Triterpénoïdes et stéroïdes isolés des feuilles de Hyperacanthus thouvenotii (Rubiaceae), une plante endémique de Madagascar

peer reviewedMadagascar, connu par sa richesse biologique, abrite une flore exceptionnelle, avec un taux d’endémisme de plus de 80%. Nombreuses plantes ont une potentialité thérapeutique. Pourtant, une partie seulement est étudiée. Beaucoup d’espèces endémiques n’ont pas fait l’objet d’études chimique ni biologique. L’espèce Hyperacanthus thouvenotii (Rubiaceae) en fait partie. L’objectif de cette étude est d’isoler et d’identifier les composés chimiques contenus dans cette espèce en vue de valoriser la plante ou ces molécules à des fins thérapeutiques. Les extractions des poudres de feuilles par macération à froid avec des solvants de polarité croissante ont donné les extraits de dichlorométhanique et méthanolique. Le fractionnement et l’isolement des constituants chimiques ont été réalisés par chromatographie sur colonne ouverte de silice. L’identification et l’élucidation structurale des produits isolés ont été faites par la technique de CPG/MS munie de librairie NIST et Wiley ainsi que par spectroscopie RMN. Cinq produits connus ont été identifiés. β-sitostérol, acide ursolique et deux autres triterpènes ont été isolés et identifiés de l’extrait de dichlorométhane. β-sitosterol-3-O-glucoside a été isolé de l’extrait méthanolique. Ces composés sont décrits pour la première fois dans le genre Hyperacathus

Triterpenoid and steroid coumponds isolated from leaves of Hyperacanthus thouvenotii (Rubiaceae), endemic plant from Madagascar

Madagascar is well known for its biodiversity. Its flora is exceptional, with an endemism rate of more than 80 %. Many plants have therapeutic potential. However many of them have not been studied. Those include the many endemic species like Hyperacathus thouvenotii (Rubiaceae) which has neither been studied for its chemical composition nor its biological activities. The aims of this study were to isolate and indentify compounds from Hyperacathus thouvenotii in order to valorize the plant and its molecules for therapeutic and chemotaxonomic purposes. To isolate, a weighed mass of air-dried and powdered leaves of the plant were extracted by maceration successively at room temperature with dichloromethan and methanol. The fractionation and isolation were carried out using an open column packed with silica gel. The chemical structures were elucidated by using GC/MS and NMR spectroscopy. Seven known coumponds have identified for the first time in Hyperacathus thouvenotii. Those are β-sitosterol, ursolic acid, uvaol, moretenol, 24-hydroxy α-amyrin, 24-hydroxy β amyrin in dichloromethan extract and β-sitosterol-3-O-glucoside in methalonic extrac

Pentas longiflora Oliv. (Rubiaceae), a plant used in the treatment of Pityriasis Versicolor in Rwanda: Chemical composition and standardization of leaves and roots

In Rwanda, the roots of Pentas longiflora Oliv. (Rubiaceae) have been used for a long time to treat Pityriasis versicolor. However, many people reported the use of leaves instead of roots. This research was conducted to compare the phytochemical composition and establish chromatographic methods for the standardization of roots and leaves extracts of P. longiflora. During this process, three new pentalongin glycosides (pentalonginoside A, pentalonginoside B, and pentalonginoside C) and two known glycosides of the same type (harounoside and clarinoside), as well as rutin, luteolin-7-rutinoside were isolated from methanol extract of leaves. In addition, pentalongin and psychorubrin, previously isolated from ethylacetate roots extract, were also identified in Pentas longiflora ethylacetate leaves extract. The presence of the antifungal compound pentalongin in leaves may explain the traditional use of leaves in the treatment of Pytiriasis versicolor. Furthermore, harounoside, psychorubrin, and pentalongin were selected as markers for HPLC fingerprints of MeOH extract. The accuracy and risk profile demonstrated the reliability of the validated method. In general, considerable variations of concentration in plant metabolites, including pentalongin, were observed between samples from different sites. The content in pentalongin (expressed as juglone) in collected samples ranged between 1.7 and 70.0 mg/100 g. The highest concentration (70.0 ± 17 mg/100 g) was registered in the cultivated samples from Mukoni. This important variation of pentalongin concentrations according to sampling sites, shows that in order to guarantee equivalent efficacy, finished products with P. longiflora should be standardized based on their pentalongin content

Isolated conpounds and bioactivity screening of extracts from three endemic species to Madagascar belonging to Hyperacanthus genus (Rubiaceae)

