Natural antimicrobial peptides against Mycobacterium tuberculosis.

TB, caused by Mycobacterium tuberculosis, is one the leading infectious diseases worldwide. There is an urgent need to discover new drugs with unique structures and uncommon mechanisms of action to treat M. tuberculosis and combat antimycobacterial resistance. Naturally occurring compounds contain a wide diversity of chemical structures, displaying a wide range of in vitro potency towards M. tuberculosis. A number of recent studies have shown that natural antimycobacterial peptides can disrupt the function of the mycobacterial cell wall through different modes of action and thereafter interact with intracellular targets, including nucleic acids, enzymes and even organelles. More importantly, the probability of antimycobacterial resistance is low. This review presents several natural antimicrobial peptides isolated from different organism sources, including bacteria, fungi, plants and animals. In addition, the molecular features of these molecules are the subject of much attention. Such peptides have common traits among their chemical features, which may be correlated with their biological activities; hence, different parts of the molecular structures can be modified in order to increase penetration into the target cells. This review also summarizes the available information on the properties of antimycobacterial peptides associated with their biological activities.