield, respectively, indicating the enzyme suppression by inhibitors in the liquid hydrolysates. Of the enzyme activities in hydrolysates tested, NaOH hydrolysate showed a higher inhibitory effect on enzyme activities (mainly β-glucosidase) compared to H2O2 liquid, where enzyme deactivation has a first-order correlation and the manner in which the vacuum-filtered inhibitors were generated from pretreated soybean straw.

Metabolomics Analysis Coupled with Weighted Gene Co-Expression Network Analysis Unravels the Associations of Tricarboxylic Acid Cycle-Intermediates with Edible Pigments Produced by Monascus purpureus (Hong Qu)

Monascus azaphilones pigments (MonAzPs) produced by microbial fermentation are widely used as food chemicals for coloring and supplying beneficial biological attributes. In this study, a fermentation perturbation strategy was implemented by separately adding different amino acids, and detecting the intracellular metabolome via UHPLC-Q-Orbitrap HRMS. With the aid of weighted gene co-expression network analysis, two metabolic intermediates, fumarate and malate, involved in the tricarboxylic acid cycle, were identified as the hub metabolites. Moreover, exogenous addition of fumarate or malate significantly promoted red pigment production, and reduced orange/yellow pigment production. The importance of the tricarboxylic acid cycle was further emphasized by detecting intracellular levels of ATP, NAD(P)H, and expression of oxidoreductase-coding genes located in the MonAzPs synthetic gene cluster, suggesting a considerable effect of the energy supply on MonAzPs synthesis. Collectively, metabolomics is a powerful approach to position the crucial metabolic regulatory factors, and facilitate the development of engineering strategies for targeted regulation, lower trial-and-error cost, and advance safe and controllable processes for fermented food chemistry industries.

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.

Azaphilone alkaloids: prospective source of natural food pigments

Azaphilone, biosynthesized by polyketide synthase, is a class of fungal metabolites. In this review, after brief introduction of the natural azaphilone diversity, we in detail discussed azaphilic addition reaction involving conversion of natural azaphilone into the corresponding azaphilone alkaloid. Then, setting red Monascus pigments (a traditional food colorant in China) as example, we presented a new strategy, i.e., interfacing azaphilic addition reaction with living microbial metabolism in a one-pot process, to produce azaphilone alkaloid with a specified amine residue (red Monascus pigments) during submerged culture. Benefit from the red Monascus pigments with a specified amine residue, the influence of primary amine on characteristics of the food colorant was highlighted. Finally, the progress for screening of alternative azaphilone alkaloids (production from interfacing azaphilic addition reaction with submerged culture of Talaromyces sp. or Penicillium sp.) as natural food colorant was reviewed. KEY POINTS: • Azaphilic addition reaction of natural azaphilone is biocompatible • Red Monascus pigment is a classic example of azaphilone alkaloids • Azaphilone alkaloids are alterative natural food colorant.

Recent Findings in Azaphilone Pigments

Filamentous fungi are known to biosynthesize an extraordinary range of azaphilones pigments with structural diversity and advantages over vegetal-derived colored natural products such agile and simple cultivation in the lab, acceptance of low-cost substrates, speed yield improvement, and ease of downstream processing. Modern genetic engineering allows industrial production, providing pigments with higher thermostability, water-solubility, and promising bioactivities combined with ecological functions. This review, covering the literature from 2020 onwards, focuses on the state-of-the-art of azaphilone dyes, the global market scenario, new compounds isolated in the period with respective biological activities, and biosynthetic pathways. Furthermore, we discussed the innovations of azaphilone cultivation and extraction techniques, as well as in yield improvement and scale-up. Potential applications in the food, cosmetic, pharmaceutical, and textile industries were also explored.