Evaluation des activités anti-Candida et immunostimulatrice de l’infusé aqueux de tiges de Gouania longipetala (Hemsl.), une plante de la pharmacopée camerounaise

Abstract

The general objective of this work was to evaluate the anti-Candida and immunostimulatory activities of the aqueous infused with stems of Gouania longipetala (Hemsl.), a plant from the Cameroonian pharmacopoeia. The anti-Candida activity of this extract was evaluated on seven strains of Candida by the liquid dilution method. Based on the results obtained, the extract inhibited the growth of all strains tested and was fungicidal on 6 of them. The extract is believed to bind to ergosterol resulting in degeneration of the fungal plasma membrane. Two bioactive compounds have been isolated there, namely alphitolic acid and epigouanic acid. In further work, the effect of the extract on microbial biofilms, antifungals and induced candidemia in rats was evaluated. At sub-inhibitory concentrations, the extract significantly reduced biofilm formation in all Candida strains tested. A significant reduction in the metabolism of preformed biofilms was also observed. The combination of the extract with the antifungals showed synergistic interactions in which the MICs of the antifungals were reduced by 50 to 98.43%. Furthermore, the extract was active on induced candidemia in rats by significantly reducing the fungal load in the blood and kidneys of infected animals. After 4 days of treatment at a dose of 400 mg/kg extract, the fungal load in the blood was reduced by 99.99%. The extract's immunostimulatory activity was then evaluated in vitro on olymorphonuclear neutrophils (PMNs) and in vivo on the rat reticuloendothelial system. Based on the results, the GLE extract stimulated phagocytic activity of PMNs at concentrations between 5 µg/mL (4.25%) and 640 µg/mL (42.55%). In vivo, the GLE extract caused a significant increase in the phagocytic index of the reticuloendothelial system of animals treated at doses of 50 mg/kg (P <0.01), 100 mg/kg (P <0.001) and 200 mg/kg (P <0.001). Finally, the toxicity of the extract was assessed. It was found that the GLE extract has a high selectivity for the Candida strains tested and could eliminate the pathogen in the host without causing tissue damage. The aqueous infusion of the stems of Gouania longipetala (Hemsl.) Could be used in therapy against infections due to Candida