The Hyperacanthus genus (Rubiaceae) contains species endemic to southern Africa and mainly to Madagascar that remain chemically and biologically underexplored. This study aimed to describe chemical constituents of three endemic species of Madagascar belonging to this genus : H. thouvenotii, H. poivrei and H. mangoroensis. The purpose is to investigate the biological activities of their crude extracts in order to valorize these plants in phytomedicine. Isolation and characterization of chemical constituents of Hyperacanthus species were achieved using different chromatographic techniques followed by structure elucidation with spectroscopic techniques. Eleven known compounds such as α-amyrin, β-sitosterol, β-sitosterol-3-O-glucoside, stigmasterol, uvaol, ursolic acid, moretenol, 24-hydroxy α-amyrin, 24-hydroxy β-amyrin, vitexin and sorbitol were isolated for the first time from Hyperacanthus genus. The antiplasmodial and cytotoxic activities of the crude extracts were performed on 3D7 strain of Plasmodium falciparum and on human melanoma A2058 and human breast cancer MDA-MB-231 cell lines, respectively. The dichloromethane extract of H. thouvenotii showed a promising antiplasmodial activity with an IC50 value of 13.40±1.61 µg/mL and a selectivity index of SIMDA-MB-231/3D7 = 4.10. The dichloromethane extracts of H. poivrei and H. mangoroensis exhibited a moderate activity with an IC50 of 19.71±1.68 µg/mL ; SI >5 and 16.47±0.64 µg/mL ; SI > 6, respectively. The in vitro antioxidant activity was assessed by DPPH method and expressed by its IC50 and antioxidant activity index (AAI). All of the methanol extracts and infusion of H. poivrei have a very strong antioxidant activity with IC50 and AAI values ranging from 9.36±0.85 to 11.18±1.31 µg/mL and 4.59±0.40 to 3.86±0.45, respectively. In acute oral toxicity test, all the methanolic extracts did not cause any toxicity effects nor mortality at the different administered doses. Theoretical lethal dose is up to 2000 mg/kg body weight. This is the first isolation of moretenol, 24-hydroxy α-amyrin and 24-hydroxy β-amyrin from plants belonging to Rubiaceae family. This is the first report on antiplasmodial, cytotoxic, antioxidant activities and acute oral toxicity of species belonging Hyperacanthus genus

Le recours aux plantes médicinales à Madagascar

Madagascar, une grande île au large de l’Afrique, est un pays avec un immense territoire mais aussi une biodiversité immensément riche. Cette richesse biologique unique est due vraisemblablement à l’évolution en vase clos, loin des grands prédateurs et mammifères herbivores que l’on trouve en Afrique ; mais également par l’existence de reliefs, écosystèmes et régions bioclimatiques variés qui hébergent cette biodiversité. Et à tout cela s’ajoute, au fil du temps, les apports des explorateurs, des voyageurs, des commerçants et des migrants venus de l’extérieur qui ont peuplé l’île au cours de son histoire. Les populations ont toujours vécu en symbiose avec la nature qui les entoure. Elles ont obtenu de la nature tout ce dont elles ont besoin dans la vie courante, comme la nourriture, les matériaux de construction et aussi les remèdes pour se soigner. En effet, les différentes communautés de l’Île savaient se soigner depuis toujours. Pour cela, elles ont eu recours à ce que la nature leur offrait, en particulier les plantes, et cela bien avant l’arrivée de la médecine occidentale. L’importance de cette « médecine » pour la population est telle qu’à l’époque de la royauté, l’utilisation et la vente des remèdes traditionnels firent déjà l’objet d’encadrements. Mais à l’arrivée du christianisme, puis de la colonisation, les médecines traditionnelles furent bannies. Il fallut attendre les années 2000 et les recommandations de l’OMS pour voir le gouvernement prendre des initiatives pour rendre ses lettres de noblesse à la médecine traditionnelle et essayer d’encadrer la « filière ». Des initiatives qui ne sont pas toujours suivies sur le terrain. Ainsi, le souhait du gouvernement d’intégrer la médecine traditionnelle dans le système de santé officiel se heurte parfois aux méfiances et appréhension réciproques des acteurs concernés. Pourtant de nombreuses enquêtes ethnobotaniques effectuées à travers tout le pays révèlent bien l’importance que représentent les thérapies traditionnelles et l’usage des plantes médicinales pour la population jusqu’à nos jours. Cela est particulièrement vrai pour les communautés des villages reculés, mais également pour la population des villes. Ces différentes communautés continuent de recourir à ces plantes médicinales pour traiter les maladies courantes et presque communes aux différentes localités à Madagascar, notamment la diarrhée, la gastralgie, les infections respiratoires et la toux, le paludisme ainsi que pour le traitement des plaies

Activités Antibactérienne et Antioxydante de Trois Espèces de Hyperacanthus (Rubiaceae) Endémiques de Madagascar

