Masters Degrees (DBMB)

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Browsing Masters Degrees (DBMB) by Subject "Acetylcholinesterase"

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    Acetylcholinesterase inhibition and Cytotoxic activity of extracts and a novel compound isolated from flowers of the wild everlasting (Helichrysum Argyrosphaerum DC)
    (University of Namibia, 2024) Mtuleni, Etuhole; Louw, Stefan
    Helichrysum argyrosphaerum is a poisonous plant responsible for livestock losses in southern Africa. Helichrysum species primarily affect the central nervous system when ingested by livestock. However, previous attempts to identify the toxins produced by these plants resulted in only tentative identification of some chemical constituents. This study aimed to isolate and characterize compounds from the flowers of H. argyrosphaerum and to determine the in vitro acetylcholinesterase inhibitory activity and cytotoxicity of the methanol (MeOH) and dichloromethane (DCM) flower extracts and isolated compounds. Several flavonoid glycosides (tentatively identified as apigenin-O-glycosides) as well as an unknown chlorogenic acid analogue were isolated from the methanol extract of H. argyrosphaerum flowers using semi- preparative high-performance liquid chromatography (HPLC). The chemical structures of three isolated compounds were elucidated as apigenin, chamaemeloside, and a novel compound, 14-acetyl chamaemeloside, based on their high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance spectroscopy (NMR) data. Interestingly, both the MeOH and DCM H. argyrosphaerum flower extracts as well as 14-acetyl chamaemeloside induced acetylcholinesterase activity. In the cytotoxicity assay, neither the MeOH and DCM extracts nor 14-acetyl- chamaemeloside exhibited toxicity against HeLa cells. This research marks the initial report of acetylcholinesterase activity and cytotoxicity in both H. argyrosphaerum MeOH and DCM flower extracts, as well as the isolated compound, 14-acetyl- chamaemeloside, against HeLa cells. Consequently, these findings will contribute to future toxicological studies and aid in developing preventative agents that can be used in the treatment of animals poisoned by H. argyrosphaerum