Aplicação de técnicas espectrométricas, cromatográficas e quimiométricas na avaliação da autenticidade de plantas utilizadas como fitoterápicos

Abstract

The use of herbal medicines in the Brazilian market has increased in the last few decades. Therefore, the quality control for herbal products, as well as traditional medicines, is extremely important and for both: the manufactured products and the raw material. However, to guarantee the product s quality implies in an increase of the process costs in an industry. Currently, the quality of herbal extracts is predicted by analysis of selected marker compounds, which are often characteristic chemicals of a specific herb, but that many times do not present any relation with bioactivity. As a consequence, the marker-based approach is an incomplete and unsatisfactory method for quality control of herbal medicines In order to cope with this problem, current developments in improving sensitivity and analytical capacity of known techniques, had made possible the plant s complex extract evaluation. The present work describes an analytical methodology for the phytomedicines catuaba, espinheira-santa and guaco, based on the metabolic profile approach, where the Nuclear Magnetic Resonance techniques, as well as the High Performance Liquid Chromatography, are employed to obtain a fingerprinting of these herbal medicines. Nevertheless, due to the complex spectral data profile (1H spectra and chromatograms) evaluation it was necessary to employ chemometrics. These multivariate methods made possible to extract some relevant information and to prove the authenticity of the analyzed commercial samples. The commercial catuaba samples analysis by HR-MAS NMR/ chemometrics showed be more efficient, when compared with liquid NMR, indicating that the species sold as the phytomedicine catuaba is Trichillia catigua. Whereas, the results obtained for espinheira-santa showed an opposite situation pointing out that the efficiency of the HR-MAS is correlated with the physiological constitution of the plant material analyzed. Beside NMR results, HPLC analysis showed that the majority of the espinheira-santa commercial samples do not employ Maytenus ilicifolia species. The guaco results obtained by both, NMR and HPLC techniques were inconclusive needing the use of a complementary technique. Therefore, the present work also describes the use of the High Performance Liquid Chromatography coupling with Abstract Tandem Mass Spectrometry, by means of SRM experiments, to evaluate some commercial guaco samples. This technique provides the detection of the coumarin 1,2-benzopyrone in all the analyzed samples, due to the SRM high sensitivity, thus certifying its authenticity. The results obtained by Nuclear Magnetic Resonance, High Performance Liquid Chromatography and chemometrics, proved to be valuable tools for the evaluation of complex phytomedicines matrix. In specific cases, where high sensitivity in the analytical method is required, Mass Spectrometry can be used as an additional technique.