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Preliminary Phytochemical Content and Antidiabetic Potential Investigations of Panda oleosa (Pierre) Used in Kisangani Areas

peer reviewedaudience: researcher, professional, studentPanda oleosa Pierre (POP), a tropical plant tree, has been used in traditional medicine in Kisangani city and around to treat various diseases including diabètes and HIV/AIDs. This study aims to evaluate the chemical composition of POP extracts while setting up chromatographic fingerprints for their quality control, and the anti-hyperglycemic potential of trunk bark aqueous extracts of POP. Common chemical reactions were used for identification of main secondary metabolic groups. Thin layer chromatography was used to set up several chromatographic fingerprints of water and alcoholic extracts while evaluating chemical composition. Oral glucose tolerance test served to induce hyperglycemia in a rabbit model. The extracts were given as 25 mg/kg, 50 mg/kg, and 100 mg/kg body weight, 30 minutes before loading animals with glucose 4 g/kg. Blood samples were collected at various times: just before extracts (T-30), before (T0) and after glucose load (T30, T60, T120, and T180). Blood glucose levels were measured with One Touch Glucometer. The identification tests revealed the presence of saponins (3.58%), tannins (5%); alkaloids, quinones, flavonoids, and terpenes sterols could not be formerly detected by the reagents used. Interesting chromatographic spots were observed whose behaviors are of catechic tannin proanthocyanes. The extract significantly reduced glucose levels in dose dependent manner as compared to control and glibenclamide reference groups. The average of mean percentage of reduction in glucose level at T120 with the extract 100 mg/kg was close to that of glibenclamide 0.25 mg/kg (49% and 40.2%). These findings back the traditional use of the plant to treat diabetic patients and constitute a foundation for an extensive study to find a new antidiabetic phythomedicine

Hyperacanthus genus (Rubiaceae): an underexplored source of bioactive compounds

peer reviewedThe Hyperacanthus genus (Rubiaceae) contains species endemic to southern Africa and mainly to Madagascar [1–5] that remains chemically and biologically underexplored. This study aimed to describe chemical constituents and investigate biological activities of hree endemic species of Madagascar belonging to this genus: H. thouvenotii, H. poivrei and H. mangoroensis. Twelve compounds were isolated, and two other compounds such as oleanolic acid and chlorogenic acid were detected for the first time from Hyperacanthus genus. The antiplasmodial and cytotoxic activities of the crude extracts and compounds were performed on Plasmodium falciparum 3D7 strain, on human melanoma A2058 and human breast cancer MDA‑MB‑231 cell lines, respectively. The dichloromethane extracts of these species showed a promising to moderate antiplasmodial activity with an IC50 ranging from 13.40 ± 1.61 to 19.71 ± 1.68 μg/mL and a selectivity index (SI) up to 3.87. The in vitro antioxidant activity was assessed by DPPH method and expressed by its IC50 and antioxidant activity index (AAI). All of the methanol extracts and infusions of the three species have a very strong antioxidant activity with IC50 and AAI values ranging from 9.36 ± 0.85 to 11.18 ± 1.31 μg/mL and 4.59 ± 0.40 to 3.86 ± 0.45, respectively. This is the first isolation of moretenol, 24-hydroxy α-amyrin and 24-hydroxy β-amyrin from plants belonging to the Rubiaceae family. These results suggest that Hyperacanthus species have a potential for exploitation as a source of antimalarial and antioxidant agents

Antiplasmodial and cytotoxic activities of Catatia cordata Humbert (Asteraceae) and Symphonia eugenioides Baker (Clusiaceae), two endemic plants of Madagascar

peer reviewedMadagascar has an important diversity of endemic plants. However, this resource is little explored. Symphonia eugenioides and Catatia cordata are two endemic species of Madagascar which haven’t yet been subjected to any biological nor chemical studies. The present research aimed to evaluate the antiplasmodial activity of these species. The purpose is to find novel antimalarial compound within these species. The antiplasmodial activity of dichloromethane and methanol extracts of S. eugenioides (bark) and C. cordata (leaves) were evaluated against the chloroquine-resistant Plasmodium falciparum strain (W2). The cytotoxicity was also tested on human melanoma A2058 and human breast cancer MDA-MB-231 cell lines. The dichloromethane extracts of S. eugenioides and C. cordata showed the best antiplasmodial activity, with IC50 values of 7.70±0.62 and 9.23±1.77 µg/mL, respectively. The dichloromethane extract of S. eugenioides had also a significant cytotoxic activity against A2058 and MDA-MB-231 cell lines with IC50 values of 17.17±2.80 and 14.48±4.94 µg/mL, respectively. The different chromatographic analysis (LC-DAD and TLC) indicated the presence of ursolic acid and oleanolic acid in dichloromethane extract and chlorogenic acid in methanolic extract in methanolic extract of C. cordata. This is the first report on antiplasmodial, cytotoxic activities and chemical content for S. eugenioides and the first findings on species belonging Catatia genus. The results have indicated that these two plants can potentially be used to treat malaria. S. eugenioides may also contain some potent active compounds for developing anticancer agent.3. Good health and well-bein