Phytochemical screening, Antimycobacterial activity of three medicinal Cameroonians plants and Acute toxicity of hydroethanolic extract of Vitellaria paradoxa

Tuberculosis (TB) is an infectious disease caused by the Mycobacterium tuberculosis (M. tuberculosis) complex, resposible  for health problems in developing countries. In Africa, various medicinal plants are traditionally used to treat  TB.  The aim of this study is to carry out the phytochemical screening, to evaluate the antimycobacterial activity of the crude extracts of three medicinal plants present in Cameroon (Zingiber officinale, Vitellaria paradoxa and Alstonia boonei) and the acute toxicity of hydroethanolic extract of Vitellaria paradoxa. The phytochemical screening was obtained by hydroethanolic extraction  and decoction. Inhibitory parameters of antimycobacterial activities were determined using the microplate alamar blue assay against M. tuberculosis H37Rv (ATCC 27294) and on one M. tuberculosis clinical strain. The crude extract with the best antimycobacterial activity was used for the acute toxicity assessment according to the OECD protocol. The results of the phytochemical screening revealed the presence of triterpenes and steroids in all the extracts, whereas  phenols were only present in the decoction of Alstonia boonei. All extracts tested showed antimycobacterial activities. The hydroethanolic extract of V. paradoxa  presented the best antimycobacterial activity with MICs of 78.13 and 625 μg/mL and MBCs of 78.13 and 2500 μg/mL respectively on M. tuberculosis H37Rv and on M. tuberculosis clinical strain. The results of the acute toxicity evaluation of V. paradoxa  showed a lethal dose 50  greater than 5000 mg/kg compared to control. The antimycobacterial activity of all the plant extracts used in this study justifies the traditional use of these medicinal plants on the treatment of  TB. Keywords: Zingiber officinale, Vitellaria paradoxa, Alstonia boonei, Phytochemical screening, Antimycobacterial activity, Acute toxicity

Mycobacterium tuberculosis lineage 4 comprises globally distributed and geographically restricted sublineages

Generalist and specialist species differ in the breadth of their ecological niches. Little is known about the niche width of obligate human pathogens. Here we analyzed a global collection of Mycobacterium tuberculosis lineage 4 clinical isolates, the most geographically widespread cause of human tuberculosis. We show that lineage 4 comprises globally distributed and geographically restricted sublineages, suggesting a distinction between generalists and specialists. Population genomic analyses showed that, whereas the majority of human T cell epitopes were conserved in all sublineages, the proportion of variable epitopes was higher in generalists. Our data further support a European origin for the most common generalist sublineage. Hence, the global success of lineage 4 reflects distinct strategies adopted by different sublineages and the influence of human migration.We thank S. Lecher, S. Li and J. Zallet for technical support. Calculations were performed at the sciCORE scientific computing core facility at the University of Basel. This work was supported by the Swiss National Science Foundation (grants 310030_166687 (S.G.) and 320030_153442 (M.E.) and Swiss HIV Cohort Study grant 740 to L.F.), the European Research Council (309540-EVODRTB to S.G.), TB-PAN-NET (FP7-223681 to S.N.), PathoNgenTrace projects (FP7-278864-2 to S.N.), SystemsX.ch (S.G.), the German Center for Infection Research (DZIF; S.N.), the Novartis Foundation (S.G.), the Natural Science Foundation of China (91631301 to Q.G.), and the National Institute of Allergy and Infectious Diseases (5U01-AI069924-05) of the US National Institutes of Health (M.E.)

Comparison of in vitro antioxidant properties of extracts from three plants used for medical purpose in Cameroon: Acalypha racemosa, Garcinia lucida and Hymenocardia lyrata

Objective: To investigate the in vitro antiradical and antioxidant properties of methanol extracts of Garcinia lucida, Hymenocardia lyrata (H. lyrata) and Acalypha racemosa. Methods: We determined the in vitro antioxidant activity and the total phenolic content, and performed the phytochemical screening of the extracts from fruits, barks, leaves, roots and stems of these plants using standard procedures. Results: The results of the antioxidant properties showed that more than 60% of DPPH., NO. and HO. radicals were inhibited by the extracts. The radical scavenging activity, the total antioxidant capacity as well as the reducing power increased with the concentration of the extracts. The 50% inhibitory concentration (IC50) varied from 1.46 to 21.65 μg/mL depending of the type of extract and the antioxidant tests. The results indicated that all the extracts exhibited antioxidant properties and the roots of H. lyrata showed the best antioxidant activity [(217.17±9.45) mg Equivalent catechin/g of extract] while the highest total phenol content was found in its barks [(169.782±3.025) mg Eq cat/g of extract]. Conclusions: The methanol extract of H. lyrata possess the most antioxidant property among the three extracts

In Vitro Assessment of Anthelmintic Activities of Rauwolfia vomitoria (Apocynaceae) Stem Bark and Roots against Parasitic Stages of Schistosoma mansoni and Cytotoxic Study

Schistosomiasis is a Neglected Tropical Diseases which can be prevented with mass deworming chemotherapy. The reliance on a single drug, praziquantel, is a motivation for the search of novel antischistosomal compounds. This study investigated the anthelmintic activity of the stem bark and roots of Rauwolfia vomitoria against two life stages of Schistosoma mansoni. Both plant parts were found to be active against cercariae and adult worms. Within 2 h of exposure all cercariae were killed at a concentration range of 62.5–1000 µg/mL and 250–1000 µg/mL of R. vomitoria stem bark and roots, respectively. The LC50 values determined for the stem bark after 1 and 2 h of exposure were 207.4 and 61.18 µg/mL, respectively. All adult worms exposed to the concentrations range of 250–1000 µg/mL for both plant parts died within 120 h of incubation. The cytotoxic effects against HepG2 and Chang liver cell assessed using MTT assay method indicated that both plant extracts which were inhibitory to the proliferation of cell lines with IC50 > 20 μg/mL appear to be safe. This report provides the first evidence of in vitro schistosomicidal potency of R. vomitoria with the stem bark being moderately, but relatively, more active and selective against schistosome parasites. This suggests the presence of promising medicinal constituent(s)