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ARS Home » Southeast Area » Little Rock, Arkansas » Microbiome and Metabolism Research Unit » Research » Publications at this Location » Publication #218699
Title: Analyses of procyanidins in foods using Diol phase HPLC

Author
item GU, LIWEI - ACNC/UAMS
item HAGER, AARON - ACNC/ACH
item ROBBINS, R - MARS, INC.
item Prior, Ronald

Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/29/2008
Publication Date: 4/9/2008
Citation: Gu, L., Hager, A., Robbins, R.J., Prior, R.L. 2008. Analyses of procyanidins in foods using Diol phase HPLC [abstract]. The FASEB Journal. 22:148.5.

Interpretive Summary: Proanthocyanidins are large complex compounds found in many foods. These substances have been shown to have potential health benefits. However, little is known about their dietary intake because quantitative information on the proanthocyanidin profiles in foods is lacking. Methods have been developed and applied to the analysis of proanthocyanidins in different foods. Separation of procyanidins using silica-based HPLC suffers from poor resolution for higher molecular weight oligomers and low sensitivity due to quenching effects. Optimization of a published Diol-phase HPLC method resulted in near baseline separation for higher molecular weight compounds. By optimizing excitation and emission wavelengths, the sensitivity was increased by 5 fold. Flavonoids other than proanthocyanidins did not generate signals at these wavelengths. Dimers and trimers in grape seed proanthocyanidins eluted as a cluster of 5 peaks of isomers on normal phase HPLC, whereas they merged into a large peak with shoulders using the Diol-phase HPLC. Proanthocyanidins in foods that contain predominantly procyanidins, such as sorghum, pear, and apple, eluted as well-separated oligomers and polymers using Diol-based HPLC.

Technical Abstract: Separation of procyanidins using silica-based HPLC suffered from poor resolution for higher oligomers and low sensitivity due to the fluorescence quenching effects of methylene chloride in the mobile phase. Optimization of a published Diol-phase HPLC method resulted in near baseline separation for pentamers to decamers at 29 min to 50 min and the elution of polymers with molecular weight higher than decamers at 66 min. By using excitation and emission wavelengths of 230 nm and 321 nm, the sensitivity was increased by 5 fold. Flavonoids other than proanthocyanidins did not generate signals at these wavelengths. Dimers and trimers in grape seed procyanidins eluted as a cluster of 5 peaks of isomers on normal phase HPLC, whereas they merged into a large peak with shoulders using the Diol-phase HPLC. Hexamers, heptamers, and octamers can be resolved on Diol-phase HPLC but not on normal-phase HPLC. Separation of procyanidins on Diol-phase HPLC was according to the degree of polymerization and was not sensitive to isomeric differences for procyanidins of the same degree of polymerization. Proanthocyanidins in foods that contain predominantly procyanidins, such as sorghum, pear, and apple, eluted as well-separated oligomers and polymers using Diol-based HPLC.