Enzymatic properties of ornithine decarboxylase from Clostridium aceticum DSM1496.

Clostridium aceticum DSM1496 is an acid-resistant strain in which ornithine decarboxylase (ODC) plays a crucial role in acid resistance. In this study, we expressed ODC derived from C. aceticum DSM1496 in Escherichia coli BL21 (DE3) and thoroughly examined its enzymatic properties. The enzyme has a molecular weight of 55.27 kDa and uses pyridoxal-5'-phosphate (PLP) as a coenzyme with a Km = 0.31 mM. ODC exhibits optimal activity at pH 7.5, and it maintains high stability even at pH 4.5. The peak reaction temperature for ODC is 30°C. Besides, it can be influenced by certain metal ions such as Mn2+. Although l-ornithine serves as the preferred substrate for ODC, the enzyme also decarboxylates l-arginine and l-lysine simultaneously. The results indicate that ODC derived from C. aceticum DSM1496 exhibits the ability to produce putrescine, cadaverine, and agmatine through decarboxylation. These polyamines have the potential to neutralize acid in an acidic environment, facilitating the growth of microorganisms. These significant findings provide a strong basis for further investigation into the acid-resistant mechanisms contributed by ODC.

Construction and characterization of a promoter library with varying strengths to enhance acetoin production from xylose in Serratia marcescens.

Serratia marcescens is utilized as a significant enterobacteria in the production of various high-value secondary metabolites. Acetoin serves as a crucial foundational compound of development and finds application in a broad range of fields. Furthermore, S. marcescens HBQA-7 is capable of utilizing xylose as its exclusive carbon source for acetoin production. The objective of this study was to utilize a constitutive promoter screening strategy to enhance both xylose utilization and acetoin production in S. marcescens HBQA-7. By utilizing RNA-seq, we identified the endogenous constitutive promoter P6 that is the most robust, which facilitated the overexpression of the sugar transporter protein GlfL445I, α-acetyl lactate synthase, and α-acetyl lactate decarboxylase, respectively. The resultant recombinant strains exhibited enhanced xylose utilization rates and acetoin yields. Subsequently, a recombinant plasmid, denoted as pBBR1MCS-P6-glfL445IalsSalsD, was constructed, simultaneously expressing the aforementioned three genes. The resulting recombinant strain, designated as S3, demonstrated a 1.89-fold boost in xylose consumption rate compared with the original strain during shake flask fermentation. resulting in the accumulation of 7.14 g/L acetoin in the final fermentation medium. Subsequently, in a 5 L fermenter setup, the acetoin yield reached 48.75 g/L, corresponding to a xylose-to-acetoin conversion yield of 0.375 g/g.

Highly efficient biosynthesis of spermidine from L-homoserine and putrescine using an engineered Escherichia coli with NADPH self-sufficient system.

Spermidine is an important polyamine that can be used for the synthesis of various bioactive compounds in the food and pharmaceutical fields. In this study, a novel efficient whole-cell biocatalytic method with an NADPH self-sufficient cycle for spermidine biosynthesis was designed and constructed by co-expressing homoserine dehydrogenase (HSD), carboxyspermidine dehydrogenase (CASDH), and carboxyspermidine decarboxylase (CASDC). First, the enzyme-substrate coupled cofactor regeneration system from co-expression of NADP+-dependent ScHSD and NADPH-dependent AfCASDH exactly provides an efficient method for cofactor cycling. Second, we identified and characterized a putative CASDC with high decarboxylase activity from Butyrivibrio crossotus DSM 2876; it showed an optimum temperature of 35 °C and an optimum pH of 7.0, which make it better suited for the designed synthetic route. Subsequently, the protein expression level of each enzyme was optimized through the variation of the gene copy number, and a whole-cell catalyst with high catalytic efficiency was constructed successfully. Finally, a yield of 28.6 mM of spermidine was produced in a 1-L scale of E. coli whole-cell catalytic system with a 95.3% molar conversion rate after optimization of temperature, the ratio of catalyst-to-substrate, and the amount of NADP+, and a productivity of 0.17 g·L-1·h-1 was achieved. In summary, this novel pathway of constructing a whole-cell catalytic system from L-homoserine and putrescine could provide a green alternative method for the efficient synthesis of spermidine. KEY POINTS: • A novel pathway for spermidine biosynthesis was developed in Escherichia coli. • The enzyme-substrate coupled system provides an NADPH self-sufficient cycle. • Spermidine with 28.6 mM was obtained using an optimized whole-cell system.

