Browsing by Author "Joan, J. E. Munissi"

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    Oxygenated Cyclohexene Derivatives from the Stem and Root Barks of Uvaria pandensis
    (ACS, 2021-11-21) Gasper, Maeda; Pieter, J. Gilissen; Anastasia, Rudenko; Jelle, van der Wal,; Catarina, Bourgard; Arvind, Kumar Gupta; Per, Sunnerhagen; Joan, J. E. Munissi; Stephen, S. Nyandoro; Máté, Erdélyi
    Five new cyclohexene derivatives, dipandensin A and B (1 and 2) and pandensenols A–C (3–5), and 16 known secondary metabolites (6–21) were isolated from the methanol-soluble extracts of the stem and root barks of Uvaria pandensis. The structures were characterized by NMR spectroscopic and mass spectrometric analyses, and that of 6-methoxyzeylenol (6) was further confirmed by single-crystal X-ray crystallography, which also established its absolute configuration. The isolated metabolites were evaluated for antibacterial activity against the Gram-positive bacteria Bacillus subtilis and Staphylococcus epidermidis and the Gram-negative bacteria Enterococcus raffinosus, Escherichia coli, Paraburkholderia caledonica, Pectobacterium carotovorum, and Pseudomonas putida, as well as for cytotoxicity against the MCF-7 human breast cancer cell line. A mixture of uvaretin (20) and isouvaretin (21) exhibited significant antibacterial activity against B. subtilis (EC50 8.7 μM) and S. epidermidis (IC50 7.9 μM). (8′α,9′β-Dihydroxy)-3-farnesylindole (12) showed strong inhibitory activity (EC50 9.8 μM) against B. subtilis, comparable to the clinical reference ampicillin (EC50 17.9 μM). None of the compounds showed relevant cytotoxicity against the MCF-7 human breast cancer cell line.
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    Polyoxygenated Cyclohexene Derivatives and Flavonoids from Uvaria pandensis Leaves
    (Elsevier, 2022-04) Gasper, Maeda; Pieter, J. Gilissen; Catarina, Bourgard; Jelle, van der Wal; Joan, J. E. Munissi; Stephen, S. Nyandoro; Máté, Erdélyi
    Abstract Three new oxygenated cyclohexene derivatives, pandensenol D - F (1–3), two new flavanoids, pandensone A and B (4–5), and seven known compounds (6–12) were isolated from the methanol extract of the leaves of Uvaria pandensis Verdc. (Annonaceae). The structures were characterized by NMR spectroscopic and mass spectrometric analyses. The isolated metabolites were evaluated for their antibacterial activity against the Gram-positive bacteria Bacillus subtilis and Staphylococcus epidermidis, the Gram-negative bacteria Enterococcus raffinosus, Escherichia coli, Paraburkholderia caledonica, Pectobacterium carotovorum and Pseudomonas putida, and for cytotoxicity against the MCF-7 human breast cancer cell line. Out of the tested compounds, pandensenol D (1) and (6′,7′-dihydro-8'α,9'β-dihydroxy)-3-farnesylindole (12) showed weak activity, whereas (8'α,9'β-dihydroxy)-3-farnesylindole (11) strong activity against B. subtilis. Four of the isolated compounds (1, 4, 11 and 12) showed moderate cytotoxicity against MCF-7 breast cancer cells (EC50 > 100 μM).