8 research outputs found
Metal-Free Addition of Boronic Acids to Silylnitronates
No full textInternational audienceWe report for the first time a metal-free addition of boronic acids to silylnitronates to afford oxime derivatives through aryl transfer on the carbon nitrogen double bond. A reaction mechanism has been proposed in relation with a DFT study on the key aryl transfer. This arylation process is effective for cycloalkenyl nitro derivatives leading to oximes that may be oxidatively converted into 3-arylisoxazole derivatives
Etude comparative des activités antioxydantes d’extraits éthanoliques de feuilles, d’écorces et de racines de <i>Cassia sieberiana</i>
No full textDans cet article, les 3 organes de C. sieberiana récoltée au Togo ont fait l’objet d’une étude comparative pour la détermination de leur composition phytochimique, teneur en phénols et flavonoïdes totaux, et activités antioxydantes. Le tri phytochimique a été réalisé grâce aux réactions de colorimétrie et précipitation. La teneur en phénols totaux a été déterminée grâce au réactif du Folin-Ciocalteu et celle des flavonoïdes par AlCl3. L’activité antioxydante a été évaluée par les méthodes de DPPH et FRAP. Les résultats obtenus ont montré que les 3 organes de la plante contiennent des grands groupes chimiques, tels que les flavonoïdes, tanins et saponosides. Les teneurs en phénols totaux des extraits éthanoliques sont (en mg EAG/g) de 276,62 ± 26,120 (feuilles) ; 345,04 ± 3,160 (écorces) ; 327,16 ± 3,990 (racines). Celles des flavonoïdes totaux sont (en mg EQ/g) de 34,134 ± 4,324 (feuilles) ; 36,430 ± 2,022 (écorces) et 37,270 ± 2,216 (racines). Les extraits éthanoliques des 3 organes ont un pouvoir antioxydant appréciable. En conclusion, les résultats obtenus révèlent que les racines et écorces ont des activités antioxydantes semblables, toutefois ne permettent pas à ce stade de la recherche de préciser l’organe approprié pouvant remplacer les racines.© 2017 International Formulae Group. All rights reserved.Mots clés: Cassia sieberiana; composition phytochimique activité antioxydante ; phénols totauxEnglish Title: Comparative antioxidant potential study of different part of Cassia sieberianaEnglish AbstractIn this article, the 3 organs of C. sieberiana harvested in Togo were the subject of a comparative study for the determination of their phytochemical composition, content of total phenols and flavonoids, and antioxidant activities. Phytochemical composition was carried out by colorimetric and precipitation reactions. The total phenol content was determined by Folin-Ciocalteu reagent and total flavonoids by AlCl3. Antioxidant activity was evaluated by DPPH and FRAP methods. The results obtained showed that the 3 organs of the plant contain large chemical groups, such as flavonoids, tannins and saponosides. The total phenol contents of the ethanolic extracts are (in mg EAG / g) of 276.62 ± 26.120 (leaves); 345.04 ± 3.160 (barks); 327.16 ± 3.990 (roots). Those of the total flavonoids are (in mg Eq / g) 34,134 ± 4,324 (leaves); 36,430 ± 2,022 (barks) and 37,270 ± 2,216 (roots). The ethanolic extracts of the 3 organs have an appreciable antioxidant power. In conclusion, the results obtained reveal that the roots and barks have similar antioxidant activities, however do not allow at this stage of research to specify the appropriate organ that can replace the roots.© 2017 International Formulae Group. All rights reserved.Keywords: Cassia sieberiana; phytochemical composition; antioxidant activity; total phenol
Self-assembling and photophysical properties of the organogelators based on cyanostyryl-substituted carbazoles
No full textConditions de synergie d’action des extraits anti-radicalaires de <i>Flueggea virosa</i> (Roxb. Ex Wild.) Royle et de <i>Crataeva adansonii</i> Forst. f. avec inductions acido-basiques extérieures
No full textSelf-assembling and photophysical properties of the organogelators based on cyanostyryl-substituted carbazoles
No full textA significant antihypertensive effect of Holarrhena floribunda supported by an exploratory phytochemical study
No full textIntroduction: Holarrhena floribunda (G.Don) T.Durand & Schinz is a tree that can grow up
to 25 m with white latex in its organs. The bark of this plant is commonly used in traditional
medicine to treat dysentery, diarrhea, diabetes, malaria, and high blood pressure. In this
study, phytochemical groups were widely investigated on trunk bark as well as on leaves of H.
floribunda harvested in Danyi (Togo). Antioxidant activity and antihypertensive properties
of the plant extracts were also evaluated on sound guinea pigs.
Methods: The hydro-ethanolic extract of the trunk bark was prepared and antioxidant activity
was evaluated via the DPPH radical-scavenging and the ferric-reducing antioxidant power
(FRAP) methods, and via the determination of the total phenolics content. This hydro-ethanolic
extract was used to assess the plant extract effect on blood pressure of sound guinea pigs.
Results: So, phytochemical screening revealed that H. floribunda contained most of the
phytochemical groups. The 50% inhibitive concentration of that extract by DPPH was 29.80
± 0.001 μg/mL. The equivalent of Fe2+ by FRAP was 1009.9 ± 0.6 μmol/g of dry extract. The
content of phenolic compounds was 139 ± 0.053 mg GAE (gallic acid equivalents)/g of dry
extract. Intravenous injection of the extract (10, 20, 40, 80 mg/kg) via the invasive method in
guinea pigs under normal strain caused a decrease in diastolic blood pressure, systolic blood
pressure, and so in mean arterial pressure (MAP) by dose cumulative and time-dependent.
