Recherche de composés à activité antiplasmodiale à partir de la biodiversité malgache

Dans le cadre de la recherche de nouveaux composés à activité antiplasmodiale, deux plantes de Madagascar ont été étudiées : Pyrostria major (Rubiaceae) et Gonioma malagasy (Apocynaceae). Leurs extraits acétate d éthyle et alcaloïdique ont montré une activité antiplasmodiale significative vis-à-vis de la souche chloroquino-résistante FcB1 lors d un criblage préliminaire. L étude phytochimique des feuilles de P. major a conduit à l isolement du b sitostérol ainsi que de huit nouveaux diarylheptanoïdes glycosylés, décrits pour la première fois dans une plante appartenant à la famille des Rubiaceae. L activité antiplasmodiale de l extrait AcOEt des feuilles est probablement due à la présence du b sitostérol. Cette activité serait due à l effet stomatocytogénique provoqué par cette famille de composés. L utilisation de l "Exciton chirality" a permis de déterminer la configuration absolue des diarylheptanoïdes glycosylés isolés. Cette étude structurale nous a permis d obtenir d une part, deux composés antiplasmodiaux sélectifs et non cytotoxiques et d autre part, un composé antileishmanien et un autre antitrypanosomal. L étude de l extrait alcaloïdique de G. malagasy a conduit à l isolement d une nouvelle série chimique, "les goniomedines". Ces dernières sont caractérisées par un squelette bisindolique constitué de deux monomères dihydroindoliques reliés par une unité dihydropyrane. Une étude configurationnelle basée sur le calcul théorique de spectres de dichroïsme circulaire ainsi que sur des considérations biogénétiques, a permis la détermination de leur configuration absolue. Parmi ces composés, un seul a montré une activité antiplasmodiale significative.As part of the search for new compounds with antiplasmodial activity, two malagasy plants were studied: Pyrostria major (Rubiaceae) and Gonioma malagasy (Apocynaceae). The Ethyl acetate and alkaloidic extracts showed significant antiplasmodial activity against the chloroquine-resistant strain FcB1 during a preliminary screening. The phytochemical study of the leaves of P. major has led to the isolation of b-sitosterol together with eight new diarylheptanoid glucoside, described for the first time in a plant belonging to the Rubiaceae family. The antiplasmodial activity of the EtOAc extract of the leaves is probably due to the presence of b-sitosterol. This activity is due to the stomatocytogenic effect caused by this family of compound. The use of the "exciton chirality" has determined the absolute configuration of the natural diarylheptanoid glucoside. This structural study allowed us to obtain, two selective antiplasmodial and non-cytotoxic compounds, as well as potential antileishmanial and antitrypanosomal compounds. The study of the alkaloidic extract of G. malagasy led to the isolation of a novel chemical series, "The goniomedines." They are characterized by a bisindole backbone consisting of two monomers connected by a dihydropyran unit. Their absolute configurations were deduced following the comparison of experimental and theoretically calculated ECD spectra and through biogenetic considerations. Among these compounds, only one showed a significant antiplasmodial activity.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Constituents from stem barks of Anacolosa poilanei Gagnep. (Olacaceae)

Four compounds were isolated from the stem barks of Anacolosa poilanei Gagnep. Theirs structures were established by spectroscopic analysis including MS and NMR. Accordingly, the isolates were identified as trichadenic acid B (1), trichadonic acid (2), amentoflavone (3) and β-sitosterol (4)

Chemical constituents from fruits of Hydnocarpus hainanensis Merr. (Flacourtiaceae) in Vietnam

Five compounds were isolated from the fruits of Hydnocarpus hainanensis Merr. Sleum. (Flacourtiaceae). Their structures were determined by spectroscopic analysis including MS and NMR. The isolates were identified as taraktophyllin (1), hydnocarpic acid (2), 3,4-dihydroxybenzyl alcohol (3), 3,4-dihydroxybenzoic acid (4) and 3-hydroxy-4-methoxybenzoic acid (5)

Thành phần hóa học và hoạt tính gây độc tế bào của lá cây Vót dạng cơm cháy Viburnum sambucinum (Caprifoliaceae)

