Engineering stilbene metabolic pathways in microbial cells

The genus Polygonum: An updated comprehensive review of its ethnomedicinal, phytochemical, pharmacological activities, toxicology, and phytopharmaceutical formulation

Polygonum is a plant genus that includes annual and perennial species and is found at various temperatures, from northern temperate regions to tropical and subtropical areas. The genus Polygonum has been used for centuries for various disorders, including hypertension, intestinal and stomach pain, dysuria, jaundice, toothaches, skin allergies, hemorrhoids, cardiac disorders, kidney stones, hemostasis, hyperglycemia, and others. Various databases, including Google Scholar, Scifinder, ScienceDirect, PubMed, Scopus, ResearchGate, and Web of Science, were utilized to collect pertinent scientific literature data. According to bibliographic studies, the Polygonum genus possesses various compounds from different families, including phenolic acids (gallic acid, caffeic acid, quinic acid, p-coumaric acid, ferulic acid, protocatechuic acid, chlorogenic acid, and many other compounds), flavonoids (quercetin, catechin, epicatechin, quercitrin, kaempferol, myricetin, etc.), tannins, stilbenes (polydatin and resveratrol), terpenes (α-pinene, β-caryophyllene and β-caryophyllene oxide, bisabolene, β-farnesene, etc.), fatty acids (decanoic acid, lauric acid, linoleic acid, oleic acid, palmitic acid, stearic acid, dodecanoic acid), polysaccharides, and others. Various chemical and biological activities (in vitro and in vivo), such as antioxidant, antimicrobial, anticancer, antitumor, anti-inflammatory, antidiabetic, antiparasitic, hepatoprotective, neuropharmacological, gastroprotective, diuretic, antipyretic, and others, have been described in several biological studies involving this species. An updated summary of Polygonum species and their ethnomedicinal, phytochemical, toxicological, pharmacological, and phytopharmaceutical formulations is necessary. Considering the numerous potentialities of the Polygonum species and their wide-ranging use, it is extremely essential to provide knowledge by compiling the accessible literature to identify the topics of intense investigation and the main gaps to better design future studies. The objective of this review is to give readers a better understanding, greater comprehension, and in-depth knowledge of the genus Polygonum's traditional applications, phytochemistry, pharmacology, toxicological features, and galenic formulation. Several species of this genus have been detailed in this review, including those that were frequently used in traditional medicine (P. minus, P. aviculare, P. hydropiper, P. cuspidatum, and P. multiflorum) and many of the genus' therapeutic species, like P. equisetiforme, which do not get enough attention.

Efficient biosynthesis of resveratrol via combining phenylalanine and tyrosine pathways in Saccharomyces cerevisiae

BACKGROUND

Resveratrol is a commercially available stilbenoid widely used as dietary supplements, functional food ingredients, and cosmetic ingredients due to its diverse physiological activities. The production of resveratrol in microorganisms provides an ideal source that reduces the cost of resveratrol, but the titer in Saccharomyces cerevisiae was still much lower than that in other hosts.

RESULTS

To achieve enhanced production of resveratrol in S. cerevisiae, we constructed a biosynthetic pathway via combining phenylalanine and tyrosine pathways by introducing a bi-functional phenylalanine/tyrosine ammonia lyase from Rhodotorula toruloides. The combination of phenylalanine pathway with tyrosine pathway led to a 462% improvement of resveratrol production in yeast extract peptone dextrose (YPD) medium with 4% glucose, suggesting an alternative strategy for producing p-coumaric acid-derived compounds. Then the strains were further modified by integrating multi-copy biosynthetic pathway genes, improving metabolic flux to aromatic amino acids and malonyl-CoA, and deleting by-pathway genes, which resulted in 1155.0 mg/L resveratrol in shake flasks when cultured in YPD medium. Finally, a non-auxotrophic strain was tailored for resveratrol production in minimal medium without exogenous amino acid addition, and the highest resveratrol titer (4.1 g/L) ever reported was achieved in S. cerevisiae to our knowledge.

CONCLUSIONS

This study demonstrates the advantage of employing a bi-functional phenylalanine/tyrosine ammonia lyase in the biosynthetic pathway of resveratrol, suggesting an effective alternative in the production of p-coumaric acid-derived compounds. Moreover, the enhanced production of resveratrol in S. cerevisiae lays a foundation for constructing cell factories for various stilbenoids.

Recent advances in synthesis of stilbene derivatives via cross-coupling reaction

The stilbenes are undoubtedly some of the most significant moieties in various bioactive natural and synthetic structures, and they are considered privileged structures. In recent years, the preparation of these structures via cross-coupling reactions has attracted much attention. In the current review, we present a summary of the recent developments in the construction of stilbene and stilbene derivatives by carbon-carbon coupling reactions of organic compounds in the presence of transition metal catalysts or under metal-free conditions. In this context, we outline the features of the important reactions, some product yields, and challenging reaction mechanisms.

