Author(s)

Jean Momeni¹, Jean Paul Tsopmejio², Francine T. Nkouam³, Martin B. Ngassoum³

¹Department of Chemistry, Faculty of Science, University of Ngaoundere, Ngaoundere, Cameroon.
²Department of Organic Chemistry, Faculty of Science, University of Yaounde 1, Yaounde, Cameroon.
³National Advanced School of Agro-Industrial Sciences, University of Ngaoundere, Ngaoundere, Cameroon.

Phytochemical studies and antioxidant activities were carried out on n-hexane, ethyl acetate, ethanol and methanol extracts of the leaves of Lippia rugosa A. Chev (Verbenaceae), a medicinal plant used traditionally in the Cameroonian savannah’s region to protect foodstuffs and to cure degenerative diseases. Results indicated that theses extracts contain terpenoids, phenolic and flavonoid compounds. Except the n-hexane extract, all of the obtained extracts exhibit antioxidant activities with the ethanol extract being the most effective with an inhibition percentage of 85.668% ± 1.233% and an inhibition concentration (IC₅₀) of 58 μg/ml (R² = 0.987, P < 0.01) at a concentration of 100 mg/ml. Chromatographic separation on silica gel of the ethanol extract led to the isolation of a pure organic compound which was characterized as 7-hydroxy-5,6,4'-trimethox- yflavone by extensive 1D and 2D NMR spectroscopy, a flavonoid exhibiting antioxidative activity with an inhibitory percentage of 25.506% ± 0.205% and inhibition concentration (IC₅₀) of 221 μg/ml (R² = 0.966, P < 0.01). This is the first time that 7-hydroxy-5,6,4'-trimethoxyflavone is being isolated from L. rugosa and its antioxidant activity evaluated.

7-Hydroxy-5, 6, 4’-trimethoxyflavone, Phenolic Compounds, Antioxidant Activity, DPPH Assay, Lippia rugosa, Organic Extracts

Momeni, J. , Tsopmejio, J. , Nkouam, F. and Ngassoum, M. (2016) Antioxidant Activity of the Natural Flavonoid 7-Hydroxy-5,6,4’-trimethoxyflavone Isolated from the Leaves of Lippia rugosa A. Chev. Natural Science, 8, 70-78. doi: 10.4236/ns.2016.82009.