Anti-parasitic activities of some selected medicinal plants and marine algae in Ghana.
Neglected tropical diseases (NTDs) are a group of major chronic conditions that affects people in the poor regions of sub-Saharan Africa, Asia, Latin America and the Caribbean. Current medications have untoward side effects and the microorganisms responsible for these NTDs have grown resistant to some of these medicines. There is the need to get new medicines for the treatment of NTDs. Ghana as a country is biodiversitically rich in medicinal plants and marine flora. In this study, extracts, fractions of extracts and isolated compounds of some plants and marine algae (U. fasciata, S. vulgare and H. dentata) were screened against Giardia lamblia, Entamoeba histolytica, Trypanosoma brucei brucei, Schistosoma mansoni and Naegleria fowleri: N. fowleri, G. lamblia and E. histolytica were screened using the CellTitre Glo luminescent cell viability assay while T. b. brucei and Schistosoma mansoni (juvenile and adult stages) were, respectively screened using the SYBR-Green assay and phenotypic observation of physical changes of the worms. The ethanol extracts of the barks of A. glaberrima and M. angolensis, pet ether fraction of M. nobilis bark and ethyl acetate fraction of E. ivorense bark exhibited IC50s ranging between 13.76 and 44.25 μg/mL against G. lamblia. For N. fowleri, ethanol bark extract of A. glaberrima had IC50 of 38.70 μg/mL. The acetone and ethyl acetate fractions of the bark of E. ivorense, the aqueous leaf extract of P. muellerianus and the pet ether fraction of M. nobilis exhibited activity against T. b. brucei (IC50: 10.53 - 25.60 μg/mL). The ethyl acetate and acetone fractions of E. ivorense caused rounding of the schistosomulae at concentrations of 0.31 and 0.63 μg/mL respectively, whiles the adult worms were killed at 1.25 μg/mL (both fractions) within 48 h. Among the algae studied, only U. fasciata showed inhibitory activity against G. lamblia (IC50 of 35.86 μg/mL). None of the plant extracts and fractions exhibited activity against E. histolytica. However, xylopic acid and geraniin inhibited E. histolytica with IC50s of 4.80 and 34.71 μg/mL iv respectively. Xylopic acid also exhibited anti-parasitic activity against G. lamblia (IC50 of 11.45), T. b. brucei (IC50 of 13.42) and N. fowleri (IC50 of 16.06 μg/mL). Geraniin as well showed inhibitory activity against T. b. brucei (IC50 of 6. 41 μg/mL). Phytochemical screening of the algae revealed the presence of saponins, tannins and alkaloids in all the three species. H. dentata and S. vulgare also possessed glycosides and flavonoids while sterols were present in H. dentata and U. fasciata. The plant extracts and compounds exhibited activity against the parasites tested and hence the use of these medicinal plants in the treatment of the studied parasitic infections may be justified.
A thesis submitted to the Department of Pharmaceutics, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health Science, KNUST in fulfillment of the requirements for the degree of Master of Philosophy (Pharmaceutical Microbiology),