Fluvirucins B7-B10, new antifungal macrolactams from a marine-derived Nonomuraea sp. MYH522

Mini review: antimicrobial compounds produced by bacteria associated with marine invertebrates

The marine environment is considered one of the most important ecosystems with high biodiversity. Microorganisms in this environment are variable and coexist with other marine organisms. The microbes associated with other marine organisms produce compounds with biological activity that may help the host's defense against invading organisms. The symbiotic association of bacteria with marine invertebrates is of ecological and biotechnological importance. Biologically active metabolites isolated from bacteria associated with marine invertebrates are considered potential sources of natural antimicrobial molecules for treating infectious diseases. Many studies have been conducted to screen the antimicrobial activity of metabolites produced by bacteria associated with marine invertebrates. This work provides an overview of the advancements in antimicrobial compound research on bacteria associated with marine invertebrates.

Marine natural products

Covering: January to the end of December 2022This review covers the literature published in 2022 for marine natural products (MNPs), with 645 citations (633 for the period January to December 2022) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, the submerged parts of mangroves and other intertidal plants. The emphasis is on new compounds (1417 in 384 papers for 2022), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. An analysis of NP structure class diversity in relation to biota source and biome is discussed.

Genome mining for macrolactam-encoding gene clusters allowed for the network-guided isolation of β-amino acid-containing cyclic derivatives and heterologous production of ciromicin A

β-Amino acid-containing macrolactams represent a structurally diverse group of bioactive natural products derived from polyketides; however we are currently lacking a comprehensive overview about their abundance across bacterial families and the underlying biosynthetic diversity. In this study, we employed a targeted β-amino acid-specific homology-based multi-query search to identify potential bacterial macrolactam producers. Here we demonstrate that approximately 10% of each of the identified actinobacterial genera harbor a biosynthetic gene cluster (BGC) encoding macrolactam production. Based on our comparative study, we propose that mutations occurring in specific regions of polyketide synthases (PKS) are the primary drivers behind the variation in macrolactam ring sizes. We successfully validated two producers of ciromicin A from the genus Amycolatopsis, revised the composition of the biosynthetic gene cluster region mte of macrotermycins, and confirmed the ciromicin biosynthetic pathway through heterologous expression. Additionally, network-based metabolomic analysis uncovered three previously unreported macrotermycin congeners from Amycolatopsis sp. M39. The combination of targeted mining and network-based analysis serves as a powerful tool for identifying macrolactam producers and our studies will catalyze the future discovery of yet unreported macrolactams.

Natural products as anthelmintics: safeguarding animal health

Covering literature to December 2022This review provides a comprehensive account of all natural products (500 compounds, including 17 semi-synthetic derivatives) described in the primary literature up to December 2022, reported to be capable of inhibiting the egg hatching, motility, larval development and/or the survival of helminths (i.e., nematodes, flukes and tapeworms). These parasitic worms infect and compromise the health and welfare, productivity and lives of commercial livestock (i.e., sheep, cattle, horses, pigs, poultry and fish), companion animals (i.e., dogs and cats) and other high value, endangered and/or exotic animals. Attention is given to chemical structures, as well as source organisms and anthelmintic properties, including the nature of bioassay target species, in vivo animal hosts, and measures of potency.

Anti-inflammatory Oleanane-Type Triterpenoids Produced by Nonomuraea sp. MYH522 through Microbial Transformation

Eleven oleanane-type triterpenoids named soyasapogenols B1-B11 have been obtained unexpectedly from a marine actinomycete Nonomuraea sp. MYH522. Their structures have been determined by extensive analysis of spectroscopic experiments and X-ray crystallographic data. Soyasapogenols B1-B11 exhibit subtle differences in the positions and degrees of oxidation on an oleanane skeleton. The feeding experiment suggested that soyasapogenols might be derived from soyasaponin Bb through microbial-mediated conversion. The biotransformation pathways from soyasaponin Bb to five oleanane-type triterpenoids and six A-ring cleaved analogues were proposed. The assumed biotransformation involves an array of reactions including regio- and stereo-selective oxidation. These compounds alleviated the 5,6-dimethylxanthenone-4-acetic acid-induced inflammation in Raw264.7 cells via the stimulator of interferon genes/TBK1/NF-κB signaling pathway. The present work provided an efficient approach for rapid diversification of soyasaponins and for developing food supplements with potent anti-inflammatory effects.