CHEMISTRY OF THE AMINO SUGARS DERIVED FROM ANTIBIOTIC SUBSTANCES.
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Residue based control of specific helical folding is explored in hybrid peptide oligomers consisting of alternating L-Ala and cis-beta-furanoid sugar amino acid (FSAA) residues as building blocks; two series of these hybrid oligomers are designed, synthesized and extensively characterized by using NMR, CD, FT-IR and MD simulation studies; results show the co-existence of left-handed 11- and 14/15-helical conformations in these short oligomers of Boc-(alpha/beta) and Boc-(beta/alpha) series.
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Eleven analogues of the C-terminal Ca(1)a(2)X motif found in natural substrates of the prenyl transferases PFT and PGGT-1 were synthesized and evaluated for their inhibition potency and selectivity against PFT and PGGT-1. Replacement of the central dipeptide part a(1)a(2) by a benzylated sugar amino acid resulted in a good and highly selective PFT inhibitor (8, IC(50) = 250 +/- 20 nM). The methyl ester of 8 (13) selectively inhibited protein farnesylation in cultured cells.
[structure: see text] Cyclopeptides containing Glucuronic acid methylamine (Gum) alternating with Gly, L-Ala, D-Ala, L-Phe, D-Phe, L-Lys, or D-Lys were synthesized by a combination of solid-phase synthesis and solution chemistry. A more effective pathway to synthesize the sugar amino acid Gum in higher yields and in a shorter period of time was developed. Gum is employed in the benzylated and deprotected form. The cyclopeptides were characterized by NMR and the structure of one deprotected cyclic peptide solved.
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In this study we describe the development of peptidomimetic analogs of the potent vasoactive intestinal peptide receptor binding inhibitor, Leu(1) -Met(2) -Tyr(3) -Pro(4) -Thr(5) -Tyr(6) -Leu(7) -Lys(8) -OH 1, by incorporating furanoid sugar amino acids (SAAs) 2-4 into the molecule. The furanoid SAAs 2-4 were used as dipeptide isosteres to replace Tyr(3) -Pro(4) or Pro(4) -Thr(5) in sequence 1. The resulting analogs 5-9 were tested for their anti-cancer activities in vitro, following the standard MTT assay on a panel of human cancer cell lines. One of the potent analogs, 6a was tested in vivo for tumor regression on primary colon tumor xenografted nude mice. Our experimental results suggest that many of these analogs show either retention or enhancement of biological activity.
An acidic O-specific polysaccharide (PS) of the agar-digesting bacterium Shewanella japonica with the type strain KMM 3299(T) was obtained by mild acid hydrolysis of the lipopolysaccharide. The polysaccharide was studied by component analysis, methylation analysis, (1)H and (13)C NMR spectroscopy, including 2D NMR experiments. The PS was determined to have the following structure involving three unusual amino sugars:
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A practical gram-scale and high-yielding synthesis of the antimicrobial peptide gramicidin S is presented. An Fmoc-based solid-phase peptide synthesis protocol is employed for the generation of the linear decapeptide precursor, which is cyclized in solution to afford the target compound. The versatility of our method is demonstrated by the construction of eight gramicidin S analogues (15a-h) having nonproteinogenic sugar amino acid residues (4-7) incorporated in the turn regions.
The effects of 4'-epi-daunorubicin, 4'-epi-adriamycin, and the corresponding beta anomers on the in vitro activity of Escherichia coli DNA polymerase I and RNA polymerase were determined and compared with the effects of the parent compounds. The observed effects parallel the cytotoxic activities, assayed by inhibition of mouse embryo fibroblast proliferation, and the inhibitory activities on DNA synthesis in cultured cells. The data indicate that the inverted configuration at position 1 of the amino sugar results in a markedly reduced biological activity. This conclusion is also substantiated by the data obtained with the beta anomer of adriamycin. A preliminary investigation on the binding properties of these derivatives suggests that the inverted configuration at C-1' produces a significant decrease in the binding to DNA. In contrast, epimerization at position 4' did not produce any significant change in activity. The relationship between biological and biochemical activity and DNA binding properties of the tested compounds are discussed with particularly reference to antitumor activity.