Shikimic acid biosynthesis in microorganisms: Current status and future direction

Shikimic acid (SA), a hydroaromatic natural product, is used as a chiral precursor for organic synthesis of oseltamivir (Tamiflu®, an antiviral drug). The process of microbial production of SA has recently undergone vigorous development. Particularly, the sustainable construction of recombinant Corynebacterium glutamicum (141.2 g/L) and Escherichia coli (87 g/L) laid a solid foundation for the microbial fermentation production of SA. However, its industrial application is restricted by limitations such as the lack of fermentation tests for industrial-scale and the requirement of growth-limiting factors, antibiotics, and inducers. Therefore, the development of SA biosensors and dynamic molecular switches, as well as genetic modification strategies and optimization of the fermentation process based on omics technology could improve the performance of SA-producing strains. In this review, recent advances in the development of SA-producing strains, including genetic modification strategies, metabolic pathway construction, and biosensor-assisted evolution, are discussed and critically reviewed. Finally, future challenges and perspectives for further reinforcing the development of robust SA-producing strains are predicted, providing theoretical guidance for the industrial production of SA.

Efficient biosynthesis of pinosylvin from lignin-derived cinnamic acid by metabolic engineering of Escherichia coli

BACKGROUND

The conversion of lignin-derived aromatic monomers into valuable chemicals has promising potential to improve the economic competitiveness of biomass biorefineries. Pinosylvin is an attractive pharmaceutical with multiple promising biological activities.

RESULTS

Herein, Escherichia coli was engineered to convert the lignin-derived standard model monomer cinnamic acid into pinosylvin by introducing two novel enzymes from the wood plant: stilbene synthase from Pinus pinea (PpSTS) and 4-Coumarate-CoA ligase from Populus trichocarpa (Ptr4CL4). The expression of Ptr4CL4 drastically improved the production of pinosylvin (42.5 ± 1.1 mg/L), achieving values 15.7-fold higher than that of Ptr4CL5 (another 4-Coumarate-CoA ligase from Populus trichocarpa) in the absence of cerulenin. By adjusting the expression strategy, the optimized engineered strain produced pinosylvin at 153.7 ± 2.2 mg/L with an extremely high yield of 1.20 ± 0.02 mg/mg cinnamic acid in the presence of cerulenin, which is 83.9% ± 1.17 of the theoretical yield. This is the highest reported pinosylvin yield directly from cinnamic acid to date.

CONCLUSION

Our work highlights the feasibility of microbial production of pinosylvin from cinnamic acid and paves the way for converting lignin-related aromatics to valuable chemicals.

Molecular Mechanistic Pathways Targeted by Natural Antioxidants in the Prevention and Treatment of Chronic Kidney Disease

Chronic kidney disease (CKD) is the progressive loss of renal function and the leading cause of end-stage renal disease (ESRD). Despite optimal therapy, many patients progress to ESRD and require dialysis or transplantation. The pathogenesis of CKD involves inflammation, kidney fibrosis, and blunted renal cellular antioxidant capacity. In this review, we have focused on in vitro and in vivo experimental and clinical studies undertaken to investigate the mechanistic pathways by which these compounds exert their effects against the progression of CKD, particularly diabetic nephropathy and kidney fibrosis. The accumulated and collected data from preclinical and clinical studies revealed that these plants/bioactive compounds could activate autophagy, increase mitochondrial bioenergetics and prevent mitochondrial dysfunction, act as modulators of signaling pathways involved in inflammation, oxidative stress, and renal fibrosis. The main pathways targeted by these compounds include the canonical nuclear factor kappa B (NF-κB), canonical transforming growth factor-beta (TGF-β), autophagy, and Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid factor 2-related factor 2 (Nrf2)/antioxidant response element (ARE). This review presented an updated overview of the potential benefits of these antioxidants and new strategies to treat or reduce CKD progression, although the limitations related to the traditional formulation, lack of standardization, side effects, and safety.

Anticancer potential of Naringenin, Biosynthesis, Molecular target, and structural perspectives

Numerous novel medicinal agents isolated from plant sources were used as indigenous remedies for the management and treatment of various types of cancer diseases. Naringenin is a naturally occurring flavanone glycoside and aglycone (genin) moiety of naringin, predominantly found in citrus and grapefruits, has emerged as a potential therapeutic agent for the management of a variety of diseases. A huge number of scientific papers have been published on naringenin describing its detailed studies and its therapeutic application in different diseases. The current study highlights, a comprehensive study on naringenin concerning its biosynthesis, molecular targets/pathways involved in carcinogenesis, mechanism of actions (MOAs), and structure-activity relationships (SARs), and patents granted have been highlighted. Naringenin and its derivatives has remarkable anti-cancer activity due to their inhibitory potential against diverse targets namely ABCG2/P-gp/BCRP, 5a-reductase, 17-bhydroxysteroid dehydrogenase, aromatase, proteasome, HDAC/Situin-1, VEGF, VEGFR-2 kinase, MMP-2/9, JAK/STAT signaling pathways, CDC25B, tubulin, topoisomerase-II, cathepsin-K, Wnt, NF-kB, B-Raf and mTOR, etc. With the huge knowledge of molecular targets, structural intuition, and SARs, the current study may be beneficial to design more potent, safe, effective, and economic anti-cancer naringenin. This is concluded that naringenin is a promising natural product for the management and therapy of cancer. Further evolution for pharmacological importance, clinical research, and trials are required to manifest its therapeutic action on metabolic syndrome in the human community.

