Determinação do teor de cumarina no xarope de guaco armazenado em diferentes temperaturas

Abstract

RESUMO:A produção magistral do xarope de guaco, obtido a partir do extrato fluido do guaco (Mikania glomerata Spreng., Asteraceae) e comercializada na Farmácia Universitária da UFJF/MG, gerou um projeto de pesquisa com o objetivo principal de estudar a estabilidade do produto acabado, tendo como ponto de referência a determinação do teor de cumarina das amostras armazenadas em diferentes temperaturas. O método aplicado para realizar a análise do teor de cumarina presente no xarope em estudo foi espectrometria no UV com comprimento de onda de 275,4 nm. Utilizouse como veículo para efetuar as diluições da amostra uma mistura de metanol/água destilada, na proporção de 80% v/v. A curva de calibração foi obtida diluindo-se 100 mg de cumarina padrão em 100 mL da solução descrito acima, obtendo-se sete concentrações distintas com variação de 2 µg a 20 µg. Os resultados obtidos demonstraram que a temperatura de armazenamento de 45 °C foi considerada ótima para desenvolver a conversão do isômero trans em cis com subseqüente conversão deste a cumarina. Os valores de cumarina encontrados na forma farmacêutica em estudo foram de 1,19 a 1,37 mg/mL, sendo que o valor mais alto refere-se às amostras armazenadas a 45°C durante seis meses.Unitermos: Xarope, guaco, temperatura, cumarina, Mikania glomerata, Asteraceae ABSTRACT: "Coumarin content of guaco syrup stored at different temperatures". The production of guaco syrup, obtained from guaco (Mikania glomerata Spreng., Asteraceae) fluid extract, and commercialized by the University Pharmacy of the Federal University of Juiz de Fora-MG, Brazil, led to a research project whose main aim was to study the stability of the finished product, with reference to the coumarin content of samples stored at different temperatures. UV spectrophotometry (275.4 nm) was used to assess the coumarin content of the study syrup. An 80% v/v methanol/distilled water mixture was used for sample dilution. The calibration curve was constructed by the dilution of 100 mg standard coumarin in 100 ml of the aforementioned solution, with seven distinct concentrations (ranging from 2 µg a 20 µg) being obtained. The results showed the 45 °C storage temperature to be optimum for the development of trans-cis isomerization, with subsequent conversion of the latter into coumarin. Coumarin content in the studied pharmaceutical presentation ranged from 1.19 to 1.37 mg/mL, the highest value corresponding to the samples stored at 45 °C for six months.Keywords: Syrup, guaco, temperature, cumarine, Mikania glomerata, Asteraceae.vulgarmente por "guaco", "coração-de-jesus", "guacoliso", "cipó-caatinga" e "erva-de-cobra", oficializada na 1ª edição da Farmacopéia Brasileira (Brandão et al., 2006;. É uma das espécies mais estudadas sobre o aspecto Artigo

Stability of hydroalcoholic extracts of two species of guaco; Mikania glomerata SPRENG. and Mikania laevigata SCHULTZ. (Asteraceae), by UHPLC-MS

“…After 6 months these concentrations dropped below the initial concentrations. This uncommon result was also reported by Amaral et al, 2009 who attributed the increase in coumarin to solvent loss by evaporation or the balance of cis-trans isomers of o-coumaric acid in function of the temperature, promoting the cyclization of o-coumaric acid into coumarin. However, this does not explain why a significant increase was observed only in commercial extracts which, if prepared according to the Pharmacopoeia, should not have any antioxidants or other compounds added.…”

Simultaneous Determination of Coumarin, O-Coumaric Acid,Dihydrocoumarin and Syringaldehyde in Guaco Extracts and Pharmaceutical Preparations by HPLC-DAD

“…For example, mostly of published [16][17][18] and therefore are laborious and require high time and chemical-consuming. In other cases no procedures of validation were applied [16,19] or the methods are especific for the determination of only one biomarker [17,18]. In the present work, the new method was totally validated and sucessfully applied for the simultaneous determination of the main guaco metabolites in extracts and preparations.…”

“…Consequently, for pharmaceutical preparations, mostly of developed methods require several extraction processes [16][17][18] and therefore are laborious and require high time and chemical-consuming. In other case, using UV analysis no extraction process was applied [19], however no assurance can be asserted specially regarding the selectivity, once the method was not validated and preservatives and another syrup constitutents can absorb in the same wavelength chosen [16].…”

Larvicidal potential of Mikania glomerata SPRENGEL extract on Ancylostoma caninum larvae

“…Despite not having its chemical composition fully elucidated the M. glomerata Sprengel is one of the most studied species in the pharmacognostic aspect. For M. glomerata several pharmacological activity were observed, including antifungal action, antimicrobial, bronchodilator, anti-allergic, anti-inflammatory (Brandão et al, 2006;Amaral et al, 2009;Celeghini et al, 2001).…”