Biosynthesis of phenylpyruvic acid from l-phenylalanine using chromosomally engineered Escherichia coli.

The efficiency of whole-cell biotransformation is often affected by the genetic instability of plasmid-based expression systems, which require selective pressure to maintain the stability of the plasmids. To circumvent this shortcoming, we constructed a chromosome engineering strain for the synthesis of phenylpyruvic acid (PPA) from l-phenylalanine. First, l-amino acid deaminase (pmLAAD) from Proteus myxofaciens was incorporated into Escherichia coli BL21 (DE3) chromosome and the copy numbers of pmLAAD were increased by chemically induced chromosomal evolution (CIChE). Fifty-nine copies of pmLAAD were obtained in E. coli BL8. The PPA titer of E. coli BL8 reached 2.22 g/L at 6 h. Furthermore, the deletion of lacI improved PPA production. In the absence of isopropyl-ß-d-thiogalactopyranoside, the resulting strain, E. coli BL8△recA△lacI, produced 2.65 g/L PPA at 6 h and yielded a 19.37% increase in PPA production compared to E. coli BL8△recA. Finally, the engineered E. coli BL8△recA△lacI strain achieved 19.14 g/L PPA at 24 h in a 5-L bioreactor.

Converting the 3-quinuclidinone reductase from Agrobacterium tumefaciens into the ethyl 4-chloroacetoacetate reductase by site-directed mutagenesis.

In this study, the 3-quinuclidinone reductase from Agrobacterium tumefaciens (AtQR) was modified by site-directed mutagenesis. And we further obtained a saturation mutant library in which the residue 197 was mutated. A single-point mutation converted the wild enzyme that originally had no catalytic activity in reduction of ethyl 4-chloroacetoacetate (COBE) into an enzyme with catalytic activity. The results of enzyme activity assays showed that the seven variants could asymmetrically reduce COBE to ethyl (S)-4-chloro-3-hydroxybutyrate ((S)-CHBE) with NADH as coenzyme. In the library, the variant E197N showed higher catalytic efficiency than others. The E197N was optimally active at pH 6.0 and 40°C, and the catalytic efficiency (kcat /Km ) for COBE was 51.36 s-1 ·mM-1 . This study showed that the substrate specificity of AtQR could be changed through site-directed mutagenesis at the residue 197.

Characterization of a putative tropinone reductase from Tarenaya hassleriana with a broad substrate specificity.

A novel short-chain alcohol dehydrogenase from Tarenaya hassleriana labeled as putative tropinone reductase was heterologously expressed in Escherichia coli. Purified recombinant protein had molecular weight of approximately 30 kDa on 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis. T. hassleriana tropinone reductase-like enzyme (ThTRL) had not detected oxidative activity. The optimum pH for enzyme activity of ThTRL was weakly acidic (pH 5.0). 50°C was the optimum temperature for ThTRL. The highest catalytic efficiency and substrate affinity for recombinant ThTRL were observed with (+)-camphorquinone (kcat /Km  = 814.3 s-1  mM-1 , Km  = 44.25 µM). ThTRL exhibited a broad substrate specificity and reduced various carbonyl compounds, including small lipophilic aldehydes and ketones, terpene ketones, and their structural analogs.

Overexpression and biochemical characterization of a carboxyspermidine dehydrogenase from Agrobacterium fabrum str. C58 and its application to carboxyspermidine production.

BACKGROUND: Carboxyspermidine (C-Spd) is a potentially valuable polyamine carboxylate compound and an excellent building block for spermidine synthesis, which is a critical polyamine with significant implications for human health and longevity. C-Spd can also be used to prepare multivalent cationic lipids and modify nucleoside probes. Because of these positive effects on human health, C-Spd is of considerable interest as a food additive and pharmaceutical target. RESULTS: A putative gene afcasdh from Agrobacterium fabrum str. C58, encoding carboxyspermidine dehydrogenase with C-Spd biosynthesis activity, was synthesized and transformed into Escherichia coli BL21 (DE3) for overexpression. The recombinant AfCASDH was purified and fully characterized. The optimum temperature and pH for the recombinant enzyme were 30 °C and 7.5, respectively. The coupled catalytic strategy of AfCASDH and various NADPH regeneration systems were developed to enhance the efficient production of C-Spd compound. Finally, the maximum titer of C-Spd production successfully achieved 1.82 mmol L-1 with a yield of 91% by optimizing the catalytic conditions. CONCLUSION: A novel AfCASDH from A. fabrum str. C58 was characterized that could catalyze the formation of C-Spd from putrescine and l-aspartate-ß-semialdehyde (L-Asa). A whole-cell catalytic strategy coupled with NADPH regeneration was established successfully for C-Spd biosynthesis for the first time. The coupled system indicated that AfCASDH might provide a feasible method for the industrial production of C-Spd. © 2021 Society of Chemical Industry.