The beauty of biocatalysis: sustainable synthesis of ingredients in cosmetics

Covering: 2015 up to July 2021The market for cosmetics is consumer driven and the desire for green, sustainable and natural ingredients is increasing. The use of isolated enzymes and whole-cell organisms to synthesise these products is congruent with these values, especially when combined with the use of renewable, recyclable or waste feedstocks. The literature of biocatalysis for the synthesis of ingredients in cosmetics in the past five years is herein reviewed.

Resveratrol-Based Nanoformulations as an Emerging Therapeutic Strategy for Cancer

Resveratrol is a polyphenolic stilbene derivative widely present in grapes and red wine. Broadly known for its antioxidant effects, numerous studies have also indicated that it exerts anti-inflammatory and antiaging abilities and a great potential in cancer therapy. Regrettably, the oral administration of resveratrol has pharmacokinetic and physicochemical limitations such as hampering its effects so that effective administration methods are demanding to ensure its efficiency. Thus, the present review explores the published data on the application of resveratrol nanoformulations in cancer therapy, with the use of different types of nanodelivery systems. Mechanisms of action with a potential use in cancer therapy, negative effects, and the influence of resveratrol nanoformulations in different types of cancer are also highlighted. Finally, the toxicological features of nanoresveratrol are also discussed.

Bioproduction process of natural products and biopharmaceuticals: Biotechnological aspects

Decades of research have been put in place for developing sustainable routes of bioproduction of high commercial value natural products (NPs) on the global market. In the last few years alone, we have witnessed significant advances in the biotechnological production of NPs. The development of new methodologies has resulted in a better understanding of the metabolic flux within the organisms, which have driven manipulations to improve production of the target product. This was further realised due to the recent advances in the omics technologies such as genomics, transcriptomics, proteomics, metabolomics and secretomics, as well as systems and synthetic biology. Additionally, the combined application of novel engineering strategies has made possible avenues for enhancing the yield of these products in an efficient and economical way. Invention of high-throughput technologies such as next generation sequencing (NGS) and toolkits for genome editing Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated 9 (CRISPR/Cas9) have been the game changers and provided unprecedented opportunities to generate rationally designed synthetic circuits which can produce complex molecules. This review covers recent advances in the engineering of various hosts for the production of bioactive NPs and biopharmaceuticals. It also highlights general approaches and strategies to improve their biosynthesis with higher yields in a perspective of plants and microbes (bacteria, yeast and filamentous fungi). Although there are numerous reviews covering this topic on a selected species at a time, our approach herein is to give a comprehensive understanding about state-of-art technologies in different platforms of organisms.

Rational Design of Resveratrol O-methyltransferase for the Production of Pinostilbene

Pinostilbene is a monomethyl ether analog of the well-known nutraceutical resveratrol. Both compounds have health-promoting properties, but the latter undergoes rapid metabolization and has low bioavailability. O-methylation improves the stability and bioavailability of resveratrol. In plants, these reactions are performed by O-methyltransferases (OMTs). Few efficient OMTs that monomethylate resveratrol to yield pinostilbene have been described so far. Here, we report the engineering of a resveratrol OMT from Vitis vinifera (VvROMT), which has the highest catalytic efficiency in di-methylating resveratrol to yield pterostilbene. In the absence of a crystal structure, we constructed a three-dimensional protein model of VvROMT and identified four critical binding site residues by applying different in silico approaches. We performed point mutations in these positions generating W20A, F24A, F311A, and F318A variants, which greatly reduced resveratrol's enzymatic conversion. Then, we rationally designed eight variants through comparison of the binding site residues with other stilbene OMTs. We successfully modified the native substrate selectivity of VvROMT. Variant L117F/F311W showed the highest conversion to pinostilbene, and variant L117F presented an overall increase in enzymatic activity. Our results suggest that VvROMT has potential for the tailor-made production of stilbenes.

New insights into the degradation of synthetic pollutants in contaminated environments

The environment is contaminated by synthetic contaminants owing to their extensive applications globally. Hence, the removal of synthetic pollutants (SPs) from the environment has received widespread attention. Different remediation technologies have been investigated for their abilities to eliminate SPs from the ecosystem; these include photocatalysis, sonochemical techniques, nanoremediation, and bioremediation. SPs, which can be organic or inorganic, can be degraded by microbial metabolism at contaminated sites. Owing to their diverse metabolisms, microbes can adapt to a wide variety of environments. Several microbial strains have been reported for their bioremediation potential concerning synthetic chemical compounds. The selection of potential strains for large-scale removal of organic pollutants is an important research priority. Additionally, novel microbial consortia have been found to be capable of efficient degradation owing to their combined and co-metabolic activities. Microbial engineering is one of the most prominent and promising techniques for providing new opportunities to develop proficient microorganisms for various biological processes; here, we have targeted the SP-degrading mechanisms of microorganisms. This review provides an in-depth discussion of microbial engineering techniques that are used to enhance the removal of both organic and inorganic pollutants from different contaminated environments and under different conditions. The degradation of these pollutants is investigated using abiotic and biotic approaches; interestingly, biotic approaches based on microbial methods are preferable owing to their high potential for pollutant removal and cost-effectiveness.

