RESUMELes plantes médicinales sont des véritables sources de molécules bioactives. L'objectif de la présente étude a été de tester les effets de l'extrait hydroéthanolique de Lippia multiflora sur le coeur isolé de crapaud et d'élucider son mécanisme d'action probable. Cet extrait a été obtenu après extraction aux solvants à polarité croissante. Le coeur de crapaud a été isolé et perfusé avec le ringer normal puis avec les différents produits selon le dispositif de Langerdhorff de mesure de la force et la fréquence des contractions du coeur. Les résultats obtenus montrent que l'extrait hydroéthanolique de Lippia multiflora provoque des effets inotrope et chronotrope positifs sur le coeur isolé de crapaud, semblables à ceux de l'adrénaline bien que moins marqués. Cet extrait semble provoquer l'augmentation de l'influx d'ions calcium consécutif à son action directe sur les récepteurs α1-adrénergiques cardiaques comme l'adrénaline. Les effets de cet extrait étant antagonisés par le propranolol et le vérapamil. Par ailleurs, cet extrait potentialise les effets inotrope et chronotrope positifs de l'adrénaline sur le coeur isolé de crapaud. Ces résultats suggèrent que l'extrait hydroéthanolique de L. multiflora provoque les effets inotrope et chronotrope positifs probablement suivant le même mécanisme que l'adrénaline. © 2016 International Formulae Group. All rights reserved.Mots clés : Lippia multiflora, inotrope, chronotrope, CaCl 2 , adrénaline, coeur.Effects of hydroethanolic extract of Lippia multiflora Moldenke on the heart isolated from toad ABSTRACT Medicinal plants are sources of bioactive molecules. The objective of this study was to test the effects of hydroethanolic extract of Lippia multiflora on the isolated toad heart and to elucidate its likely mechanism of action. This extract was obtained after extraction with solvents of increasing polarity. The toad heart was isolated and perfused with the normal ringer then with different products according to the Langerdhorff device for measuring the strength and frequency of heart contractions. The results obtained show that the A.W. ETOU OSSIBI et al. / Int. J. Biol. Chem. Sci. 10(6): 2617-2636 2618 hydroethanolic extract of Lippia multiflora produces positive inotropic and chronotropic effects on the isolated heart of toads, similar to those of adrenaline, although less marked. This extract seems to cause an increase in the influx of calcium ions following its direct action on cardiac α1-adrenergic receptors such as adrenaline. The effects of this extract are antagonized by propranolol and verapamil. Moreover, this extract potentiates the positive inotropic and chronotropic effects of adrenaline on the isolated heart of toad. These results suggest that the hydroethanolic extract of L. multiflora causes the positive inotropic and chronotropic effects probably following the same mechanism as adrenaline.

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Introduction: Bacillus cereus and spores produced in various ecological niches are responsible for toxic infections in humans. This study is conducted to determine the antibiotics resistance profile of B. cereus strains isolated from soil and pepper consummated in Brazzaville. Methodology: An antimicrobial susceptibility test of 16 B. cereus strains from soil and peppers was performed using 11 antibiotics by the Kirby-Bauer's diffusion on disc method. Results: Results revealed 100% (16/16) of resistance in penicillin G, amoxicillin, ceftazidime, rifampicin, and colistin, also 18.75% (3/16), 11.76% (2/16), and 18.75% (3/16) of resistance in doripenem, vancomycin and chloramphenicol respectively. In addition, we have observed 100% (16/16), 81.25% (13/16), 76.47% (13/16), 35.29% (5/16), 35.50% (6/16), and 12.5% (2/16) of sensitivity to linezolid, tigecycline, ciprofloxacin, vancomycin, doripenem and chloramphenicol respectively. However, all strains have been multidrug resistant (MDR) to betalactams, polypeptides, and ansamycins. Moreover, 7 strains (43.75%) have been variably multiresistant. One strain, Ri10 has been resistant to beta-lactams, polypeptides, ansamycins, cyclins and glycopeptides. No strain was ultraresistant (XDR) or largely insensitive (PDR) to different antibiotics. Conclusion: This study reveals that 51% of strains have been resistant to antibiotics, 32% are sensitive, and 17% have intermediate resistance. These results partly explain the high rate of gastroenteritis observed in Brazzaville due to food poisoning.