ANTIOXIDANT AND ANTIBACTERIAL ACTIVITIES OF HYDROALCOHOLIC EXTRACTS FROM ALOYSIA POLYSTACHYA GRISEB MOLDENKE AND LIPPIA TURBINATA GRISEB (VERBENACEAE)

Objective: The aims of this study were to determine polyphenols and flavonoids composition, to evaluate the antioxidant and antibacterial activities and possible antibacterial synergistic effects of hydroalcoholic extracts of Aloysia polystachya and Lippia turbinata. Methods: The flavonoids analysis was carried out in ethyl acetate fractions by means of high-performance liquid chromatography coupled to electrospray ionization quadrupole time of flight mass spectrometry (HPLC-ESI-Q-TOF-MS). The phenolic content was measured using Folin Ciocalteu reagent. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical method was used to estimate the antioxidant capacity. The antibacterial activity was determined by the agar microdilution and broth microdilution methods. The checkerboard assay was carried out to determine possible antibacterial synergism. Results: Several flavonoid compounds were detected for the first time in these species, being Lippia turbinata extract the one that presented the highest total phenolic content and antioxidant activity. Extracts from both species would have bactericidal activity against Staphylococcus strains employed in this work. The extract combinations had a synergistic effect against three bacteria, one of them Gram-negative. Conclusion: These extracts have demonstrated antioxidant and antibacterial activity, and its combination showed a synergistic effect against methicillin-resistant Staphylococcus aureus . Biological activities would be attributed to the whole of phytochemical constituents present in the respective crude extracts. However, it could be considered that the found flavonoids play an important role in the development of these activities. Keywords: Aloysia polystachya , Antibacterial activity, Antioxidant activity, Flavonoids, Lippia turbinata