UHPLC–MS quantification of coumarin and chlorogenic acid in extracts of the medicinal plants known as guaco (Mikania glomerata and Mikania laevigata)

In Brazil, Mikania glomerata Spreng. and M. laevigata Sch. Bip. ex Baker, Asteraceae, known popularly as guaco, are widely used for colds and asthma. Although coumarin is adopted as the chemical marker of both species, it was not always detected in M. glomerata, for which chlorogenic acid was identified and quantified instead. The purpose of this study was to develop and validate a method to quantify both coumarin and chlorogenic acid and apply it to extracts of plants identified as M. glomerata, M. laevigata, or as guaco, to determine the pattern of composition of these two species and to observe differences between oven-dried and lyophilized leaves. A method using ultra-high resolution liquid chromatography–mass spectrometry (UHPLC–MS) in the full scan mode was validated for selectivity, matrix effect, linearity, limits of detection and quantification, precision and accuracy. The concentration of coumarin varied between species and samples, therefore these two species should not be used interchangeably. The concentration of chlorogenic acid was also determined for all samples. The UHPLC–MS method permitted the quantification of coumarin and chlorogenic acid in 16 samples of guaco and several commercial samples were possibly misidentified.

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