Natural products in drug discovery: meeting the urgency for new antimicrobials for human and veterinary use

The scenario of growing microbial resistance and of lack of interest of pharmaceutical companies in developing new antimicrobial drugs jeopardizes the present and the future of the treatment of infectious diseases. Different approaches such as antimicrobial peptides and CRISP-R have been explored to manage this situation, however, they have important limitations such as their high cost. Natural products comprise complex molecular structures for which reports of bacterial resistance are rare. They present specific and/or unspecific mechanisms of action that can be explored to provide safe and effective management of infectious diseases. In this review we assessed phytoextracts with evidence of their benefits for treating infectious diseases in humans and animals, towards the use of data for clinical and experimental purposes. Mechanisms of bacterial resistance to antimicrobials are also discussed.