Fans of Korean skincare may be familiar with 'hero ingredient' Madecassic acid for its skin-soothing properties, but researchers at the University of Kent have revealed its greater potential for use in the battle against antibiotic resistance.
Using a combination of computational screening and laboratory experiments, scientists in the School of Natural Sciences together with those at University College London (UCL) have demonstrated how this natural chemical from the common Asian herb Centella asiatica, is an effective antibacterial drug.
Their findings come at a time when drug-resistant bacteria pose a serious worldwide health challenge, with predictions that bacterial antimicrobial resistance will cause 39 million deaths between 2025 and 2050. The race to create new antibiotics is costly and slow, so any advance in this area can prove an important breakthrough. As Kent researchers have demonstrated here, applying modern methods to analyse natural plant extracts is bringing those breakthroughs a step closer.
The study, published in RSC Medicinal Chemistry , showed that madecassic acid, a plant chemical and known anticancer agent, can inhibit the ability of antibiotic-resistant E. coli to grow. This molecule binds strongly to the cytochrome bd complex, a respiratory protein complex that does not exist in humans and animals but is essential for the survival of many pathogenic bacteria during infection. When it binds to the cytochrome bd, the madecassic acid stops it from functioning normally, suggesting that this natural product could serve as an alternative antimicrobial.
One of the advantages of madecassic acid as an antibacterial drug is that it has a chemical structure that is amenable to modification. The scientists isolated madecassic acid from a plant extract in Vietnam and modified it to create three different variants. All variants effectively inhibited cytochrome bd and shut down bacterial growth, with one variant also killing E. coli at higher concentrations. Future work will build on these findings to optimise madecassic acid as a more effective drug.
These findings also provide insights into how this plant extract component might impact upon bacterial skin flora when used in skincare products.
Lead author Dr Mark Shepherd, Reader in Microbial Biochemistry at Kent said: 'Plants have been a source of natural medicines for millennia, and now contemporary research approaches can reveal the mechanisms of action. This is an exciting time, and we hope to further our understanding of natural antimicrobials from plants, nature's great chemical factories.'
The article (University of Kent: Samantha A. Henry, Geraud N. Sansom, Ryan A. Boughton, Guy Joiner, Calum M. Webster, Michelle D. Garrett, Gary K. Robinson and Mark Shepherd) is available at https://doi.org/10.1039/d5md01116g
