PHD-School of Health Sciences
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This collections contains bibliographic information and abstracts of PHD theses and dissertation in the School of Health Sciences held in Kenyatta University Library
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Browsing PHD-School of Health Sciences by Author "Gikonyo, Nicholas K."
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Item Efficacy of Crude Extracts from Allium Sativum, Callistemon Citrinus and Moringa Stenopetala of Kenya against Leishmania Major(2014-02-22) Kinuthia, Geoffrey Kariuki; Kabiru, Ephantus W.; Gikonyo, Nicholas K.; Anjili, C. O.Cutaneous leishmaniasis (CL) is endemic in more than 80 countries worldwide and it causes skin ulcers and disfigurement. Leishmania major causes CL in Kenya and its drugs are expensive, toxic and require prolonged use. Multidrug combination therapy prevents drug resistance and reduces toxicity. Herbal extracts can be safe and cheaper. This study investigated in vitro and in vivo efficacy of single and blends of crude aqueous and methanolic extracts from Moringa stenopetala, Callistemon citrinus, and Allium sativum against L. major. Controls were contemporary Leishmania drugs pentostam and liposomal amphotericin B, and phosphate buffered saline. Dry ground test materials were soaked in H2O at 70oC for 1½ hours, filtered, and freeze dried. Similarly, ground test materials were soaked in 500 ml of analytical grade methanol for 72 hours at room temperature, filtered and concentrated using rotary evaporator. T-test and ANOVA were used for data analysis. P-value of < 0.05 was considered significant. The minimum inhibitory concentrations (MICs) of aqueous extracts of M. stenopetala (A), C. citrinus (B), and A. sativum (C) ranged from 3 to 5mg/ml while IC50 from 297.79 to 575.75μg/ml against L. major promastigotes as compared to MICs of 12.50 and 6.25μg/ml and IC50 of 0.26 and 0.82μg/ml for pentostam and liposomal amphotericin B respectively. MICs of methanolic extracts of M. stenopetala (H), C. citrinus (G), and A. sativum (F) ranged from 1 to 5mg/ml with IC50 of 572.69 to 1752.92μg/ml against L. major promastigotes. The extracts’s cytotoxicity against vero cells ranged from 467.11 to 2105.93μg/ml as compared to 60.95μg/ml and 108.58μg/ml for pentostam and liposomal amphotericin B respectively. Methanolic extracts of C. citrinus and aqueous A. sativum extracts stimulated production of 20μM nitric oxide in BALB/c mice peritoneal macrophages signifying their immuno-modulatory role. Blends of M. stenopetala & C. citrinus (AB), M. stenopetala & A. sativum (AC) and C. citrinus & A. sativum (BC) at concentrations based on MICs of individual extracts, were active at ratios 1:1, 1:9 and 1:1 with promastigotes’ viabilities of 33.82%, 17.41% and 60.74 % respectively. The ratios and promastigotes viabilities for methanolic blends were, FG (1:1; 31.32%), FH (1:9; 34.59%) and GH (9:1; 7.44%). The IC50 for any blends of two extracts ranged from 174μg/ml to 1314μg/ml against L. major promastigotes. There was strong synergistic (1:9) and additive (1:1 and 2:8) interactions for the blend AC. Blend BC interacted additively at ratio 1:1. Blend AC at 125μg/ml had infection rate (IR) of 71% and multiplication index (MI) of 48.20% for L. major amastigotes in vitro, and compared well to pentostam at 12.50μg/ml with IR of 67% and MI of 47.51%. Methanolic blends of three different extracts were more efficacious with MIs of 33.48 to 38.24%. Oral aqueous and methanolic A. sativum extracts (A and F) reduced the foot pad lesion sizes significantly (P < 0.05) in infected BALB/c mice. Oral blend BC reduced the footpad lesion size significantly (P < 0.05) like Leishmania control drugs. Oral blends BC and AC reduced spleen amastigotes in mice by 48.33% and 60.94% corresponding to total LDUs of 6.35±0.66 and 4.80±0.95 respectively. Oral/ip blend HGF (2:2:1) had amastigotes inhibition rate of 63.95% compared to 66.40% and 60.62% for pentostam and liposomal amphotericin B respectively. In conclusion, aqueous and methanolic crude extracts of C. citrinus, A. sativum and M. stenopetala were less toxic but active against L. major in vitro and in vivo and their blends that had additive or synergistic interaction lowered L. major survival. This study recommends that Kenyatta University in collaboration with relevant stakeholders to consider developing natural products based on these results for the management of CL in poverty stricken leishmaniases endemic areas of Kenya.Item Safety and Antimicrobial Activities of Herbal Materials used in Management of Oral Health by Traditional Medical Practitioners in Nairobi County, Kenya(2014-02-26) Waiganjo, Florence Wanja; Gikonyo, Nicholas K.; Wanjau, R. N.The use of herbs for treatment and management of oral diseases is practiced in the developing countries including Kenya. The herbs are used in form of powders, pastes, saps, chewing sticks and seeds. They are sold in Nairobi along streets and open markets with claims of healing all oral diseases. However, safety issues in terms of microbial contaminants, levels of mineral elements profiles, toxicity, phytochemical composition and antimicrobial properties of the herbal materials in the market have not been evaluated. The aim of the study was to evaluate safety aspects and antimicrobial properties of herbal materials used in oral health care in Nairobi. Documentation of herbal materials was carried out by interviewing 60 herbalists using a questionnaire and through informal discussions. Investigation of safety and antimicrobial properties was carried out on 23 herbal products purchased from the herbalists. Evaluation of microbial contaminants was carried out as described by World Health Organisation. Samples were inoculated in enrichment culture medium, then subculturing in selective media, followed by microscopy and biochemical test to confirm the identity of the microbes. Elemental analysis was evaluated by use of Total X-ray Fluorescence Technique. Qualitative phytochemical constituents of herbal materials were investigated using standard methods. The antimicrobial properties were studied using disc and agar well diffusion method. Toxicity effects of herbal materials was investigated by administering 1000 mg/kg body weight of seven herbal material extracts and 3 herbal pastes on mice for twenty one days, and then biochemical, haematological parameters, relative organ weight and their histopathological changes were evaluated. Results indicated that 35 plant species were used in preparation of herbal products for management of oral conditions. Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Candida albicans were isolated in some of the products. High levels of aluminium, phosphorous, potassium, calcium, vanadium, chromium, manganese, iron, nickel, copper, zinc, strontium and lead were observed. Major phytochemical groups were recorded in herbal powders. However, pastes and liquids lacked detectable levels of major phytochemical groups. Antimicrobial properties were reported in 78% of the herbal materials. Mortality was reported in mice treated with herbal materials of Warbugia ugandensis, Zantoxyllum chalybeum and Senna didymobotrya. The extracts of Euclea divinorum and herbal mixtures of Warbugia ugandensis, Z. chalybeum and Terminalia brownii showed retarded growth in mice and hypertrophy of liver and brain. There was significant (P>0.05) alteration of the red blood cells and neutrophils, creatine, alanine aminotransferase and thrombocytes of animals treated with some herbal extracts while severe pathological conditions on vital organs of mice was seen. The toxic effects could be due to presence of heavy metal due to poor handling by herbalists. Most of the products in the market did not meet the WHO standards. These findings may be used to sensitise the Traditional Medical Practitioners, policy makers and consumers on the safety issues and lack of antimicrobial activities in some products. This study recommends that full evaluation of safety and antimicrobial properties of herbal materials be carried out before they are released to the market. .