Synthese et activite biologique d'antiviraux derivant de la thymidine

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Chemical composition and antimicrobial activity of the essential oils of leaves, roots and bark of Glossocalyx staudtii

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Probing for the presence of glucosinolates in three Drypetes spp. ( Drypetes euryodes (Hiern) Hutch., Drypetes gossweileri S. Moore, Drypetes laciniata Hutch.) and two Rinorea spp. ( Rinorea subintegrifolia O. Ktze and Rinorea woermanniana (Büttner) Engl.) from Gabon

International audienceDrypetes euryodes (Hiern) Hutch., Drypetes gossweileri S. Moore, Drypetes laciniata Hutch. (Putranjivaceae), Rinorea subintegrifolia O. Ktze, and Rinorea woermanniana (Büttner) Engl. (Violaceae) from Gabon were probed for the presence of glucosinolates (GLs). When present, the GLs were identified and quantified by HPLC analysis. 2-Hydroxy-2-methyl GL (1) was the major GL in the cork of D. euryodes. Moreover, 4-hydroxybenzyl GL (2) was the major GL in the seed of D. gossweileri whereas the bark contained 2 as the minor GL and benzyl GL (3) was the major one. In addition, 4-methoxybenzyl GL (4), 3-methoxybenzyl GL (5), and 3 were found in the root of R. subintegrifolia. However, no GL was detected in D. laciniata (leaf and stem), D. euryodes (leaf and stem), and R. woermanniana (leaf and stem-branch). Our results support the hypothesis of the existence of GLs in plants of the Putranjivaceae and Violaceae families (order Malpighiales)

Essential Oil of Plectranthus tenuicaulis Leaves from Gabon, Source of (R),(E)-6,7-Epoxyocimene. An Unusual Chemical Composition within the Genus Plectranthus

International audienceWater distilled essential oils from leaves of Plectranthus tenuicaulis (Hook. f.) J. K. Morton collected in Gabon were analyzed using GC-FID and GC-MS. The main constituent, unusual within the genus Plectranthus, was isolated and formally identified as being the (+)-(R)- enantiomer of (E)-6,7-epoxyocimene [(E)-myroxide]. This enantiomer, which represents about 75% of the essential oil, has been previously identified as a pheromone emitted by the male fruit-spotting bug Amblypelta nitida; this insect is responsible of destruction of most fruit crops in tropical and subtropical areas. The potential application of P. tenuicaulis essential oil in crop protection programs is discussed and the atypical chemical profile of the gabonese essential oil is compared with those previously reported in the genus Plectranthus (or Coleus)

Probing for the presence of glucosinolates in three <i>Drypetes</i> spp. (<i>Drypetes euryodes</i> (Hiern) Hutch., <i>Drypetes gossweileri</i> S. Moore, <i>Drypetes laciniata</i> Hutch.) and two <i>Rinorea</i> spp. (<i>Rinorea subintegrifolia</i> O. Ktze and <i>Rinorea woermanniana</i> (Büttner) Engl.) from Gabon

<p><i>Drypetes euryodes</i> (Hiern) Hutch., <i>Drypetes gossweileri</i> S. Moore, <i>Drypetes laciniata</i> Hutch. (Putranjivaceae), <i>Rinorea subintegrifolia</i> O. Ktze, and <i>Rinorea woermanniana</i> (Büttner) Engl. (Violaceae) from Gabon were probed for the presence of glucosinolates (GLs). When present, the GLs were identified and quantified by HPLC analysis. 2-Hydroxy-2-methyl GL (<b>1</b>) was the major GL in the cork of <i>D. euryodes</i>. Moreover, 4-hydroxybenzyl GL (<b>2</b>) was the major GL in the seed of <i>D. gossweileri</i> whereas the bark contained <b>2</b> as the minor GL and benzyl GL (<b>3</b>) was the major one. In addition, 4-methoxybenzyl GL (<b>4</b>), 3-methoxybenzyl GL (<b>5</b>), and <b>3</b> were found in the root of <i>R. subintegrifolia</i>. However, no GL was detected in <i>D. laciniata</i> (leaf and stem), <i>D. euryodes</i> (leaf and stem), and <i>R. woermanniana</i> (leaf and stem-branch). Our results support the hypothesis of the existence of GLs in plants of the Putranjivaceae and Violaceae families (order Malpighiales)<i>.</i></p

Antidiabetic potential of two medicinal plants used in Gabonese folk medicine

International audienceAbstractBackgroundDiabetes mellitus is a metabolic disorder which is rising globally in rich and developing countries. In the African region this rate is the highest, with 20 million diagnosed diabetics. Despite a noticeable progress in the treatment of diabetes mellitus by synthetic drugs, the search for new natural anti-diabetic agents is going on. Nauclea diderrichii (De Wild.) Merr. (ND) and Sarcocephalus pobeguinii Hua ex Pellegr. (SP) are used as traditional medicines in Gabon for the treatment of different diseases, especially in the case of diabetes. The aim of this study was to evaluate the antidiabetic potential of these two medicinal plants traditionally used in Gabon.MethodsPharmacological (inhibitory action on α and β-glucosidases) and toxicological (effect on human T cell proliferation) studies were conducted on aqueous extracts of ND (leaves and bark) and SP (bark) collected in Gabon. All raw extracts were analyzed by HPTLC and their content in phenolic compounds was determined by using standard method. The most active extracts were submitted to preparative HPLC in order to evidence the most efficient subfractions by biological evaluation.ResultsThe results showed that two extracts from ND were potent α-glucosidase inhibitors, the leaf extract being more active that the bark extract: the first one was more than 60 fold more active than Acarbose, which is an oral medication used to treat type 2 diabetes; the extract from SP bark was less efficient. The HPLC subfractions of the extracts of ND leaves and SP bark were tested in the same experimental conditions. In each case, the most active subfractions still show very potent inhibitory effect on α-glucosidase (80-90 % inhibition at 0.1 mg/mL). The most efficient extract, from ND leaves, was also characterized by the highest percentage of phenolic compounds, which suggests a relationship between its inhibitory potential on α-glucosidase and its content in phenolic compounds. Conversely, only a moderate inhibitory activity of the three extracts was observed on β-glucosidase.ConclusionThese results clearly indicated that active compounds present in N. diderrichii and S. pobeguinii leaves or/and bark were selective and highly potent inhibitors of α-glucosidase and validate their popular use for the treatment of diabetes