The immunoregulatory effects of edeine analogues in mice

The edeines analogs were tested in several in vitro and in vivo assays using the mouse model, with edeine B (peptide W1) and cyclosporine A as reference compounds. The peptides displayed moderate, stimulatory effects on concanavalin A-induced (ConA-induced) splenocyte proliferation, whereas their effects on pokeweed mitogen-induced (PWM-induced) splenocyte proliferation were inhibitory. The peptides inhibited lipopolysacharide-induced (LPS-induced) tumor necrosis factor alpha production but had little effect on interleukin 6 production. In the model of the humoral immune response in vitro to sheep red blood cells, peptide 1 was distinctly stimulatory in the investigated concentrations (1-100 μg/ml), whereas peptides 3 and 4 only stimulated the number of antibody-forming cells at the highest concentration (100 μg/ml). In the model of the delayed type hypersensitivity in vivo to ovalbumin, the peptides were moderately suppressive (3 being the most active). The reference peptide W1 stimulated ConA-induced cell proliferation at 1–10 μg/ml but was inhibitory at 100 μg/ml. It also inhibited PWM-induced cell proliferation in a dose-dependent manner. This peptide had no effect on the humoral immune response in vitro or on cytokine production, but inhibited DTH reaction in vivo. The relationship between structure and activity, and a possible mode of action of the peptides, is discussed in this paper.

Structure activity relationship studies on the antimicrobial activity of novel edeine A and D analogues

Edeines are pentapeptide amide antibiotics composed of four nonprotein amino acids, glycine, and polyamine. They exhibit antimicrobial and immunosuppressive activities and are universal inhibitors of translation. Moreover, it was proven that the free ionizable carboxy group in the (2R, 6S, 7R)-2,6-diamino-7-hydroxyazelaic acid moiety is not essential for biological activity of these compounds. In this paper we describe the synthesis of four novel edeine A and D analogues in which the above-mentioned acid residue was replaced with the (3R, 4S)- or (3S, 4S)-4,5-diamino-3-hydroxypentanoic acid moiety. In one compound we also introduced into molecule the 3-N,N-dimethyl derivative of (S)-2,3-diaminopropanoic acid to prevent the transpeptidation process, which results in the loss of biological activity of alpha-isomers of edeines. All peptides were synthesized applying the active ester and azide methods and on the basis of the coupling of suitable N-terminal tripeptides with proper C-terminal dipeptide amides. The activities of the newly obtained edeine analogues against selected strains of bacteria and fungi are also presented.

Crystal structures of complexes of the small ribosomal subunit with tetracycline, edeine and IF3

The small ribosomal subunit is responsible for the decoding of genetic information and plays a key role in the initiation of protein synthesis. We analyzed by X-ray crystallography the structures of three different complexes of the small ribosomal subunit of Thermus thermophilus with the A-site inhibitor tetracycline, the universal initiation inhibitor edeine and the C-terminal domain of the translation initiation factor IF3. The crystal structure analysis of the complex with tetracycline revealed the functionally important site responsible for the blockage of the A-site. Five additional tetracycline sites resolve most of the controversial biochemical data on the location of tetracycline. The interaction of edeine with the small subunit indicates its role in inhibiting initiation and shows its involvement with P-site tRNA. The location of the C-terminal domain of IF3, at the solvent side of the platform, sheds light on the formation of the initiation complex, and implies that the anti-association activity of IF3 is due to its influence on the conformational dynamics of the small ribosomal subunit.