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.

Context and objective As elsewhere, disadvantaged children in Senegal are those most affected by dental diseases and difficulties in obtaining dental care. Studies conducted mainly in developed countries suggest that a low level of mothers' OHL is correlated with poor oral health of their children. The objective of this study is to estimate the level of mothers' OHL in Senegal and its relationto the dental health of their children. Methods This cross-sectional epidemiological survey took place among 315 children aged from 3 to 9 years old and their mothers. It estimated the children's dental health status by clinical examination which used a disposable examination kit and a headlamp, took place at the child's home, in the mother's presence. Examiners interviewing the mothers administered the Oral Health Literacy-Adult Questionnaire to determine their OHL and questioned them further about their social characteristics and their children's dental health behaviour. Logistic regression and correlations were used for the statistical analysis. Results The OHL score ranges from 0 to 17; mothers' mean score was 6.5 (±3.1) and 56.5% had a low score (below the median). The prevalence of dental caries in children was 64.8%. Mothers' high OHL is associated with children caries free and low prevalence of dental caries. The logistic regression showed a significantly protective relation between children's dental caries and mothers' high OHL scores (mean score 12-17) (OR = 0.51, 95% CI: 0.29-0.88), high educational level (OR = 0.42, 95% CI: 0.23-0.76) and a high level of social contact (OR = 0.31, 95% CI: 0.15-0.63). The structural analysis showed that OHL was significantly correlated with both the mothers' social position (r = 0.61 and P<0.001) and the children's caries (r =-0.26 and P<0.001).

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