Effets d’un acide fort sur la réaction de la DPPH avec deux huiles essentielles de deux plantes aromatiques acclimatées au Togo

Des études ont montré que les extraits de certaines plantes médicinales ainsi que leurs huiles essentielles (HE) sont sources de substances bioactives avec de potentiels antioxydants remarquables. L’objectif de ce travail est l’étude de l’influence du milieu réactionnel sur l’action des HE des plantes, de O. basilicum et O. gratissimum acclimatées au Togo, sur la 2,2-diphényl-1-picrylhydrazyle. Les constituants chimiques des HE sont identifiés par la chromatographie en phase gazeuse. Le test de réduction de la 2,2-diphényl-1-picrylhydrazyle (DPPH) et celui de réduction de l’ion ferreux Fe2+ (FRAP) sont utilisés pour déterminer la capacité antioxydante. Les propriétés antioxydantes des HE ont été mises en évidence par la recherche de l’intensité colorante (IC50) et la détermination de l’équivalent en Fe2+ des solutions testées. L’introduction d’un acide fort (acide chlorhydrique) influence les paramètres cinétiques. Les huiles essentielles étudiées contiennent le thymol et l'eugénol et sont anti oxydants. Toutefois, en se référant à la classification de Sanchez-Moreno, ces huiles essentielles ont un pouvoir anti-radicalaire faible. Dans l’intervalle de concentrations étudié [0,025-0,1] M, la réaction est accélérée les cinq premières minutes avec un taux de conversion, comme la vitesse de réaction très élevés. Le mécanisme (electron transfer – proton transfer) est prédominant. L’augmentation de la concentration en HCl et le temps ont favorisé le mécanisme SPLET. Cette étude a montré que les huiles essentielles étudiées ont un pouvoir anti-radicalaire faible mais, elles ont des vitesses de réaction intermédiaires avec la DPPH.© 2015 International Formulae Group. All rights reserved.Mots clés: O. basilicum et O. gratissimum, DPPH, antioxydant, facteurs cinétiques, huiles essentiellesEnglish Title: Effects of a strong acid on the reaction of DPPH with two essential oils from two aromatic plants acclimatized in TogoEnglish AbstractStudies have shown that extracts of certain medicinal plants as their HE are sources of bioactive substances with potential remarkable antioxidants. The objective of this work is to study the influence of the reaction medium on the essential oils, O basilicum and O gratissimum, from Togo, their action on 2,2-dipheny-1-picrylhydrazyl. The chemical constituents of essential oils are identified using gas chromatography. The reduction tests with DPPH and reduction of Fe2+ ion (FRAP) are used to determine the antioxidant capacity. Antioxidant properties of the essential oils are shown up by the detection of colored intensity (IC50) and by the determination of Fe2+ ion equivalent in the solutions. The addition of a strong acid (HCl) influences the kinetic parameters. The studied essential oils contain thymol and eugenol and are antioxidants. Although, based on the Sanchez-Moreno classification, these essential oils have weak antiradical activity. Within the studied concentration range from 0.025M to 0.1M, the reaction runs fast in the first five minutes as well as a high reaction speed. The mechanism (electron-proton transfer) is predominant. Increasing time and HCl concentration favored SPLET mechanism. This study showed that essential oils studied have low anti-radical power, but they have intermediate reaction rates with DPPH.© 2015 International Formulae Group. All rights reserved.Keywords: O. basilicum, O. gratissimum, DPPH, antioxidant, kinetic factors, essential oil

Que sont devenues les plantes autrefois consommées par les divers groupes ethnoculturels du Togo?

