15 research outputs found
In Vitro Proliferation and Production of Cytokine and IgG by Human PBMCs Stimulated with Polysaccharide Extract from Plants Endemic to Gabon
No full textPolysaccharides were extracted from seven plants endemic to Gabon to study their potential immunological activities. Peripheral blood mononuclear cell (PBMC) (5 × 105 cells/mL) proliferation, cytokine and immunoglobulin G (IgG) assays were performed after stimulation with different concentrations of polysaccharide fractions compared with lipopolysaccharides (LPS) and concanavalin A (ConA) from healthy volunteers. The culture supernatants were used for cytokine and IgG detection by enzyme-linked immunosorbent assay (ELISA). The results show that pectin and hemicellulose extracts from Uvaria klainei, Petersianthus macrocarpus, Trichoscypha addonii, Aphanocalyx microphyllus, Librevillea klaineana, Neochevalierodendron stephanii and Scorodophloeus zenkeri induced production levels that were variable from one individual to another for IL-12 (3–40 pg/mL), IL-10 (6–443 pg/mL), IL-6 (7–370 pg/mL), GM-CSF (3–170 pg/mL) and IFN-γ (5–80 pg/mL). Only hemicelluloses from Aphanocalyx microphyllus produce a small amount of IgG (OD = 0.034), while the proliferation of cells stimulated with these polysaccharides increased up to 318% above the proliferation of unstimulated cells. However, this proliferation of PBMCs was abolished when the pectin of some of these plants was treated with endopolygalacturonase (p < 0.05), but the trend of cytokine synthesis remained the same, both before and after enzymatic treatment or saponification. This study suggests that these polysaccharides stimulate cells in a structure-dependent manner. The rhamnogalacturonan-I (RGI) fragment alone was not able to induce the proliferation of PBMC
Screening of antioxidant activities of polysaccharides extracts from endemic plants in Gabon
No full textInternational audienceThe usage of plants as food, cosmetics or medicinal products is common throughout the world, particularly in the traditional medicines of Africa, Asia, and South America. Despite this long-standing use, many properties of plant constituents, including their capacity to inactivate reactive oxygen species, remain unknown today. In this context, polysaccharides were isolated from barks, leaves or stems of endemic plants of Gabon by sequential extractions of crude cell walls with oxalate and KOH. Analysis of fractions indicated that pectic extracts are mainly composed of HG and RG-I in various proportions whereas hemicellulose fractions are composed of both XXXG-type xyloglucans and (1,4)-xylans substituted by 4-O-Me GlcUA residues. Antioxidant activities of these plant extracts were evaluated by monitoring their free radical scavenging activity of 2-2-diphenyl, 1-picrylhydrazyl, iron reducing capacity and metal chelating activity. Pectin from four extracts presented antioxidant activity in the DPPH assay compared to ascorbic acid (AA). These extracts also exhibited high ferric iron reducing powers compared to AA but low ferrous ion-chelating properties compared to EDTA. These activities were concentration-dependent. In contrast, commercially available pectins, xyloglucan and arabinoxylan were found to be inactive in both assays. The free scavenging activity of these molecules disappeared after enzymatic digestion and saponification, whereas the iron reducing power partially remains after these two treatments. The fact that all pectins and hemicelluloses from the three plants reacted differently suggests that specific structural motifs are involved for generation of antioxidant activit
In vitro Studies on Proliferation and Production of Cytokine and IgG by Human PBMCs Stimulated with Polysaccharide Extract from Plants Endemic to Gabon
No full textIn vitro Studies on Proliferation and Production of Cytokine and IgG by Human PBMCs Stimulated with Polysaccharide Extract from Plants Endemic to Gabon
