Estabelecimento de culturas de raízes e avaliação fitoquímica e da atividade antioxidante de Passiflora pohlii Mast

Abstract

Passiflora pohlii Mast., known as maracujá-do-campo or maracujazinho, is a wild species native to Brazil, with a potential agronomic interest, especially regarding to its tolerance to soil-borne pathogens from genus Phytophthora sp, which cause great damages to the passion fruit cultures. Although there is little work on this species, recent studies with other species of the genus described biological and pharmacological activities in extracts of different organs, including leaves and roots. The goal of this work was the establishment of adventitious roots from stem and root segments excised from in vitro-grown plants of P. pohlii, and the phytochemical evaluation and antioxidant potential of the extracts obtained from different in vitro materials, in comparison with in vivo-grown plants. Different culture systems, types and concentrations of auxins were evaluated for the induction of in vitro adventitious roots from stem and root segments. Cultures were maintained at 25 ± 2 °C, in the presence or absence of light. In vitro responses varied according to the type of explant. Internodal segments showed the best rhizogenesis induction on solidified medium supplemented with 2.7 μM NAA, in the absence of light, whereas root segments showed the best proliferation rate on liquid medium, supplemented with 2.85 μMIAA, in the dark. The in vitro plant materials, including whole plants and adventitious roots obtained from internodal and root segments, as well as in vivo-grown plants, were used for the production of ethanolic extracts for phytochemical evaluation and of the antioxidant potential. TLC and HPLC analysis indicated the presence of flavonoids and saponins in extracts of leaves from in vivo and in vitro-grown plants, whereas root extracts showed only saponins. Extracts from leaves were also subjected to HPLC-UV-ESI-MS analysis aiming at the identification of the molecular mass of the compounds. Two flavonoids, possibly isomers, were identified, with molecular masses of 607.2, in extracts from leaves of in vivo and in vitro-grown plants. The antioxidant potential of the different materials was determined by 2,2-diphenyl-1- picrylhydrazyland TLC-DPPH assays. The highest antioxidant activities were observed in extracts from primary and secondary roots of in vivo-grown plants. The in vitro root culture strategies described in this work were successfully applied to P. pohlii. In addition, the characterization of the phytochemical profile of the in vitro and in vivo materials, as well as its pharmacological potential, were reported for the first time for this species