L'alimentation végétale chez l'homme a subi beaucoup de mutations dues essentiellement à l'adoption de régimes alimentaires dits évolués dans lesquels les ressources végétales locales rustiques occupent de moins en moins de place. Une étude ethnobotanique sur les plantes alimentaires mineures ou menacées de disparition a été menée entre 2003 et 2006 dans 280 localités distribuées sur toute l'étendue du territoire togolais en tenant compte des 5 zones écologiques et des différents groupes ethnoculturels. Cent trente deux espèces alimentaires mineures ou menacées de disparition ont été recensées. Elles sont classées en 85 espèces spontanées (64 %) et 47 espèces cultivées (36 %). Quarante-quatre espèces de plantes ont été signalées comme menacées de disparition au niveau de tous les groupes ethnoculturels du pays. Tandis que la menace de disparition ne pèse sur d'autres qu'au niveau régional, voire local. Suivant la réduction de la zone d'occurrence et / ou de leurs implications l'alimentation des populations, 6 plantes sont considérées comme très menacées, 19 comme assez menacées, 86 comme menacées et 129 comme peu menacées. Le nombre de plantes alimentaires menacées de disparition a varié de 2 à 40, suivant les localités et de 10 à 50 chez la plupart des ethnies.Nowadays, traditional plants are less used for food by human because of more sophisticated eating habits. An ethno botanical study was carried out on both minor and food plants threatened for extinction in 280 localities in Togo throughout the 5 ecological zones and socio-ethnic groups. The study revealed 132 species of minor or threatened food plants. They were distinguished in 85 spontaneous species (64 %) and 141 varieties belonging to 47 cultivated ones (36 %). Twenty-fourth cultivated species have only one variety, while 23 other species have 2 to 18. Forty-four plants species are considered as threatened throughout the whole country. According to the reduction in areas of occurrence or in the usage, 6, 19, 86 and 129 plant species were considered as very, somewhat and less threatened, respectively. The number of threatened food plants varied from 2 to 40, according to localities and from 10 to 50 local varieties and species at the majority of the ethnic groups, except for the Éwe, Lamba, Nawdba, Ife and Moba groups, which numbered more than 50 plants.Keywords: Threatened food plants, ethnobotanic, ethnocultural groups, Tog

Effect of a zinc oxide, at the cathode interface, on the efficiency of inverted organic photovoltaic cells based on the CuPc/C60 couple

The effect of ZnO buffer layer on the performances of inverted multilayers organic solar cells has been studied. ZnO:Al conductive films and insulating ZnO films deposited by spin coating have been probed. The ZnO buffer layer has been introduced between the ITO cathode and the Organic acceptor. The cells are based on the multilayer junctions bathocuproine/fullerene/copper phthalocyanine. The organic photovoltaic cells performances improvement depends of the ZnO layer introduced. ZnO:Al conductive layers decreases the potential barrier at the interface cathode/organic. This allows decreasing the series resistance which improves significantly the cell efficiency. Insulating ZnO increases only slightly the solar cells performance by increasing significantly the shunt resistance and therefore the open circuit voltage of the cells

Kentucky bluegrass invaded rangeland: ecosystem implications and adaptive management approaches

USDA-NRCS National Resources Inventory data indicates that between 2011 and 2015 Kentucky bluegrass (Poa pratensis) was present in 14.5% on non-Federal rangelands nationally and 86% in North Dakota, 63% in South Dakota, 40% in Kansas, 38% in Nebraska, and 32% in Montana. Native grasslands provide important services such as nutrient cycling, forage and habitat for wildlife and livestock, pollinator habitat, carbon capture, and regulation of hydrologic cycles, among others. Therefore, grassland degradation due to invasive plant species has far-ranging consequences for both human and ecological systems. We present information from a symposium at the 2019 Society for Range Management Annual Meeting. The symposium covered three topic areas that have been the foci of NGP Kentucky bluegrass research in the last five years: (1) impacts of Kentucky bluegrass on ecosystem services (especially soil water regulation, pollinator services, and forage production); (2) opportunities for using adaptive management approaches that include natural disturbances (such as fire and livestock grazing) for restoring and maintaining diverse grasslands; and (3) how to effectively overcome social barriers to treatment options aimed at restoring these grasslands. We present brief summaries of research progress on these topics. We conclude that despite great advances in knowledge related to Kentucky bluegrass invaded ecosystems there are still knowledge gaps regarding management of this novel ecosystem under changing climatic conditions as well as challenges regarding large scale adoption of management practices needed to manage these systems appropriately

