Plants as a Source of Bacterial Resistance Modulators and Anti-Infective Agents

Abstract

The spread of multidrug-resistant (MDR) strains of bacteria necessitates the discovery of new classes of antibacterials and compounds that inhibit these resistance mechanisms. At present, there are no single chemical entity plant-derived antibacterials used clinically, and this chemically diverse group deserves consideration as a source for two major reasons. First, plants have exceptional ability to produce cytotoxic agents and second there is an ecological rationale that antimicrobial natural products should be present or synthesised de novo in plants following microbial attack to protect the producer from pathogenic microbes in its environment. We have been characterising plant-derived products that are either antibacterial in their own right, or modulators of resistance in bacterial strains possessing multidrug efflux mechanisms. These efflux transporters are responsible for resistance to certain antibiotics and antiseptics and occur in strains of methicillin-resistant Staphylococcus aureus (MRSA), a major clinical problem at present. We are also investigating plant sources for compounds with activity against mycobacteria with a view to discovering drug leads with potential activity toward tuberculosis (TB) producing species. This paper will briefly review the literature on plant derived bacterial resistance modifying agents and antibacterials. Examples in this area from our own work will be given. The activities of plant-derived antibacterials show that there are many potential new classes of antibacterial agents which should undergo further cytotoxicity, microbial specificity and preclinical studies.

Synergistic activity of doped zinc oxide nanoparticles with antibiotics: ciprofloxacin, ampicillin, fluconazole and amphotericin B against pathogenic microorganisms

“…It has been assumed that if present trends continue, antibiotic failure will claim 10 million lives per year by 2050 (O'Neill 2014). Therefore, there has been increasing interest in the role of inhibitors of antibiotic resistance for combination therapy (Gibbons 2005, Wright 2005). Nanotechnology represents a modern and forward-looking approach to develop new formulations based upon metallic nanoparticles with antimicrobial properties.…”

Effects of coadministration of natural polyphenols with doxycycline or calcium modulators on acute Chlamydia pneumoniae infection in vitro

“…First, plants have exceptional ability to produce cytotoxic agents and second there is an ecological rationale that antimicrobial natural products should be present or plants following microbial attack to protect the producer from pathogenic microbes in its environment. 22 We have previously shown that dietary phenolic compounds are effective against the intracellular bacterium C. pneumoniae. 17,18 As it has been proposed that natural compounds in combination with antibiotics could be a new strategy for developing therapies for infections caused by bacterial species and that natural plant products can potentiate the activity of antibiotics in combination, 23,24 we wanted to investigate whether coadministration of phenolic compounds with the antichlamydial compound doxycycline results in synergistic inhibition of acute C. pneumoniae infection.…”

Antimicrobial activity, total phenolic content and flavonoid concentrations of Teucrium species

“…The use of natural antibiotics from plants does not induce side effects such as abdominal pain, diarrhea, cramping, headache, nausea and vomiting. Plant products may be used as antibiotic alternatives and do not cause resistance in bacteria [5].…”