Synthesis and antimicrobial activity of N-alkyl substituted p-methyl (E)-3- and 4-azachalconium bromides

摘要

Twenty new N-alkyl substituted p-methyl (E)-3- and4-azachalcones (1a-j, 2a-j){3-[(1E)-3-(4-methylp-henyl)-3-oxoprop-1-en-1-yl]-1-alkyl (C_{5-12,_{14-15) pyridinium bromides(1a-j) and 4-[(1E)-3-(4-methylp-henyl)-3-oxoprop-1-en-1-yl]-1-alkyl(C_{5-12,_{14-15) pyridinium bromides (2a-j)} were synthesized andtested for antimicrobial activities against Staphylococcus aureus,Staphylococcus epidermidis, Bacillus subtilis, Enterococcus faecalis,Proteus vulgaris, and Escherichia coli. They showed goodantimicrobial activity especially against the gram-positive bacteriatested with minimal inhibitory concentration (MIC) values less than4.7 mu g/mL in most cases. The optimum length of the alkyl chain forbetter and broader activity is situated in the range of 8-12 carbonatoms in the series of compounds 1a-j, 2a-j. The non-alkylatedcompounds 1-2 were not effective as were the ones alkylated with 14 or15 C alkyl groups (1i, 1j, 2i, 2j). N-Alkyl derivatives of p-methyl(E)-3-azachalcone (1a-h) showed better activity in comparison to thoseof p-methyl (E)-4-azachalcone (2a-h). The antimicrobial activityincreased as the length of the alkyl substitution increased from 5 to12 carbons.