Variability between organs of proanthocyanidins in Geranium sylvaticum analyzed by off-line 2-dimensional HPLC-MS

Abstract

Proanthocyanidins have been characterized in the different organs of Geranium sylvaticum by using an off-line 2-dimensional chromatographic method. In the first dimension, proanthocyanidins were separated according to their increasing degree of polymerization by hydrophilic interaction liquid chromatography. In the second dimension, reversed-phase liquid chromatography was used to separate the same size isomers based on their hydrophobicity. Ultraviolet detection and high-resolution electrospray ionization time-of-flight mass spectrometry were used for the identification and characterization of proanthocyanidins. The method was proven to be suitable for the analysis of plant organ fractions of G. sylvaticum that contained complex mixtures of phenolic compounds and proanthocyanidins from several classes. Procyanidins, prodelphinidins and mixed proanthocyanidins composed of both (epi)catechin and (epi)gallocatechin units including monomers, oligomers and polymers up to the degree of polymerization of 20 were identified. The type and size of proanthocyanidins varied between eight studied organs of G. sylvaticum. The 2-dimensional analysis revealed that each proanthocyanidin type occur in the equally complex isomeric pattern. The mean degree of polymerization of different proanthocyanidins in the eight plant organs of G. sylvaticum was 5 and it varied only slightly between plant organs.