Pharmacognostic study of Vernonia ferruginea, Vernonia polyanthes and Vernonia westiniana species

Abstract

Introduction: Medicinal plants have always been the subject of discussion, with knowledge of their use dating back to ancient times in the history of civilization. Vernonias are species known as “assa-peixe”, and Vernonia polianthes is popularly used to treat various pathologies. The aim of this study was to carry out pharmacognostic methods to identify species of Vernonia ferruginea, Vernonia polyanthes and Vernonia westiniana. Identifying a species becomes difficult when the plants are acquired in the form of powders, dry extracts or in liquid form such as tinctures and extracts. In this way, pharmacognostic tests were carried out, making it easier to identify the species. Methodology: Based on the physical and chemical methods described in the Brazilian Pharmacopoeia VI edition and on the website of the Brazilian Society of Pharmacognosy, some tests were carried out to identify the secondary metabolites present in the species: Vernonia ferrugínea, Vernonia polyanthes and Vernonia westiniana. Results and Discussion: In the results obtained, chemical reactions and physical methods were used to reliably identify the species studied. When determining the ash content, it is possible to differentiate them, which is more evident through chemical methods, which through reactions, determine the presence of flavonoid glycosides, alkaloids, terpenes and saponin compounds. Another practical method that provided an identification of the compound 3,7dimethyl-quercetin, isolated by high-performance liquid chromatography (HPLC), was comparative thin layer chromatography (SDLC), which verified its presence in Vernonia polyanthes and was not found in Vernonia westiniana. From the same isolated substance it was possible to quantify it in methanolic extracts and in the infusion, with higher concentrations being found in Vernonia ferruginea extracts and lower in Vernonia polyanthes infusion. Conclusion: From this pharmacognostic study, it was possible to establish a method for identifying Vernonias species, however, for better security it is necessary to use more technologically modern methods.