Deconvolution of E/Z tetrahydroisoquinoline amide rotamers and conformers from a marine-derived Streptomyces strain

A Streptomyces tendae Specialized Metabolite Inhibits Quorum Sensing in Group A Streptococcus

Quorum sensing (QS) is a means of bacterial communication accomplished by microbe-produced signals and sensory systems. QS systems regulate important population-wide behaviors in bacteria, including secondary metabolite production, swarming motility, and bioluminescence. The human pathogen Streptococcus pyogenes (group A Streptococcus [GAS]) utilizes Rgg-SHP QS systems to regulate biofilm formation, protease production, and activation of cryptic competence pathways. Given their reliance on small-molecule signals, QS systems are attractive targets for small-molecule modulators that would then affect gene expression. In this study, a high-throughput luciferase assay was employed to screen an Actinobacteria-derived secondary metabolite (SM) fraction library to identify small molecule inhibitors of Rgg regulation. A metabolite produced by Streptomyces tendae D051 was found to be a general inhibitor of GAS Rgg-mediated QS. Herein, we describe the biological activity of this metabolite as a QS inhibitor. IMPORTANCE Streptococcus pyogenes, a human pathogen known for causing infections such as pharyngitis and necrotizing fasciitis, uses quorum sensing (QS) to regulate social responses in its environment. Previous studies have focused on disrupting QS as a means to control specific bacterial signaling outcomes. In this work, we identified and described the activity of a naturally derived S. pyogenes QS inhibitor. This study demonstrates that the inhibitor affects three separate but similar QS signaling pathways.

Marine natural products

This review covers the literature published between January and December in 2018 for marine natural products (MNPs), with 717 citations (706 for the period January to December 2018) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1554 in 469 papers for 2018), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. The proportion of MNPs assigned absolute configuration over the last decade is also surveyed.

Computational prediction of chiroptical properties in structure elucidation of natural products

Covering: up to 2019This review covers the current status of the quantum mechanical prediction of chiroptical properties, such as electronic CD and optical rotation, as needed for stereochemical assignments in new natural products. The reliability of the prediction of chiroptical properties is steadily increasing, with a parallel decrease in the required computational resources. Now, quantum mechanical calculations for a medium-sized natural product can be reliably performed by natural product chemists on a mainstream PC. This review is aimed to guide natural product chemists through the numerous steps involved in such calculations. Through a concise, but comprehensive, discussion of the current computational practice, enriched by a few illustrative examples, this review provides readers with the theoretical background and practical knowledge needed to select the most appropriate parameters for performing the calculations, to anticipate possible problems, and to critically evaluate the reliability of their computational results. Common reasons for mistakes are also discussed; in particular, the importance of the correct evaluation of conformational ensembles of flexible molecules (an aspect often overlooked in current research) is stressed.