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A variety of N-[(4,6-diaryl-3-pyridinecarbonitrile)-2-yl] amino acid esters 2-4 were synthesized through the reaction of 2-bromo-3-pyridinecarbonitriles 1 with the appropriate alpha-amino acid ester hydrochloride in refluxing dioxane in the presence of triethylamine as dehydrohalogenating agent. Similarly, N'-glycylglycine analogues 5 were obtained through the reaction of 1 with the dipeptide ester. On the other hand, attempts were made towards the construction of amino acid derivatives 7 through the reaction of 1 with aqueous solution alpha-amino acids 6 in refluxing pyridine, but were unsuccessful, and instead the unexpected 2-amino-3-pyridinecarbonitriles 8 were isolated. The fluorescence properties of the newly synthesized pyridines 2-5 were evaluated. Some of the prepared compounds show considerable antibacterial activity.

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A series of new Schiff bases were synthesized by condensation of isatins with the nalidixic acid- l -amino acid hydrazides. Prior to hydrazide formation, a peptide linkage has been prepared via coupling of nalidixic acid with appropriate l -amino acid methyl esters to yield 3a – c . The chemical structures of the new Schiff bases ( 5b and 5d – h ) were confirmed by means of IR, NMR, mass spectroscopic, and elemental analyses. The anti-inflammatory activity of these Schiff bases was evaluated via measurement of the expressed inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in the lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells model. The Schiff bases exhibited significant dual inhibitory effect against the induction of the pro-inflammatory iNOS and COX-2 proteins with variable potencies. However, they strongly down-regulated the iNOS expression to the level of 16.5% ± 7.4%–42.2% ± 19.6% compared to the effect on COX-2 expression (<56.4% ± 3.1% inhibition) at the same concentration (10 μM). The higher iNOS inhibition activity of the tested Schiff bases, relative to that of COX-2, seems to be a reflection of the combined suppressive effects exerted by their nalidixic acid, isatins ( 4a – c ), and l -amino acid moieties against iNOS expression. These synthesized nalidixic acid- l -amino acid-isatin conjugates can be regarded as a novel class of anti-inflammatory antibacterial agents.

Abstract:A new series of fused triazolo-and tetrazolopyrimidine derivatives 2-14 were synthesized and their anti-inflammatory and ulcerogenic activities were evaluated. The pharmacological screening showed that many of these obtained compounds have good anti-inflammatory activities, comparable to the reference drug. The toxicity of the compounds was also assayed via the determination of their LD 50 values. The structures of newly synthesized compounds were confirmed by IR, 1 H-NMR, MS spectral data and elemental analysis.