Phytostilbenes as agrochemicals: biosynthesis, bioactivity, metabolic engineering and biotechnology

Covering: 1976 to 2020. Although constituting a limited chemical family, phytostilbenes represent an emblematic group of molecules among natural compounds. Ever since their discovery as antifungal compounds in plants and their ascribed role in human health and disease, phytostilbenes have never ceased to arouse interest for researchers, leading to a huge development of the literature in this field. Owing to this, the number of references to this class of compounds has reached the tens of thousands. The objective of this article is thus to offer an overview of the different aspects of these compounds through a large bibliography analysis of more than 500 articles. All the aspects regarding phytostilbenes will be covered including their chemistry and biochemistry, regulation of their biosynthesis, biological activities in plants, molecular engineering of stilbene pathways in plants and microbes as well as their biotechnological production by plant cell systems.

Recent Advances in Synthesis, Bioactivity, and Pharmacokinetics of Pterostilbene, an Important Analog of Resveratrol

Pterostilbene is a natural 3,5-dimethoxy analog of resveratrol. This stilbene compound has a strong bioactivity and exists widely in Dalbergia and Vaccinium spp. Besides natural extraction, pterostilbene can be obtained by biosynthesis. Pterostilbene has become popular because of its remarkable pharmacological activities, such as anti-tumor, anti-oxidation, anti-inflammation, and neuroprotection. Pterostilbene can be rapidly absorbed and is widely distributed in tissues, but it does not seriously accumulate in the body. Pterostilbene can easily pass through the blood-brain barrier because of its low molecular weight and good liposolubility. In this review, the studies performed in the last three years on resources, synthesis, bioactivity, and pharmacokinetics of pterostilbene are summarized. This review focuses on the effects of pterostilbene on certain diseases to explore its targets, explain the possible mechanism, and look for potential therapeutic applications.

l-arginine production in Corynebacterium glutamicum: manipulation and optimization of the metabolic process

As an important semi-essential amino acid, l-arginine is extensively used in the food and pharmaceutical fields. At present, l-arginine production depends on cost-effective, green, and sustainable microbial fermentation by using a renewable carbon source. To enhance its fermentative production, various metabolic engineering strategies have been employed, which provide valid paths for reducing the cost of l-arginine production. This review summarizes recent advances in molecular biology strategies for the optimization of l-arginine-producing strains, including manipulating the principal metabolic pathway, modulating the carbon metabolic pathway, improving the intracellular biosynthesis of cofactors and energy usage, manipulating the assimilation of ammonia, improving the transportation and membrane permeability, and performing biosensor-assisted high throughput screening, providing useful insight into the current state of l-arginine production.

Screening of an Endophyte Transforming Polydatin to Resveratrol from Reynoutria Japonica Houtt and the Optimization of Its Transformation Parameters

Resveratrol showed various kinds of bioactivities, such as antioxidant, antimicrobial, anticancer effects and, therefore, has been used widely as an important ingredient in medication, healthy foods and cosmetics. However, in nature, resveratrol usually exists at low content and more often exists as polydatin. Therefore, it becomes important to find the cost-effective and environmental-friendly way to transform polydatin to resveratrol. In this study, endophytes were isolated from the rhizome tissue of Reynoutria japonica and screened for transforming polydatin to resveratrol using reversed-phase high-performance liquid chromatography (RP-HPLC) and confirmed by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) spectroscopy. A bacterium identified as Bacillus aryabhattai using 16S rRNA phylogenetic tree analysis showed highest transformation rate. The transforming conditions were optimized including substrate concentration, substrate addition time, culture temperature and inoculation ratio. Our results demonstrated that the bacteria isolated from R. japonica rhizome tissue showed high activity in transforming polydatin into resveratrol. Crude extract of R. japonica root and rhizome (RJE) was also tested as substrate and it was found that the transformation was significantly inhibited at 10.0 mg/mL RJE. Emodin at equivalent concentration of 10.0 mg/mL RJE showed no inhibition activity, and glucose content in RJE was trace and far from enough to exhibit the inhibitory activity. Successive solvent partition followed by an inhibition activity assay revealed that the ethyl acetate fraction showed the main inhibition activity. However, due to the coexistence of polydatin and compounds with inhibitory activity, the concentration of RJE can only be used at limited concentration as substrate.

The Role of Saccharides in the Mechanisms of Pathogenicity of Fusarium oxysporum f. sp. lupini in Yellow Lupine (Lupinus luteus L.)

