A new flavonol derivative and other compounds from the leaves of Bauhinia thonningii Schum with activity against multidrug-resistant bacteria

  • Nat Prod Res. 2023 Aug-Sep;37(16):2653-2661. doi: 10.1080/14786419.2022.2128347.
Guy Raphael Sado Nouemsi  1 ,  Jean-Bosco Jouda  2 ,  Peron Bosco Leutcha  1 ,  Valaire Yemene Matieta  3 ,  Virginie Flaure Tsague Tankeu  1 ,  Jenifer Reine Ngnouzouba Kuete  4 ,  İlhami Çelik  5 ,  Victor Kuete  3 ,  Norbert Sewald  6 ,  Alain Meli Lannang  2  7
Affiliations
  • 1. Department of Chemistry, Faculty of Science, University of Maroua, Maroua, Cameroon.
  • 2. Department of Chemical Engineering, School of Chemical Engineering and Mineral Industries, University of Ngaoundere, Ngaoundere, Cameroon.
  • 3. Department of Biochemistry, Faculty of Science, University of Dschang, Dschang, Cameroon.
  • 4. Department of Chemistry, Faculty of Science, University of Dschang, Dschang, Cameroon.
  • 5. Department of Chemistry, Faculty of Science, Eskişehir Technical University, Eskisehir, Turkey.
  • 6. Department of Chemistry, Inorganic and Structural Chemistry, Bielefeld University, Bielefeld, Germany.
  • 7. Department of Chemistry, Higher Teachers Training College, University of Maroua, Maroua, Cameroon.
PMID: 36175178 DOI: 10.1080/14786419.2022.2128347
Abstract

Investigation of the leaves of Bauhinia thonningii Schum led to the isolation and identification of a new flavonol derivative, 6-C-methylquercetin-3,4'-dimethyl ether (1) together with eleven known compounds (2-13), with two of them (10 and 11) obtained as a mixture. Their structures were established by extensive spectroscopic analyses. Antibacterial activity of compound 1 as well as the reference Antibiotic, ciprofloxacin was tested on Gram-negative multidrug-resistant bacteria overexpressing active efflux pumps, and against methicillin-resistant strains of Staphylococcus aureus (MRSA). Samples were tested alone and in combination with an efflux pump inhibitor (EPI), phenylalanine-arginine-β-naphthylamide (PAßN). Results show that when compound 1 was tested alone, its inhibitory effects were obtained on 7/10 tested bacteria with the highest MIC value of 128 µg/mL whilst in the presence of EPI, this activity significantly increase in all the 10 bacteria. An interesting Antibacterial activity was obtained with compound 1 against Klebsiella pneumoniae ATCC11296 (MIC of 4 µg/mL), KP55 and Staphylococcus aureus MRSA6 in the presence of the PaßN.

Keywords
Bauhinia thonningii; antibacterial activity; flavonoids.
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