The effect of alkyl chain length of (R)-3-Hydroxybutyric alkyl ester on antibacterial activity and its antibacterial mechanism

This work describes the relationship between the antibacterial activity and the ester chain length (C1-C8) of ( R)-3-Hydroxybutyric (( R)-3-HB) alkyl esters that synthesized from ( R)-3-HB acid (( R)-3-HBA) by esterification reaction. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) decrease as the length of the ( R)-3-HB alkyl ester chain increases from 1 to 6, but ( R)-3-HB-C7 and ( R)-3-HB-C8 have their own rules for different microorganisms. Among them, the ( R)-3HB-C6 has the relatively best antibacterial and antifungal properties, which MIC were 1.95 mg mL −1 against E. coli and S. aureus; 0.98 mg mL −1 against C. albicans and B. subtilis; 0.49 mg mL −1 against A. niger. Finally, the antimicrobial mechanisms of the ( R)-3HB-C6 are revealed, and these include disruption of biofilm and the bacterial wall/membrane, leakage of the intracellular content, and change in the transmembrane potential. These results imply the potential application of ( R)-3-HB alkyl ester as new antimicrobial agents; future research can use this as an antibacterial element to synthesize new polymer materials or agents with high-efficiency antibacterial activity.