CONICET | Buscador de Institutos y Recursos Humanos

Introduction: Viola arguta, purple violet or violet red field, is endemic of Ecuador. It grows in the Andes, at 1500-3500 masl, in the provinces of Zamora-Chinchipe, Azuay Bolivar Canar, Carchi, Chimborazo, Cotopaxi, Imbabura, Loja, Morona-Santiago, Pichincha and Loja. It is traditionally used to treat various conditions, including some related to inflammatory processes. To our knowledge, there are no data on its chemical composition or pharmacological action that support its traditional use. In order to provide elements to support their eventual identification and quality control, we performed preliminary phytochemical tests and screening of the characteristic secondary metabolites. Materials and Methods: The aerial parts of dried and ground V. arguta (10 g) (Specimen Voucher LPE1161) were extracted at room temperature with a solvent serie of increasing polarity: hexane, dichloromethane and methanol. The extraction of organic acids was carried out from the hexane extract diluted with methanol by precipitation with Ca(OH)2 . The precipitate was resuspended in acidified water an then extracted with ethyl acetate to give an ethyl acetate fraction (EF) according to the method of Costa Soares Oliveira. Simultaneously, an aqueous extract was obtained by making an infusion of 10 gr. of plant material in 100 mL of water. The hexane, dichloromethane and methanol extracts were evaporated in vacuum and the infusion was lyophilized. Each extract was subjected to a series of chemical tests and Thin-Layer Chromatography (TLC) on silica gel plates in different solvent systems to determine the kind of phytochemical group, as well as the chromatographic profiles. Methanol extract was analyzed by HPLC against vitexin as reference compound. The HPLC assay was carried out using a LiChrocart RP-18 analytical column with UV-detection at 336 nm. The mobile phase consisted in an isopropanol:tetrahydrofuran:water (5:15:85) mixture and flow rate was set at 1.0 ml/min. Results and Discussion: By chemical reactions we established the presence of the following phytochemical groups: tannins and saponins in methanol and aqueous extracts; mucilage in the aqueous extract, confirmed by histochemical reaction with methylene blue; and flavonoids in all extracts (hexane, dichloromethane, methanol and aqueous). TLC analysis allowed us to obtain a set of typical chromatographic profiles for each extract, which were in agreement with the results obtained from the preliminary reactions. The characteristics of color, fluorescence and Rf of the bands revealed the presence of coumarin aglycones in the hexane extract; flavone aglycones in the dichloromethane extract; flavone glycosides and coumarin heterosides in the methanol extract and absence of salicylic acid against a standard. TLC in ethyl acetate:acetic acid:formic acid:water (100:11:11:26) and HPLC analysis confirmed the presence of C-glycoside vitexin (Retention time 0 10.25) in the methanol extract. The TLC of EF in the system ethyl ether:petroleum ether:formic acid (70:30:1) and subsequent UV light, bromophenol blue and sulfuric anisaldehyde detection, suggested that an acid substance was isolated, probably a triterpene as a saponin aglycone. Conclusions: Taking into account the traditional use of V. arguta and the future possibility that it integrates a phytotherapeutic formulation, chemical tests and chromatographic profiles, in addition to the micrographic analysis constitutes the basis for a future quality control. The presence of vitexin, a flavone C-glycoside, which exhibits several biological and pharmacological properties such as anti-hypertensive, anti-inflammatory, antispasmodic, antimicrobial and antioxidant, turns V. arguta into a promising species from the perspective of its potential medical use.

enviar mensaje