Abstract

Ethnobotanical investigations have shown that the redder Amaranthus spinosus (A. spinosus) and Boerhavia erecta (B. erecta) specimens are, the more they are used for traditional medicinal purposes. This work aimed to elucidate the role of the betalain pigments in the bioactivity of the Caryophyllales species. Histochemical and biochemical studies on the two species (A. spinosus L. and B. erecta L) indicate that the synthesis and subsequent storage of betalain pigments in the stems, leaves and root epidermis or in the cortical parenchyma are induced by stress (biotic or abiotic). Radical scavenging activity assays using 2, 2’-Azinobis, 3-ethylbenzothiazoline-6-sulphonic acid (ABTS⁺) free radicals showed that the betalain-containing fractions of these plants have the highest activity. We suggest that reactive oxygen species (ROS), of either biotic or abiotic origin, are signals that induce the biosynthesis of betalains, which act as ROS scavengers. The formation of these compounds has been observed and appreciated by traditional healers as evidence of the usefulness of this drug.

Key words: Betalains, phenolic, oxidative stress, antioxidants, Amaranthus spinosus, Boerhavia erecta.

Abbreviation

Abbreviations: ABTS, 2, 2’-Azinobis (3-ethylbenzothiazoline-6-sulphonic acid; ROS,reactive oxygen species; FCR, Folin-Ciocalteu reagent; H₂O₂, hydrogen peroxide; RSC₅₀,radical scavenging capacity 50%.