Viburnum sambucinum is a small woody tree belongs to the genus Viburnum (Caprifoliaceae), mainly distributed in Vietnam, Lao and Cambodia. Extensive studies of the genus Viburnum have led to the identification of many compounds, such as diterpenes, triterpenes, iridoids, monoterpenes, sesquiterpenes, flavonoids, lignans, etc. In previous study, we reported 6 terpenoids isolated from the leaves of Viburnum sambucinum. In this study, we describe the isolation and structural characterizations of  four compounds hupehenol D (1), hupehenol A (2), 12β-hydoxy-3,15-dioxo- 20,21,22-23,24,25,26,27-octanordammanran (3), luteolin (4) and in vitro cytotoxic activities of ten compounds (1-10) from the leaves of  Viburnum sambucinum. Compound 1 and 3 exhibited significant cytotoxic activity against 4 cancer cell lines with IC50 value 4.71±0.03-5.35±0.04 μM. The compounds 2, 4, 6, 7 and 9 displayed week cytotoxicity with IC50 values ranging from 9.31± 0.12 to 82.06±0.94 mM

Terpenoids from leaves of Viburnum sambucinum Reinw. ex. Blume (Caprifoliaceae)

Six compounds were isolated from the leaves of Viburnum sambucinum Reinw. ex Blume (Caprifoliaceae).  The structures of the isolates were determined by spectroscopic analysis including MS and NMR. Accordingly, the isolated compounds were identified as a-amyrin (1), ursolic acid (2), 3β,28-dihydroxy-urs-12-ene (3), oleanolic acid (4), 16β-hydroxylup-20(29)-ene-3-one (5) and trans-2-phyten-1-ol (6)

Alkaloids from alphonsea elliptica barks and their biological activities

This study was carried out to investigate the phytochemicals from the barks of Alphonsea elliptica. The barks were harvested from Hutan Simpan Sembarong, Kluang, Johor; and extracted using dichloromethane (DCM), hexane and methanol successively. Isolation of dichloromethane crude extract was then performed using silica gel column chromatography and preparative thin layer chromatography (PTLC) techniques. Structural identification were carried out via 1D and 2D NMR, UV, IR, MS and comparison with reported data. Phytochemical study of the barks led to the isolation of five alkaloid in which two were oxoaporphines; atherospermidine (1) and liriodenine (2),two were dioxoaporphines;cepharadione A (3) and N-methylouregidione (4), and an azafluorenone alkaloid; kinabaline (5). The hexane, DCM, and methanol crude extracts, together with five isolated alkaloids, were tested for their radical scavenging activity, inhibition of xanthine oxidase activities and cytotoxicity. Atherospermidine and liriodenine possessed antioxidative activities with IC50 value of 20.17 and 10.73, respectively. Atherospermidine, liriodenine, N-methylouregidione and kinabaline showed xanthine oxidase inhibitiory activityof 46.29, 7.66, 42.10 and 50.72 μM,respectively. Meanwhile, atherospermidine, liriodenine, cepharadione A and kinabaline showed cytotoxicity against breast cancer cell line with IC50 89, 86, 79.85 and 62 μg/mL respectively. All the alkaloids tested in this study were isolated for the first time from this species while cepharadione A is reported for the first time in a species belongs to Alphonsea genus

Reshaping of Bulbar Odor Response by Nasal Flow Rate in the Rat

The impact of respiratory dynamics on odor response has been poorly studied at the olfactory bulb level. However, it has been shown that sniffing in the behaving rodent is highly dynamic and varies both in frequency and flow rate. Bulbar odor response could vary with these sniffing parameter variations. Consequently, it is necessary to understand how nasal airflow can modify and shape odor response at the olfactory bulb level.To assess this question, we used a double cannulation and simulated nasal airflow protocol on anesthetized rats to uncouple nasal airflow from animal respiration. Both mitral/tufted cell extracellular unit activity and local field potentials (LFPs) were recorded. We found that airflow changes in the normal range were sufficient to substantially reorganize the response of the olfactory bulb. In particular, cellular odor-evoked activities, LFP oscillations and spike phase-locking to LFPs were strongly modified by nasal flow rate.Our results indicate the importance of reconsidering the notion of odor coding as odor response at the bulbar level is ceaselessly modified by respiratory dynamics