Planta Med 2009; 75 - PA62
DOI: 10.1055/s-0029-1234387

Activity guided isolation of antioxidants from the stem bark of Diospyros sanza-minika A. Chevalier

JG Tangmouo 1, 2, R Ho 2, A Meli Lannang 3, J Komguem 1, K Hostettmann 2
  • 1Department of Organic Chemistry, University of Yaoundé I, P.O. Box 812 Yaoundé, Cameroon
  • 2Laboratory of Pharmacognosy and Phytochemistry, School of Pharmaceutical Sciences, EPGL, University of Geneva, University of Lausanne, Quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland
  • 3Department of Chemistry, Higher Teachers' Training College, University of Maroua, P.O.Box 46 Maroua, Cameroon

Many species of Diospyros (Ebenaceae) are used in African and Chinese traditional medicinal systems for the prevention of gastric ulcers, inflammatory disorders and hepatotoxicity [1]. Recent studies show that some of these species possesses antitumor, antidiabetic and antioxidant effects [2]. The methanol extract from the stem bark of Diospyros sanza-minika showed radical scavenging activity against DPPH with IC50 values of 1.33mg/mL. This extract was exhausted with hexane, dichloromethane and ethyl acetate. The strongest active fraction (ethyl acetate, 1.18mg/mL) was subjected to activity-guided purification to give norbergenin (1) and 4-O-galloylnorbergenin (2). These compounds were isolated for the first time from Diospyros sanza-minika. Norbergenin and 4-O-galloylnorbergenin, the main components of the plant, showed DPPH scavenging activities with IC50 values of 1.12 and 0.61mg/mL, respectively, which were comparable to that of quercetin (0.74mg/mL).

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Acknowledgments: Jean Gustave Tangmouo wishes to acknowledge AUF for „Bourse post-doctorat“ in University of Geneva, Switzerland.

References: [1] Mallavadhani, U.V. et al. (1998) Phytochemistry 49:901–951.

[2] Chen, X.N. et al. (2008)J. Food Sci. 73:C24–28.