Biophysical and electrochemical studies of protein-nucleic acid interactions

This review is devoted to biophysical and electrochemical methods used for studying protein-nucleic acid (NA) interactions. The importance of NA structure and protein-NA recognition for essential cellular processes, such as replication or transcription, is discussed to provide background for description of a range of biophysical chemistry methods that are applied to study a wide scope of protein-DNA and protein-RNA complexes. These techniques employ different detection principles with specific advantages and limitations and are often combined as mutually complementary approaches to provide a complete description of the interactions. Electrochemical methods have proven to be of great utility in such studies because they provide sensitive measurements and can be combined with other approaches that facilitate the protein-NA interactions. Recent applications of electrochemical methods in studies of protein-NA interactions are discussed in detail

Conformational Changes in DNA upon Ligand Binding Monitored by Circular Dichroism

Circular dichroism (CD) spectroscopy is an optical technique that measures the difference in the absorption of left and right circularly polarized light. This technique has been widely employed in the studies of nucleic acids structures and the use of it to monitor conformational polymorphism of DNA has grown tremendously in the past few decades. DNA may undergo conformational changes to B-form, A-form, Z-form, quadruplexes, triplexes and other structures as a result of the binding process to different compounds. Here we review the recent CD spectroscopic studies of the induction of DNA conformational changes by different ligands, which includes metal derivative complex of aureolic family drugs, actinomycin D, neomycin, cisplatin, and polyamine. It is clear that CD spectroscopy is extremely sensitive and relatively inexpensive, as compared with other techniques. These studies show that CD spectroscopy is a powerful technique to monitor DNA conformational changes resulting from drug binding and also shows its potential to be a drug-screening platform in the future

Biogenic and Synthetic Polyamines Bind Cationic Dendrimers

Biogenic polyamines are essential for cell growth and differentiation, while polyamine analogues exert antitumor activity in multiple experimental model systems, including breast and lung cancer. Dendrimers are widely used for drug delivery in vitro and in vivo. We report the bindings of biogenic polyamines, spermine (spm), and spermidine (spmd), and their synthetic analogues, 3,7,11,15-tetrazaheptadecane.4HCl (BE-333) and 3,7,11,15,19-pentazahenicosane.5HCl (BE-3333) to dendrimers of different compositions, mPEG-PAMAM (G3), mPEG-PAMAM (G4) and PAMAM (G4). FTIR and UV-visible spectroscopic methods as well as molecular modeling were used to analyze polyamine binding mode, the binding constant and the effects of polyamine complexation on dendrimer stability and conformation. Structural analysis showed that polyamines bound dendrimers through both hydrophobic and hydrophilic contacts with overall binding constants of Kspm-mPEG-G3 = 7.6×104 M−1, Kspm-mPEG-PAMAM-G4 = 4.6×104 M−1, Kspm-PAMAM-G4 = 6.6×104 M−1, Kspmd-mPEG-G3 = 1.0×105 M−1, Kspmd-mPEG-PAMAM-G4 = 5.5×104 M−1, Kspmd-PAMAM-G4 = 9.2×104 M−1, KBE-333-mPEG-G3 = 4.2×104 M−1, KBe-333-mPEG-PAMAM-G4 = 3.2×104 M−1, KBE-333-PAMAM-G4 = 3.6×104 M−1, KBE-3333-mPEG-G3 = 2.2×104 M−1, KBe-3333-mPEG-PAMAM-G4 = 2.4×104 M−1, KBE-3333-PAMAM-G4 = 2.3×104 M−1. Biogenic polyamines showed stronger affinity toward dendrimers than those of synthetic polyamines, while weaker interaction was observed as polyamine cationic charges increased. The free binding energies calculated from docking studies were: −3.2 (spermine), −3.5 (spermidine) and −3.03 (BE-3333) kcal/mol, with the following order of binding affinity: spermidine-PAMAM-G-4>spermine-PAMMAM-G4>BE-3333-PAMAM-G4 consistent with spectroscopic data. Our results suggest that dendrimers can act as carrier vehicles for delivering antitumor polyamine analogues to target tissues

Effect of SGLT2 inhibitors on stroke and atrial fibrillation in diabetic kidney disease: Results from the CREDENCE trial and meta-analysis

