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Two new flavone glycosides from the leaves of Ochna afzelii Oliv. (Ochnaceae)

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journal contribution
posted on 23.09.2022, 08:40 authored by Morel Hervé D. Kakabi, James D. Simo Mpetga, Jean-De-Dieu Tamokou, Germaine Takongmo Matsuete, Romeo Désiré T. Nago, Gabin Thierry M. Bitchagno, Bruno N. Lenta, Norbert Sewald, Mathieu Tene, Augustin Silvère Ngouela

Two new glycosylflavones, 6′′-O-acetyl-8-C-β-D-galactopyranosylchrysoeriol (1) and 8-C-β-D-galactopyranosylchrysoeriol (2) were isolated from the methanol extract of the leaves of Ochna afzelii Oliv., along with four known compounds namely 8-C-β-D-galactopyranosylapigenin (3), ochnaflavone (4), sitosterol-3-O-β-D-glucopyranoside (5) and D-mannitol (6). Isolation was performed chromatographically and the structures of the purified compounds were elucidated by analyzing their spectroscopic and mass spectrometric data. The antibacterial activity of extract, fractions, and compounds 1 − 4 was evaluated using broth microdilution method against Gram-positive and Gram-negative bacteria while the antioxidant capacity was performed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the ferric reducing antioxidant power (FRAP) methods. The new flavones (1 and 2) displayed moderate antibacterial activities (MIC = 32 − 64 µg/mL) and weak antioxidant properties.

Funding

The authors are thankful to the German Academic Exchange Service (DAAD) for financial support to the Yaounde-Bielefeld Graduate School of Natural Products with Antiparasite and Antibacterial activities (YaBiNaPA), project N° 57316173. We also thank Dr Roland T. Tchuenguem for the antioxidant tests. The financial support from the University of Dschang is also gratefully acknowledged.

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