The primary aim of this study was to determine the relationship between soluble sugar levels (sucrose, glucose, or fructose) in yellow lupine embryo axes and the pathogenicity of the hemibiotrophic fungus Fusarium oxysporum f. sp. Schlecht lupini. The first step of this study was to determine the effect of exogenous saccharides on the growth and sporulation of F. oxysporum. The second one focused on estimating the levels of ergosterol as a fungal growth indicator in infected embryo axes cultured in vitro on sugar containing-medium or without it. The third aim of this study was to record the levels of the mycotoxin moniliformin as the most characteristic secondary metabolite of F. oxysporum in the infected embryo axes with the high sugar medium and without it. Additionally, morphometric measurements, i.e., the length and fresh weight of embryo axes, were done. The levels of ergosterol were the highest in infected embryo axes with a sugar deficit. At the same time, significant accumulation of the mycotoxin moniliformin was recorded in those tissues. Furthermore, it was found that the presence of sugars in water agar medium inhibited the sporulation of the pathogenic fungus F. oxysporum in relation to the control (sporulation of the pathogen on medium without sugar), the strongest inhibiting effect was observed in the case of glucose. Infection caused by F. oxysporum significantly limited the growth of embryo axes, but this effect was more visible on infected axes cultured under sugar deficiency than on the ones cultured with soluble sugars. The obtained results thus showed that high sugar levels may lead to reduced production of mycotoxins by F. oxysporum, limiting infection development and fusariosis.

Resveratrol and Resveratrol-Aspirin Hybrid Compounds as Potent Intestinal Anti-Inflammatory and Anti-Tumor Drugs

Resveratrol (3,4,5-Trihydroxy-trans-stilbene) is a naturally occurring polyphenol that exhibits beneficial pleiotropic health effects. It is one of the most promising natural molecules in the prevention and treatment of chronic diseases and autoimmune disorders. One of the key limitations in the clinical use of resveratrol is its extensive metabolic processing to its glucuronides and sulfates. It has been estimated that around 75% of this polyphenol is excreted via feces and urine. To possibly alleviate the extensive metabolic processing and improve bioavailability, we have added segments of acetylsalicylic acid to resveratrol in an attempt to maintain the functional properties of both. We initially characterized resveratrol-aspirin derivatives as products that can inhibit cytochrome P450 Family 1 Subfamily A Member 1 (CYP1A1) activity, DNA methyltransferase (DNMT) activity, and cyclooxygenase (COX) activity. In this study, we provide a detailed analysis of how resveratrol and its aspirin derivatives can inhibit nuclear factor kappa B (NFκB) activation, cytokine production, the growth rate of cancer cells, and in vivo alleviate intestinal inflammation and tumor growth. We identified resveratrol derivatives C3 and C11 as closely preserving resveratrol bioactivities of growth inhibition of cancer cells, inhibition of NFκB activation, activation of sirtuin, and 5’ adenosine monophosphate-activated protein kinase (AMPK) activity. We speculate that the aspirin derivatives of resveratrol would be more metabolically stable, resulting in increased efficacy for treating immune disorders and as an anti-cancer agent.

Anthocyanins, multi-functional natural products of industrial relevance: Recent biotechnological advances

Anthocyanins, the color compounds of plants, are known for their wide applications in food, nutraceuticals and cosmetic industry. The biosynthetic pathway of anthocyanins is well established with the identification of potential key regulatory genes, which makes it possible to modulate its production by biotechnological means. Various biotechnological systems, including use of in vitro plant cell or tissue cultures as well as microorganisms have been used for the production of anthocyanins under controlled conditions, however, a wide range of factors affects their production. In addition, metabolic engineering technologies have also used the heterologous production of anthocyanins in recombinant plants and microorganisms. However, these approaches have mostly been tested at the lab- and pilot-scales, while very few up-scaling studies have been undertaken. Various challenges and ways of investigation are proposed here to improve anthocyanin production by using the in vitro plant cell or tissue culture and metabolic engineering of plants and microbial culture systems. All these methods are capable of modulating the production of anthocyanins , which can be further utilized for pharmaceutical, cosmetics and food applications.

Induced extracellular production of stilbenes in grapevine cell culture medium by elicitation with methyl jasmonate and stevioside

We report the high production of stilbenes, including resveratrol and viniferin, in grapevine (Vitis labruscana L.) cell cultures through elicitation with methyl jasmonate (MeJA) and stevioside (STE). Methyl-β-cyclodextrin (MeβCD) is widely used as a solubilizer for resveratrol production. For the first time, we used STE as a solubilizer for stilbene production in plant cell cultures. MeJA was most effective elicitor in activating VvSTS expression and stimulating stilbene biosynthesis in grapevine cell cultures. The maximum concentration of δ-viniferin (892.2 mg/L) production with a small amount of trans-resveratrol (12.2 mg/L) was observed in the culture medium by co-treatment of cells with MeJA and STE, whereas the highest level of trans-resveratrol (371.9 mg/L) with a slight amount of δ-viniferin (11.5 mg/L) was accumulated in the culture medium of cells treated with MeJA and MeβCD. However, neither trans-resveratrol nor δ-viniferin were significantly elevated within the cells by the applications. Notably, predominant production of δ-viniferin and trans-resveratrol was observed in shake and static flask culture medium, respectively, by co-treatment of MeJA and STE. Furthermore, stilbene compounds of resveratrol, ε-viniferin, and δ-viniferin were mainly produced in a 3-L bioreactor culture following elicitation of cells with MeJA and STE. These results provide new strategies for conditional, high-level production of resveratrol and viniferin in cell cultures by utilizing the solubilizing properties of STE or MeβCD.

