RESUMO
Quinoa was the traditional grain crop used by the prehispanic civilizations in America. Grains are white, black, yellow, and red-violet and plants are cultivated in vast areas of Peru, Bolivia and Ecuador. The recent description of the betacyanin pigment betanin in red-violet varieties is here further analyzed detecting the presence of amaranthin not previously identified in quinoa grains. Yellow-orange grains are characterized for the first time and up to four different betaxanthins are found to be responsible for this coloration. The native fluorescence of the identified betaxanthins makes the surface of the yellow quinoa grains glow with green fluorescent light. The presence of betalains is correlated with high antioxidant and free radical scavenging activities measured under the FRAP, ABTS and ORAC assays in grain extracts of 29 Peruvian varieties. TEAC equivalence is as high as 44.1 and 47.4mmol Trolox/kg for the yellow and red-violet varieties analyzed respectively.
Assuntos
Antioxidantes/química , Betalaínas/química , Chenopodium quinoa/química , Saponinas/química , Equador , Peru , PigmentaçãoRESUMO
Betalains are plant pigments of hydrophilic nature with demonstrated chemopreventive potential in cancer cell lines and animal models. Among the betalains, those containing an aromatic moiety with two free hydroxyl groups possess the strongest antioxidant and free radical scavenging activities. The betaxanthins dopaxanthin and miraxanthin V and the betacyanins betanidin and decarboxy-betanidin are the only natural betalains with catecholic substructures. These four pigments have been produced in cell cultures established from hypocotyls of the plant Celosia argentea. Two stable and differentially colored cell lines, yellow and red, were maintained on Murashige and Skoog medium supplemented with the plant growth regulators 6-benzylaminopurine (6.66 µM) and 2,4-dichlorophenoxyacetic acid (6.79 µM). Derived suspension cultures showed increased production of dihydroxylated betalains in the cells and secreted to the medium with a maximum reached after 8 days of culture. In addition, precursor molecules betalamic acid and dopamine, with content up to 42.08 mg/g dry weight, were also obtained. The joint presence of the bioactive betalains together with the production of dopamine and betalamic acid show the ability of cell cultures of C. argentea to become a stable source of valuable phytochemicals.