Browsing by Author "Kinyua, J."

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    In vivo antimalarial and acute toxicity properties of hexane and chloroform extracts from Clausena anisata (Willd.) Benth
    (2012) Irungu, Beatrice N.; Mbabu, Murungi J.; Kiboi, Daniel M.; Moindi, Enock; Kinyua, J.; Mwirichia, Romano K.
    Background: Drugs are an important tool for control of malaria. However, drug resistance is likely to compromise available antimalarial drugs with time. As a result, efforts are being directed towards discovery and development of novel and affordable malaria drug molecules including those from medicinal plants. Objectives: To investigate suppressive, curative, prophylactic and acute toxicity properties of hexane and chloroform extracts of Clausena anisata against murine malaria. Method: Activity of the extracts was tested against Plasmodium berghei ANKA strain. Extracts were administered orally to mice (n=5) at 500, 250 and 100 mg/kg/day. Median lethal dose was evaluated after oral administration of the extracts in doses ranging from 500 to 5000 mg/kg. Results: 500 mg/kg/day of the chloroform extract exhibited 66.1% and 73.4% parasite reduction in the prophylactic and suppressive tests, respectively, while the same dose of the hexane extract comparatively lower suppressive and prophylactic properties (56.7% and 30.7 %, respectively). In the curative test, 500 mg/kg/day of the chloroform and the hexane extracts resulted in mean survival times (MST) of 12.3 days and 9.3 days, respectively. No mortality was observed in mice that received the hexane extract, whereas the LD50 of mice that received the chloroform extract was 4166.7 mg/kg. These results suggest that the chloroform extract at 500 mg/kg/day had notable in vivo antimalarial activity and partly explain therapeutic efficacy claimed for this plant in traditional medicine.
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    Isolation and characterization of bacillus species from soil in Ngere tea catchment area of Murang’a county, Kenya
    (2014-07) Wafula, Eliud N.; Kinyua, J.; Karuiki, D.; Muigai, A.; Mwirichia, Romano K.
    Bacteria are a very diverse group of organisms in soil, and major taxonomic groups are represented in most soils. The extent of the diversity of microorganisms in soil is seen to be critical to the maintenance of soil health and quality, since a wide range of bacteria are involved in the important soil functions. The objectives of this study were to isolate, characterise and identify groups of bacteria from Bacillus species that are associated with soil quality in tea growing areas of Ngere. 10 isolates were obtained using dilute nutrient broth agar and the bacterial morphology was identified as gram-positive rod-shaped bacteria, they grew well at pH ranging from 5 6.5 and temperature range of 25o C 35o C. Based on different biochemical tests and sequence of 16S rDNA, the isolated bacteria were identified as belonging to genus Bacillus. Phylogenetic analysis of isolates D61, D19, and, D51, suggested that they were closely related to Bacillus cereus with 89-96% rDNA sequence analysis similarity while isolates D5, D16, S31, D70 and D2 were closely related to Bacillus thuringiensis with 83% - 96% rDNA sequence analysis similarity. Isolate S30 was closely related to Bacillus subtilis with 99% rDNA sequence analysis similarity and isolate D29 was closely related to Bacillus mycoides with 97% rDNA sequence analysis similarity. Given the low similarity values some isolates had to their closest relatives, chances are high that Ngere tea catchment area harbours a diverse population of as yet, uncultured and uncharacterized microbes.