Browsing by Author "Muyenga, Tumelo"

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    An investigation of the effect of Kigelia Africana fruit fractions on diabetes bio-markers in alloxan monohydrate induced diabetes Wistar rat models
    (University of Namibia, 2025) Muyenga, Tumelo; Bamitale, S.K.D.
    Diabetes affects 19 million people in Africa, with 60% of diabetic patients opting for traditional therapies due to cost-effectiveness, accessibility, and perceived safety. Kigelia africana (Bignoniaceae) is used as a traditional antidiabetic remedy, but data on the specific phytochemicals responsible for its benefits and safety are limited. This study investigated the antidiabetic properties of Kigelia africana fruit fractions and their effects on diabetes markers in alloxan-induced diabetic rats. The chemical composition of the bioactive fractions was determined, while cytotoxic and genotoxic effects of the crude extracts were also analysed. The antidiabetic effects of the Kigelia africana fruit extract were compared with those of glibenclamide in 54 alloxan-induced diabetic rats. Fractions were obtained using liquidliquid and column fractionation. The effects of Kigelia fractions on lipid profile, blood glucose, alanine aminotransferase, and creatinine levels were determined. Histopathological changes in the liver, kidneys, heart, brain, and pancreas were examined. In vitro bioactivity against alpha-amylase, alpha-glucosidase, glucose utility, and glucose uptake in Caco2 colorectal cells was determined for the bioactive ethyl acetate fraction. The phytochemical profile was obtained using Gas Chromatography-Mass Spectrometry (GC-MS). Total phenolic content, total flavonoid content, and free radical scavenging activity were determined. Mutagenicity and genotoxicity were assessed using quantitative fluorescence microscopy and compared with Ames results obtained in this study. The ethyl acetate fraction at 1000mg/kg significantly reduced blood glucose levels to 8.16 ± 4.4 mmol/L from 28.42 ± 2.7 mmol/L after 28 days, comparable to glibenclamide xi (p=0.15). In vitro studies showed its α-glucosidase inhibitory activity. Animals receiving Kigelia fruit fractions and extracts showed decreased weight (p<0.05). The ethyl acetate fraction produced a more favourable lipid profile than glibenclamide. Inter-group variations were observed in triglycerides (p=0.03), total cholesterol (p =0.001), and nonHDL cholesterol (p=0.0007) levels. Biochemical and histological examinations revealed improved cell viability in the liver, kidneys, and nervous system of treated rats. No significant differences in DPPH inhibition, TPC, or TFC were observed amongst the fractions. GC-MS analysis showed that the most bioactive fraction contained 11"(2- cyclopenten-1-yl) undecanoic acid, (+)- and cyclopentane undecanoic acid, along with the indole alkaloids Akuammilan-17-ol-10-methoxy, N-nitroso-2-methyl-oxazolidine and epoxide Oxirane2.2″ -(1.4-butanediyl) bis-. The aqueous extract had no effect on cell viability, whereas the ethyl acetate extract caused a concentration-dependent decrease in cell viability (IC50 = 414.8 ± 8.69 µg/mL). Fruit extracts showed similar effects on His+ revertants as the negative control, indicating no mutagenic activity. The highest concentration of ethyl acetate fruit extract increased the average nuclear area of Vero cells (IC50 EtOAc = 338.6± 1.058 µg/mL). After 48 hours, no significant changes were observed in the ratio of multi+dual to mononucleated Vero cells. K. africana fruit fraction improved glucose and lipid profiles and the histoarchitecture of organs in diabetes-induced rats. It showed notable alpha-glucosidase inhibitory activity, whereas its alpha-amylase inhibitory activity was limited. At therapeutic doses, the extracts did not display genotoxic properties. This study identified the bioactive phytocomposition xii of this fruit, highlighting its potential as a medicinal agent for the treatment of diabetes mellitus. It suggests a potential natural alpha-glucosidase inhibitor and phytocompounds that could serve as lead compounds for developing new antidiabetic medications.