Comparison of Isolated Cranberry (Vaccinium macrocarpon Ait.) Proanthocyanidins to Catechin and Procyanidins A2 and B2 for Use as Standards in the 4-(Dimethylamino)cinnamaldehyde Assay

Abstract

The 4-(dimethylamino)cinnamaldehyde (DMAC) assay is currently used to quantify proanthocyanidin (PAC) content in cranberry products. However, this method suffers from issues of accuracy and precision in the analysis and comparison of PAC levels across a broad range of cranberry products. Current use of procyanidin A2 as a standard leads to an underestimation of PACs content in certain cranberry products, especially those containing higher molecular weight PACs. To begin to address the issue of accuracy, a method for the production of a cranberry PAC standard, derived from an extraction of cranberry (c-PAC) press cake, was developed and evaluated. Use of the c-PAC standard to quantify PAC content in cranberry samples resulted in values that were 2.2 times higher than those determined by procyanidin A2. Increased accuracy is critical for estimating PAC content in relationship to research on authenticity, efficacy, and bioactivity, especially in designing clinical trials for determination of putative health benefits.

Proanthocyanidin accumulation and transcriptional responses in the seed coat of cranberry beans (Phaseolus vulgaris L.) with different susceptibility to postharvest darkening

“…Here, the levels of total extractable proanthocyanidins were measured in the seed coat of both cranberry bean RILs as a function of seed development. This assessment was based on a simple spectrophotometric assay following the incubation of seed coat extracts with acidified DMACA to yield a chromophore having a maximum absorbance at 640 nm [43, 44]. Total extractable proanthocyanidin levels in cranberry bean seed coats were quantified by comparison to a known range of authentic procyanidin A2 dimer standard [41].…”

Deconvolution of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry isotope patterns to determine ratios of A-type to B-type interflavan bonds in cranberry proanthocyanidins

“…1). Our previous work using MALDI TOF MS in linear mode detected c-PAC with a DP of up to 26 and chromatographic data suggested that c-PAC did not contain other classes of flavonoids (Feliciano et al, 2012). The observed m/z values were within ±0.5 amu of predicted m/z based on the equation m/z = 290 + 288dÀ2A + c, where 290 represents the molecular weight of the terminal catechin/epicatechin unit, d is the degree of polymerization, A is the number of A-type interflavan bonds and c is the molecular weight of sodium or potassium cations (Supplementary Information- Table 1).…”

“…However, we did not estimate range in DP in this research because reflectron mode MALDI-TOF MS did not detect oligomers above undecamers with a S/N greater than 3. Linear mode MALDI-TOF MS is capable of detecting oligomers with a DP of up to 26 flavan units in cranberry PAC (Feliciano et al, 2012), but does not have sufficient baseline resolution to adequately deconvolute isotope patterns. The use of reflectron mode MALDI-TOF MS as described in this paper gave baseline resolution of 1 amu for oligomers up to the undecamers and therefore we were able to determine ratios of interflavan bonds for oligomers with DP from 2 to 11.…”

Absorption, Metabolism and Excretion of Cranberry (Poly)phenols in Humans: A Dose Response Study and Assessment of Inter-Individual Variability

“…Here we used the OS4-dimethylaminocinnamaldehyde (DMAC) method rather than the often used BL DMAC method. The latter overestimates (poly)phenol levels due to the use of procyanidin A2 as a standard instead of a better representation of cranberry proanthocyanidin complexity; OS DMAC includes a standardized extract comprehending larger polymers [29]. Therefore, using what we believe is a more appropriate method of quantification of (poly)phenols in cranberry juice may explain the low urinary recovery.…”