Synthesis and chemical shifts of five new rotenoids.

Five new rotenoids are prepared using the synthetic approach developed by Pastine and Sames with some modifications. The 1H and 13C NMR resonances were assigned completely with certainty using a concerted application of one- and two-dimensional experiments (DEPT; gs-COSY, gs-HMQC and gs-HMBC). Keywords: 1H NMR; 13C NMR; COSY; DEPT; HMQC, HMBC; Rotenoids

Pot experiment of the uptake of metals by Amaranthus cruentus grown in artificially doped soils by copper and zinc

The supplementation of metals is a mean used to ameliorate the nutritional quality of vegetables. Pot experiment was carried to evaluate the addition effects of copper (Cu) and zinc (Zn) in soils on their distribution and those of other metals in plant tissues. The experiment consisted of growth Amaranthus cruentus, a leafy vegetable, for 30 days in a soil to which copper and zinc were added singly and in combination. At the end of the experiment roots, stems and leaves of plants were analyzed for metal uptake in tissues. The results show that accumulation of Cu and Zn was significantly higher in roots than in leaves and stems (p < 0.0001). There were no significant difference between Cu and Zn uptake in leaves and roots. The supplementation of Cu and Zn in soil had an obvious effect on the enrichment of Cu and Zn in Amaranthus cruentus, the leaves had better enrichment effect of Cu and the roots had better enrichment effect of Zn. Furthermore, the enrichment effect of Zn in leaves was also important (until 237%). The present study showed that Amaranthus cruentus plant can accumulate higher concentrations of Cu and Zn if the cultivated soil contains moderately higher Cu and Zn levels. Antagonist effects were observed between Cu and Zn supplementation and other metals in roots. In stems, it was synergic effects which were observed. Many synergic and antagonist effects between Cu and Zn added in soil and other metal transfer in leaves were often observed. Keywords: pot experiment; copper; zinc; Amaranthus cruentus; metal uptak

An overview of anti-diabetic plants used in Gabon: Pharmacology and Toxicology

© 2017 Elsevier B.V. All rights reserved.Ethnopharmacological relevance: The management of diabetes mellitus management in African communities, especially in Gabon, is not well established as more than 60% of population rely on traditional treatments as primary healthcare. The aim of this review was to collect and present the scientific evidence for the use of medicinal plants that are in currect by Gabonese traditional healers to manage diabetes or hyperglycaemia based here on the pharmacological and toxicological profiles of plants with anti-diabetic activity. There are presented in order to promote their therapeutic value, ensure a safer use by population and provide some bases for further study on high potential plants reviewed. Materials and methods: Ethnobotanical studies were sourced using databases such as Online Wiley library, Pubmed, Google Scholar, PROTA, books and unpublished data including Ph.D. and Master thesis, African and Asian journals. Keywords including ‘Diabetes’ ‘Gabon’ ‘Toxicity’ ‘Constituents’ ‘hyperglycaemia’ were used. Results: A total of 69 plants currently used in Gabon with potential anti-diabetic activity have been identified in the literature, all of which have been used in in vivo or in vitro studies. Most of the plants have been studied in human or animal models for their ability to reduce blood glucose, stimulate insulin secretion or inhibit carbohydrates enzymes. Active substances have been identified in 12 out of 69 plants outlined in this review, these include Allium cepa and Tabernanthe iboga. Only eight plants have their active substances tested for anti-diabetic activity and are suitables for further investigation. Toxicological data is scarce and is dose-related to the functional parameters of major organs such as kidney and liver. Conclusion: An in-depth understanding on the pharmacology and toxicology of Gabonese anti-diabetic plants is lacking yet there is a great scope for new treatments. With further research, the use of Gabonese anti-diabetic plants is important to ensure the safety of the diabetic patients in Gabon.Peer reviewedFinal Accepted Versio

Assessment of Fe(II), Fe(III) and Al(III) in a mineralogical profile of Gabonese soil

Four depths of a soil were sampled, extracted successively with water, 1 N KCl and aqua regia and analyzed. The soil displays a lithogenic discontinuity with a soil profile which was loam, sandy loam or clay. It was from slightly acid to strongly acid. Data showed significant correlations between soil properties and antagonist effects between Fe ions in the iron oxide formation. Metal speciation by a three extraction scheme showed that the total concentration of Fe(II) in the four soil horizons decreased as function of depth when the concentration of Al(III) and Fe(III) increased in the same time. The mineralogical fraction, the bigger fraction, decreased for all elements studied. This change led to increase significatively the water-soluble and exchangeable fractions of Fe(II) and exchangeable fraction of Al(III) and Fe(III). Significant correlations indicated inter-dependence of fractions and showed the influence of soil properties on the solubility and mobility of aluminum and iron. Keywords: acid soils; metals; sequential extractio

Adapter et réinterpréter l’histoire : transformation fictionnelle et résurgences des origines chez Henri Troyat, Joseph Roth et Pierre Sammy

