Ndile, Michael Musila2025-08-292025-08-292025-04https://ir-library.ku.ac.ke/handle/123456789/31307A thesis submitted in fulfillment of the requirements for the award of the degree of Doctor of Philosophy (Medical Biochemistry) in the School of Pure and Applied Sciences of Kenyatta University April, 2025 Supervision: Prof. Mathew Piero Ngugi Dr. Wycliffe Arika Makori Dr. Cromwell Mwiti Kibiti.Diabetes mellitus is a longstanding endocrine condition that results in high blood glucose than normal. It leads to various health problems including retinopathy, nephropathy, nerve damage, gum disease, cardiovascular diseases and premature death. While lifestyle changes are often recommended in managing diabetes, conventional medications are prescribed to correct hyperglycaemia. However, they are marked with adverse effects and reduced effectiveness. Herbal remedies are often used as an alternative owing to their effectiveness, biodegradability, widespread availability, and arguably low cost. The medicinal plant X. spekei is used among Embu and Mbeere communities to manage diabetes mellitus. However, there is limited information regarding its phytochemical profile, mineral elements composition, antioxidant potential, anti-diabetes activity and toxicity profiles. Hence, the purpose of this study was to investigate quantitative phytochemical and mineral elements composition, antioxidant activity, antidiabetic potential and safety profiles of the plant. Samples of the whole plant were collected from Nthawa location in Embu County, Kenya. Extraction was done using Dichloromethane (DCM). The quantitative analysis of phytochemicals was conducted using Gas Chromatography-Mass Spectrometry (GC-MS), and the detection of mineral elements was through Atomic Absorption Spectroscopy (AAS). The antioxidant activity was determined through various in vitro methods. To evaluate the efficacy of the extract in managing diabetes, a total of seven groups were formed, each consisting of five male mice. These groups included a normal control, diabetic control, positive control (administered with 3 mg/kg bw of Glibenclamide), and four extract-administered groups (50, 100, 150, and 200 mg/kg body weight). Alloxan monohydrate (186.9 mg/kg bw) was used to induce diabetes. The blood glucose in mice was determined on an hourly basis for the first six hours, and once after 12 and 24 hours on the first day. Thereafter, the blood glucose in mice was determined once a week for three weeks. During this period, the body weights of the mice were determined on the initial day and at seven-day intervals. After 21 days, the mice were euthanized, and blood samples were collected to assess changes in renal and liver functions. The liver, kidney, and pancreas were also detached and their homogenates were used for ex vivo antioxidant assays. Finally, toxicity studies were carried out following OECD Guidelines. The classes of phytochemicals identified using GC-MS included flavonoids, phenolic acids, phytosterols, terpenoids, fatty acids, tocopherols, and alkaloids. Among the phytochemicals, stigmasterol had the highest concentration (12.99 ± 2.56 mg/g), while phenol, 2,4-bis(1,1-dimethylethyl), had the least (0.30 ± 0.04 mg/l). The extract was also found to be rich in several essential mineral elements, with the most abundant being calcium (Ca, 148.1±8.62 mg/L), potassium (K, 25.55±2.48 mg/L), and magnesium (Mg, 15.2±1.47 mg/L). The DCM plant extract of X. spekei attenuated loss of body weight, hyperglycaemia, and aberrant biochemical parameters. Additionally, the extract reduced levels of malonaldehyde and enhanced the enzymatic antioxidant activities of CAT, GPX, and SOD in extract-treated mice compared to the diabetic control group (p < 0.01). In oral acute toxicity studies, the LD50 of the extract was beyond 2000 mg/kg. Furthermore, in the oral sub-acute toxicity test, the extract did not negatively affect the haematological parameters, nor the hepatic and renal biochemical markers in the treated mice, relative to the normal control group (p ˃ 0.01). The study confirms that the X. spekei extract contains phytochemicals and mineral elements with antioxidant and antidiabetic properties. These finding authenticates the folkloric use of X. spekei in managing diabetes mellitus and highlight its potential for the development of antidiabetic agents. However, further investigation is needed to isolate the active compounds and evaluate their antidiabetic efficacy.enThesis