Insights on the Effects of Resveratrol and Some of Its Derivatives in Cancer and Autoimmunity: A Molecule with a Dual Activity

In recent years, the interest in natural compounds exerting immunoregulatory effects has enormously increased. Among these, the polyphenol resveratrol, found in a variety of foods and beverages, including red grapes and red wine, has been demonstrated to exert both in vitro and in vivo biological activities. More specifically, it has antiaging, cardioprotective, antioxidant, immunomodulatory, anti-inflammatory and chemopreventive activities. Due to its anti-proliferative, pro-apoptotic and immunoregulatory effects, resveratrol has gained substantial attention for the treatment of cancer or autoimmunity, which represent frequently diagnosed diseases with important consequences for the health of the patients affected. The aim of the present review is to focus on the role of resveratrol in the modulation of cancer as well as of several organ-specific or systemic autoimmune diseases, including autoimmune hepatitis, type 1 diabetes mellitus, inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus and multiple sclerosis.

Recent Advances of L-ornithine Biosynthesis in Metabolically Engineered Corynebacterium glutamicum

L-ornithine, a valuable non-protein amino acid, has a wide range of applications in the pharmaceutical and food industries. Currently, microbial fermentation is a promising, sustainable, and environment-friendly method to produce L-ornithine. However, the industrial production capacity of L-ornithine by microbial fermentation is low and rarely meets the market demands. Various strategies have been employed to improve the L-ornithine production titers in the model strain, Corynebacterium glutamicum, which serves as a major indicator for improving the cost-effectiveness of L-ornithine production by microbial fermentation. This review focuses on the development of high L-ornithine-producing strains by metabolic engineering and reviews the recent advances in breeding strategies, such as reducing by-product formation, improving the supplementation of precursor glutamate, releasing negative regulation and negative feedback inhibition, increasing the supply of intracellular cofactors, modulating the central metabolic pathway, enhancing the transport system, and adaptive evolution for improving L-ornithine production.

Proteome analysis guided genetic engineering of Corynebacterium glutamicum S9114 for tween 40-triggered improvement in L-ornithine production

BACKGROUND

L-ornithine is a valuable amino acid with a wide range of applications in the pharmaceutical and food industries. However, the production of L-ornithine by fermentation cannot compete with other methods, because of the low titers produced with this technique. Development of fermentation techniques that result in a high yield of L-ornithine and efficient strategies for improving L-ornithine production are essential.

RESULTS

This study demonstrates that tween 40, a surfactant promoter of the production of glutamate and arginine, improves L-ornithine production titers in engineered C. glutamicum S9114. The intracellular metabolism under tween 40 triggered fermentation conditions was explored using a quantitative proteomic approach, identifying 48 up-regulated and 132 down-regulated proteins when compared with the control. Numerous proteins were identified as membrane proteins or functional proteins involved in the biosynthesis of the cell wall. Modulation of those genes revealed that the overexpression of CgS9114_09558 and the deletion of CgS9114_13845, CgS9114_02593, and CgS9114_02058 improved the production of L-ornithine in the engineered strain of C. glutamicum Orn8. The final strain with all the exploratory metabolic engineering manipulations produced 25.46 g/L of L-ornithine, and a yield of 0.303 g L-ornithine per g glucose, which was 30.6% higher than that produced by the original strain (19.5 g/L).

CONCLUSION

These results clearly demonstrate the positive effect of tween 40 addition on L-ornithine accumulation. Proteome analysis was performed to examine the impact of tween 40 addition on the physiological changes in C. glutamicum Orn8 and the results showed several promising modulation targets for developing L-ornithine-producing strains.

VpSTS29/STS2 enhances fungal tolerance in grapevine through a positive feedback loop

Accumulation of stilbene phytoalexins stimulates resistance mechanisms against the grapevine fungus Uncinula necator. However, the defensive mechanisms triggered by stilbene synthase (STS) genes, remain largely unknown. Here, we report the function and molecular mechanism of the stilbene synthase gene VpSTS29/STS2 from Vitis pseudoreticulata in the regulation of plant responses to powdery mildew. Stilbene synthesis occurred mainly in root tips and mesophyll cells of transgenic grapevines via transport through the vascular bundles. Overexpression of VpSTS29/STS2 in Vitis vinifera increased the abundance of STSs in mesophyll tissue and resulted in the accumulation of biologically active resveratrol derivatives at the invasion site. Similarly, expression of VpSTS29/STS2 in Arabidopsis increased resistance to Golovinomyces cichoracearum. The VpSTS29/STS2-expressing Arabidopsis lines showed increased piceid accumulation together with more local hypersensitive reactions, inhibition of mycelial growth, and a reduced incidence of pathogens. Transcriptome profiling analyses demonstrated that VpSTS29/STS2-induced defences led to reprograming of global gene expression and activation of salicylic acid (SA) signalling, thus increasing expression of WRKY-MYB transcription factors and other defence response genes. We propose a model for resveratrol-mediated coordination of defence responses in which SA participates in a positive feedback loop.

