Browsing by Author "Nako, Ndikho"

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    Characterization of new pyrone-containing flavones from Helichrysum petiolare Hilliard & B.L. Burtt
    (Elsevier B.V., 2025) Makhaba, Masixole; Yalo, Masande; Koki, Mkhuseli; Nako, Ndikho; Mabusela, Wilfred T.; Pearce, Keenau; Benjeddou, Mongi
    Helichrysum petiolare Hilliard & B.L. Burtt. (Asteraceae), native to the Cape Floral Region of South Africa, is traditionally used in the management of wounds, respiratory complaints, and diabetes. Although extensive studies on its extracts, few have focused on the bioactivity of the individual phytochemicals. In this study, chromatographic processing of the H. petiolare leaf total extract led to the isolation and identification of ten compounds C1–C10) using NMR, FTIR, and HRESIMS spectroscopy. Two pyrone-containing flavones (C1 and C2) are reported for the first time from natural sources. The known compounds identified included flavonoids (C3–C5), phenolics (C6–C9), and a sterol (C10). The MTT assay revealed dose-dependent cytotoxicity of C1–C4 only against MDA-MB-231 (breast cancer), HeLa (cervical cancer), and HEK-293 (non-cancerous kidney) cell lines after 24 h exposure. Notably, C4 demonstrated selective activity toward HeLa cells (45 % viability reduction at 100 µM; IC₅₀ = 89.19 µg/mL). This is the first report of compounds C1–C10 from H. petiolare and their in vitro cytotoxic profile. Despite moderate activity, this work provides a foundation for further pharmacological investigations of derivatives of these metabolites in cancer management.
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    Chemical studies on some natural products from Myrothamnus flabellifolius
    (University of the Western Cape, 2014) Nako, Ndikho; Mabusela, Wilfred Thozamile
    Crude extracts from Myrothamnus flabellifolius were fractionated through variouschromatography techniques in order to achieve satisfactory separations. Two compounds, arbutin and lupeol, were isolated from the butanol and ethyl acetate extracts, respectively. Structural elucidation of the compounds was carried out on the basis of 1H and 13C NMR spectroscopy. It was the first time that lupeol had been isolated from M. flabellifolius.The water extract was found to contain heterogeneous pectic polysaccharides. Three polysaccharide fractions were separated from the water extract, namely; MPS, MPS-I and MPS-II. The predominant fraction was found to be MPS, with a molecular weight distribution of 2 X 105 Da. The polysaccharides were made up the following monosaccharides; arabinose, rhamnose, xylose, mannose, galactose and glucose. Monosaccharide composition was determined through acid hydrolysis at high temperatures, followed by GC analysis. The linkage analysis was carried out by GC-MS, following partial methylation of the polysaccharides. The use of human serum albumin (HSA) following its anchoring on magnetic nanoparticles, in order to isolate targeted saponins from Sutherlandia frutescens led to successful isolation of four saponins, namely; sutherlandiosides A-D. The saponins showed great affinity to bind to the HSA.