Abstract

This study investigated the effect of maturity on the total phenolic content, antioxidant properties and minerals of Sesamum radiatum leaves. S. radiatum seeds were sown on an unfertilized land and the leaves were harvested on weekly basis from the fourth to the tenth week after planting (WAP) when senenescence has started setting in. The total phenolic content, minerals and antioxidant properties of the plant were determined using standard methods. The results obtained showed that total phenol increased from 7, 200 to 16, 907 mg/100 g) during 4 to 10 WAP, respectively. There was no significant difference in the ferric iron reducing antioxidant power (8.96 to 19.19 mg gallic acid equivalents GAE/g) and the free radical scavenging (1, 1 -diphenyl-2-picrylhydrazylDPPH; 24.44 to 62%) from 5 WAP to 10, but that of 4 WAP was significantly lower compared with others. Calcium (1.85 to 8.00 mg/100 g), iron (0.042 to 0.068 mg/100 g), magnesium (12.50 mg/100 g to 85.83 mg/100 g) and phosphorus (10.17 mg/100 g to 35.60 mg/100 g) were significantly (p< 0.05) affected by the maturity of the plant. The study indicated that as the leaf matures total phenol, calcium, phosphorus and iron contents increased and the optimum values were obtained in leaves harvested at the 7 WAP.

Key words: Sesamum radiatum, age of plant, antioxidant properties, total phenol, mineral contents.