Synthesis of two novel series of azoaldonitrones and preliminary evaluation of their antibacterial activity


Abstract In this work two series of new azoaldonitrones have been synthesized. At first, azoaldehydes [A1-A10] were prepared via coupling reactions between the diazonium salts of the primary aromatic amines (2-amino-5-mercapto-1,3,4-thiadiazole, 3-aminopyridine,4-methoxyaniline, 2,4-dichloroaniline, 4-chloroaniline, 2-chloroaniline, 3-bromoaniline, 3-nitroaniline, 4-nitroaniline and benzidine, respectively) and alkaline solution of 2-hydroxybenzaldehyde as coupling reagent. Next, the resulting azoaldehydes [A1-A10] were introduced in acid-catalyzed condensation reactions with N-phenylhydroxylamine in absolute ethanol to obtain ten new azoaldonitrones [N1-N10] respectively. Later, treatment of azoaldehydes [A1-A5] with N-benzylhydroxylamine under the same conditions afforded five new azoaldonitrones [A11-A15] respectively. The structures of the synthesized azoaldonitrones were confirmed by (C.H.N.S.) elementary analysis and the spectroscopic methods including FT-IR and 1H NMR. The synthesized azoaldonitrones [N1-N15] were tested for their antibacterial activity against two pathogenic strains of bacteria Staphylococcus aureous (Gram-positive) and Escherichia coli (Gram-negative). The results revealed that azoaldonitrones [N1] and [N11] which are containing thiadiazole moiety showed higher activity against both strains of bacteria, while compound [N6] appeared higher activity only against Gram-positive bacteria. Moreover, most of the prepared azoaldonitrone compounds showed medium activity against Gram-positive bacteria and weak activity against Gram-negative bacteria.