Antioxidant activities of red versus green leaves in Elatostema rugosum

Abstract

Anthocyanin biosynthesis in leaves increases under stresses which also generate reactive oxygen species (RES). In the present study the hypothesis that red leaves are better equipped to scavenge ROS than green leaves was tested. Antioxidants in leaf extracts from red and green morphs of Elatostema rugosum were identified, and activities quantified using enzymatic and α,αdiphenyl-β-picrylhydrazyl (DPPH) assays and cyclic voltammetry. Red leaves from E. rugosum held greater amounts of superoxide dismutase, catalase, anthocyanins, and hydroxycinnamic acids, were significantly more effective at scavenging DPPH radicals, and produced higher voltammetric currents than green leaves. Anthocyanins contributed to the antioxidant pool more than all other constituent phenolics. Anthocyanin concentrations, and antioxidant activities declined with leaf age. Purified anthocyanin fractions displayed oxidative activities at both pH 7-0 and pH 5.5. Implications of the antioxidant potential of anthocyanin in its cytoplasmic and vacuolar locations are discussed.