RUDN microbiologists obtained antimicrobial drugs from the bark of an African tree

For the first time, microbiologists from RUDN University have fully studied the composition of Enantia chlorantha bark extract, an African tree which is used in folk medicine in Cameroon and some other African countries. Moreover, with the help of the extract and using an eco-friendly, one-step and cost-effective method, they obtained silver nanoparticles with desirable characteristics. Both dried ethanolic extract and silver nanoparticles obtained were found to be effective broad-spectrum antimicrobial agents. The results are published in Fermentation.

Enantia chloranta, also known as yellow wood, is an African tree used in folk medicine for the treatment of various infections such as malaria, typhoid fever, jaundice, and dysentery. This plant mainly grows in Cameroon and other countries in central and west Africa. So far despite its use, data on its full chemical composition was lacking and very few investigations have been made in this direction. RUDN University microbiologists noticed that the bark of the plant abounds in alkaloids, among which the major constituents were palmatine, columbamine, jatrorrhizine, and pseudocolumbamine. They also found that E. chlorantha can become an environmentally friendly source of silver nanoparticles with noteworthy antimicrobial properties.

“In recent years, interest in silver nanoparticles has increased. They are used in various fields, including medicine, drug delivery, food, and healthcare, and for consumer and industrial purposes, due to their unique physical and chemical properties. The synthesis of silver nanoparticles is usually carried out chemically or using microwave processing, electron irradiation, lasers. However, these methods are increasingly being replaced by more environmentally friendly approaches. Nanosilver can be obtained using microorganisms, enzymes, and plant extracts. However, to our knowledge, no study had yet used E. chlorantha in nanotechnology.” — Mbarga Joseph Arsene, Lecturer-assistant and researcher in the Department of Microbiology V.S. Kiktenko, RUDN University.

Microbiologists used freshly harvested E. chlorantha bark. The plant material was dried at room temperature for 7 days and then sent to the laboratory. There, after an extraction procedure, the dried extract was obtained, and the composition was investigated. Also, with the help of the extract from the bark and a solution of silver nitrate, the microbiologists from RUDN University obtained silver nanoparticles. The effect of the obtained substances was tested against 22 types of bacteria and 2 fungi.

The bark extract in different concentrations was able to destroy 20 (out of 24) types of microorganisms, including Staphylococcus aureus, Escherichia coli and Candida albicans. Silver nanoparticles obtained using the extract was found to be effective against all studied microorganisms with approximately the same efficiency.

“For the first time, we have optimized the extraction of phytochemicals from the bark of E. chlorantha, studied the composition, and carried out a green synthesis of silver nanoparticles. Our results provide a solid experimental baseline to consider the E. chlorantha bark and its green synthesized as powerful antimicrobial compounds. This is especially important given the growth of resistance to antimicrobials,” Mbarga Joseph Arsene, Lecturer-assistant and researcher in the Department of Microbiology V.S. Kiktenko, RUDN University.