Phytochemical screening of plant species known to have anti-tuberculosis properties in Mbujimayi (DR Congo)

Background: Tuberculosis (TB) is a serious public health problem in the Democratic Republic of Congo (DRC) and worldwide. However, the lack of appropriate treatment and poverty are driving the population of Mbujimayi to resort to traditional medicine, which uses medicinal plants. Objective: This study aimed to identify groups of bioactive substances with therapeutic properties present in plant species known to be effective against tuberculosis in Mbujimayi. Methods: Extracts from samples of plant species known to have anti-tuberculosis properties were subjected to semi-quantitative identification tests using precipitation reactions to detect the presence of alkaloids, foaming reactions to identify saponins, and color change reactions to characterize anthocyanins, flavonoids, quinones, steroids, catechin tannins, gallic tannins, terpenoids, and cyanogenic glycosides. Results: A total of 1,330 chemical screening tests were performed on 133 samples, including 47 leaves, 20 roots, 20 stems, 19 stem barks, 18 root barks, and 9 whole plants, from 56 well-identified plant species including 718 positive tests (53.9%). The plant species analyzed contain at least three groups of the bioactive substances sought. All nine groups of substances were identified in the following six species: Antidesma meiocarpum, Catharanthus roseus, Coleus hybridus, Gaertnera parvipaniculata, Tithonia diversifolia, and Treculia africana. Leaves are the organ that contains the highest number of bioactive substances, with 62.6% of positive tests. Terpenoids were found in all species analyzed, with 95.5% of tests positive overall, while alkaloids were the least abundant group, with 39.3% of positive tests. Conclusion: This study is the first chemical screening conducted on medicinal plants known to be effective against tuberculosis in Mbujimayi. It provides valuable insight into the phytochemistry of plant species used by traditional practitioners in their recipes for treating TB. Much further research is needed, for example, biological screening, bioguided fractionation, the isolation and characterization of compounds with anti-tuberculosis properties.