In the last decades, the indiscriminate use of conventional antibiotics has generated high rates of microbial resistance.
This situation has increased the need for obtaining new antimicrobial compounds against infectious diseases.
Among these, antimicrobial peptides (AMPs) constitute a promising alternative as therapeutic agents against various
pathogenic microbes. These therapeutic agents can be isolated from different organisms, being widespread in nature and
synthesized by microorganisms, plants and animals (both invertebrates and vertebrates). Additionally, AMPs are usually
produced by a non-specific innate immune response. These peptides are involved in the inhibition of cell growth and in
the killing of several microorganisms, such as bacteria, fungi, enveloped viruses, protozoans and other parasites. They
have many interesting properties as potential antibiotics, such as relatively small sizes (below 25-30 kDa), amphipathic
structures, cationic nature, and offer low probability for the generation of microbial resistance. In recent years, many
novel AMPs, with very promising therapeutic properties, have been discovered. These peptides have been the base for the
production of chemical analogs, which have been designed, chemically synthesized and tested in vitro for their antimicrobial
activity. This review is focused on antibacterial (against Gram (-) and Gram (+) bacteria) and antifungal peptides, discussing
action mode of AMPs, and recent advances in the study of the molecular basis of their anti-microbial activity. Finally,
we emphasize on their current pharmacological development, future directions and applications of AMPs as promising
antibiotics of therapeutic use for microbial infections.