CONICET | Buscador de Institutos y Recursos Humanos

Introduction Knowledge of the therapeutic properties of plants is a challenge for modern science. Currently, 25% of the therapeutic arsenal is of natural origin and many served as prototypes for the design of new drugs. In the Argentine Northwest, the fruit of chañar (Geoffroea decorticans Gill. ex Hook. & Arn.) and mistol (Ziziphus mistol Griseb) and their arropes (derived from the two types of fruit cooked in their own juices without added sugar), were used by indigenous communities, not only for food but also for the treatment of various diseases, especially respiratory diseases. Biofilm microorganisms are very difficult to deal with commercial antimicrobial agents, making the search for bioactive metabolite in native plants is a valid project that should be explored. The aim of this study was to evaluate the activity of extracts and arropes of mistol and chañar on growth and biofilm production on Pseudomonas aeruginosa. Materials and Methods Plant material: The ripe fruit of two native species of NOA, Z. mistol (mistol) and G. decorticans (chañar) were collected during the months of December and January, in Icaño, province of Santiago del Estero, Argentina. Extraction: Alcoholic and aqueous extracts were obtained by maceration. Arropes were prepared, following the technique used by locals of Icaño, Santiago del Estero (1). Microorganism: P. aeruginosa ATCC 27853. Culture medium: Luria Bertani pH 6.0. The incubation in micro plates was for 24 hours at 37 °C. Determination of growth: by optical density at 560 nm. Biofilm formation was measured using the protocol (2). Two concentrations were tested (50 μg/ml and 5μg/ml). The extracts were dissolved in distilled water. Azithromycin and ciprofloxacin were employed as positive controls in the same concentrations as the extracts. Results: Chañar extracts and arropes, both doses tested, produced an inhibition between 20 to 30% in the production of biofilm and bacterial growth. Furthermore, none of the mistol extracts were able to inhibit bacterial growth; however, they significantly inhibited the production of biofilm. The greatest effect was observed in mistol arrope at a dose of 5 mg/ml (40%). Conclusions and Discussion These studies suggest that the observed decrease in the biofilm in both types of fruit is due to different mechanisms. The specific production of biofilm for chañar (Biofilm produced/number of cells), is kept constant, that is, inhibition of bacterial growth was responsible for the decrease in the production of biofilm. In contrast, the specific production of biofilm in the presence of mistol extract is modified by mechanisms unrelated to the bacterial growth, so that, subsequent studies of the mechanisms of action should be performed. References 1) Figueroa G, Dantas M. La Zaranda de Ideas, Revista de Jóvenes Investigadores en Arqueología 2006; 2: 35-50. 2) O'Toole GA, Kolter R. Molecular Microbiology 1998; 28: 449-61.