Location: Dairy Forage ResearchTitle: Rapid qualitative and quantitative analysis of proanthocyanidin oligomers and polymers by ultra-performance liquid chromatography – tandem mass spectrometry (UPLC-MS/MS)) Author
Submitted to: Analytical Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/25/2014
Publication Date: 3/25/2014
Citation: Engstrom, M., Palijarvi, M., Fryganas, C., Grabber, J.H., Mueller-Harvey, I., Salminen, J. 2014. Rapid qualitative and quantitative analysis of proanthocyanidin oligomers and polymers by ultra-performance liquid chromatography – tandem mass spectrometry (UPLC-MS/MS). Analytical Chemistry. 62:3390-3399. Interpretive Summary: Many plant species produce complex mixtures of proanthocyanidins that are of considerable interest because they naturally deter plant pests and affect the availability of nutrients in foods, feeds, and decaying plant matter. Proanthocyanidins also influence the palatability and flavor of food and beverages, and they serve as antioxidants beneficial to human health. The chemical makeup and size of proanthocyanidins influence their biological activity, but current analytical methods for determining these characteristics are laborious and slow. This paper describes a rapid method for partially separating different types of proanthocyanidins extracted from plants by liquid chromatography and then characterizing their chemical makeup and size by fragmentation and mass spectrometry techniques. The new method increases the number of samples that can be analyzed in a day about 10 times over current commonly used methods; thus it is a valuable new tool for rapidly screening large numbers of plants for bioactive proanthocyanidins. We anticipate the new method will be widely used by plant breeders to develop food and feed crops with desirable proanthocyanidan characteristics. The method will also be valuable to a wide range of other scientists who are trying to understand the effects of proanthocyanidans on biological systems and enhance their use in beverages, foods, and feeds.
Technical Abstract: We developed a rapid method with ultra-performance liquid chromatography – tandem mass spectrometry (UPLC-MS/MS) for the qualitative and quantitative analysis of plant proanthocyanidins (PAs) directly from crude plant extracts. The method utilizes a range of cone voltages to achieve the depolymerization step of both smaller oligomers and larger polymers in the ion source. The formed depolymerization products are further fragmented in the collision cell to enable their selective detection. This UPLC-MS/MS method is able to separately quantify the terminal and extension units of the most common PA sub-classes, i.e. procyanidins (PC) and prodelphinidins (PD). The resulting data enable (1) quantification of the total PA content, (2) quantification of total PCs and PDs including the PC/PD ratio, (3) estimation of the mean degree of polymerization for the oligomers and polymers, (4) estimation of how the different PC and PD types are distributed along the chromatographic hump typically produced by large PAs. All this is achieved within the 10-minute period of analysis, which makes the presented method a robust and efficient addition to the chemistry tools currently available for the qualitative and quantitative analysis of complex proanthocyanidin mixtures from plant extracts.