Conclusion: The results show that hydro-ethanolic extract of H. floribunda trunk bark has
antihypertensive and antioxidant properties. This might be the reason for the use of that extract
for the treatment of hypertension in traditional medicin
Chemical composition and antioxidant activities of different parts of Ficus sur
No full textIntroduction: Ficus sur is a plant widely used in traditional pharmacopoeia in Togo. So, this
study aimed the assessment of antioxidant properties and identification of some compounds
from the ethanolic extracts of different parts of the plant (leaves, fruits, roots, and barks).
Methods: The phenolic and flavonoid contents of the ethanolic extracts of different organs of
Ficus sur were assessed using conventional known methods. The DPPH radical scavenging and
the ferric-reducing antioxidant power (FRAP) assays were used to highlight the antioxidant
activities. The different extract samples were also analysed by liquid chromatography coupled
to a quadrupole-time of flight mass detector (ESI-QTOF).
Results: Total phenolic contents (TPCs) for 1 mg of dry extract ranged from 489.40 ± 7.48 μg
GAE (gallic acid equivalents) for the bark to 62.34 ± 2.66 μg GAE for unripe fruits. The bark
exhibited the highest flavonoid content, which was closed to 90.20 ± 3.72 μg QE (quercetin
equivalents)/mg of dry extract. The radical scavenging activities of the bark and unripe fruits
were 56.50 ± 0.29 and 7.3 ± 0.30 μg QE/mg of dry extract, respectively. In the same order,
the FRAP values of the two organs were 104.57 ± 4.75 and 19.61 ± 0.22 μmol FeSO4
Eq/mg
of dry extract. Many compounds including notoginsenoside R10; 4’,5,7-trihydroxyflavan-3-ol;
catechin; and boviquinone 4 were identified.
Conclusion: The various organs of Ficus sur are a source of bioactive compounds especially
phenolic compounds and flavonoids with antioxidant activit
Identification de deux phytostérols biologiquement actifs de l’extrait cyclohexanique des feuilles de <i>Ficus sur</i> (Moraceae)
No full textFicus sur est une plante alimentaire couramment utilisée en médecine traditionnelle au Togo. Elle a cependant fait l’objet de très peu d’études phytochimiques. Le présent travail a pour but de valoriser cette espèce à travers l’identification continue de ses métabolites. Ainsi, l’extraction cyclohexanique au Soxhlet a été réalisée sur les feuilles de Ficus sur. Cet extrait cyclohexanique obtenu a été ensuite fractionné puis purifié par chromatographie sur colonne de gel de silice. L’identification des composés a été réalisée par GC-MS, précédée quelquefois d’une étape de dérivatisation. Treize fractions (A1 à A13) ont été obtenues du fractionnement de cet extrait. Après deux purifications successives de la fraction A5, deux sous-fractions A5.1 et A5.2 ont été obtenues. Le spectre de masse d’un composé de A2 présente un pic moléculaire à m/z 426 et des pics fragments [M-69]+, [M-154]+, [M-169]+, [M-197]+, [M-208]+ et [M-219]+ caractéristique du taraxastérol. Pour A5.2 dérivatisée, un composé présente un spectre de masse de pic moléculaire à m/z 486 et des pics fragments [M-90]+, [M-129]+ et [M-357]+ propres au β-sitostérol triméthylsilyl éther dérivé du β-sitostérol. La présence de ces deux phytostérols bioactifs serait un atout majeur dans l’usage thérapeutique de cette plante.© 2017 International Formulae Group. All rights reserved.Mots clés: Ficus sur, GC-MS, taraxastérol, β-sitostérolEnglish Title: Identification of two bioactive phytosterols of the cyclohexane extract of Ficus sur (moraceae) leavesEnglish AbstractFicus sur is a food plant commonly used in traditional medicine in Togo. However, few phytochemical studies of this species are available. This work aims at contributing to the enhancement of this approach through an identification of its metabolites. The leaves of Ficus sur were then extracted with cyclohexane using soxhlet. The obtained cyclohexane extract was fractionated and purified by chromatography on silica gel column. Identification of the compounds was carried out by GC-MS, sometimes preceded by a derivatization step. Thirteen fractions (A1 to A13) were obtained from the fractionation of this extract. After two successive purifications of the fraction A5, two subfractions A5.1 and A5.2 were obtained. The mass spectrum of a compound of A2 has a molecular peak at m/z 426 and peaks [M-69]+, [M-154]+, [M-169]+, [M-197]+, [M-208]+ and [M-219]+ characteristic of taraxasterol. For the derivatized fraction A5.2, a compound has a mass spectrum of molecular peak at m/z 486 and peaks [M-90]++ and [M-357]+ characteristic of β-sitosterol trimethylsilyl ether derived from β-sitosterol. The presence of these two bioactive phytosterols would be a major asset in the therapeutic use of this plant.© 2017 International Formulae Group. All rights reserved.Keywords: Ficus sur, GC-MS, taraxasterol, β-sitostero
