Beta-Pinene Derived Products With Enhanced In Vitro Antimicrobial Activity

The development of new antimicrobials has always been a research hotspot. In this study, beta-pinene-based derivatives were synthesized, and their antimicrobial activity was evaluated. The purpose was to develop some novel, promising new fungicides. Three beta-pinene derivatives containing bis-hydronopyl were prepared, and their antifungal and antibacterial activities were evaluated against 6 plant pathogenic fungi and 4 bacterial species; a preliminary structure-activity relationship is discussed. The results indicated that the derivatives containing the blend of alkyl group and bis-hydronopyl had potent inhibitory activities against plant fungal pathogens and bacteria. Among these molecules, bis-hydronopyl &methyl ammonium bromide showed excellent effects on CoPito:Web= acutatuty with a half-maximal effective concentration of 0.538 mu g/mL, which was lower than that of carbendazim. Scanning electron microscope showed that after administration of bis-hydronopyl dimethyl ammonium bromide (compound 3a), the C. acutatum mycelia were sunken and deformed in comparison with the control group. Furthermore, the inhibitory activities of the methyl derivatives against the plant pathogens were better than those of the ethyl derivatives. These results provide new insights into the inhibition of fungi and bacteria by beta-pinene derivatives, which may lead them to be used as precursor molecules for novel pesticides and antimicrobials in further research.