The total polyphenols and the antioxidant potentials of some selected cereals and pseudocereals

Abstract

The objective of the present study was to in­ vestigate the effect of phenolic substances and proteins on the antioxidant potentials in some cereals and pseudocereals and to compare their bioability. The polyphenol dry mat­ ter extracts (PDME) from the investigated seeds of buck­ wheat, rice, soybean, amaranth and quinoa with 1.2 M HCI in 50% methanol/water (PDME50%Met/HCI) exhib­ ited higher inhibition of lipid peroxidation than the ones ex­ tracted with 50% methanol/water (PDME50%Met) and were comparable to the antioxidant activity of butylated hydrox­ yanisole at concentration of 0.2 mg mL -t. The antioxidant activities of these seed extracts determined by 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate)-ABTS"+ /K2 S2 0x, {3- carotene bleaching ({3-carotene), and I,1-diphenyl-2- picrylhydrazyl (DPPH) radical scavenging methods showed high correlation coefficients (R 2 ) such as 0.9515, 0.9058 and 0.8723, respectively, with the presence of total polyphe­ nols estimated by Folin-Ciocalteu assay. These results indi­ cate that the major antioxidant components in these extracts mostly derived from the polyphenols, and proteins showed only minimal values of bioactivity. Based on high contents of polyphenols, anthocyanins, ftavonoids and their antioxi­ dant activities pseudocereals such as buckwheat, quinoa and amaranth can be a substitute for cereals for common and atherosclerotic diets and sometimes in the allergic cases.