Determination of A-type and B-type procyanidins in apple, cocoa and cinnamon extracts

Flavan-3-ols, known also as proanthocyanidins or condensed tannins, after lignans are the second most common class of natural phenolic substances found in nature. Single linked, B-type procyanidins occur in many foods, with those from apples and cocoa being the most prominent in western diet. A possible connection between procyanidins and cardiovascular disease is particularly interesting. The double linked, A-type procyanidins occur in cinnamon and cranberries and are believed to contribute to anti-diabetic and anti-UTI properties of these foods. Procyanidins form chains containing polymerized subunits of epicatechin and catechin, with the number of subunits being between 2 and 30. With the ever increasing interest in determining their significance as dietary antioxidants and pharmacologically active components, better analytical techniques allowing their standardization in dietary supplements are required. We developed a sensitive and selective gradient HPLC method combining photodiode array and coulometric electrochemical array detection to resolve and quantify numerous procyanidins in different foods/supplements. This approach also enabled the estimation of standard purity and abundance of contaminants. A second method, using charged aerosol detection, was used to determine the presence of impurities that either lack a chromophore or are not electrochemically active. A third method was developed using gradient UHPLC with UV detection. This approach significantly shortened the analysis time from 30 to < 5 minutes, while maintaining analyte resolution.