UN ESTUDIO EXPERIMENTAL DE PROPIEDADES FÍSICAS DE SAPONINAS Y SU INTERACCIÓN CON UN MODELO DE MEMBRANA DE BACTERIAS GRAM-NEGATIVAS EMPLEANDO PELÍCULAS LANGMUIR-BLODGETT Y MICROSCOPÍA DE FUERZA ATÓMICA

Saponins are non-ionic biosurfactants that exhibit antifungal, antiviral and antibacterial properties. However, the mechanisms by which saponins exhibits these properties are not well understood. In the present work, Langmuir and atomic force microscopy (AFM) techniques were employed to investigate the interactions of saponins with a model of Gramnegative bacterial membranes. The lipid films contained extracts of phosphatidylethanolamine and phosphatidylglycerol from Escherichia coli bacteria. The results suggest that saponins repel phospholipids, thereby increasing membrane fluidity. They also showed evidence of adsorption of the saponin by the membrane model. These results were cross-checked with AFM images. A mechanism for how saponin alters the phospholipid membrane is proposed. Langmuir technique and atomic force microscopy proved to be useful tools to investigate the interaction of biologically relevant compounds with cell membrane models. The results of the surface pressure measurements, combined with those obtained from AFM, provided evidence for the susceptibility of membranes to the insertion of saponins and their possible modes of action. The results of this study may contribute to a better understanding of the mechanisms of antifungal, antiviral and antibacterial activity of saponins