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Träfflista för sökning "WFRF:(Nyandoro Stephen S. 1975) "

Sökning: WFRF:(Nyandoro Stephen S. 1975)

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11.
  • Kalenga, Thobias M, et al. (författare)
  • Antibacterial and cytotoxic biflavonoids from the root bark of Ochna kirkii
  • 2021
  • Ingår i: Fitoterapia. - : Elsevier BV. - 1873-6971 .- 0367-326X. ; 151
  • Tidskriftsartikel (refereegranskat)abstract
    • The new isoflavonoid kirkinone A (1) and biflavonoid kirkinone B (2) along with six known compounds (3-8) were isolated from the methanolic extract of the root bark of Ochna kirkii. The compounds were identified by NMR spectroscopic and mass spectrometric analyses. Out of the eight isolated natural products, calodenin B (4) and lophirone A (6) showed significant antibacterial activity against the Gram-positive bacterium Bacillus subtilis with MIC values of 2.2 and 28μM, and cytotoxicity against the MCF-7 human breast cancer cell line with EC50 values of 219.3 and 19.2μM, respectively. The methanolic crude extract of the root bark exhibited cytotoxicity at EC50 8.4μg/mL. The isolated secondary metabolites and the crude extract were generally inactive against the Gram-negative Escherichia coli (MIC ≥400μg/mL). Isolation of biflavonoids and related secondary metabolites from O. kirkii demonstrates their chemotaxonomic significance to the genus Ochna and to other members of the family Ochnaceae.
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12.
  • Kalenga, Thobias M, et al. (författare)
  • Biflavanones, Chalconoids, and Flavonoid Analogues from the Stem Bark of Ochna holstii.
  • 2021
  • Ingår i: Journal of Natural Products. - : American Chemical Society (ACS). - 1520-6025 .- 0163-3864. ; 84:2, s. 364-372
  • Tidskriftsartikel (refereegranskat)abstract
    • Two new biflavanones (1 and 2), three new bichalconoids (3-5), and 11 known flavonoid analogues (6-16) were isolated from the stem bark extract (CH3OH-CH2Cl2, 7:3, v/v) of Ochna holstii. The structures of the isolated metabolites were elucidated by NMR spectroscopic and mass spectrometric analyses. The crude extract and the isolated metabolites were evaluated for antibacterial activity against Bacillus subtilis (Gram-positive) and Escherichia coli (Gram-negative) as well as for cytotoxicity against the MCF-7 human breast cancer cell line. The crude extract and holstiinone A (1) exhibited moderate antibacterial activity against B. subtilis with MIC values of 9.1 μg/mL and 14 μM, respectively. The crude extract and lophirone F (14) showed cytotoxicity against MCF-7 with EC50 values of 11 μg/mL and 24 μM, respectively. The other isolated metabolites showed no significant antibacterial activities (MIC > 250 μM) and cytotoxicities (EC50 ≥ 350 μM).
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13.
  • Maeda, Gasper, et al. (författare)
  • Oxygenated Cyclohexene Derivatives and Other Constituents from the Roots of Monanthotaxis trichocarpa.
  • 2020
  • Ingår i: Journal of Natural Products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 83:2, s. 210-215
  • Tidskriftsartikel (refereegranskat)abstract
    • Three new oxygenated cyclohexene derivatives, trichocarpeols A (1), B (2), and C (3), along with nine known secondary metabolites, were isolated from the methanolic root extract of Monanthotaxis trichocarpa. They were identified by NMR spectroscopic and mass spectrometric analyses, and the structure of trichocarpeol A (1) was confirmed by single-crystal X-ray diffraction. Out of the 12 isolated natural products, uvaretin (4) showed activity against the Gram-positive bacterium Bacillus subtilis with a MIC value of 18 μM. None of the isolated metabolites was active against the Gram-negative Escherichia coli at a ∼5 mM (2000 μg/mL) concentration. Whereas 4 showed cytotoxicity at EC50 10.2 μM against the MCF-7 human breast cancer cell line, the other compounds were inactive or not tested.
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14.
  • Maeda, Gasper, et al. (författare)
  • Oxygenated Cyclohexene Derivatives from the Stem and Root Barks of Uvaria pandensis
  • 2021
  • Ingår i: Journal of Natural Products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 84:12, s. 3080-3089
  • Tidskriftsartikel (refereegranskat)abstract
    • 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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15.
  • Maeda, Gasper, et al. (författare)
  • Polyoxygenated cyclohexene derivatives and flavonoids from the leaves of Uvaria pandensis.
  • 2022
  • Ingår i: Fitoterapia. - : Elsevier BV. - 1873-6971 .- 0367-326X. ; 158
  • Tidskriftsartikel (refereegranskat)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 and 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 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>100μM).
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16.
  • Zandi, Linda, et al. (författare)
  • Secoiridoids and Iridoids from Morinda asteroscepa
  • 2020
  • Ingår i: Journal of Natural Products. - : AMER CHEMICAL SOC. - 0163-3864 .- 1520-6025. ; 83:9, s. 2641-2646
  • Tidskriftsartikel (refereegranskat)abstract
    • The new 2,3-secoiridoids morisecoiridoic acids A (1) and B (2), the new iridoid 8-acetoxyepishanzilactone (3), and four additional known iridoids (4-7) were isolated from the leaf and stem bark methanol extracts of Morinda asteroscepa using chromatographic methods. The structure of shanzilactone (4) was revised. The purified metabolites were identified using NMR spectroscopic and mass spectrometric techniques, with the absolute configuration of 1 having been established by single-crystal X-ray diffraction analysis. The crude leaf extract (10 mu g/mL) and compounds 1-3 and 5 (10 mu M) showed mild antiplasmodial activities against the chloroquine-sensitive malaria parasite Plasmodium falciparum (3D7).
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  • Resultat 11-16 av 16

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