Biosynthesis of bioactive tamarixetin in recombinant Escherichia coli

Research Progress of Tamarixetin and its Glycosides

Tamarixetin and its glycosides are widely distributed in natural plants, and they are also natural flavonoid derivatives of quercetin. Its main pharmacological effects include antioxidant, antiinflammatory, antiviral, anticancer, cardiovascular effects, etc. The pharmacokinetics showed that the distribution of direct absorption differed from that of biosynthesis. At the same time, research shows that tamarixetin is safe to use because it has little self-toxicity. In this paper, 181 articles on tamarixetin published from 1976 to 2023 are obtained from PubMed, China Knowledge Base Database, Wanfang Data, and other electronic databases. Tamarixetin is searched based on keywords, and 121 articles remain. Transformation synthesis, pharmacokinetics, pharmacological action, and structureactivity relationship of tamarixetin were reviewed.

Potential Therapeutic Targets of Quercetin in the Cutaneous Melanoma Model and Its Cellular Regulation Pathways: A Systematic Review

Melanoma is a skin cancer with a high mortality rate due to its invasive characteristics. Currently, immunotherapy and targeted therapy increase patient survival but are ineffective in the advanced stages of the tumor. Quercetin (Que) is a natural compound that has demonstrated chemopreventive effects against different types of tumors. This review provides evidence for the therapeutic potential of Que in melanoma and identifies its main targets. The Scopus, Web of Science, and PubMed databases were searched, and studies that used free or encapsulated Que in melanoma models were included, excluding associations, analogs, and extracts. As a result, 73 articles were retrieved and their data extracted. Que has multiple cellular targets in melanoma models, and the main regulated pathways are cell death, redox metabolism, metastasis, and melanization. Que was also able to regulate important targets of signaling pathways, such as PKC, RIG-I, STAT, and P53. In murine models, treatment with Que reduced tumor growth and weight, and decreased metastatic nodules and angiogenic vasculature. Several studies have incorporated Que into carriers, demonstrating improved efficacy and delivery to tumors. Thus, Que is a promising therapeutic agent for the treatment of melanoma; however, further studies are needed to evaluate its effectiveness in clinical trials.

Production of (2S)-sakuranetin from (2S)-naringenin in Escherichia coli by strengthening methylation process and cell resistance

(2S)-Sakuranetin is a 7-O-methylflavonoid that has anticancer, antiviral, and antimicrobial activities. Methylation process is involved in biosynthesizing (2S)-sakuranetin from (2S)-naringenin, in which S-adenosylmethionine (SAM) serves as the methyl donor. In this study, after methyl donor and substrate inhibition were identified as limiting factors for (2S)-sakuranetin biosynthesis, an efficient (2S)-sakuranetin-producing strain was constructed by enhancing methyl donor supply and cell tolerance to (2S)-naringenin. Firstly, PfOMT3 from Perilla frutescens was selected as the optimal flavonoid 7-O-methyltransferase (F7-OMT) for the conversion of (2S)-naringenin to (2S)-sakuranetin. Then, the methylation process was upregulated by regulating pyridoxal 5′-phosphate (PLP) content, key enzymes in methionine synthesis pathway, and the availability of ATP. Furthermore, genes that can enhance cell resistance to (2S)-naringenin were identified from molecular chaperones and sRNAs. Finally, by optimizing the fermentation process, 681.44 mg/L of (2S)-sakuranetin was obtained in 250-mL shake flasks. The titer of (2S)-sakuranetin reached 2642.38 mg/L in a 5-L bioreactor, which is the highest titer ever reported. This work demonstrates the importance of cofactor PLP in methylation process, and provides insights to biosynthesize other O-methylated flavonoids efficiently in E. coli.

Biotechnological application of Streptomyces for the production of clinical drugs and other bioactive molecules

Streptomyces is one of the most relevant genera in biotechnology, and its rich secondary metabolism is responsible for the biosynthesis of a plethora of bioactive compounds, including several clinically relevant drugs. The use of Streptomyces species for the manufacture of natural products has been established for more than half a century; however, the tremendous advances observed in recent years in genetic engineering and molecular biology have revolutionised the optimisation of Streptomyces as cell factories and drastically expanded the biotechnological potential of these bacteria. Here, we illustrate the most exciting advances reported in the past few years, with a particular focus on the approaches significantly improving the biotechnological capacity of Streptomyces to produce clinical drugs and other valuable secondary metabolites.