SOLVENT EFFECTS ON EXTRACTION OF CHLOROGENIC ACIDS, CAFFEINE AND TRIGONELLINE IN Coffea arabica.In this research work the effects of four solvents and their mixtures on the extraction of chlorogenic acids, caffeine and trigonelline in crude extracts of four coffee cultivars, traditional red bourbon, IAPAR59, IPR101 and IPR108 cultivars, were investigated by UV spectrophotometry and UV spectra obtained from RP-HPLC-DAD. The experimental results and the principal component analysis of UV spectra showed that the effect of solvent extraction of the metabolites does not depend on cultivars, because the spectral characteristics are similar, but the concentrations are different. The UV and UV-DAD spectra for four simplex centroid design mixtures were also similar but the concentrations of caffeine, trigonelline and the chlorogenic acids are different and depend on the solvent used in the extraction.Keywords: fingerprint; mixture design; Coffea arabica. INTRODUÇÃOOs grãos do café contêm proteinas, lipidios, ácidos nucleicos, carboidratos, clorofila, carotenóides, enzimas e hormônios. Quando torrados, estes constituintes são destruidos ou podem ser transformados em uma grande variedade de novos compostos. 1 Os grãos do café verde também contém compostos biologicamente ativos como a cafeína, ácidos clorogenicos (ACG), trigonelina, entre outros. Estes metabólitos são alguns dos precursores do aroma do café. 2 A trigonelina é rapidamente decomposta na torra do café em muitos componentes voláteis, mas mesmo assim é encontrada no café torrado em concentrações mais baixas. 1 Os ACG são os principais compostos fenólicos encontrados no café, sendo ésteres de ácidos trans-cinâmico tais como, ácidos cafeico, ferúlico e p-cumárico com ácido quínico. 3 São metabólitos secundários de grande interesse econômico porque também contribuem na formação de pigmentos e sabor dos grãos do café, determinando assim a qualidade e aceitação da bebida. A cafeína, por ser o principal metabólito fisiologicamente ativo e o alcalóide quantitativamente mais importante do café, foi e ainda é o mais estudado desde a sua descoberta e identificação. 1 As duas variedades comerciais mais importantes de café são a Coffea arabica e a Coffea canephora syn. Coffea robusta, sendo C. arabica de qualidade superior. Por esta razão, vários trabalhos relatam métodos para discriminar as duas espécies. 4-9 Embora existam milhares de artigos na literatura sobre cafés defeituosos e não-defeituosos, 10,11 propriedades antioxidantes dos metabólitos, 12 os efeitos do café na saúde, 13-15 os efeitos da torrefação dos grãos de café, 12 a qualidade da bebida, 16-20 entre outros, poucos são os relatos na literatura sobre o efeito do solvente na extração de ácidos clorogênicos, cafeína e trigonelina, principalmente na variedade Coffea arabica.Nos programas de melhoramento genético do café o objetivo é desenvolver diferentes cultivares para promover ganhos na produtividade e também agregar características agronômicas de resistência às pragas e doenças. Por outro lado, a composição...
Rollinia mucosa fruit has generated great interest due to the presence of bioactive compounds, which exhibit promising biological activities. Fingerprinting analytical techniques, chromatographic-diode array detection (DAD), infrared, mass spectrometric, 1 H and 13 C nuclear magnetic resonance (NMR) spectra, associated with chemometric analysis and mixture design, were used to determine chemical discriminations of sun-exposed and self-shaded leaves of Rollinia mucosa in each of the four seasons. Sunlit leaves in winter presented higher metabolite signals related to the acetogenins, whereas shaded leaves have higher abundances of carbohydrates and terpenes. Sunlit leaves harvested in the summer had the smallest metabolite abundances. Fingerprints confirmed the presence of two acetogenins, annonacin A and annonastatin. Ternary and quaternary mixtures of the statistical mixture design were most effective for revealing important discriminations.
The simultaneous voltammetric determination of binary mixture containing hydrochlorothiazide (HCTZ) and enalapril (ENP) using a multi-walled carbon nanotubes paste (MWCNTsP) electrode is reported for the first time in the literature. Compared with the glassy carbon electrode or carbon paste electrode, MWCNTsP electrode showed excellent responses for the oxidation of HCTZ and especially for ENP. Square-wave voltammetry was used to simultaneous determination of HCTZ and ENP in their binary mixture in BR buffer solution (pH 5.0), which linear calibration curves were obtained in the range of 4.9×10 −7 -4.5×10 −5 mol L −1 and 5.0×10 −6 -8.3× 10 −5 mol L −1 , respectively. The detection limits were found to be 1.4×10 −8 mol L −1 and 4.1×10 −8 mol L −1 for the determination of HCTZ and ENP, respectively. The feasibility of the developed method for real sample analysis was investigated and the accuracy checked from analysis by HPLC.
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