Endophytes: a uniquely tailored source of antibiotic adjuvants

Abstract

Multidrug resistance is growing at an alarming rate risking the loss of lives of more than 10 million people per year by 2050. Solutions include rational use of antibiotics and more effectively the use of drugs that reduce resistance or completely obliterate them. Several plant extracts were reported as active antimicrobial agents, but their supply problem and low rate of compound isolation retarded their advancement in this field. Here endophytes come to play due to their high yield production and inherent nature to produce antimicrobial molecules where 40%, 45% and 17% of antibacterial agents were obtained from fungi, actinomycetes, and bacteria, respectively, whose secondary metabolites revealed effectiveness against resistant microbes such as Bacillus sp., MRSA, MRSE, and Shigella flexneri. Biological activities included anticancer, antimicrobial, antiviral and anti-inflammatory effects. Endophyte’s role was not confined to bactericidal effect but extended to other mechanisms against MDR microbes, among which was the adjuvant role or the “magic bullets" that could revive obsolete antibiotics again. Scarce focus was given to antibiotic adjuvants, and many laboratories today just screen for the antimicrobial activity without considering combinations with traditional antibiotics, which means real loss of promising resistance combating molecules. This review, comprehensively and for the first time, sheds light on the significance of endophytes secondary metabolites in solving AMR problem as AB adjuvants. Examples of promising antibiotic adjuvants were listed from endophytes showing their potency in rescuing bacterial susceptibility by folds magnitude.