Résumé : Henri Troyat, Joseph Roth et Pierre Sammy recomposent les événements historiques en fonction de leurs objectifs narratifs et identitaires. Ils mêlent fidélité apparente et esthétique littéraire. Les romanciers s’appuient pour ainsi dire sur la transmotivation (modification des causes) et la transpragmatisation (altération des faits) pour exprimer une vision personnelle et nuancée de l’Histoire. Dans La Lumière des justes, Henri Troyat explore la Russie impériale et raconte la conspiration décembriste de 1825 à travers une reconstitution mêlant faits historiques et détails fictionnels. Il parvient à recréer des scènes réalistes tout en les adaptant aux enjeux dramatiques de son récit. Cette hybridité narrative reflète les dilemmes des personnages face aux bouleversements politiques et culturels. Joseph Roth, dans La Marche de Radetzky et La Crypte des capucins, revisite la bataille de Solferino en introduisant le personnage fictif de Joseph Trotta, héros sauvant l’empereur François-Joseph. Cette récriture, absente des récits officiels, magnifie un patriotisme autrichien. Pierre Sammy, dans L’Odyssée de Mongou, revisite l’histoire des tirailleurs africains pendant la Première Guerre mondiale en intégrant des éléments culturels africains comme le « bakolai », un pacte de fraternité. Ce procédé transforme la participation des Noirs en un acte enraciné dans les traditions africaines, substituant aux rapports de domination une vision fraternelle et mystique. Ces auteurs réinterprètent l’Histoire pour enrichir la mémoire collective et donner voix à des perspectives marginalisées. Mots-clés : Récriture historique, Hybridité narrative, Transmotivation, Transpragmatisation, Identité culturelle

Phytochemical screening, total polyphenols and flavonoids content and antiradical activity of methanolic extract of Lannea welwitschii (Hiern) Engl. (Anacardiaceae) from Gabon

The present study was carried out to identify chemical groups, measure polyphenols and total flavonoids, and evaluate the anti-free radical activity of the methanolic extract of the trunk bark of Lannea welwitschii who is a plant currently used to treat various diseases in the gabonese pharmacopoeia so as respiratory tract infections. The phytochemical screening was carried out on the methanolic (maceration) extract using standard laboratory methods. Total polyphenols and total flavonoids were measured by spectrophotometric assay while anti-free radical activity was assessed by ABTS method. The Phytochemical screening revealed the presence of polyphenols, tannin, flavonoids, alkaloids, reducing compounds, terpenes and coumarins. The determination of the total polyphenols of the methanolic extract from gallic acid showed a content of 598.18 ± 6.69 mg EAG/100 g of dry matter and the total flavonoids from quercetin showed a content of 91.71 ± 2.43 mg EQ/100 g of dry matter. Finally, the evaluation of the anti-free radical activity showed that the methanolic extract of the trunk bark of Lannea welwitschii has a weak free radical activity compared to that of gallic acid: IC50 are respectively 76.57 μg/ml and 0.47 μg/ml

Spectrokinetic studies of two 6,6a-dihydrochromeno(3,4-b) chromene derivatives

Benzo and Naphthopyrans (chromenes) have been extensively studied since the discovery of photochromic reaction of 2H-1-benzopyrans in 1966 by Becker and Michl. Researchers have investigated chromenes for their use in sunglass lenses and also other potential applications such as optical memories and optical switches. Femto/picosecond and nano/microsecond experiments were released on two 6,6a-dihydrochromeno(3,4-b)chromene derivatives. After disappearance of the singlet state S1 formed from each compound, photoproducts with short lifetime (2.2 to 21 ?s) obtained were attributed to the open forms. Keywords: 6,6a-dihydrochromeno(3,4-b)chromene, photochromic, nano/microsecond domain, femto/picosecond domain, wavelength, lifetime.

Phytochemical analyses of aqueous extracts of two medicinal plants from Gabon: Pseudospondias longifolia and Antrocaryon klaineanum

Pseudospondias longifolia (Anacardiaceae) and Antrocaryon klaineanum (Anacardiaceae) are two plants used in the traditional medicine in Gabon. The aqueous extracts of their stem barks were phytochemically analysed. Alkaloids, saponins, tannins and reductor compounds were found in the extract of both plants. Flavonoids were only found in the extract of Pseudospondias longifolia whereas both extracts did not contain sterols and terpenoids. Keywords: Pseudospondias longifolia, Antrocaryon klaineanum, phytochemical, medicinal plants

The Effect of the Oxygen Concentration on the Zinc Oxide Films Properties Deposited by Magnetron Sputtering

The influences of the oxygen concentration variation on the zinc oxide films structural properties were studied. ZnO films were deposited on silicon substrate by rf magnetron sputtering in reactive plasma using a zinc oxide target. They exhibited a c-axis orientation of below 0.32° FWHM of X-ray rocking curves, an extremely high resistivity of 1012 ?cm and an energy gap of 3.3 eV at room temperature. It was found that a substrate temperature of 100°C, very low gas pressures of 3.35x10-3 Torr in argon and oxygen mixed gas atmosphere giving to ZnO thin films a good homogeneity and a high crystallinity. Measurements of the ac conductivity properties of ZnO sandwich structures with silver and platinum electrodes are reported. The frequency dependence of the both the ac conductivity and dielectric constant of thin films of ZnO have been investigated in the frequency range 5Khz-13Mhz. It is shown that the total ac conductivity ; obeys the equations  where s is an index which increases with frequency and decreases with temperature. The dielectric constant, , lies in the range 8–9 at room temperature and is independent of the frequency in the dielectric thin films.   Keywords: ZnO; R.F sputtering magnetron; X-ray diffraction; conductivity; electrical properties; dielectric properties; optical properties