Traditional Kenyan herbal medicine: exploring natural products' therapeutics against schistosomiasis.

Praziquantel (PZQ) remains the only drug of choice for the treatment of schistosomiasis, caused by parasitic flatworms. The widespread use of PZQ in schistosomiasis endemic areas for about four decades raises concerns about the emergence of resistance of Schistosoma spp. to PZQ under drug selection pressure. This reinforces the urgency in finding alternative therapeutic options that could replace or complement PZQ. We explored the potential of medicinal plants commonly used by indigenes in Kenya for the treatment of various ailments including malaria, pneumonia, and diarrhoea for their antischistosomal properties. Employing the Soxhlet extraction method with different solvents, seven medicinal plants Artemisia annua, Ajuga remota, Bredilia micranta, Cordia africana, Physalis peruviana, Prunus africana and Senna didymobotrya were extracted. Qualitative phytochemical screening was performed to determine the presence of various phytochemicals in the plant extracts. Extracts were tested against Schistosoma mansoni newly transformed schistosomula (NTS) and adult worms and the schistosomicidal activity was determined by using the adenosine triphosphate quantitation assay. Phytochemical analysis of the extracts showed different classes of compounds such as alkaloids, tannins, terpenes, etc., in plant extracts active against S. mansoni worms. Seven extracts out of 22 resulted in <20% viability against NTS in 24 h at 100 µg/ml. Five of the extracts with inhibitory activity against NTS showed >69.7% and ≥72.4% reduction in viability against adult worms after exposure for 24 and 48 h, respectively. This study provides encouraging preliminary evidence that extracts of Kenyan medicinal plants deserve further study as potential alternative therapeutics that may form the basis for the development of the new treatments for schistosomiasis.

In vitro activities of Maesa lanceolata extracts against fungal plant pathogens.

In vitro tests were carried out using extracts of Maesa lanceolata var. goulungensis weir against a broad range of fungal plant pathogens such as Phytophthora cryptogea, Trichoderma virens, Aspergillus niger, Phoma sp., Fusarium oxysporium, Pythium ultimum, Cochliobolus heterostrophus, Rhizoctonia solani, Sclerotium rolfsii and Pyrenophora teres. M. lanceolata extracts were very active against all the pathogens tested except P. ultimum and R. solani.

Methanolic extracts of Aloe secundiflora Engl. inhibits in vitro growth of tuberculosis and diarrhea-causing bacteria.

BACKGROUND: The emergence of resistance to antimicrobials by pathogens has reached crisis levels, calling for identification of alternative means to combat diseases. OBJECTIVE: To determine antimicrobial activity of crude methanolic extract of Aloe secundiflora Engl. from Lake Victoria region of Kenya. MATERIALS AND METHODS: Extract was tested against four strains of mycobacteria (Mycobacterium tuberculosis, M. kansasii, M. fortuitum and M. smegmatis), Salmonella typhi, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and a fungus Candida albicans. activity of the extract was determined using BACTEC(™) MGIT(™) 960 system. General antibacterial and antifungal activity was determined using standard procedures: zones of inhibition, Minimum Inhibitory Concentrations (MICs) and Minimum Bactericidal/Fungicidal Concentrations (MBCs/MFCs). RESULTS: The extract was potent against M. fortuitum, M. smegmatis and M. kansasii where it completely inhibited growth (Zero growth units (GUs)) in all the extract concentrations used. It gave strong antimycobacterial activity (157 GUs) against M. tuberculosis. It showed strong antimicrobial activity (P≤0.05), giving inhibition zones ≥9.00 mm against most microorganisms, such as P. aeruginosa (MIC 9.375 mg mL(-1) and MBC of 18.75 mg mL(-1)), E. coli (both MIC and MBC of 18.75 mg mL(-1)), S. aureus and S. typhi (both with MIC and MBC of 37.5 mg mL(-1)). Preliminary phytochemistry revealed presence of terpenoids, flavonoids and tannins. CONCLUSION: The data suggests that Aloe secundiflora could be a rich source of antimicrobial agents. The result gives scientific backing to its use by the local people of Lake Victoria region of Kenya, in the management of conditions associated with the tested microorganisms.

Antifungal, antibacterial and antimycobacterial activity of Entada abysinnica Steudel ex A. Rich (Fabaceae) methanol extract.

The purpose of the study was to investigate the antifungal, antibacterial and antimycobacterial properties of methanol extract of Entada abysinnica steudel ex. A. Rich (Fabaceae) leaves used by herbalists from the Lake Victoria region, Kenya. The extract was tested against four strains of mycobacteria (Mycobacterium tuberculosis, Mycobacterium kansasii, Mycobacterium fortuitum, and Mycobacterium smegmatis) using BACTEC Mycobacteria Growth Indicator Tube (MGIT) 960 system and the proportional method. Standard procedures were used to determine the zones of inhibition, minimum inhibitory concentrations (MICs) and minimum bactericidal/fungicidal concentrations (MBCs/MFCs) for Candida albicans, Salmonella typhi, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae. The extract showed activity against some mycobacteria strains, especially M. tuberculosis. It also showed strong antimicrobial activity (zones of inhibition were between 9.00 and 14.10 mm) against C. albicans, Sa. typhi, and St. aureus. The extract gave a better zone of inhibition against C. albicans than fluconazole whose zone of inhibition was 13.00 mm. The MICs and MBCs for C. albicans and Sa. typhi were good. The crude extracts were also analyzed for the presence of phytochemicals. Phytochemical screening indicated that the extract most abundantly contained tannins, saponins, and flavonoids. The data suggest that the methanolic leaves extract of E. abysinnica could be a rich source of antimicrobial agents, especially antifungals. The results further show that there is some merit in the use of the plant in alternative medical practices. However, bioassays of isolated compounds are underway and will be reported during subsequent communications.

Antibacterial activity of Tabernaemontana stapfiana britten (Apocynaceae) extracts.

Antibacterial and phytochemical screening of methanolic, sequential extracts (hexane, dichloromethane, ethyl acetate and methanol) and alkaloid rich fractions of Tabernaemontana stapfiana Britten was carried out. The phytochemical screening showed the presence of alkaloids, flavonoids, coumarins, tannins and saponins that have been associated with antimicrobial activity. The stem and root bark methanolic extracts showed good activity against the bacterial strains used including the multiple drug resistant Staphylococcus aureus strain with minimum inhibitory concentrations ranging from 15.6 to 500 microg/ml and minimum bactericidal concentrations ranging from 31.25 to 500 microg/ml. The sequential extracts of the root and stem bark had high antimicrobial activity with minimum inhibitory concentrations (MICs) ranging between 3.9 and 250 microg/ml and minimum bactericidal concentrations (MBCs) ranging between 7.8 and 500 microg/ml against the tested microorganisms. The dichloromethane extract of the alkaloid rich fractions however exhibited reduced antibacterial activities as compared to methanol and sequential extracts but the dichloromethane:methanol (4:1) mixture showed high activity with MICs ranging between 15.6 and 250 microg/ml. These antibacterial efficacy studies suggest that Tabernaemontana stapfiana Britten could be a source of antibacterial agents.