Antimicrobial Effect of Cannabidiol on Intracellular Mycobacterium tuberculosis .

Introduction: Mycobacterium tuberculosis , the etiologic agent of tuberculosis (TB), has killed nearly one billion people during the last two centuries. Nowadays, TB remains a major global health problem ranked among the top 10 causes of death worldwide. One of the main challenges in developing new strategies to fight TB is focused on reducing the duration and complexity of drug regimens. Cannabidiol (CBD) is the main nonpsychoactive ingredient extracted from the Cannabis sativa L . plant, which has been shown to be biologically active against bacteria. The purpose of this work was to investigate the antimicrobial effect of CBD on M. tuberculosis intracellular infection. Materials and Methods: To assess the minimum inhibitory concentration (MIC) of CBD on mycobacterial strains, the MTT assay was performed on Mycobacterium smegmatis , and the Colony-Forming Unit (CFU) assay was conducted on Mtb H37Rv. Additionally, the cytotoxic effect of CBD on THP-1 cells was assessed by MTT assay. Moreover, macrophages derived from the THP-1 cell were infected with Mtb H37Rv (multiplicity of infection 1:10) to evaluate the intracellular activity of CBD by determining the CFU/mL. Results: Antimicrobial activity against M. smegmatis (MIC=100 μM) and Mtb H37Rv (MIC=25 μM) cultures was exhibited by CBD. Furthermore, the effect of CBD was also evaluated on Mtb H37Rv infected macrophage cells. Interestingly, a reduction in viable intracellular Mtb H37Rv bacteria was observed after 24 h of treatment. Moreover, CBD exhibited a safe profile toward human THP-1 cells, since it showed no toxicity (CC 50 =1075 μM) at a concentration of antibacterial effect (selectivity index 43). Conclusion: These results extend the knowledge regarding the antimicrobial activity of CBD and demonstrate its ability to kill the human intracellular pathogen M. tuberculosis.