Étude in vitro de l’effet antifalcémiant des globules rouges et de l’activité antioxydante d’extraits de la poudre de racines de Maytenus senegalensis Lam (Celestraceae)

La drépanocytose est une hémoglobinopathie largement répandue chez les populations africaines noires. Actuellement, très peu de traitements conventionnels existent sur le marché, d’où le recours à la médecine traditionnelle. Maytenus senegalensis est une plante prescrite par les tradipraticiens dans la prise en charge de la drépanocytose. L’activité antifalcémiante des extraits de la poudre de racines de Maytenus senegalensis a été étudiée dans ce travail. Après obtention de l’extrait hexanique par extraction à l’aide d’un Soxhlet, le marc est macéré dans de l’acétate d’éthyle puis dans du méthanol pour donner les extraits correspondants. L’activité des fractions a été évaluée sur des drépanocytes de type SS. Les activités antifalcémiantes les plus importantes ont été observées pour les fractions polaires du méthanol et de l’acétate d’éthyle avec des taux d’inversion de la falciformation respectivement de 77% et de 65% à 10 mg/mL. Les activités antioxydantes de M. senegalensis (CI50 = 0,195 ± 0,004 mg/mL) et de l’acide ascorbique (CI50 = 0,078 ± 0,002 mg/mL) ont été déterminées. Les pouvoirs antioxydants (PA) montrent que l’activité antiradicalaire de l’acide ascorbique (PA = 12,85) est 2,5 fois meilleure que celle de M. senegalensis (PA = 5,14). Les résultats de l’étude justifient l’utilisation traditionnelle des racines de Maytenus senegalensis dans la prise en charge de la drépanocytose.Mots clés : Hémoglobine, drépanocytose, Maytenus senegalensis, activité antifalcémiante, stress oxydant, radicaux libres, activité antioxydante

A Novel HPLC Method for Direct Detection of Nitric Oxide Scavengers from Complex Plant Matrices and Its Application to Aloysia triphylla Leaves

The present study aimed at developing an original pre-column HPLC assay allowing rapid characterization of nitric oxide (NO) scavengers from complex plant extracts. Sodium nitroprusside (SNP) was employed as a NO donor and spiked with an aqueous extract from Aloysia triphylla leaves prior to HPLC analysis. Relying on the ability of radical scavenging constituents to be oxidized upon reaction with radicals, this assay successfully allowed direct identification of three potential NO scavengers, including verbascoside, isoverbascoside, and luteolin-7-O-diglucuronide. These three phenolics were also individually assessed for their NO scavenging activities by using a Griess colorimetric assay. With respective IC50 values of 56 ± 4, 51 ± 3, and 69 ± 5 µg/mL, verbascoside, isoverbascoside, and luteolin-7-O-diglucuronide were all reported as potent NO scavenging compounds, confirming the efficiency of the SNP spiking HPLC assay. The present method can, thus, be considered as a valuable and effective approach for speeding up the discovery of NO scavenging constituents

Antioxidant and antiglycation properties of two mango (Mangifera indica L.) cultivars from Senegal

Objective: To evaluate the total phenolic contents, antioxidant and antiglycation activities of leaves, barks, roots and kernels from two cultivars of Mangifera indica (Anacardiaceae). Methods: Total phenolic contents were determined by using Folin-Ciocalteu's method. The antioxidant activities were assessed by three different protocols including DPPH, oxygen radical absorbance capacity and iron (II) chelation assays. In addition, in vitro bovine serum albumin/D-ribose assay was chosen to evaluate the antiglycation properties of the extracts. Results: All the investigated extracts were found to contain high level of total phenols as well as potent antioxidant activities. Kernel extracts showed the highest total phenol contents and DPPH radical scavenging activities whereas higher oxygen radical absorbance capacity values were observed for leave, root and bark extracts. Besides, extracts from leaves, roots and barks from both cultivars exhibited potent inhibitory effects against the formation of advanced glycation end products, with IC50 values lower than the standard positive control aminoguanidine. Conclusions: The potent antiglycation and antioxidative activities of these two Mangifera indica cultivars suggest a possible role in targeting aging, diabetic complications and oxidative stress related diseases

Evaluation of antibacterial and antifungal activities of N-benzylthienopyrimidinone derivatives

