| Abstrakt: |
Through bioassay-guided fractionation, 13 compounds ( 1- 13) were isolated from the CHCl/MeOH (1:1) extracts of the root bark of Newbouldia leavis and characterized mainly by NMR and X-ray spectroscopy. Among these, nine quinone derivatives ( 1- 7, 12- 13), one triterpeniod ( 8), and three steroids ( 9- 11) were isolated. The stereochemistry of 3-hydroxy furonaphthoquinones isolated from this plant has been established for the first time as (2 S,3 R) on the basis of single X-ray crystal structure analysis and show marked J deviations from the Karplus curve from H-NMR spectral analysis. The fractions together with three of the isolated compounds namely lapachol, 2-acetyl-naphtho [2,3- b]furan-4,9-dione, and 2-(1-hydroxyethyl)-2-acetyl-naphtho[2,3- b]furan-4,9-dione were screened against Onchocerca ochengi parasites. Lapachol and 2-(1-hydroxyethyl)-2-acetyl-naphtho[2,3- b]furan-4,9-dione showed 100 % inhibition at a concentration of 5 μg/mL after 5 days. [ABSTRACT FROM AUTHOR] |
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