title: Antioxidants from the bark of Burkea africana, an African medicinal plant.
abstract: The bark of the tree Burkea africana is used medicinally in large areas of sub-Saharan Africa. The constituents responsible for its putative activity are not well known. We have investigated the bark of B. africana for antioxidant and radical scavenging activity. A hydroethanol bark extract showed high activity, and most of this activity was located in semipolar fractions of the extract. From chromatographic purification and spectroscopical structure studies, we conclude that the active constituents are proanthocyanidins. Two major components appear to be fisetinidol-(4alpha- --> 8)-catechin 3-gallate and bis-fisetinidol-(4alpha- --> 6, 4alpha- --> 8)-catechin 3-gallate. The latter compound is a new natural product. Smaller amounts of monomeric flavan-3-ols (catechin, epicatechin and fisetinidol) were also found.
authors.affiliation: Department of Pharmacognosy, School of Pharmacy, The University of Oslo, P.O. Box 1068 Blindern, N-0316 Oslo, Norway.
authors.forename: Elin
authors.initials: E
authors.lastname: Mathisen
authors.forename: Drissa
authors.initials: D
authors.lastname: Diallo
authors.forename: Øyvind M
authors.initials: ØM
authors.lastname: Andersen
authors.forename: Karl Egil
authors.initials: KE
authors.lastname: Malterud
mesh_terms: D000818:Animals; D000872:Anthocyanins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D015764:Bepridil / Q000031:analogs & derivatives* / Q000378:metabolism; D001713:Biphenyl Compounds; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002417:Cattle; D007887:Fabaceae; D016166:Free Radical Scavengers / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D016859:Lipoxygenase Inhibitors; D009682:Magnetic Resonance Spectroscopy; D016488:Medicine, African Traditional; D015394:Molecular Structure; D010851:Picrates; D024301:Plant Bark / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D044945:Proanthocyanidins
chemical_list: D000872:Anthocyanins; D000975:Antioxidants; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D016859:Lipoxygenase Inhibitors; D010851:Picrates; D010936:Plant Extracts; D044945:Proanthocyanidins; C457879:bis-fisetinidol-(4alpha-6,4alpha-8)catechin 3-gallate; C457860:fisetinidol-(4alpha-8)catechin 3-gallate; C013221:proanthocyanidin; D015764:Bepridil; D002392:Catechin; C004931:1,1-diphenyl-2-picrylhydrazyl