Advanced strategy for metabolite exploration in filamentous fungi.

Filamentous fungi comprise an abundance of gene clusters that encode high-value metabolites, whereas affluent gene clusters remain silent during laboratory conditions. Complex cellular metabolism further limits these metabolite yields. Therefore, diverse strategies such as genetic engineering and chemical mutagenesis have been developed to activate these cryptic pathways and improve metabolite productivity. However, lower efficiencies of gene modifications and screen tools delayed the above processes. To address the above issues, this review describes an alternative design-construction evaluation optimization (DCEO) approach. The DCEO tool provides theoretical and practical principles to identify potential pathways, modify endogenous pathways, integrate exogenous pathways, and exploit novel pathways for their diverse metabolites and desirable productivities. This DCEO method also offers different tactics to balance the cellular metabolisms, facilitate the genetic engineering, and exploit the scalable metabolites in filamentous fungi.

Biosynthesis of D-danshensu from L-DOPA using engineered Escherichia coli whole cells.

D-Danshensu (D-DSS), a traditional Chinese medicine, is used to treat cardiovascular and cerebrovascular diseases. However, current isolation protocols for D-DSS both natural and synthetic are not ideal; therefore, in this study, we have developed a whole-cell biotransformation method to produce D-DSS from L-DOPA. This was done by co-expressing L-amino acid deaminase (aadL), D-lactate dehydrogenase (ldhD), and glucose dehydrogenase (gdh). To begin to optimize the production of D-DSS, varying copy number plasmids were used to express each of the required genes. The resulting strain, Escherichia coli ALG7, which strongly overexpressed aadL, ldhD, and weakly overexpressed gdh, yielded a 378% increase in D-DSS production compared to E. coli ALG1. Furthermore, the optimal reaction conditions for the production of D-DSS were found to be a pH of 7.5, temperature at 35 °C, and 50 g/L wet cells for 12 h. Under these optimized conditions, the D-DSS amount achieved 119.1 mM with an excellent ee (> 99.9%) and a productivity of 9.9 mM/h.

Redox self-sufficient biocatalyst system for conversion of 3,4-Dihydroxyphenyl-L-alanine into (R)- or (S)-3,4-Dihydroxyphenyllactic acid.

We developed an efficient multi-enzyme cascade reaction to produce (R)- or (S)-3,4-Dihydroxyphenyllactic acid [(R)- or (S)-Danshensu, (R)- or (S)-DSS] from 3,4-Dihydroxyphenyl-L-alanine (L-DOPA) in Escherichia coli by introducing tyrosine aminotransferase (tyrB), glutamate dehydrogenase (cdgdh) and D-aromatic lactate dehydrogenase (csldhD) or L-aromatic lactate dehydrogenase (tcldhL). First, the genes in the pathway were overexpressed and fine-tuned for (R)- or (S)-DSS production. The resulting strain, E. coli TGL 2.1 and E. coli TGL 2.2, which overexpressed tyrB with the stronger T7 promoter and cdgdh, csldhD or tcldhL with the weaker Trc promoter, E. coli TGL 2.1 yielded 57% increase in (R)-DSS production: 59.8 ± 2.9 mM. Meanwhile, E. coli TGL 2.2 yielded 54% increase in (S)-DSS production: 52.2 ± 2.4 mM. The optimal concentration of L-glutamate was found to be 20 mM for production of (R)- or (S)-DSS. Finally, L-DOPA were transformed into (R)- or (S)-DSS with an excellent enantiopure form (enantiomeric excess > 99.99%) and productivity of 6.61 mM/h and 4.48 mM/h, respectively.

Alcohol dehydrogenases from Proteus mirabilis contribute to alcoholic flavor.

