David G. Cunningham

Development of a Thiolysis HPLC Method for the Analysis of Procyanidins in Cranberry Products.

The objective of this study was to develop a thiolysis HPLC method to quantify total procyanidins, the ratio of A-type linkages, and A-type procyanidin equivalents in cranberry products. Cysteamine was utilized as a low-odor substitute of toluene-α-thiol for thiolysis depolymerization. A reaction temperature of 70 °C and reaction time of 20 min, in 0.3 M of HCl, were determined to be optimum depolymerization conditions. Thiolytic products of cranberry procyanidins were separated by RP-HPLC and identified using high-resolution mass spectrometry. Standards curves of good linearity were obtained on thiolyzed procyanidin dimer A2 and B2 external standards. The detection and quantification limits, recovery, and precision of this method were validated. The new method was applied to quantitate total procyanidins, average degree of polymerization, ratio of A-type linkages, and A-type procyanidin equivalents in cranberry products. Results showed that the method was suitable for quantitative and qualitative analysis of procyanidins in cranberry products.

Single-Laboratory Validation for Determination of Total Soluble Proanthocyanidins in Cranberry Using 4-Dimethylaminocinnamaldehyde

American cranberry (Vaccinium macrocarpon) is native to Eastern North America. Recent studies have suggested that the A-type proanthocyanidins (PACs) in cranberries are effective in preventing urinary tract infection. To meet the growing interest in the cranberry market, an accurate, reliable, and simple method to determine PAC concentration is needed. In this study, a modified method using 4-dimethylaminocinnamaldehyde to quantify total PACs in cranberry products was validated. Cranberry juice extract powder, cranberry capsules containing juice extract, and cranberry juice concentrate were used as the samples in this study. With the modified method, the calibration curves for proanthocyanidin A2 had correlation coefficients (r2) of >0.99. The recoveries of two different concentrations after spiking were 97.1 and 99.1%, and the RSDs for repeatability and reproducibility were <2.7 and <1.6%, respectively.