Unique antioxidant effects of herbal leaf tea and stem tea from Moringa oleifera L. especially on superoxide anion radical generation systems

Abstract

ABSTRACT This study aimed to investigate the unique antioxidative effects of Japanese moringa products, herbal leaf tea and stem tea, using established free radical assays, focusing on superoxide anion (O2−) radical generation systems. Hot-water extracts from moringa teas resulted in different but lower scavenging activities than Trolox in four synthetic free radical models. Interestingly, these extracts further showed higher O2− radical scavenging effects than Trolox in the phenazine methosulfate-NADH-nitroblue tetrazolium and xanthine oxidase assay systems. Incubating human neutrophils in the presence of these tea extracts rather than Trolox effectively suppressed cellular O2− radical generation. Among the eight known phenolic constituents of moringa leaves, caffeic acid and chlorogenic acid may be responsible for the O2–specific radical scavenging capacity stronger than that of Trolox. These results suggest that moringa herbal teas are a good source of natural antioxidants for preventing O2− radical-mediated disorders. Abbreviations: O2−: superoxide anion; ROS: reactive oxygen species; H2O2: hydrogen peroxide; XOD: xanthine oxidase; DPPH: 1,1-diphenyl-2-picrylhydrazyl; ABTS+: 2,2′-azinobis(2-ethylbenzothiazoline-6-sulfonic acid) cation; CPZ+: chlorpromazine cation; PMS: phenazine methosulfate; NBT: nitroblue tetrazolium; PMA: phorbol 12-myristate 13-acetate