Relationship between the structures of fatty acid amide derivatives and their antimicrobial activities

The structure-activity relationships of derivatives of the antibiotic cerulenin were investigated by chemically modifying dodecanoic acid, its skeletal back-bone. The dimethylamide derivatives were active against both gram-positive and -negative bacteria, and fungi. Among the compounds having modified groups at positions C2 and C4, the most active were those with a carbonyl group at C4 and a double bond at C2. The dimethylamide and pyrrolidine amide derivatives of this structure type were the most active. Activity against bacteria and yeast increased with the number of carbon atoms in the skeleton, with the maximum activity being observed at C=12. No significant differences in activity against fungi were observed with change in chain length.