No full textPolysaccharides were extracted from seven plants endemic to Gabon to study their potential immunological activities. Peripheral blood mononuclear cell (PBMC) (5 × 105 cells/mL) proliferation, cytokine and immunoglobulin G (IgG) assays were performed after stimulation with different concentrations of polysaccharide fractions compared with lipopolysaccharides (LPS) and concanavalin A (ConA) from healthy volunteers. The culture supernatants were used for cytokine and IgG detection by enzyme-linked immunosorbent assay (ELISA). The results show that pectin and hemicellulose extracts from Uvaria klainei, Petersianthus macrocarpus, Trichoscypha addonii, Aphanocalyx microphyllus, Librevillea klaineana, Neochevalierodendron stephanii and Scorodophloeus zenkeri induced production levels that were variable from one individual to another for IL-12 (3–40 pg/mL), IL-10 (6–443 pg/mL), IL-6 (7–370 pg/mL), GM-CSF (3–170 pg/mL) and IFN-γ (5–80 pg/mL). Only hemicelluloses from Aphanocalyx microphyllus produce a small amount of IgG (OD = 0.034), while the proliferation of cells stimulated with these polysaccharides increased up to 318% above the proliferation of unstimulated cells. However, this proliferation of PBMCs was abolished when the pectin of some of these plants was treated with endopolygalacturonase (p < 0.05), but the trend of cytokine synthesis remained the same, both before and after enzymatic treatment or saponification. This study suggests that these polysaccharides stimulate cells in a structure-dependent manner. The rhamnogalacturonan-I (RGI) fragment alone was not able to induce the proliferation of PBMC. This study confirms the immunostimulatory properties of polysaccharides
In Vitro Proliferation and Production of Cytokine and IgG by Human PBMCs Stimulated with Polysaccharide Extract from Plants Endemic to Gabon
No full textInternational audiencePolysaccharides were extracted from seven plants endemic to Gabon to study their potential immunological activities. Peripheral blood mononuclear cell (PBMC) (5 × 10 5 cells/mL) proliferation, cytokine and immunoglobulin G (IgG) assays were performed after stimulation with different concentrations of polysaccharide fractions compared with lipopolysaccharides (LPS) and concanavalin A (ConA) from healthy volunteers. The culture supernatants were used for cytokine and IgG detection by enzyme-linked immunosorbent assay (ELISA). The results show that pectin and hemicellulose extracts from Uvaria klainei, Petersianthus macrocarpus, Trichoscypha addonii, Aphanocalyx microphyllus, Librevillea klaineana, Neochevalierodendron stephanii and Scorodophloeus zenkeri induced production levels that were variable from one individual to another for IL-12 (3–40 pg/mL), IL-10 (6–443 pg/mL), IL-6 (7–370 pg/mL), GM-CSF (3–170 pg/mL) and IFN-γ (5–80 pg/mL). Only hemicelluloses from Aphanocalyx microphyllus produce a small amount of IgG (OD = 0.034), while the proliferation of cells stimulated with these OPEN ACCESS Molecules 2014, 19 18544 polysaccharides increased up to 318% above the proliferation of unstimulated cells. However, this proliferation of PBMCs was abolished when the pectin of some of these plants was treated with endopolygalacturonase (p < 0.05), but the trend of cytokine synthesis remained the same, both before and after enzymatic treatment or saponification. This study suggests that these polysaccharides stimulate cells in a structure-dependent manner. The rhamnogalacturonan-I (RGI) fragment alone was not able to induce the proliferation of PBMC
Cytotoxicity and lymphoproliferative activities of polysaccharides from two endemic plants of Gabon
No full textInternational audienc
In vitro antioxidant activities of polysaccharides from endemic plants of Gabon
No full textInternational audienc
Etude Phytochimique de Senna occidentalis (L.) Link et Cissus quadrangularis (Linn) deux Plantes Médicinales Gabonaises Utilisées Contre la Filaire Loa Loa
No full textObjectif : Cette étude avait pour objectif de valoriser deux plantesmédicinales utilisées au Gabon pour traiter la filaire Loa loa. Matériels etMéthodes : Les poudres des feuilles de Senna occidentalis et des tiges etfeuilles de Cissus quadrangularis ont été soumis à une successiond’extractions par des solvants de polarités croissantes (cyclohexane,dichlorométhane, méthanol et l’eau déminéralisée). Un criblagephytochimique qualitatif a été effectué en utilisant la méthode standard baséesur desréactions de colorations et/ou de précipitations. Résultats: lesrésultatsrévèlent la prédominance des sucres totaux, des alcaloïdes, et des phénols danstous les extraits. Les des tanins cathéchiques, les sucres réducteurs, et lesflavonoïdes sur de nombreux extraits testés. Les tanins galliques et les coumarines sont retrouvés dans quelques extraits. Très peu de quinones, detriterpènes ou stérols dans les deux plantes. Conclusions : Certainsmétabolites secondaires ont déjà prouvé leurs activités filaricides. La richesseen composés chimiques présents dans ces plantes médicinales étudiées,justifierait leur utilisation. Cependant, l’évaluation des activités biologiquessur la filariose à Loa loa ainsi que leur toxicité reste à explorer.
