Proanthocyandins (PACs), polymeric flavan-3-ols, are recognized for their bioactivities including: bacterial anti-adhesion, biofilm inhibition, cytotoxicity to cancer cells, and anti-inflammatory activities. Quantification of PACs, by both HPLC and spectrophotometric methods, has been problematic due to the lack of readily available pure standards. Proanthocyanidins are differentiated by the hydroxylation patterns of their subunits, degree-of-polymerization (DP-2 to > 10), and whether units are linked by a single bond (B-type) or doubly-linked with an additional ether bond (A-type). A spectrophotometric method using 4-dimethylaminocinnamaldehyde (DMAC) assay was developed to quantify the A-type PACs from cranberry and B-type oligomers from cocoa. Since it has been assumed the DMAC reagent only reacts with the end unit, the various DP would have similar extinction coefficients. Molar extinction coefficients for DMAC appear to be variable across the DP series of both A-type and B-type oligomers, as well as between A versus B-type, and location of the double linkage.

Influence of degree-of-polymerization and linkage on the quantification of proanthocyanidins

246th National Meeting (2013)

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