Total synthesis of verucopeptin, an inhibitor of hypoxia-inducible factor 1 (HIF-1)

Chemistry and biology of specialized metabolites produced by Actinomadura

Covering: up to the end of 2022In recent years rare Actinobacteria have become increasingly recognised as a rich source of novel bioactive metabolites. Actinomadura are Gram-positive bacteria that occupy a wide range of ecological niches. This review highlights about 230 secondary metabolites produced by Actinomadura spp., reported until the end of 2022, including their bioactivities and selected biosynthetic pathways. Notably, the bioactive compounds produced by Actinomadura spp. demonstrate a wide range of activities, including antimicrobial, antitumor and anticoccidial effects, highlighting their potential in various fields.

Matteson Homologation-Based Total Synthesis of Meliponamycin A

The first total synthesis of meliponamycin A, an antimicrobial cyclodepsipeptide isolated from Streptomyces, is reported. Two key building blocks, the substituted tetrahydropyranyl side chain and an azido analogue of protected β-hydroxyleucine, were constructed via iterative Matteson homologations. A fragment coupling of a tetrapeptide, a depsidipeptide building block, macrocyclization, Staudinger reduction, and N-acylation are further steps in the synthesis.

Convergent synthesis of tetrahydropyranyl side chain of verucopeptin, an antitumor antibiotic active against multidrug-resistant cancers

A concise synthesis of the tetrahydropyranyl side chain of verucopeptin, an antitumor antibiotic cyclodepsipeptide efficacious against MDR cancers in vivo, is achieved using 12 steps in the longest linear sequence and 21 total steps, in which Julia-Kocienski olefination for the segments coupling, asymmetric hydroxylation as well as stereoselective synthesis of stable tetrahydropyran ring from a D-isoascorbic acid derivative are key steps. This convergent synthetic strategy enables the structural modification and mechanism study of verucopeptin for its clinical applications.

Stereoselective Synthesis of a Protected Side Chain of Meliponamycin A

The Matteson homologation was found to be a versatile tool for the construction of the linear polyketide side chain of meliponamycin and related compounds in only four steps. The ester dienolate version of this reaction allowed the introduction of the unsaturated ester moiety in a highly stereoselective fashion. Boronate oxidation/deoxygenation and Sharpless dihydroxylation are additional key steps in the stereoselective construction of this highly functionalized tetrahydropyran ring system, which is characteristic of this substance class.

Hypoxia Constructing the Prognostic Model of Colorectal Adenocarcinoma and Related to the Immune Microenvironment

Background: Hypoxia is a common phenomenon in solid tumors, which plays an important role in tumor proliferation, apoptosis, angiogenesis, invasion and metastasis, energy metabolism and chemoradiotherapy resistance. However, comprehensive analysis of hypoxia markers in colorectal adenocarcinoma (COAD) is still lacking. And there is a need for mechanism exploration and clinical application.

Methods: The gene expression, mutation and clinical data of COAD were downloaded from The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) databases, respectively. Tumor samples from TCGA were randomly divided into the training and internal validation groups, while tumor samples from GEO were used as the external validation group. Univariate COX—LASSO—multivariate COX method was applied to construct the prognostic model. We clustered all TCGA tumor samples into high, medium and low hypoxia groups, evaluated the correlation between hypoxia degree and immunoactivity, and explored the combined effect of mutation for common target genes and model riskscore on survival in COAD patients. Finally, we developed a dynamic nomograph App online for direct clinical application and carried out multiple validations of the prognostic model.

Results: Our hypoxia-related prognostic model for COAD patients is accurate and has been successfully validated internally and externally. Single Sample Gene Set Enrichment Analysis (ssGSEA) and Gene Set Enrichment Analysis (GSEA) results suggest that for COAD patients with higher hypoxia, the stronger the associated immunosuppressive activity, providing a possible mechanism for the lower survival rate. Finally, the dynamic nomograph App online enhances the clinical translational significance of the study.

Conclusion: In this study, an accurate prognostic model for COAD patients was established and validated. In addition, our innovative findings include correlations between hypoxia levels and immune activity, as well as an in-depth exploration of common target gene mutations.