High-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) as a tool in the determination of biomarkers of Passiflora-based herbal medicines.

High-resolution magic-angle spinning nuclear magnetic resonance spectroscopy (HR-MAS NMR) for the identification of the metabolic profile of plants under conditions very close to that in which the compounds are present in the matrix, the herbal medicines in this case. This enables selectivity in the determination of the active principle and other biomarkers present in the complex matrix, avoiding degradation products, which may occur in the extractive processes required in several analytical methods. In this study, HR-MAS analysis was applied in the quality control of seven Passiflora-based herbal medicines, using metabolic fingerprinting to confirm plant species and identify biomarkers. Vitexin and isovitexin were identified as major compounds in three of these herbal medicines (0.17 to 0.55%), while salicin was the majority in two others. On the other hand, no significant flavonoid contents were observed in the remaining two. In addition, it was possible to detect ethanol, a non-target compound, in all herbal medicines in concentrations varying between 0.009 and 0.342%. In this way, combined with chemometrics 1H HR-MAS NMR proved to be suitable for the qualitative and quantitative study of Passiflora biomarkers, using a minimal pre-treatment of the sample.