Mannich base derivatives of 3-hydroxy-6- methyl-4H-pyran-4-one with antimicrobial activity.

A series of 3-hydroxy-6-methyl-2-[(substitutedpiperidine-1-yl)methyl]-4H -pyran-4-one structured compounds were synthesized by reacting 5-hydroxy-2-methyl-4H -pyran-4-one with suitable piperidine derivatives using Mannich reaction conditions. Antibacterial activities of the compounds for E. coli ATCC 25922, S. paratyphi ATCC BAA-1250, S. flexneri ATCC 12022, E. gergoviae ATCC 33426, and M. smegmatis ATCC 14468 were assessed in vitro by the broth dilution method for determination of minimum inhibitory concentration (MIC). In addition, their inhibitory effects over DNA gyrase enzyme were evaluated using a DNA gyrase supercoiling assay. All the synthesized compounds showed a MIC value of either 8 or 16 μg/mL for M. smegmatis, whereas minimum to moderate activity was achieved for the others. Those tested in the supercoiling assay had at best a very mild inhibition of the enzyme. This series deserves further attention for testing over Mycobacterium species and topoisomerase II inhibition to develop new lead drugs to treat non-tuberculous mycobacterial infections. [ABSTRACT FROM AUTHOR]