Essai de Production d’extrait Bioactif et Bioaromatisant à Partir des Racines de Mondia whitei (Hook f.) Skeels (Apocynaceae) d’écologie Béninoise

Mondia whitei est une plante médicinale et aromatique populaire endémique en Afrique tropicale utilisée dans le traitement de diverses affections humaines et pour l’aromatisation de plusieurs aliments . Le présent travail vise à déterminer les meilleures conditions d’extraction desextraits bioactifs et aromatisants des racines de M. whitei pour une utilisation efficiente des vertus de ce dernier. A cet effet, une caractérisation des racines de cette plante a été réalisée à travers l’évaluation de sa toxicité larvaire, le criblage phytochimique et la recherche de l’isovanilline. Ensuite, la méthode de réponse de surface à travers un plan composite centré a été utilisée pour la détermination des conditions d’extraction. Les paramètres d’extraction variés sont la température d’extraction (25 à 75°C) et la composition du solvant (eau et chlorure de méthylène : 0 à 100%). La qualité des différents extraits obtenus lors de l’exécution du plan expérimental a été évaluée à travers la  détermination de leur densité en vanilline, en anthocyanes, de leur teneur en phénols totaux et de leur activité antioxydante. Il a été révélé la non toxicité des racines de M. whitei (CL50> 0,1mg/mL) et la présence de l’isovalline dans les racines. Le criblage phytochimique a mis en exergue la présence de huit groupes phytochimiques ayant des activités pharmacologiques avérées. L’analyse de la variance a montré que seule la composition du solvant d’extraction (eau – chlorure de méthylène) a eu un effet significatif (P<0,05) sur la qualité des extraits notamment la densité en vanilline, en anthocyanes et la teneur en phénols totaux avec des coefficients de détermination respectivement de 0,753, 0,734 et de 0,596 pour des valeurs maximales respectives de 3,00 UA (Unité d’Absorbance)/g, 1,29 UA/g et 0,426 g/100 g. Par ailleurs, aucun des paramètres d’extraction n’a affecté l’activité antioxydante des extraits. La détermination de la teneur en vanilline des racines de Mondia whitei, peut servir de marqueur de contrôle de qualité des racines de Mondia whitei. Il faudra définir d’autres paramètres pour une extraction optimale des principes bioactifs des racines de Mondia whitei.  Mondia whitei is a popular medicinal and aromatic plant endemic in tropical Africa used in the treatment of various human ailments and for the flavoring of several foods. This paper focuses on determining the best conditions for extraction of bioactive and flavoring extracts from the roots of M. whitei for an efficient use of its virtues. To this end, a characterization of the roots of Mondia whitei was made through the evaluation of its larval toxicity, phytochemical screening, and the search for isovanillin. Then, the surface response method across a centeral composite design was used to determine the extraction conditions. The extraction parameters varied are the extraction temperature (25 to 75 ° C) and the solvent composition (water and methylene chloride: 0 to 100%). The quality of the extracts obtained during the execution of the experimental plan was evaluated through the determination of their vanillin density, anthocyanins, their content of total phenols, and their antioxidant activity. The non-toxicity ofM. whitei roots (CL  50> 0.1mg / mL) and the presence of isovalline in the roots were revealed. Phytochemical screening has highlighted the presence of eight phytochemical groups with proven pharmacological activities. Analysis of the variance showed that only the composition of the extraction solvent (water - methylene chloride) had a significant effect (P <0.05) on the quality of the extracts, especially the density in vanillin, in anthocyanins, and the total phenol content. This is with coefficients of determination of 0.753, 0.734 and 0.596 for respective maximum values of 3.00 AU (Absorbance Unit) / g, 1.29 AU / g and 0.426g/100g respectively. In addition, none of the extraction parameters affected the antioxidant activity of the extracts. The determination of the vanillin content of Mondia whitei roots can serve as a quality control marker for Mondia whitei roots. It will be necessary to define other parameters for optimal extraction of the bioactive principles of Mondia whitei roots

