Intracellular antioxidant activities of selected cereal phenolic extracts and mechanisms underlying the protective effects of adlay phenolic extracts on H2O2-induced oxidative stress in human erythrocytes

The intracellular antioxidant activities of millet, rice, wheat, brown rice, oat, buckwheat, corn and adlay phenolic extracts were evaluated in an ex vivo erythrocytes system. Buckwheat, corn, and brown adlay free phenolic extracts could effectively attenuate H2O2-induced erythrocyte hemolysis. The protective effects and involved mechanisms of polished adlay, brown adlay and adlay bran phenolic extracts were studied further. The intracellular antioxidant activities of adlay phenolic extracts decreased in the following order: adlay bran > brown adlay > polished adlay. Adlay bran free phenolic extract possessed stronger intracellular antioxidant activity than chlorogenic acid, p-coumaric acid and ferulic acid. The free phenolic extracts were more effective than bound phenolic extracts to suppress hemolysis and plasma oxidation through inhibition of MDA equivalents, MetHb and ROS generation and to restore the activities of Na+K+-ATPase, Ca2+Mg2+-ATPase and intracellular antioxidant enzyme to normal levels. Adlay-rich diets could reduce the incidence of cancer, cardiovascular and neurodegenerative diseases.