BACKGROUND AND PURPOSE: Chronic kidney disease with reduced estimated glomerular filtration rate or elevated albuminuria increases risk for ischemic and hemorrhagic stroke. This study assessed the effects of sodium glucose cotransporter 2 inhibitors (SGLT2i) on stroke and atrial fibrillation/flutter (AF/AFL) from CREDENCE (Canagliflozin and Renal Events in Diabetes With Established Nephropathy Clinical Evaluation) and a meta-Analysis of large cardiovascular outcome trials (CVOTs) of SGLT2i in type 2 diabetes mellitus. METHODS: CREDENCE randomized 4401 participants with type 2 diabetes mellitus and chronic kidney disease to canagliflozin or placebo. Post hoc, we estimated effects on fatal or nonfatal stroke, stroke subtypes, and intermediate markers of stroke risk including AF/AFL. Stroke and AF/AFL data from 3 other completed large CVOTs and CREDENCE were pooled using random-effects meta-Analysis. RESULTS: In CREDENCE, 142 participants experienced a stroke during follow-up (10.9/1000 patient-years with canagliflozin, 14.2/1000 patient-years with placebo; hazard ratio [HR], 0.77 [95% CI, 0.55-1.08]). Effects by stroke subtypes were: ischemic (HR, 0.88 [95% CI, 0.61-1.28]; n=111), hemorrhagic (HR, 0.50 [95% CI, 0.19-1.32]; n=18), and undetermined (HR, 0.54 [95% CI, 0.20-1.46]; n=17). There was no clear effect on AF/AFL (HR, 0.76 [95% CI, 0.53-1.10]; n=115). The overall effects in the 4 CVOTs combined were: Total stroke (HRpooled, 0.96 [95% CI, 0.82-1.12]), ischemic stroke (HRpooled, 1.01 [95% CI, 0.89-1.14]), hemorrhagic stroke (HRpooled, 0.50 [95% CI, 0.30-0.83]), undetermined stroke (HRpooled, 0.86 [95% CI, 0.49-1.51]), and AF/AFL (HRpooled, 0.81 [95% CI, 0.71-0.93]). There was evidence that SGLT2i effects on total stroke varied by baseline estimated glomerular filtration rate (P=0.01), with protection in the lowest estimated glomerular filtration rate (45 mL/min/1.73 m2]) subgroup (HRpooled, 0.50 [95% CI, 0.31-0.79]). CONCLUSIONS: Although we found no clear effect of SGLT2i on total stroke in CREDENCE or across trials combined, there was some evidence of benefit in preventing hemorrhagic stroke and AF/AFL, as well as total stroke for those with lowest estimated glomerular filtration rate. Future research should focus on confirming these data and exploring potential mechanisms

Safety of intravenous ferric carboxymaltose versus oral iron in patients with nondialysis-dependent CKD: an analysis of the 1-year FIND-CKD trial.

Background: The evidence base regarding the safety of intravenous (IV) iron therapy in patients with chronic kidney disease (CKD) is incomplete and largely based on small studies of relatively short duration. Methods: FIND-CKD (ClinicalTrials.gov number NCT00994318) was a 1-year, open-label, multicenter, prospective study of patients with nondialysis-dependent CKD, anemia and iron deficiency randomized (1:1:2) to IV ferric carboxymaltose (FCM), targeting higher (400-600 µg/L) or lower (100-200 µg/L) ferritin, or oral iron. A post hoc analysis of adverse event rates per 100 patient-years was performed to assess the safety of FCM versus oral iron over an extended period. Results: The safety population included 616 patients. The incidence of one or more adverse events was 91.0, 100.0 and 105.0 per 100 patient-years in the high ferritin FCM, low ferritin FCM and oral iron groups, respectively. The incidence of adverse events with a suspected relation to study drug was 15.9, 17.8 and 36.7 per 100 patient-years in the three groups; for serious adverse events, the incidence was 28.2, 27.9 and 24.3 per 100 patient-years. The incidence of cardiac disorders and infections was similar between groups. At least one ferritin level ≥800 µg/L occurred in 26.6% of high ferritin FCM patients, with no associated increase in adverse events. No patient with ferritin ≥800 µg/L discontinued the study drug due to adverse events. Estimated glomerular filtration rate remained the stable in all groups. Conclusions: These results further support the conclusion that correction of iron deficiency anemia with IV FCM is safe in patients with nondialysis-dependent CKD