Abstract
Following previous experiments, 3-aryl-4-hydroxy-7-nitrocoumarin was synthesized by the direct cyclization following condensation of p-nitrosalicylic acid acetate chloride with β-ketonic esters in absolute ether. The compounds synthesized were 3-acetyl-, 3-butyryl and 3-decanoyl compounds which all showed similar ultraviolet absorption curves. The antibacterial action of these 7-nitro and 7-hydroxy compounds against Staphylococcus aureus and Escherichia coli was as follows:
1) Generally, the antibacterial action decreased with the introduction of a substituent as compared to that of non-substituted 3-acyl-4-hydroxycoumarin, the effect being greater in hydroxyl than in the nitro group.
2) In the presence of a substituent, the greater the aryl group substituted, the greater becomes the antibacterial action. The antibacterial action reaches the maximum with the decanoyl group in 7-hydroxy compounds.
3) When the acyl group in the 3-position of the 7-nitro compounds is small, i.e. in 3-acetyl compound, a slightly abnormal phenomenon is observed, the introduction of the nitro group heightening antibacterial action.
4) Of compounds substituted in the 7-position, 3-decanoyl-4-hydroxy-7-nitrocoumarin showed the strongest antibacterial action, being effective at 8, 000, 000 dilution against Staph. aureus.
