Nutraceutical potential of sorghum bran: hyaluronidase inhibition

Hyaluronidases (Hyases) degrade hyaluronan, a glycosaminoglycan found in cartilage and extracellular matrix. Increased Hyase activity causes imbalanced hyaluronan metabolism, increasing cartilage breakdown in inflammatory joint disease, e.g., osteorarthritis (OA). Sorghum bran has high polyphenolic content with anti‐oxidant and anti‐inflammatory activities. We tested whether extracts of 7 sorghum bran varieties would directly inhibit Hyase. We prepared ethanolic extracts (1:9 wt/vol 50% EtOH) and measured total phenolic, anthocyanin and FRAP (ferric reducing antioxidant power) values. We found a range of potencies for inhibition of Hyase: three varieties had IC50s at 1:5000 total dilution and four had significant, but lesser, activities (25–50% inhibition range) at 1:700 total dilution. Inhibition of Hyase correlated positively with total phenolic and FRAP values, but not with anthocyanin content for each of the 7 varieties. Current management of OA involves decreasing mechanical, inflammatory and oxidative injury while providing substrates to increase cartilage synthesis (e.g., glucosamine and chondroitin). Sorghum bran extracts may provide a complementary nutraceutical approach with high Hyase inhibition, anti‐oxidant and anti‐inflammatory activities. In summary, Hyase inhibition is a heretofore unrecognized property of sorghum bran that provides rationale for its development as a nutraceutical/food supplement. USDA‐CRA # 58‐5430‐4‐363