This study is part of the biological investigation of the chemical library of molecules already described by the Laboratory of Organic Chemistry and Therapeutic Chemistry of the University of Bordeaux. The main objective was to explore the contribution of a thienyl moiety attached to the pyrimidinone nucleus, in the expression of an antimicrobial activity. The structural modifications mainly concerned the conservation or not of  the  benzo fragment attached to the thienyl, the saturation or not in position-1,2 of the pyrimidinone ring, the substitution on N-benzyl with more or less lipophilic units, the modification of the orientation of the thienyl fragment with, on  the one hand, the compounds in which the sulfur is located near the N1 nitrogen (series of thieno[2,3-d]pyrimidin-4-ones) and on the other hand, compounds in which the sulfur is located near the ketone group (series of thieno[3,2-d]pyrimidin-4-ones). In general, thienyl fragment with sulfur located near the ketone group and the unsaturated pyrimidinone nucleus in the 1,2-position, seem to promote a broad spectrum of antibacterial activity, with compound 9c which is active on both Gram + bacteria and Gram – bacteria studied. The same pattern was observed for antifungal activity, which is maximum with the compounds of the thieno[3,2-d]pyrimidin-4-ones series for an MIC of 31.25 μg/ml on the strains of Candida albicans and Candida kruzei studied. Keywords: Thienopyrimidinones, antibacterial activity, antifungal activity

Syntheses and crystal structure of 4-[(pyridin-3-yl)diazen­yl]morpholine and 1-[(pyridin-3-yl)diazen­yl]-1,2,3,4-tetra­hydro­quinoline

Two new heterocyclic 1,2,3-triazenes were synthesized by diazo­tation of 3-amino­pyridine following respectively by coupling with morpholine or 1,2,3,4-tetra­hydro­quinoline. 4-[(Pyridin-3-yl)diazen­yl]morpholine (I), C9H12N4O, has monoclinic P21/c symmetry at 100 K, while 1-[(pyridin-3-yl)diazen­yl]-1,2,3,4-tetra­hydro­quinoline (II), C14H14N4, has monoclinic P21/n symmetry at 100 K. These 1,2,3-triazene derivatives were synthesized by the organic medium method by coupling reactions of 3-amino­pyridine with morpholine and 1,2,3,4-tetra­hydro­quinoline, respectively, and characterized by 1H NMR, 13C NMR, IR, mass spectrometry, and single-crystal X-ray diffraction. The mol­ecule of compound I consists of pyridine and morpholine rings connected by an azo moiety (–N=N–). In the mol­ecule of II, the pyridine ring and the 1,2,3,4-tetra­hydro­quinoline unit are also connected by an azo moiety. The double- and single-bond distances in the triazene chain are comparable for the two compounds. In both crystal structures, the mol­ecules are connected by C—H⋯N inter­actions, forming infinite chains for I and layers parallel to the bc plane for II

Chemical Constituents and Antimicrobial and Antioxidant Activities of Essential Oil from Dried Seeds of Xylopia aethiopica

The study aimed to investigate the chemical composition and antimicrobial and antioxidant activities of the essential oil from dried seeds of Xylopia aethiopica. The essential oil was obtained by hydrodistillation and analyzed by GC/FID and GC/MS. The essential oil yield was 1.35%. Forty-nine compounds were identified in the essential oil with 1,8-cineole (16.3%), β-pinene (14.8%), trans-pinocarveol (9.1%), myrtenol (8.3%), α-pinene (5.9%), and terpinen-4-ol (5.6%) as major components. The antimicrobial activity of this essential oil was studied using disk diffusion and broth microdilution methods on four bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa) and one fungus (Candida albicans). The essential oil exhibited excellent activity against S. aureus, E. faecalis, and C. albicans and moderate activity against E. coli. Among all strains tested, C. albicans showed the best sensitivity with a MIC of 50 mg/mL. The antioxidant activity was examined using a DPPH-free radical scavenging assay. The essential oil of X. aethiopica showed low antioxidant activity (IC50 = 784.604 ± 0.320 mg/mL) compared to that of ascorbic acid and the reference compound (IC50 = 0.163 ± 0.003 mg/mL). The results indicate that consumption of X. aethiopica seeds can reduce the virulence of food-borne pathogens and their resistance to antibiotics

Some medicinal plants from Senegal used in the management of infectious diseases: evaluation of their antimicrobial and antiparasitic activities

Infectious diseases with bacterial origin are one of the leading causes of death worldwide, with about 17 million deaths each year. Beside these bacterial infections, several parasitic infections deserve special attention due to a lack of effective treatments. Among these infections, human African trypanosomiasis, or sleeping sickness, and leishmaniasis have a strong impact on morbimortality and makes them a public health problem. These infectious diseases, which are part of the neglected tropical diseases, urgently need to be addressed through research and development of new antibiotics and antiparasitics. The search for new drugs can be based on plant biodiversity, which is an inexhaustible reserve of bioactive natural products. Africa, and Senegal in particular, is rich in many medicinal plants used by traditional medicine in the treatment of infectious diseases. [...