Whole-cell biocatalytic, enzymatic and green chemistry methods for the production of resveratrol and its derivatives

Resveratrol and the biosynthetically related stilbenes are plant secondary metabolites with diverse pharmacological effects. The versatile functions of these compounds in plant defense mechanisms as phytoalexins on one hand, and in human health as potential pharmaceutical agents on the other, have attracted lots of interest in recent years to understand their biosynthetic pathways and their biological properties. Because of difficulties in obtaining resveratrol and its glucosylated derivatives as well as oligomeric forms in sufficient amounts for evaluation of their activity by plant sourcing or total synthesis, biotechnology may provide a competitive approach for the large-scale and low cost production of biologically active stilbenes. Additionally, one major limitation in the use of resveratrol and related aglycone derivatives as therapeutic agents is associated with their inherent poor aqueous solubility and low bioavailability. This article examines approaches for the synthesis of potential pharmacologically resveratrol derivatives in vivo by exploiting whole microorganisms, enzymatic and biocatalytic approaches allowing their full utilization for medicine, food and cosmetic applications. These methods also have the advantage of enabling the one-step production of stilbene compounds, compared to the time-consuming and environmentally unfriendly procedures used for their total synthesis or their extraction from plants. Increasing the desired products yield and biological activity through glucosylation (β-D-glucosides versus α-D-glucosides) and oligomerization methodologies of resveratrol including green chemistry methods in organic solvent-free media are discussed as well.

Biotechnological Advances in Resveratrol Production and its Chemical Diversity

The very well-known bioactive natural product, resveratrol (3,5,4'-trihydroxystilbene), is a highly studied secondary metabolite produced by several plants, particularly grapes, passion fruit, white tea, and berries. It is in high demand not only because of its wide range of biological activities against various kinds of cardiovascular and nerve-related diseases, but also as important ingredients in pharmaceuticals and nutritional supplements. Due to its very low content in plants, multi-step isolation and purification processes, and environmental and chemical hazards issues, resveratrol extraction from plants is difficult, time consuming, impracticable, and unsustainable. Therefore, microbial hosts, such as Escherichia coli, Saccharomyces cerevisiae, and Corynebacterium glutamicum, are commonly used as an alternative production source by improvising resveratrol biosynthetic genes in them. The biosynthesis genes are rewired applying combinatorial biosynthetic systems, including metabolic engineering and synthetic biology, while optimizing the various production processes. The native biosynthesis of resveratrol is not present in microbes, which are easy to manipulate genetically, so the use of microbial hosts is increasing these days. This review will mainly focus on the recent biotechnological advances for the production of resveratrol, including the various strategies used to produce its chemically diverse derivatives.

Production and localization of hydrogen peroxide and nitric oxide in grapevine cells elicited with cyclodextrins and methyl jasmonate

The use of methyl jasmonate, alone or in combination with cyclic oligosaccharides such as cyclodextrins, has proved to be a successful strategy for increasing the production of trans-resveratrol in Vitis vinifera cell cultures. However, understanding the intracellular signalling pathways involved in its production would improve the management of grapevine cells as biofactories of this high-value natural product. The results obtained herein confirm the involvement of hydrogen peroxide and nitric oxide in cyclodextrins and methyl jasmonate-induced trans-resveratrol production in grapevine cell cultures. In fact, methyl jasmonate led to maximal intracellular levels of hydrogen peroxide and nitric oxide after 24 h of treatment, but extracellular hydrogen peroxide was only detected in the culture medium when grapevine cells were treated with cyclodextrins. The results derived from the cytochemical detection of H₂O₂ in elicited grapevine cell cultures also suggested that the combined treatment with cyclodextrins and methyl jasmonate not only increased the production of H₂O₂ but also released cell wall fragments with electron-dense deposits. Moreover, nitric oxide was localized in all the cellular compartments, particularly in the nucleus and cytoplasmic organelles, whereas hydrogen peroxide was mainly found in cytoplasmic areas close to the cell wall, and in the nucleoplasm.

