Herbal tea kinkéliba prepared from the leaves of Combretum micranthum has been widely consumed in West African countries for its flavor, nutritional and medicinal properties. Under bio-guided screening, the kinkéliba leaves were chemically investigated using various chromatographic and spectrometric methods that led to the identification of thirteen different flavonoid compounds. Further biological tests illustrated that the identified compounds may have synergistic effects to decrease the expression of phosphoenolpyruvate carboxykinase (PEPCK) mRNA and glucose production in an H4IIE hepatoma cell line, indicating its potential use for insulin-resistant diabetes treatment. Further in vivo study on C57BL/6J mice indicates that kinkéliba can lower plasma glucose levels in a dose-dependent manner without significant weight loss and toxicity. The ethyl acetate extract in rich of flavonoids could also increase the glucose tolerance (GT) after seven weeks' administrations. Both in vitro and in vivo experiments support a potential new application of kinkéliba leaves as an anti-diabetes agent.

RESUMELes radicaux libres étant impliqués dans la genèse de plusieurs maladies, l'intérêt porté à la recherche d'antioxydants naturels a considérablement augmenté ces dernières années. L'objectif de cette étude était d'évaluer l'activité antioxydante des extraits hydro-éthanoliques des feuilles et écorces de Piliostigma thonningii. La détermination de la teneur en polyphénols a été effectuée par la méthode de Folin Denis. L'activité antiradicalaire a été évaluée par les tests de réduction du DPPH (2, 2-diphenyl-l-picrylhydrazyl) et de l'ABTS (acide 2,2'-azino-bis-(3-éthylbenzothiazoline-6-sulfonique)). Le pouvoir réducteur vis-à-vis de l'ion ferrique a été également évalué. Il ressort de ces tests que les écorces sont environ deux fois plus riches en polyphénols que les feuilles. Les CI50 des extraits des écorces et des feuilles sur DPPH sont respectivement de 46,8 ± 5,77 µg/ml et 138,9 ± 2,03 µg/ml. Concernant le test ABTS les CI50 des deux extraits sont 39,3 ± 1,00 µg/ml et 109 ± 6,25 µg/ml respectivement. Le pouvoir réducteur des écorces est supérieur à celui des feuilles à toutes les concentrations testées. Donc les écorces présentent une activité antioxydante meilleure que celle des feuilles de cette plante. © 2017 International Formulae Group. All rights reserved.Mots clés : Piliostigma thonningii, activité antioxydante, phénols totaux.Evaluation of the antioxidant activity of hydro-ethanolic leaf and bark extracts of Piliostigma thonningii Schumach ABSTRACT Free radicals are involved in the genesis of several diseases, what makes increasing research for natural antioxidants in recent years. The purpose of this study was to evaluate the antioxidant activity of the hydro-ethanolic leaf and bark extracts of Piliostigma thonningii. The polyphenol content was determined with Folin Denis reagent. The antiradical activity was evaluated using S. I. M. DIENG et al. / Int. J. Biol. Chem. Sci. 11(2): 768-776, 2017 769 DPPH (2, 2-dipheny l-picrylhydrazyl) and ABTS (2,2'-azino-bis-(3-ethylbenzothiazolin-6-sulfonic acid) reduction tests. The reducing power was also performed using ferric reducing. (FRAP). All experiments were done in triplicate. From these tests, it appears that the bark is approximately twice as rich in polyphenols as the leaves.The IC50 of the bark and leaf extracts on DPPH are respectively 46.8 ± 5.77 μg/ml and 138.9 ± 2.03 μg/ml. On ABTS test, bark and leaf extracts had exhibited scavenger activity with respective IC50 values 39.3 ± 1.00 μg / ml and 109 ± 6.25 μg / ml. Reducing power of bark extract was higher than that of leaf extract at all tested concentrations. Therefore, the bark exhibits a better antioxidant activity than that of the leaves of this plant.

Seed oils ofSterculia tomentosa andS. tragacantha (Sterculiaceae) were found to contain malvalic (5.8 and 5.1%), sterculic (11.3 and 30.2%) and dihydrosterculic (0.9 and 0.5%) acids. The total amount of these two cyclopropenoid fatty acids was established by1H nuclear magnetic resonance and their cooccurrence by gas chromatography. Besides these unusual compounds, the main common fatty acids were palmitic (20 and 24%), oleic (21 and 15%) and linoleic (30 and 16%) acids.

No abstract

No abstract

Vitexin, the main flavonoid was extracted from the leaves of Combretum micranthum in soxhlet with ethanol. The extract evaporated to dryness and retrieved thanks to hot water. That liquid extract went through a degreasing and extracted again with butanol. The butanolic extract evaporated to dryness and dissolved in methanol, in which the vitexin precipitated after the washing and the recrystallisation of the first obtained precipitate. From 500g of dry kinkeliba leaves, a series of manipulations led to the isolation of 0.0576 g of vitexin, yielding 0.013% per ounce of the kinkeliba leaves dry powder. The degree of purity of vitexin was 94.79% on the basis of HPLC/UV-Vis/MS of the chemical formula C21H20O10. According to the spectral data NMR 1 H and 13 C the molecular structure of the vitexin is identified.

No abstract

No abstract