Produção in vitro e in vivo, análise química e avaliação do potencial antioxidante de raízes de Pereskia aculeata Miller (Cactaceae)

Abstract

Pereskia aculeata Miller is a basal cactus classified as a non-conventional plant food. The species is widely consumed in Brazil, mainly at Minas Gerais state, where it is known as "ora-pro-nobis". Traditional communities use this species for the treatment of inflammation and burns. Studies related to medicinal potential of P. aculeata showed expectorant, analgesic, antioxidant and antitumoral activities for extracts obtained from different parts of the plant. Moreover, phytochemical analyses revealed the presence of betalains and others biomolecules of interest. Taking into account the medicinal plants, plant tissue culture techniques are a viable alternative for mass production, providing botanical material with hight phytosanitary quality. Among these techniques, root culture represents one of the most efficient for bioactive molecules production, due to the high capacity of this organ to storage secondary metabolites. Considering the nutritional and the medicinal importance of P. aculeata, the aims of this study were the establishment of in vitro and in vivo adventitious root culture and the chemical evaluation of this material. The in vitro rhizogenesis capacity was evaluated using different types of explants (root, stem and leaf) obtained from in vitro propagated plants. The explants were cultivated in MS liquid medium supplemented with the auxins (2,4-D, IAA, IBA and NAA) in different concentrations (5; 10; 20; 30 μM). The in vivo rhizogenesis was established applying the technique of cutting using different substrates, soil and water. Methanolic extracts obtained from roots developed by cutting were evaluated for total protein and total betalains. In addition, the production of betalains was investigated by high performance liquid chromatography, mass spectrometry and the antioxidant potential of the extracts was quantified by the DPPH radical capture and the iron quenching II activity. The results demonstrated that stem explants were more efficient to in vitro multiplication of roots. The highest root biomass accumulation was reached by stem cultures maintained in medium supplemented with 5 μM of NAA. Root multiplication increased during subcultures when the explants were individualized but maintaining attached the newly formed roots attached. In vivo rhizogenesis by cutting technique was achieved in both soil and water substrates. However, the chromatographic analysis showed that the type of substrate influenced the diversity of chemical compounds synthetized by roots. The extracts also presented high level of proteins and were detected some molecules derived of betalain. The antioxidant potential of the extracts was demonstrated by the iron quenching II activity. The establishment of adventitious root culture of P. aculeata and the synthesis of proteins and betalains in root extracts demonstrate a promising perspective in the use of these materials for the development of nutraceutical and pharmacological products.