Influence of Resveratrol on the Immune Response

Resveratrol is the most well-known polyphenolic stilbenoid, present in grapes, mulberries, peanuts, rhubarb, and in several other plants. Resveratrol can play a beneficial role in the prevention and in the progression of chronic diseases related to inflammation such as diabetes, obesity, cardiovascular diseases, neurodegeneration, and cancers among other conditions. Moreover, resveratrol regulates immunity by interfering with immune cell regulation, proinflammatory cytokines’ synthesis, and gene expression. At the molecular level, it targets sirtuin, adenosine monophosphate kinase, nuclear factor-κB, inflammatory cytokines, anti-oxidant enzymes along with cellular processes such as gluconeogenesis, lipid metabolism, mitochondrial biogenesis, angiogenesis, and apoptosis. Resveratrol can suppress the toll-like receptor (TLR) and pro-inflammatory genes’ expression. The antioxidant activity of resveratrol and the ability to inhibit enzymes involved in the production of eicosanoids contribute to its anti-inflammation properties. The effects of this biologically active compound on the immune system are associated with widespread health benefits for different autoimmune and chronic inflammatory diseases. This review offers a systematic understanding of how resveratrol targets multiple inflammatory components and exerts immune-regulatory effects on immune cells.

Resveratrol Inhibits the Migration and Metastasis of MDA-MB-231 Human Breast Cancer by Reversing TGF-β1-Induced Epithelial-Mesenchymal Transition

Metastasis is a major cause of death in patients with breast cancer. In the process of cancer development, epithelial-mesenchymal transition (EMT) is crucial to promoting the invasion and migration of tumor cells. In a previous study, the role of resveratrol in migration and metastasis was investigated in MDA-MB-231 (MDA231) human breast cancer cells and a xenograft-bearing mouse model. Additionally, the related mechanism was explored. In the present study, in vitro Transwell assays showed that resveratrol can inhibit the migration of transforming growth factor (TGF)-β1-induced MDA231 cells in a concentration-dependent manner. An enzyme-linked immunosorbent assay (ELISA) showed that resveratrol can reduce the secretion of matrix metalloproteinase (MMP)-2 and MMP-9. Immunofluorescence was performed to confirm the expression of EMT-related markers. Immunofluorescence assays confirmed that resveratrol changed the expression of the EMT-related markers E-cadherin and vimentin. Western blot analysis demonstrated that resveratrol decreased the expression levels of MMP-2, MMP-9, Fibronectin, α-SMA, P-PI3K, P-AKT, Smad2, Smad3, P-Smad2, P-Smad3, vimentin, Snail1, and Slug, as well as increased the expression levels of E-cadherin in MDA231 cells. In vivo, resveratrol inhibited lung metastasis in a mouse model bearing MDA231 human breast cancer xenografts without marked changes in body weight or liver and kidney function. These results indicate that resveratrol inhibits the migration of MDA231 cells by reversing TGF-β1-induced EMT and inhibits the lung metastasis of MDA231 human breast cancer in a xenograft-bearing mouse model.

Modulation of the central carbon metabolism of Corynebacterium glutamicum improves malonyl-CoA availability and increases plant polyphenol synthesis

In recent years microorganisms have been engineered towards synthesizing interesting plant polyphenols such as flavonoids and stilbenes from glucose. Currently, the low endogenous supply of malonyl-CoA, indispensable for plant polyphenol synthesis, impedes high product titers. Usually, limited malonyl-CoA availability during plant polyphenol production is avoided by supplementing fatty acid synthesis-inhibiting antibiotics such as cerulenin, which are known to increase the intracellular malonyl-CoA pool as a side effect. Motivated by the goal of microbial polyphenol synthesis being independent of such expensive additives, we used rational metabolic engineering approaches to modulate regulation of fatty acid synthesis and flux into the tricarboxylic acid cycle (TCA cycle) in Corynebacterium glutamicum strains capable of flavonoid and stilbene synthesis. Initial experiments showed that sole overexpression of genes coding for the native malonyl-CoA-forming acetyl-CoA carboxylase is not sufficient for increasing polyphenol production in C. glutamicum. Hence, the intracellular acetyl-CoA availability was also increased by reducing the flux into the TCA cycle through reduction of citrate synthase activity. In defined cultivation medium, the constructed C. glutamicum strains accumulated 24 mg·L ^-1 (0.088 mM) naringenin or 112 mg·L ^-1 (0.49 mM) resveratrol from glucose without supplementation of phenylpropanoid precursor molecules or any inhibitors of fatty acid synthesis.

The Therapeutic Potential of Naringenin: A Review of Clinical Trials

Naringenin is a flavonoid belonging to flavanones subclass. It is widely distributed in several Citrus fruits, bergamot, tomatoes and other fruits, being also found in its glycosides form (mainly naringin). Several biological activities have been ascribed to this phytochemical, among them antioxidant, antitumor, antiviral, antibacterial, anti-inflammatory, antiadipogenic and cardioprotective effects. Nonetheless, most of the data reported have been obtained from in vitro or in vivo studies. Although some clinical studies have also been performed, the main focus is on naringenin bioavailability and cardioprotective action. In addition, these studies were done in compromised patients (i.e., hypercholesterolemic and overweight), with a dosage ranging between 600 and 800 μM/day, whereas the effect on healthy volunteers is still debatable. In fact, naringenin ability to improve endothelial function has been well-established. Indeed, the currently available data are very promising, but further research on pharmacokinetic and pharmacodynamic aspects is encouraged to improve both available production and delivery methods and to achieve feasible naringenin-based clinical formulations.