High-Molecular-Weight Polyphenols from Sorghum Bicolor Retain Higher Glycation Inhibition and Cancer Cell Inhibition In vitro Compared to Small-Molecular-Weight Polyphenols after Separation Using Sephadex LH-20

Abstract

Sorghum contains a diverse array of phenolic compounds, including condensed tannins, phenolic acids, and 3-deoxyanthocyanidins. The differences in bioactivity among these phenolics are not well studied. This work improved existing methods to selectively separate polyphenols based on size using extracts of highly phenolic sorghum varieties. Sephadex LH-20 resin was used to separate large-molecular-weight condensed tannins from oligomeric and monomeric polyphenols. Flavonoid monomers, including 3-deoxyanthocyanidins, were highly concentrated in ethanolic fractions, while the large polyphenol polymers were concentrated in acetone fractions. The bioactivity of separated fractions was evaluated via glycation inhibition and colorectal cancer cell inhibition (HCT116 and RKO). The results demonstrated that high- molecular-weight fractions demonstrated significantly higher (p < 0.05) bioactivity than low- molecular-weight fractions in both assays. This work provides valuable information on the separation of sorghum polyphenols by size and their bioactivity.