Objective: This study aimed to valorize two medicinal plants usedagainst Loa loa filarial in Gabon. Material and Methods: Powders of leavesof Senna occidentalis and stems and leaves of Cissus quadrangularis wereproposal to successive extractions by solvents with increasing polarities (cyclohexan, dichloromethan, methanol and demineralized water). QualitativePhytochemistry screening was established using the standard color and/orprecipitation reactions. Results: The results reveal the predominance of totalsugar, alkaloids, and phenols in all extracts. Cathechic tannins, reducing sugar,and flavonoids on many extracts were tested. Gallic tannins and coumarins arefound in some extracts. They are very few quinones, triterpenes or sterols inthe two species. Conclusion: Some secondary metabolites have provedfilaricide activities already. The abundance of chemical compounds present inthese medicinal plants would justify their usage. However, the evaluation ofbiological activities on the Loa loa filarial along with toxicity remainsunexplored.
 
Antiproliferative Effect Of Alcoholic Extracts Of Some Gabonese Medicinal Plants On Human Colonic Cancer Cells
No full textExtracts from Piptadeniastrum africanum Brenan (Mimosaceae),
Petersianthus macrocarpus (Breauv) L. (Lecydaceae), Cissus debilis
Planch (Vitaceae) and Dieffenbachia seguine Jacq. (Araceae) were
tested in vitro for their antiproliferative activity on human colon
cancer cell line (CaCo-2). The highest antiproliferative activities
were obtained with the alcoholic extracts of the roots of
Piptadeniastrum africanum (G-PAR), the leaves of Petersianthus
macrocarpus (G-PMF) and the stem of Cissus debilis (G-CDL), with 50%
inhibition concentrations (IC50) of 15 μg/ml, 17 μg/ml and 25
μg/ml respectively. Only one extract (leaves of Dieffenbachia
seguine (G-DSF)) exhibited weak antiproliferative activity with 50%
inhibition concentration (IC50) higher than 50 μg/ml
Analysis of toxicity and hemostatic properties of polysaccharides from plants endemic to Gabon
No full textInternational audiencePlants are commonly used throughout the world, most particularly in Africa for different purposes including use as drugs, food and cosmetics. Polysaccharides were extracted from the cell walls of seven plants endemic to Gabon, Uvaria klainei, Petersianthus macrocarpus, Trichoscypha addonii, Aphanocalyx microphyllus, Librevillea kleaneana, Neochevalierodendron stephanii and Scorodophloeus zenkeri. Pectins and hemicelluloses from these plants were extracted using ammonium oxalate and potassium hydroxide and their sugar compositions were determined using gas chromatography. These fractions were used to test their toxicity compared to standard products such as mercuric chloride (HgCl2), 4-Nitro-quinoloine (4-NOQ), 2-Amino-Anthracene (2AA) and ivermectin. Their anticoagulant capacity was tested by measuring Activated Partial Thromboplastin Time (APTT), prothrombin time (PT/QT) compared to snake venom and the heparin response. The results showed that these extracts had no cytotoxicity since the IC50 of polysaccharide extracts and ivermectin varied from 456.62 to 892.42 &mug/mL compared to standard toxic HgCl, 4-NOQ, 2AA: 1.8-22 &mug/mL. No genotoxicity or pro-genotoxicity was found: the SOS test Inhibiting Factor (IF) from pectins and hemicelluloses varied from 0.4 to 1.2 compared to the standard genotoxic 4-NOQ, with an IF of 9.33. Acute toxicity was not observed, as indicated by the minimum inhibition at 20% (MIC20) that varied from 25.45 to 65.85 for polysaccharides, while the standard toxic level was at a MIC20 of 0.0284. However, in vitro anticoagulant activities were detected. De-esterification and enzyme degradation of the homogalacturonan pectin chains did not change the hemostatic trend of pectic fractions
