Recent advances in discovery and biosynthesis of natural products from myxobacteria: an overview from 2017 to 2023

Covering: 2017.01 to 2023.11Natural products biosynthesized by myxobacteria are appealing due to their sophisticated chemical skeletons, remarkable biological activities, and intriguing biosynthetic enzymology. This review aims to systematically summarize the advances in the discovery methods, new structures, and bioactivities of myxobacterial NPs reported in the period of 2017-2023. In addition, the peculiar biosynthetic pathways of several structural families are also highlighted.

Discovery, Biosynthesis and Biological Activity of a Succinylated Myxochelin from the Myxobacterial Strain MSr12020

Myxobacteria feature unique biological characteristics, including their capability to glide on the surface, undergo different multicellular developmental stages and produce structurally unique natural products such as the catecholate-type siderophores myxochelins A and B. Herein, we report the isolation, structure elucidation and a proposed biosynthesis of the new congener myxochelin B-succinate from the terrestrial myxobacterial strain MSr12020, featuring a succinyl decoration at its primary amine group. Myxochelin-B-succinate exhibited antibacterial growth inhibition and moderate cytotoxic activity against selected human cancer cell lines. This unique chemical modification of myxochelin B might provide interesting insights for future microbiological studies to understand the biological function and biosynthesis of secondary metabolite succinylation.

Three New Stigmatellin Derivatives Reveal Biosynthetic Insights of Its Side Chain Decoration

Myxobacteria generate natural products with unique chemical structures, which not only feature remarkable biological functions, but also demonstrate unprecedented biosynthetic assembly strategies. The stigmatellins have been previously described as potent inhibitors of the mitochondrial and photosynthetic respiratory chain and originate from an unusual polyketide synthase assembly line. While previous biosynthetic investigations were focused on the formation of the 5,7-dimethoxy-8-hydroxychromone ring, side chain decoration of the hydrophobic alkenyl chain in position 2 was investigated less thoroughly. We report here the full structure elucidation, as well as cytotoxic and antimicrobial activities of three new stigmatellins isolated from the myxobacterium Vitiosangium cumulatum MCy10943^T with side chain decorations distinct from previously characterized members of this compound family. The hydrophobic alkenyl chain in position 2 of the herein described stigmatellins feature a terminal carboxylic acid group (1), a methoxy group at C-12′ (2) or a vicinal diol (3). These findings provide further implications considering the side chain decoration of these aromatic myxobacterial polyketides and their underlying biosynthesis.

Stereoselective total synthesis of obolactones and 7′,8′-dihydroobolactones

A concise stereoselective total synthesis of two diastereomeric obolactones and 7′,8′-dihydroobolactones has been achieved using a metal-free catalytic δ-hydroxyalkynone rearrangement and ring-closing metathesis.