Synthesis and antimicrobial activity of new prenylated 2-pyrone derivatives

Abstract

A series of new monoprenylated and diprenylated 2-pyrone derivatives with different halogen substituents were synthesized from the corresponding 6-aryl-4-hydroxy-2-pyrones by prenylation reactions. The compounds were evaluated for antibacterial activity and displayed significant in vitro activity with the highest activity shown by the monoprenylated 6-aryl-2-pyrones. All the compounds except the bromine-containing analogs were active against one or more tested bacteria, with Escherichia coli being the most susceptible of the test organisms. With the remarkable antibacterial activity of eight of the compounds against a drug-resistant β-lactamase-producing Klebsiella pneumoniae, a synergistic evaluation between each of these compounds and ampicillin was undertaken. Out of the eight combinations studied, synergistic effects were observed with two compounds, 4-(3-methylbut-2-enoxy)-6-phenyl-2H-pyran-2-one and 6-(4-fluorophenyl)-4-(3-methylbut-2-enoxy)-2H-pyran-2-one. Both compounds, at half the individual MIC values, were able to lower the MIC of ampicillin in combinations from 2500 to 2.4 µg/mL (1/1041 of MIC).

Graphical Abstract

Keywords:

• Antibacterial activity
• halogenated aromatics
• prenylated pyrone
• 2-pyrone

Additional information

Funding

This work was supported by the National Research Foundation (South Africa) under [Grant number 98345] and the University of KwaZulu-Natal.