Minor and trace sterols in marine invertebrates. 62. Novel coprostanols with unusual side chains from the marine sponge Calyx nicaeensis

Diversity and Activity of Bacteria Cultured from a Cup-The Sponge Calyx nicaeensis

Marine sponges are well-known for hosting rich microbial communities. Sponges are the most prolific source of marine bioactive compounds, which are frequently synthesized by their associated microbiota. Calyx nicaeensis is an endemic Mediterranean sponge with scarce information regarding its (bioactive) secondary metabolites. East Mediterranean specimens of mesophotic C. nicaeensis have never been studied. Moreover, no research has inspected its associated bacteria. Thus, we studied the sponge's bacterial diversity and examined bacterial interspecific interactions in search of a promising antibacterial candidate. Such novel antimicrobial agents are needed since extensive antibiotic use leads to bacterial drug resistance. Bacteria cultivation yielded 90 operational taxonomic units (OTUs). A competition assay enabled the testing of interspecific interactions between the cultured OTUs. The highest-ranked antagonistic bacterium, identified as Paenisporosarcina indica (previously never found in marine or cold habitats), was mass cultured, extracted, and separated using size exclusion and reversed-phase chromatographic methods, guided by antibacterial activity. A pure compound was isolated and identified as 3-oxy-anteiso-C15-fatty acid-lichenysin. Five additional active compounds await final cleaning; however, they are lichenysins and surfactins. These are the first antibacterial compounds identified from either the C. nicaeensis sponge or P. indica bacterium. It also revealed that the genus Bacillus is not an exclusive producer of lichenysin and surfactin.

Cytotoxic and anti-bacterial evaluation of two new aromatic A-ring steroids isolated from the Red Sea soft coral Dendronephthya spp

A successful column chromatography of a CHCl3/MeOH crude extract of Dendronephthya spp. soft coral led to the isolation of two new aromatic A-ring steroids (1-2), together with three known compounds (3-5). Both 1 and 2 are 19-norsteroids. The chemical structures were elucidated based on extensive 1D, 2D NMR, and EIMS analyses. In cytotoxic bioassays, compounds 1-5 were tested against three cancer cell lines: MCF-7, NCI-1299, and HepG2, with IC50 in the ranges of 22.1-85.4, 26.9-88.7, and 25.9-93.7 μM, respectively. Compounds 1, 2, and 5 showed moderate degrees of inhibition against Escherichia coli and Pseudomonas sp. at 100 and 150 µg/mL, while exhibiting weak inhibition against Bacillus cereus and Staphylococcus aureus at 150 µg/mL.