Aloysia polystachya is popularly used to treat various conditions. The aim of the study was to evaluate the chemical composition, some physicochemical properties and in vitro antioxidant activity of an ethanolic extract of the species. Extracts retain a higher content of essences that infusions or decoctions. It was detected five groups of metabolites (two of them as traces) and the physicochemical properties were similar to those of the employed solvent. It was quantified total phenols (2.32 ± 0.16 mg GAE/mL E), total flavonoids (0.37 ± 0.01 mg QE/mL E) and in vitro antioxidant activity by UV-visible spectrophotometry. The free radical scavenging capacity would be about three times smaller than the reference substance and the total antioxidant activity equivalent to 0.83 mg of Trolox/mL extract.

Aloysia polystachya se usa popularmente para tratar diversas afecciones. El objetivo del estudio fue evaluar la composición química, algunas propiedades fisicoquímicas y la actividad antioxidante in vitro de un extracto etanólico de la especie. Los extractos conservan un mayor contenido de esencias que las infusiones o decocciones. Se detectaron cinco grupos de metabolitos (dos de ellos como trazas) y las propiedades fisicoquímicas resultaron similares a las del solvente. Se cuantificaron fenoles totales (2,32 ± 0,16 mg EAG/ml E), flavonoides totales (0,37 ± 0,01 mg EQ/ml E) y actividad antioxidante in vitro por espectrofotometría. La capacidad de captar radicales libres sería aproximadamente tres veces menor que la sustancia de referencia y la actividad antioxidante total equivaldría a 0,83 mg de Trolox/ml de extracto.

Potentiometric studies of sulfathiazole (HST) in the presence and absence of cobalt(II) were performed. Equilibrium constants for the formation of the detected species, [Co(ST)]+ and [Co(ST)(OH)], are reported. UV-Vis spectrophotometric measurements suggest that the coordination Co(II)-sulfathiazole might be through a N atom, which, in agreement with MO calculations, could be a thiazolic one. In spite of sulfonamides being better ligands at pH >7, [Co(ST)]+ was found at pH » 3.