Synthetic Pathways to Not Psychotropic Phytocannabinoids as Promising Molecules to Develop Novel Antibiotics: A Systematic Review

Abstract

Due to the rapid emergence of multi drug resistant (MDR) pathogens against which current an-tibiotics are no longer functioning, severe infections are becoming practically untreatable. Con-sequently, the discovering of new classes of effective antimicrobial agents with novel modes of action is becoming increasingly urgent. The bioactivity of Cannabis sativa, an herbaceous plant used for millennia for medicinal and recreational purposes, is mainly due to its content in phytocan-nabinoids (PCs). Among the 180 PCs detected, cannabidiol (CBD), Δ8 and Δ9-tetrahydrocannabinols (Δ8-THC and Δ9-THC), cannabichromene (CBC), cannabigerol (CBG), cannabinol (CBN) and some their acidic precursors have demonstrated from moderate to potent antibacterial effects against Gram-positive bacteria (MICs 0.5–8 µg/mL), including methicillin-resistant Staphylococcus aureus (MRSA), epidemic MRSA (EMRSA), as well as fluoroquinolones and tetracycline-resistant strains. Particularly, the not psychotropic CBG was also capable to inhibit MRSA biofilm formation, to eradicate that mature, and to rapidly exterminate MRSA persiters cells. On this scenario, CBG, as well as other minor not psychotropic PCs, such as CBD, and CBC could represent promising compounds for developing novel antibiotics with high therapeutic potential. Anyway, further studies are necessary, needing abundant quantities of such PCs, scarcely provided naturally by Cannabis plants. Here, after an extensive overture on cannabinoids including their reported an-timicrobial effects, aiming at easing the synthetic production of the necessary amounts of CBG, CBC and CBD for further studies, we have, for the first time, systematically reviewed the synthetic pathways utilized for their synthesis, reporting both reaction schemes and experimental details.