Inhibition of hyaluronidase activity by select sorghum brans

Hyaluronidase hydrolyzes glycosaminoglycans, including hyaluronan, in the extracellular matrix during tissue remodeling. Hyaluronidase activity increases in chronic inflammatory conditions, e.g., inflammatory joint disease. In this study, we tested the ability of ethanolic extracts (1:9 [wt/vol] of 50% ethanol) of bran from six cultivated varieties of Sorghum bicolor to inhibit hyaluronidase activity in vitro in comparison to extracts of wheat and rice bran. Each extract inhibited hyaluronidase activity with this order of potency: Sumac > Shanqui Red > Black > Mycogen > Fontanelle > White sorghum. Extracts of wheat and rice bran had weak inhibitory activities relative to the high phenolic sorghum brans. Hyaluronidase inhibition correlated positively with total phenolic content and ferric reducing antioxidant power values for each bran extract. Inhibition was not only due to condensed tannins (proanthocyanidins) because the Black sorghum cultivar lacks condensed tannins but has abundant anthocyanins and other polyphenols. Since hyaluronidase activity is important in conditions such as osteoarthritis and skin aging, these sorghum varieties deserve consideration for functional foods and beverages, and for nutraceutical and cosmeceutical ingredients.