8,9-Dihydrocannabidiol, an Alternative of Cannabidiol, Its Preparation, Antibacterial and Antioxidant Ability

Cannabidiol (CBD) from Cannabis sativa is used in cosmetics in North America due to its antibacterial and antioxidant properties, but has been prohibited in many countries except recently; so, finding a non-intoxicating CBD alternative and elucidating the structure-function relationship of CBD analogues is becoming increasingly relevant. Herein, a set of CBD analogues including 8,9-dihydrocannabidiol (H₂CBD) was synthesized, and their antibacterial, bactericidal, and antioxidant activity, as well as their structure-function relationship, were studied. The results present a catalytic selectivity near 100% towards H₂CBD with a production yield of 85%. Each CBD analogue presented different antibacterial and antioxidant activity. It is revealed that the phenolic hydroxyl moiety is an essential group for CBD analogues to perform antibacterial and antioxidant activities. Among them, H₂CBD presented much stronger antibacterial activity than the assayed popular antibiotics. H₂CBD and Compound 4 presented very similar radical scavenging activity and inhibition on lipid oxidation to vitamin C, but better thermostability. Moreover, H₂CBD presented lower toxicity to human skin fibroblasts at concentrations up to 64-fold higher than its MIC value (1.25 μg/mL) against S. aureus. Above all, in all property experiments, H₂CBD presented extremely similar performance to CBD (p < 0.05), including similar time-kill kinetics curves. This research finds H₂CBD to be an alternative for CBD with very high potential in the aspects of antibacterial, bactericidal, and antioxidant activity, as well as lower toxicity to human skin fibroblasts.