Aims: The Samburu are a marginalized nomadic people in Kenya who have no access to conventional medical services thus they mainly depend on the medicinal plants for most of their medicare. Antimicrobial activity of the commonly used medicinal plant (Plumbago dawei Rolfe.) by the Samburu community was investigated to verify claims by locals of its medicinal properties. Methodology and results: The antimicrobial bioassays of the methanol extracts of P. dawei Rolfe was carried out by the disc diffusion method against Staphylococcus aureus ATCC 20591, Bacillus subtilis local isolate, Salmonella typhi ATCC 2202, Escherichia coli STD-25922 and Pseudomonas aeruginosa ATCC 25852. By use of the micro dilution method MICs and MBCs were also determined. Preliminary phytochemical screening was done on the extracts. The methanol extracts were highly active against all the test strains. The inhibitory zones ranged from 16-25.66 mm. The zones of inhibition were not significantly different except for the E. coli (16.33 mm) at p< 0.05. The extract showed strong MIC and MBC against S. typhi, S. aureus, E. coli and P. aeruginosa (MIC = 9.38 mg/mL and MBC = 9.38mg/mL). Thus the extract was more of bactericidal than bacteriostatic in most test strains. Preliminary phytochemistry revealed presence of flavonoids, tannins and cardiac glycosides. Conclusion significance and impact of study: The data suggests that methanolic extracts of P. dawei could be a rich source of antimicrobial agents. These results give scientific backing for the use of the P. dawei Rolfe, barks by the Samburu in the treatment of conditions associated with diarrhea and other associated infections caused by the test organisms.

Aims:The anti-bacterial effect of some selected Samburu medicinal plants were evaluated on bacterial strains like Staphylococcus aureus-ATCC 20591, Bacillus subtillis-local isolate, Salmonella typhi-ATCC 2202, Escherichia coli-STD- 25922 and Pseudomonas aeruginosa-ATCC 25852. Methodology and Results: Methanol was used as an extraction solvent for the medicinal plants after they had been ried and ground using the laboratory grinding miller. The in vitro anti-bacterial activity was performed by agar disc diffusion method. The significant anti-microbial activity of active extracts was compared with the standard antibiotics, cefrodoxima and amoxicillin. These results were significant at p < 0.01. The MICs were also determined by the micro titre-plate method. The MICs of the most active plants ranged from 18.75 mg/mL to 37.5 mg/mL. The MBCs ranged between 18.75 mg/mL to 37.5 mg/mL. The most active plant that had substantial activity in at least all the test cultures was found to be Lannea triphylla (A.Rich) Engl. A number of phytochemicals were also found to be present with tannins being the most abundant followed by flavonoids and saponins. Conclusion, significance and impact of study: The findings show that most of the medicinal plants used by the Samburu community have some significant activity on the bacterial isolates known to cause diarrhoea.

Aims: The study aimed at determining the antimicrobial activities and cytotoxicity properties of medicinal plants collected from southwestern Kenya. Methods and results: A total of 23 ethanol extracts of selected medicinal plants were bio-assayed against Gramnegative bacterial strains (Escherichia coli NU14, Helicobacter pylori ATCC 700824, and Porphyromonas gingivalis ATCC 33277). Cytotoxicity tests were also carried out on mammalian cell lines (AGS, KB, and TR146). Preliminary type of phytochemical compounds present in the extracts was determined by thin-layer chromatography. Cassia didymobotrya plant extract (1 mg/mL) had strong antimicrobial activity against P. gingivalis (average zone of inhibition of 21.70 ± 0.88 mm, MIC 0.13 ± 0.00 mg/mL and MBC 0.50 ± 0.00 mg/mL). Escherichia coli was resistant to all the extracts bioassayed. Leonotis nepetifolia (15.80 ± 0.20 mm) and Clerodendrum myriacoides (14.20 ± 0.44 mm) showed only moderate activity against H. pylori. Cell cytotoxicity results indicated a dose-dependent response against KB, TR146 and AGS cell lines with C. didymobotrya having IC50 values of 47.64 and 704.00 µg/mL on KB and TR146 cell lines, respectively. L. nepetifolia and C. myriacoides did produce IC50 of 0.1883 mg/mL and 0.1061 mg/mL against the AGS cell line respectively. Conclusion, significance and impact of the study Most of the extracts had no or weak activity against test isolates, but C. didymobotrya leaves extracts showed strong activity against P. gingivalis. C. didymobotrya can offer alternative medicare to P. gingivalis conditions.
Plants, Medicinal--adverse effects ; Kenya (Southwestern)