Synthesis and Antibacterial Activity of Capsaicin Derivatives Containing Phenolic Hydroxyl Groups

Abstract Bacterial infections tend to cause a series of cytopathic reactions and have become a major threat to human life. Among them, phenolic compounds are widely used as a natural antibacterial derivative for antifouling and antibacterial applications. In this study, four phenolic hydroxyacrylamide monomers have been successfully prepared using capsaicinoid derivatives as inspiration (named as OHABA, PHABA, AHMA, and AMTHBA, respectively) and the chemical structures were confirmed by FT‐IR, 1 H‐NMR, 13 C‐NMR. The minimum inhibitory concentration (MIC) assay and plate antibacterial assay were measured to explore the antibacterial properties of the monomer. The results showed that four capsaicin derivatives exhibited antibacterial activity, and the antibacterial properties of the four monomers from strong to weak were PHABA, OHABA, AHMA and AMTHBA. The best antibacterial activity was PHABA (MIC for E. coli : 1.6 mg/mL, bacteriostasis rate: 82.46 %, MIC for S. aureus : 1.6 mg/mL, bacteriostasis rate: 69.58 %). Both the cluster effect of monomers and the spatial distribution of phenolic hydroxyl groups in the structure of derivatives affect the antibacterial properties.