LAUSR

Abstract H. laricifolium Juss is a native shrub from the Andes used for the treatment of antibacterial infections among other illnesses. Nowadays, due to the growing need of new antibiotic substances, this medicinal plant would represent an important source for the investigation of antibacterial activity due to the wide medicinal potential of its genus, property that can be analyzed through its chemical fingerprint profile. The objectives of this research were, to develop a predictive model for the antibacterial potential of the genus Hypericum using chromatographic fingerprinting with three Hypericum species collected at Ecuadorian Andes (H. laricifolium, H. quitense R. Keller and H. decandrum Turcz); and to evaluate the influence of natural variables such as altitude and soil composition on the pharmacological effect of lipophilic extracts of H. laricifolium. Antibacterial activity of the plants extracts was assessed by plate microdilution technique against Methicillin-resistant Staphylococcus aureus (MRSA). The fingerprint was obtained by HPLC-DAD. The predictive model was constructed from the chromatographic fingerprint of H. laricifolium and H. quitense and their IC50 values using the "Partial least squares" multivariate analysis tool. Using the regression coefficients of the model, the predictive equation of antibacterial activity for new samples of H. decandrum was established. The extracts of H. laricifolium exhibited a high antibacterial activity with the pH and the organic matter as main factors influencing the activity. The prediction model obtained did not have predictive ability to different Hypericum species, which could be explained by differences in the chemical composition of the three species.