BIOACTIVE COMPOUNDS AND ANTIOXIDANT ACTIVITY OF PERIPHERAL LAYERS OF SOFT WHEAT GROWN IN ALGERIA DURING SEED FILLING

Abstract

Wheat bran is a by-product rich in bioactive compounds. However, little is known about the arrangement, composition and secondary metabolisms of the grain outer layers during grain development. To this end, the objective of this study is to evaluate the variations in cell wall structure and chemical composition of the outer layers during the cellularization phase, the actual filling of the grain and the maturation phase. Morphological and structural aspects were evaluated by scanning electron microscopy;  phytochemical study also was carried out: Extracts from the peripheral layers (CP) of wheat grain (cultivar Triticum aestivum HD1220) were analyzed to determine: Total phenols content by Folin-Ciocâlteu method, flavonoids by aluminum trichloride and sodium hydroxide method; Antioxidant power was evaluated by free radical scavenging (DPPH) and iron reduction (FRAP). The results of histological analysis showed that the outer layers become thinner during grain development, the main tissues develop and differentiate synchronously; the phenolic content ranged from 47.58± 3.23 mg GAE/g to 108.67± 10.7 mg GAE/g wheat outer layers, the wheat outer layers contained 6.96±2.61-35.297±8.68 mg EAQ/g flavonoids. The contents of total phenols (TPC) and flavonoids (TFC) increased during development; the antioxidant activity, depended on the developmental phase of the peripheral layers; the antioxidant activity studied for 70% ethanolic extracts was highest in the peripheral layers of mature grains. These results underline that the peripheral layers of wheat bran derived from maternal tissues are constituted by a superposition of different tissues and are considered as an important source of bioactive compounds.