BACKGROUND: Cheese ripening involves a complex series of metabolic reactions and numerous concomitant secondary transformations. Alcohol dehydrogenase (ADH) converts aldehydes into their corresponding alcohols, which enrich cheese aroma. RESULTS: In this study, we identified five ADH genes in Proteus mirabilis JN458, and these genes were overexpressed and characterized in Escherichia coli BL21 (DE3). The optimum pH was 7.0 for the purified recombinant ADH-1, ADH-2, and ADH-3 and 8.0 for ADH-4 and ADH-5. The optimum temperature was 40 °C for ADH-1, ADH-3, and ADH-5 and 45 °C for ADH-2 and ADH-4. The Km value of ADH-1, ADH-2, and ADH-3 was 34.45, 16.90, and 10.01 µmol L-1 for phenylacetaldehyde, respectively. The Km value of ADH-4 and ADH-5 was 14.81 and 24.62 µmol L-1 for 2-methylbutanal, respectively. CONCLUSION: Proteus species play important roles during cheese ripening. The results of our study are important for further research on cheese flavor and for quality control during cheese production. © 2019 Society of Chemical Industry.

Estrogen Enhances the Expression of the Multidrug Transporter Gene ABCG2-Increasing Drug Resistance of Breast Cancer Cells through Estrogen Receptors.

BACKGROUND: Multidrug resistance is a major obstacle in the successful therapy of breast cancer. Studies have proved that this kind of drug resistance happens in both human cancers and cultured cancer cell lines. Understanding the molecular mechanisms of drug resistance is important for the reasonable design and use of new treatment strategies to effectively confront cancers. RESULTS: In our study, ATP-binding cassette sub-family G member 2 (ABCG2), adenosine triphosphate (ATP) synthase and cytochrome c oxidase subunit VIc (COX6C) were over-expressed more in the MCF-7/MX cell line than in the normal MCF7 cell line. Therefore, we believe that these three genes increase the tolerance of MCF7 to mitoxantrone (MX). The data showed that the high expression of COX6C made MCF-7/MX have more stable on mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) expression than normal MCF7 cells under hypoxic conditions. The accumulation of MX was greater in the ATP-depleted treatment MCF7/MX cells than in normal MCF7/MX cells. Furthermore, E2 increased the tolerance of MCF7 cells to MX through inducing the expression of ABCG2. However, E2 could not increase the expression of ABCG2 after the inhibition of estrogen receptor α (ERα) in MCF7 cells. According to the above data, under the E2 treatment, MDA-MB231, which lacks ER, had a higher sensitivity to MX than MCF7 cells. CONCLUSIONS: E2 induced the expression of ABCG2 through ERα and the over-expressed ABCG2 made MCF7 more tolerant to MX. Moreover, the over-expressed ATP synthase and COX6c affected mitochondrial genes and function causing the over-expressed ABCG2 cells pumped out MX in a concentration gradient from the cell matrix. Finally lead to chemoresistance.

Characterization and Application of an Aspartate Dehydrogenase from Achromobacter denitrificans.

A novel gene encoding aspartate dehydrogenase (ASPDH) has been discovered in Achromobacter denitrificans. The product of this gene has a strict dependence on NADH and demonstrated significant reductive activity towards not only oxaloacetate (OAA) but also 2-ketobutyric acid. Further enzymatic characterization revealed the kinetic parameters of ASPDH for OAA and 2-ketobutyric acid were as follows: Km values of 4.25 mM and 0.89 mM, Vmax values of 10.67 U mg-1 and 2.10 U mg-1, and Kcat values of 3.70 s-1 and 0.72 s-1, respectively. The enzyme also showed a dependency on metal ions, with EDTA and Cu2+ exerting strong inhibitory effects, while Ca2+ and Fe2+ exhibited pronounced enhancing effects. By utilizing a whole-cell biocatalyst system comprising glucose dehydrogenase (GDH) and ASPDH as a coupled system to replenish cofactors by oxidizing glucose, enabling the effective conversion of 2-ketobutyric acid to L-2-aminobutyric acid (L-2-ABA) with 97.2% yield.

Characterization and Application of a Stationary Phase Promoter Library from Serratia marcescens.

Serratia marcescens has garnered increasing attention as a promising host for valuable compound production. However, the lack of an efficient gene regulation toolkit severely hampers its applications. Here, a library of stationary phase promoters was screened in S. marcescens HBA7 using RNA-seq and RT-qPCR, revealing a 43-fold regulatory range with the red fluorescent protein mKate2 as the reporter. The ß-galactosidase was employed to demonstrate the universality in driving the expression of different proteins. The wide-ranging utility of these promoters in different hosts was demonstrated in Escherichia coli. Moreover, to assess their potential application, the strongest promoter, P2, was employed to express the swrW gene, resulting in a roughly 20-fold increase in serrawettin W1 production in S. marcescens HBQA7ΔswrW. In summary, this study successfully constructed a gradient-strength stationary phase promoter library, providing an effective toolkit for gene regulation and secondary metabolite production in diverse prokaryotes, including S. marcescens and E. coli.

