Medicinal chemistry in Djibouti
Located in the Horn of Africa, bordering Ethiopia, Somalia, and Eritrea, in front of the Gulf of Aden and the Red Sea, the Republic of Djibouti (or simply Djibouti) is the third-smallest country in mainland Africa. With a dry climate and hot temperatures, which may reach 45 ºC, Djibouti is a biodiversity hotspot, serving as a habitat for more than 1,500 animal and 800 plant species.
It is also a country where science and scientific research are steadily growing. Mohamed Ahmed Said, an outstanding chemist with the Medical Research Institute at the Djibouti Study and Research Center (Centre d'Etude et de Recherche de Djibouti), received a TWAS research grant that aided his research to enhance the activity of natural substances with therapeutic properties. He is first-ever TWAS grantee from Djibouti.
"The UNESCO-TWAS research grant was a booster to my career," acknowledged Ahmed Said, who earned his PhD in chemistry in 2016 from the University of Franche-Comté in Besançon, France, before returning home. "With the grant, I was able to develop my original idea and initiate a new research topic within the Institute for Medical Research."
Ahmed Said chose chemistry because he was fascinated by the way molecules combine and react mutually. Initially, he focused on organic chemistry as a tool to learn how to synthesize molecules of potential value to research. However, soon he turned to modification of natural chemical substances, to merge the two fields.
"Djibouti is rich in plant varieties, many of which belong to the traditional healthcare system of this country," he observed. "However, for many of them, very few scientific studies have been carried out. We know that they have [or might have] some therapeutic properties, but for many of them more detailed studies would be useful, to implement their curative activity."
This consideration led Ahmed Said to develop an interest in natural substances, to improve their biological activities, referring to local traditional medicine. This field of investigation is called medicinal chemistry and aims to integrate traditional and indigenous knowledge with modern scientific methods.
Moving from traditional usage of plants as medicine to research on a plant’s medically relevant molecule, however, requires a great effort. One must locate or cultivate the plant, wait for it to mature, and harvest its flowers or fruits. After the harvest arrives in a laboratory, scientists proceed with the extraction, a process that is typically expensive and time-consuming, Ahmed Said explained.
"I started preliminary studies to assess the feasibility of carrying out the hemisynthesis of natural substances, which is a new axis of research within the Institute of Medicinal Research," he added. Hemisynthesis is the chemical synthesis of a new compound using an existing natural one as the starting material. "Through this process, we can improve the biological activity of a compound."
It is extremely difficult to acquire and isolate small quantities of natural substances from a plant that is rare or difficult to access. This is why the synthesis process is indispensable, Ahmed Said added. Synthetic substances are produced faster, in greater quantity and are identical to those existing in nature, with exactly the same properties.
Traditional Djiboutian medicine uses a number of plants for medicinal purposes, and Ahmed Said focused on some of them: with colleagues, they obtained extracts containing molecules that he will further modify for therapeutic purposes.
For example, he is currently working on extracts from Avicennia marina, commonly known as grey or white mangrove, a species that likes high salt soils and that has antioxidant and antibacterial activity. Avicennia marina is one of the four species of mangrove growing in Djibouti; the other three have not been researched as thoroughly. "I will continue to study the three other species of mangrove plants growing locally; I believe that they should all be made more valuable for their medicinal properties," Ahmed Said.
In another research, the scientist synthesized organometallic compounds with effects the fight breast and prostate cancer. These compounds will be further evaluated in tests in lab equipment to confirm that they can be considered for preliminary tests in living organisms.
Even during the havoc of the COVID-19 pandemic, Dr. Ahmed Said and his colleagues were able to find positive uses for local plants. The need to fight the viral infection spurred new research with promising outcomes: "We chose three Djiboutian medicinal plants—Acacia seyal, Cymbopogon commutatus, and Indigofera caerulea—whose anti-SARS-Cov 2 efficacy were previously evaluated through in silico tests. We found that they have inhibitory activity towards SARS-Cov 2 infections. Subsequently, we could also improve the activity of these substances by modifying their basic structure," explained Ahmed Said.
"The optimization of the synthesis and the hemisynthesis of natural substances are very useful in the medicinal and pharmaceutical fields, and allow the scaling-up of interesting molecules, with lower costs than those of the extraction procedure," he concluded.
Ahmed Said's short-term plans are aligned with his early successful results. As the founder of medicinal chemistry in Djibouti, he hopes to create an accomplished and competitive research group that is highly regarded internationally.