Four bioactive new steroids from the soft coral Lobophytum pauciflorum collected in South China Sea

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.

Lobosteroids A-F: Six New Highly Oxidized Steroids from the Chinese Soft Coral Lobophytum sp

To explore the steroidal constituents of the soft coral Lobophytum sp. at the coast of Xuwen County, Guangdong Province, China, a chemical investigation of the above-mentioned soft coral was carried out. After repeated column chromatography over silica gel, Sephadex LH-20, and reversed-phase HPLC, six new steroids, namely lobosteroids A-F (1-6), along with four known compounds 7-10, were obtained. Their structures were determined by extensive spectroscopic analysis and comparison with the spectral data reported in the literature. Among them, the absolute configuration of 1 was determined by X-ray diffraction analysis using Cu Kα radiation. These steroids were characterized by either the presence of an α,β-α',β'-unsaturated carbonyl, or an α,β-unsaturated carbonyl moiety in ring A, or the existence of a 5α,8α-epidioxy system in ring B, as well as diverse oxidation of side chains. The antibacterial bioassays showed that all isolated steroids exhibited significant inhibitory activities against the fish pathogenic bacteria Streptococcus parauberis FP KSP28, Phoyobacterium damselae FP2244, and Streptococcus parauberis SPOF3K, with IC90 values ranging from 0.1 to 11.0 µM. Meanwhile, compounds 2 and 6-10 displayed potent inhibitory effects against the vancomycin-resistant Enterococcus faecium bacterium G7 with IC90 values ranging from 4.4 to 18.3 µM. Therefore, ten highly oxidized steroids with strong antibacterial activities were isolated from the Chinese soft coral Lobophytum sp., which could be developed as new chemotypes of antibacterial drug leads.

A Comprehensive In Silico Study of New Metabolites from Heteroxenia fuscescens with SARS-CoV-2 Inhibitory Activity

Chemical investigation of the total extract of the Egyptian soft coral Heteroxenia fuscescens, led to the isolation of eight compounds, including two new metabolites, sesquiterpene fusceterpene A (1) and a sterol fuscesterol A (4), along with six known compounds. The structures of 1–8 were elucidated via intensive studies of their 1D, 2D-NMR, and HR-MS analyses, as well as a comparison of their spectral data with those mentioned in the literature. Subsequent comprehensive in-silico-based investigations against almost all viral proteins, including those of the new variants, e.g., Omicron, revealed the most probable target for these isolated compounds, which was found to be M^pro. Additionally, the dynamic modes of interaction of the putatively active compounds were highlighted, depending on 50-ns-long MDS. In conclusion, the structural information provided in the current investigation highlights the antiviral potential of H. fuscescens metabolites with 3β,5α,6β-trihydroxy steroids with different nuclei against SARS-CoV-2, including newly widespread variants.