ESTUDO QUÍMICO E FARMACOLÓGICO DA Verbena minutiflora (VERBENACEAE)

Abstract

Verbena minutiflora (Verbenaceae) is popularly known as gervão. It is consumed as an infusion for the treatment of various diseases. However, so far there is no pharmacological or chemical validation to support its therapeutic applications. Therefore, the analysis of the chemical composition and pharmacological activities of V. minutiflora is of paramount importance. In this study, extracts and infusions of the aerial parts of V. minutiflora (leaves, flowers and stems) were analysed during four consecutive years. Extracts of leaves and flowers had significantly higher phenolic content and antiradical capacity than stems regardless of the year of collection. The infusions of leaves presented constant composition throughout the studied period with high levels of bioactive compounds and high antioxidant potential. The chemical composition was elucidated by HPLC-DAD and LC-ESI-MS/MS. The phenylpropanoids, verbascoside and isoverbascoside and the iridoid hastatoside were identified by interpretation and comparison of its UV and ESI-MS/MS spectra with data from literature. An in house validation study showed good accuracy and precision to determine the bioactive compounds in V. minutiflora by HPLC-DAD. Phenylpropanoids varied in extracts (leaves 139.70 to 221.20 mg/g, flowers 106.43 to 227.22 mg/g, stems 42.18 to 56.48 mg/g). Verbascoside was in higher concentration in extracts of leaves (87.66 – 136.16) mg/g and flowers (58.12 – 148.96) mg/g than in stems (19.24 – 24.62) mg/g. Iridoids in extracts were: leaves (46.60 − 54.79) mg/g, flowers (55.88 − 93.87) mg/g and stems (40.05 to 61.74) mg/g. High levels of iridoids (314.70 − 415.10) μg/mL, phenylpropanoids (1996.39 − 2674.13) μg/mL and verbascoside (1029.38 − 1456.42 μg/mL) in infusions support the popular consume of V. minutiflora. The content of metal ions pointed out that Verbena minutiflora is rich in K, Ca, Na and Mg. The analysis in acute diuresis model in rats has shown that ethyl acetate fraction and infusion Verbena minutiflora has diuretic activity.