ANTIMICROBIAL, ANTIOXIDANT, CYTOTOXIC ACTIVITIES AND PHYTOCHEMICAL ASSESSMENT OF COLA ACUMINATA USED IN BENIN

Objective: The aim of this study was to make a phytochemical screening and measure some biological activities of Cola acuminata's seeds and leaves extracts.Methods: The secondary metabolite was detected by the method based on coloring and precipitation differential reactions. The antibacterial and antifungal activities were assessed in vitro by the macrodillution and solid medium agar diffusion method. 2,2-diphényl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods were used to evaluate the antioxidant activity of the tested extracts of which larval cytotoxicity was studied.Results: Our data revealed that the seeds contain more polyphenols than the leaves. The seeds extracts displayed a good antibacterial activity against both reference strains and food Staphylococcus strains. The inhibition diameters varied from 7±2.82 to 21.5±4.94 mm. The smallest Minimum Inhibitory Concentrations (MIC) on the food strains (0.08 mg/ml) is twice less than the reference strains one (0.15 mg/ml), this observation is contrary to the Minimum Bactericidal concentrations (MBC). Susceptibility of fungal strains varies according to the extracts (p = 0.0016). The seeds ethyl acetate extracts had the best antioxidant activity with DPPH and ABTS methods. The Lethal Doses (LD50) showed that no extract was toxic.Conclusion: Cola acuminata seeds are richer than the leaves in compounds with biological activities. These two organs have interesting antimicrobial, antifungal and antioxidant activity variables depending to the extracts. The seeds have better biological activity than the leaves.Â

Spasmolytic Effects of Aqueous Extract of Sterculia setigera Delile on Isolated Rat Trachea

The spasmolytic properties of aqueous extract of Sterculia setigera was tested on Rat isolated trachea. Inhibition of the contraction was observed in presence of the aqueous extract (EC50 = 0.91mg/mL ± 0.02) after a pre contraction of the trachea by acetylcholine (10-5M). In the presence of propranolol (10-6M), the spasmolytic activity of the extract was inhibited. The EC50 value was 0.46mg/mL ± 0,11. The aqueous extract of Sterculia setigera also inhibited contraction induced by KCl (4.10-2 M) with EC50 value = 1.9mg/mL ± 0.48).  These results clearly show a relaxing effect of aqueous extract of Sterculia setigera on the trachea isolated from rat. This effect involves at least in part β-adrenergic receptor inhibition

Variation in the phytochemical composition of Chromolaena odorata (L.) King and Robinson (Asteraceae) across climatic zones in Benin (West Africa)

Chromolaena odorata (L.) King and Robinson (Asteraceae) is a tropical shrub with interesting chemical potential widely used in agriculture and medical science and which can be affected by several geographic and climatic conditions. Therefore, we investigated the phytochemical composition of this plant across climatic zones in Benin. The plant material collected from different locations was phytochemically screened by staining and precipitation tests. The total phenolic, flavonoid and tannin contents were determined using, the colorimetric method of Folin-Ciocalteu, the method of aluminum chloride and the method of vanillin, respectively, then the obtained data were subjected to analysis of variance. The phytochemical analysis revealed the presence of the main chemical groups such as alkaloids, free anthracene, coumarins, flavonoids, mucilage, tannins, reducing compounds, saponins, quinone derivatives, steroids. There was a significant difference (P < 0.05) in the phytochemical contents across geographical sites. In comparing the levels of phytochemicals among geographical locations, the raw material collected from the north climatic zone contained the highest phenolic and flavonoid contents, 147.59 ± 3.04 mg/g and 17.17 ±0.31 mg/g, respectively, compared to others. Overall, the study highlighted the potential of C. odorata as source of natural products. There was no difference in the phytochemical markers whereas the phytochemical contents vary across climatic zones. These results can be of use in the development of biopesticides from the raw material of C. odorata

SPASMOLYTIC EFFECTS OF AQUEOUS EXTRACT OF MIXTURE FROM AFRAMOMUMUM MELEGUETA (K SCHUM) – CITRUS AURANTIFOLIA (CHRISTM AND PANZER) ON ISOLATED TRACHEA FROM RAT

