No abstract

Theonella swinhoei is a fairly common inhabitant of reefs throughout the Indian and Pacific Oceans. Metabolomic analyses of samples of T. swinhoei collected in different depths in the Gulf of Aqaba revealed two chemotypes differing in the profiles of the theonellamides they produce, some of which seem to be unknown. Driven by this finding, we examined a sample of T. swinhoei collected more than 40 years ago in the southern part of the Gulf of Aqaba. Large-scale extract of this sample yielded four theonellamides, the known theopalauamide (4), as the major component, and three new metabolites, theonellamide J (1), 5-cis-Apoa-theopalauamide (2), and theonellamide K (3), as the minor components. The planar structure of these complex cyclic glycopeptides was elucidated by combination of 1D and 2D NMR techniques and HRESIMS. The absolute configuration of the amino acids was established by Marfey’s and advanced Marfey’s methods, and the absolute configuration of its galactose unit using “Tanaka’s method” for monosaccharides. The biological activity of the pure compounds was tested for antibacterial activity and for cytotoxicity to HTC-116 cell line. The compounds presented significant cytotoxicity against the HTC-116 cell line, illuminating the importance of the Apoa subunit for the activity.

The hydrophilic extract of Microcystis sp. bloom material collected from Bror Hayil Reservoir in southern Israel afforded four new metabolites, (2S,3S)-3hydeoxy-1,4-diphenylbutan-2-yl-acetate, aeruginosins BH604, BH462A and BH462B, and two known metabolites cyanopeptolins S and SS. The planar structure of 1-4 was established by analyses of their 1D and 2D NMR data and mass spectrometric data. The absolute configurations of the chiral centers of 1 were established by Mosher method and analysis of the coupling constants between H-2 and H-3, and those of 2-4 by Merfay's method and advanced Merfay's method and chiral HPLC. The compounds do not inhibit the serine proteases trypsin and thrombin.