Treatment with cardiotonic pills(®) after ischemia-reperfusion ameliorates myocardial fibrosis in rats.

OBJECTIVE: The present study was designed to evaluate whether CP was beneficial in alleviating myocardial fibrosis following I/R injury. METHODS: Sprague-Dawley rats were subjected to 30 minutes occlusion of the LADCA, followed by reperfusion. CP (0.4 or 0.8 g/kg) was daily administered starting from three hour after reperfusion until day 6. Coronary venular diameter, RBC velocity, albumin leakage, MBF, heart function, myocardial infarction and fibrosis size, myocardium ultrastructure, MPO activity, and MDA level were evaluated. The expression of MCP-1, RP S19, TGF-ß1, P-Smad3, Smad4, MMP-9 and α-SMA, and the infiltration of leukocytes were examined. RESULTS: CP post-treatment ameliorated I/R-induced myocardial RBC velocity reduction, MBF decrease, cardiac dysfunction, and albumin leakage increase. Moreover, myocardial infarction and fibrosis size, MPO activity, MDA level, the expression of RP S19, TGF-ß1, P-Smad3, Smad4, MMP-9 and α-SMA, the number of CD68-positive cells increased significantly after I/R, and myocardium collagen deposition was observed on day 6 after reperfusion. All the alterations after I/R were significantly ameliorated by CP. CONCLUSIONS: Post-treatment with CP ameliorates I/R-induced myocardial fibrosis, suggesting that CP may be applied as an option for preventing cardiac remodeling after I/R injury.

Chemogenomics approaches to rationalizing the mode-of-action of traditional Chinese and Ayurvedic medicines.

Traditional Chinese medicine (TCM) and Ayurveda have been used in humans for thousands of years. While the link to a particular indication has been established in man, the mode-of-action (MOA) of the formulations often remains unknown. In this study, we aim to understand the MOA of formulations used in traditional medicine using an in silico target prediction algorithm, which aims to predict protein targets (and hence MOAs), given the chemical structure of a compound. Following this approach we were able to establish several links between suggested MOAs and experimental evidence. In particular, compounds from the 'tonifying and replenishing medicinal' class from TCM exhibit a hypoglycemic effect which can be related to activity of the ingredients against the Sodium-Glucose Transporters (SGLT) 1 and 2 as well as Protein Tyrosine Phosphatase (PTP). Similar results were obtained for Ayurvedic anticancer drugs. Here, both primary anticancer targets (those directly involved in cancer pathogenesis) such as steroid-5-alpha-reductase 1 and 2 were predicted as well as targets which act synergistically with the primary target, such as the efflux pump P-glycoprotein (P-gp). In addition, we were able to elucidate some targets which may point us to novel MOAs as well as explain side effects. Most notably, GPBAR1, which was predicted as a target for both 'tonifying and replenishing medicinal' and anticancer classes, suggests an influence of the compounds on metabolism. Understanding the MOA of these compounds is beneficial as it provides a resource for NMEs with possibly higher efficacy in the clinic than those identified by single-target biochemical assays.

The quest for modernisation of traditional Chinese medicine.

Traditional Chinese medicine (TCM) is an integral part of mainstream medicine in China. Due to its worldwide use, potential impact on healthcare and opportunities for new drug development, TCM is also of great international interest. Recently, a new era for modernisation of TCM was launched with the successful completion of the Good Practice in Traditional Chinese Medicine Research in the Post-genomic Era (GP-TCM) project, the European Union's Seventh Framework Programme (FP7) coordination action on TCM research. This 3.5-year project that involved inputs from over 200 scientists resulted in the production of 20 editorials and in-depth reviews on different aspects of TCM that were published in a special issue of Journal of Ethnopharmacology (2012; volume 140, issue 3). In this narrative review, we aim to summarise the findings of the FP7 GP-TCM project and highlight the relevance of TCM to modern medicine within a historical and international context. Advances in TCM research since the 1950s can be characterised into three phases: Phase I (1950s-1970s) was fundamental for developing TCM higher education, research and hospital networks in China; Phase II (1980s-2000s) was critical for developing legal, economic and scientific foundations and international networks for TCM; and Phase III (2011 onwards) is concentrating on consolidating the scientific basis and clinical practice of TCM through interdisciplinary, interregional and intersectoral collaborations. Taking into account the quality and safety requirements newly imposed by a globalised market, we especially highlight the scientific evidence behind TCM, update the most important milestones and pitfalls, and propose integrity, integration and innovation as key principles for further modernisation of TCM. These principles will serve as foundations for further research and development of TCM, and for its future integration into tomorrow's medicine.