The spasmolytic properties of the aqueous extract of Aframomum melegueta (K Schum) and Citrus aurantifolia (Christm and Panzer) (AMCA) mixture were tested on isolated rat trachea. Inhibition of the contraction was observed the in presence of the AMCA (EC 50 = 1.80 ± 0.48 mg/mL) after a pre contraction of the trachea by acetylcholine (10 -5 M). With propranolol (10 -6 M), the spasmolytic activity of the mixture was inhibited and the concentration-response curve shifted to the right. The EC50 value was then 2.60 ± 0.41 mg/mL. AMCA also inhibited contraction induced by KCl (4.10 -2 M) with EC50 value = 1.86 ± 0.65 mg/mL. These results clearly show the relaxing effect of the aqueous extract on the isolated rat trachea. This effect involved some β-adrenergic receptor inhibition

In vitro screening of selected essential oils from medicinal plants acclimated to Benin for their effects on methane production from rumen microbial fermentation

Enteric methane production lowers the efficiency of feed utilization in ruminants and contributes to greenhouse gas emissions which are responsible for global climate change. This study examined the effects of nine essential oils (EO) from Citrus aurantifolia, Cymbopogon citratus, Eucalyptus citriodora, Laurus nobilis, Lippia multiflora, Mentha piperita, Ocimum basilicum, Ocimum gratissimum and Zingiber officinalis on enteric methane production in in vitro batch cultures screening experiments using Andropogon gayanus grass. Two in vitro batch culture incubation runs were conducted independently on separate days at two different ranges of dosages: 0 (control), 150, 300, 600 and 1200 mg/L inoculum and 0 (control), 25, 50, 100 and 150 mg/L inoculum. The effects of EO on in vitro gas production, methane production and apparent dry matter disappearance (DMD) were assessed relative to the control containing no additive. O. basilicum, E. citriodora, O. gratissimum and C. aurantifolia, significantly inhibited (Z’ ˃ 0 and relative decrease ≥ 15%) enteric methane production (g DM incubated) relative to control at dosages of 300-1200 mg/L and L. nobilis, C. citratus and M. piperita significantly decreased it at 600 and 1200 mg/L. A substantial decrease (Z’ ˃ 0 and relative decrease ≥ 15%) in methane production per g DM incubated was apparent for Z. officinalis and L. multiflora at dosage of 1200 mg/L. Most EO had globally negligible effects on methane production (Z’ ≤ 0 and relative decrease &lt; 15%) at dosages of 25 to 150 mg/L. Substantial decrease in apparent DMD together with gas production (g DM) incubated was observed relatively to the control with Z. officinalis and L. multiflora at 1200 mg/L and with the remaining EO at 600 and 1200 mg/L. Overall, this screening investigation demonstrated that addition of assayed EO (except Z. officinalis and L. multiflora) at dosages close to 300 mg/L seem to potentially decrease enteric methane production with limited negative effects on dry matter digestibility of forage grass in vitro.Key words: Essential oil, in vitro, rumen, digestibility, methane production

identification, purification et quantification de deux triterpènes bio-actifs par CCMHP dans mitracarpuss scaber

Ce travail, relate l'identification, l'isolement et la quantification densotométrique de l'acide oléanolique et de l'acide ursolique, deux acides bio-actifs dans le Mitracarpus scaber (RUBIACEAE). Une méthode de Chromatographie sur Couche Mince à Haute Performance (CCMPH) rapide, moins coûteuse que la Chromatographie Liquide à Haute Performance (CLHP) et facile à réaliser, a été développée et validée pour quantifier ces deux molécules dans Mitracarpus scaber. Nous avions utilisé une phase mobile composé d'un mélange toluène/acétate d'éthyle/méthanol (80/18/2, v/v/v) et une phase stationnaire de silicagel HP. La lecture densiométrique des plaques après développement a été faite à 215 mm. /e coefficient de variation (CV) de la méthode développée pour la calibration des standarfd était inférieur à 5% (infra-jour) et à 3% (inter-jour) pour toutes les concentrations de 0,5 mg/mL. Le tauc de récupération des deux acides de la plante par la méthode d'extraction était d'environ 98% pour les deux molécules. Les limites de détection et de quantification ont été déterminées pour respectivement 100µg/mL (soit 1µg) et 300µg/mL (soir 3 µg