An ECD and NMR/DP4+ Computational Pipeline for Structure Revision and Elucidation of Diphenazine-Based Natural Products

Marine natural products

Covering: January to the end of December 2023This review covers the literature published in 2023 for marine natural products (MNPs), with 582 citations (541 for the period January to December 2023) 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 (1220 in 340 papers for 2023), 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 the progress in the study of prokaryote involvement in macro-invertebrate MNP production is discussed.

Anthoteibinenes F-Q: New Sesquiterpenes from the Irish Deep-Sea Coral Anthothela grandiflora

New technology has opened opportunities for research and exploration of deep-water ecosystems, highlighting deep-sea coral reefs as a rich source of novel bioactive natural products. During our ongoing investigation of the chemodiversity of the Irish deep sea and the soft coral Anthothela grandiflora, we report 12 unreported cadinene-like functionalized sesquiterpenes, anthoteibinenes F-Q. The metabolites were isolated using both bioassay- and 1H NMR-guided approaches. One-/two-dimensional NMR spectroscopy and high-resolution mass spectrometry were used for structure elucidation, while a combination of NOESY NMR experiments, GIAO NMR calculations coupled with DP4+ probabilities measures, and ECD comparisons were incorporated to propose relative and absolute configurations of the anthoteibinenes. The metabolites were screened against the Respiratory Syncytial Virus (RSV), ESKAPE pathogens, five Candida albicans strains, and one strain of C. auris.

Conformational Sampling in Computational Studies of Natural Products: Why Is It Important?

Conformational sampling is a vital component of a reliable computational chemistry investigation. With the aim of illustrating the importance of conformational sampling, and building awareness among new practitioners, we present a series of case studies that show how the quality and reliability of computational studies depend on undertaking a thorough conformer search. The examples are drawn from the most common types of research questions in natural products chemistry, but the fundamental principles apply more generally to computational studies of molecular structure and behavior in any field of chemistry.

Tepuazines A-E: Phenazine Glycosides from a Venezuelan Quartz-Rich (Tepui) Cave Soil-Derived Streptomyces virginiae CMB-CA091

Investigation of the secondary metabolites of Streptomyces virginiae CMB-CA091 isolated from the quartz-rich (tepui) soil of a cave in Venezuela yielded two new dimeric phenazine glycosides, tepuazines A and B (1 and 2); three new monomeric phenazine glycosides, tepuazines C-E (3-5); and a series of known analogues, baraphenazine G (6), phenazinolin D (7), izumiphenazine C (8), 4-methylaminobenzoyl-l-rhamnopyranoside (9), and 2-acetamidophenol (10). Structures were assigned to 1-10 on the basis of detailed spectroscopic analysis and biosynthetic considerations, with 1 and 2 featuring a rare 2-oxabicyclo[3.3.1]nonane-like ring C/D bridge shared with only a handful of known Streptomyces natural products. We propose a plausible convergent biosynthetic relationship linking all known members of this structure class that provides a rationale for the observed ring C/D configuration.