HPLC fingerprint of thirty seven hop granulates with antioxidant activity tests and chemometric calculations

Abstract Chemometric techniques (principal component analysis, PCA, hierarchical cluster analysis, HCA, partial least squares, PLS) were applied to compare and predict the antioxidant activity of hops based on chromatographic fingerprints. Besides, isoxanthohumol (IXH) was quantified in order to compare its content in hop extracts. Reversed phase-high performance liquid chromatography with diode array detection (RP-HPLC-DAD) was used to obtain chromatographic fingerprints. Isoxanthohumol was used as fingerprint marker and validation (linearity, accuracy, precision, robustness, limit of detection (LOD), limit of quantification (LOQ)) of HPLC was performed. The chemical similarity between samples was evaluated using PCA and HCA. The total phenolics was determined by Folin-Ciocalteu (F-C) test and the antioxidant activity was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). The highest antioxidant activity (DPPH and FRAP) was observed for Cascade, the highest phenolic content was for Callista and Halertauer Tradition. The high antioxidant activity by FRAP test was obtained for Cascade and Magnum. The fingerprints combined with the antioxidant activity were evaluated using the PLS.