In silico prediction and biological assessment of novel angiogenesis modulators from traditional Chinese medicine.

Uncontrolled angiogenesis is a common denominator underlying many deadly and debilitating diseases such as myocardial infarction, chronic wounds, cancer, and age-related macular degeneration. As the current range of FDA-approved angiogenesis-based medicines are far from meeting clinical demands, the vast reserve of natural products from traditional Chinese medicine (TCM) offers an alternative source for developing pro-angiogenic or anti-angiogenic modulators. Here, we investigated 100 traditional Chinese medicine-derived individual metabolites which had reported gene expression in MCF7 cell lines in the Gene Expression Omnibus (GSE85871). We extracted literature angiogenic activities for 51 individual metabolites, and subsequently analysed their predicted targets and differentially expressed genes to understand their mechanisms of action. The angiogenesis phenotype was used to generate decision trees for rationalising the poly-pharmacology of known angiogenesis modulators such as ferulic acid and curculigoside and validated by an in vitro endothelial tube formation assay and a zebrafish model of angiogenesis. Moreover, using an in silico model we prospectively examined the angiogenesis-modulating activities of the remaining 49 individual metabolites. In vitro, tetrahydropalmatine and 1 beta-hydroxyalantolactone stimulated, while cinobufotalin and isoalantolactone inhibited endothelial tube formation. In vivo, ginsenosides Rb3 and Rc, 1 beta-hydroxyalantolactone and surprisingly cinobufotalin, restored angiogenesis against PTK787-induced impairment in zebrafish. In the absence of PTK787, deoxycholic acid and ursodeoxycholic acid did not affect angiogenesis. Despite some limitations, these results suggest further refinements of in silico prediction combined with biological assessment will be a valuable platform for accelerating the research and development of natural products from traditional Chinese medicine and understanding their mechanisms of action, and also for other traditional medicines for the prevention and treatment of angiogenic diseases.

The chinese herbal decoction danggui buxue tang inhibits angiogenesis in a rat model of liver fibrosis.

In this study, we investigated the anti-angiogenic effect of the Chinese herbal decoction Danggui Buxue Tang (DBT; Radix Astragali and Radix Angelicae sinensis in 5 : 1 ratio) in a rat model of liver fibrosis, in order to elucidate its mechanisms of action against liver fibrosis. Liver fibrosis was induced with CCl(4) and high-fat food for 6 weeks, and the rats were treated with oral doses of DBT (6 g raw herbs/kg/d) and N-Acetyl-L-cysteine (NAC; 0.1 g/kg/d). The results showed that both DBT and NAC attenuated liver fibrosis and neo-angiogenesis. Furthermore, DBT and NAC improved SOD activity but decreased MDA content and 8-OH-dG in fibrotic livers, with DBT being more effective than NAC. DBT decreased the expression of VEGF, Ang1 and TGF-ß1 and their signaling mediators, whereas NAC had no effect on VEGF and VEGFR2 expression. Both DBT and NAC reduced HIF-1α gene and protein expression in fibrotic livers, with DBT being more effective. These data clearly demonstrate that the anti-fibrotic properties of DBT are related to its ability to inhibit angiogenesis and its anti-angiogenic mechanisms are associated with improving oxidative stress, regulating the expression and signaling of angiogenic factors, and especially modulating HIF-1α in fibrotic livers.

Advances and perspectives on perylenequinone biosynthesis.

Under illumination, the fungal secondary metabolites, perylenequinones (PQs) react with molecular oxygen to generate reactive oxygen species (ROS), which, in excess can damage cellular macromolecules and trigger apoptosis. Based on this property, PQs have been widely used as photosensitizers and applied in pharmaceuticals, which has stimulated research into the discovery of new PQs and the elucidation of their biosynthetic pathways. The PQs-associated literature covering from April 1967 to September 2022 is reviewed in three sections: (1) the sources, structural diversity, and biological activities of microbial PQs; (2) elucidation of PQ biosynthetic pathways, associated genes, and mechanisms of regulation; and (3) advances in pathway engineering and future potential strategies to modify cellular metabolism and improve PQ production.