18. Synthesis, characterization, theoretical calculations and antimicrobial studies of substituted 3-aminocyclohexanespiro-5-hydantoins

This article presents the synthesis of 6- and 8- substituted 3-aminocyclohexanespiro-5-hydantoins. The initial substituted cyclohexanespiro-5-hydantoins were prepared by means of the Bucherer-Lieb method. The products obtained were treated with hydrazine hydrate. As a result of this interaction the corresponding substituted 3-aminocyclohexanespiro-5-hydantoins were synthesized. The compounds obtained were characterized by physicochemical parameters, 1H, 13C NMR and IR spectroscopy. The structures of the target products were optimized using Density Functional Theory (DFT) methods at B3LYP/6-31G(d,p) level. The theoretical IR and NMR spectra of the compounds were calculated at B3LYP/6-31G(d,p) and B3LYP/6-31+G(2d,p) levels, respectively and compared with the experimental data.

The antimicrobial efficiency of the substituted 3-aminocyclohexanespiro-5-hydantoins was examined using the agar well diffusion method. The antimicrobial tests were carried out against the following microorganisms: Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, Gram-negative bacteria Esсherichia coli, Pseudomonas aeruginosa and Salmonella abony, the yeasts Candida albicans and Saccharomyces cerevisiae, the molds Penicillium chrysogenum and Aspergillus niger, plant pathogenic fungi Fusarium oxysporum and Pythium ultimum and the plant pathogenic bacterium Pseudomonas syringae.