Investigação de aspectos fitoquímicos e do potencial farmacológico de materiais obtidos in vivo, in vitro e criopreservados de Passiflora pohlii Mast.

Abstract

Passiflora pohlii Mast. is a native species of Brazil that presents characteristics of agronomic interest, especially regarding to the tolerance to soil pathogens that cause great damage to passion fruit culture. Although there are few studies on this species, recent biotechnological studies have resulted in the development of systems for in vitro plant production and adventitious root culture. In addition, the phytochemical profile and antioxidant potential of different in vitro materials were compared with plants kept under natural conditions, with the presence of flavonoids in leaf extracts and saponins with high antioxidant activity in root extracts. Thus, the aim of this work was to provide further studies with the establishment of new culture and cryopreservation systems for P. pohlii, with the investigation of phytochemical and histological aspects, and the pharmacological potential of materials obtained in vivo and produced and preserved in vitro. For this, the technique of Nuclear Magnetic Resonance was used for the structural elucidation of the flavonoids present in the leaf extracts of the studied species. Two isomers, called iso-spinosyn, the major compound, and spinosyn were identified. Subsequently, leaf segments were excised from in vitro-propagated and cultivated in the presence of auxins and high concentrations of sucrose, aiming at the establishment of callus cultures for the large scale production of bioactive compounds. Although the induction of friable calli had occurred in response to NAA and PIC, callus obtained in the presence of PIC at 20.7 μM and sucrose at 0.3 or 0.5 M showed intense cellular proliferation and the production of phenolic substances with antioxidant potential. However, the production of flavonoids in these materials was not observed. Considering the recent description of the presence of saponins in P. pohlii root extracts, a methodology was also established for the cryopreservation of root apices of in vitro plants with the V-Cryoplate technique, using PVS2 as a cryoprotectant solution. A high recovery rate was obtained indicating the efficiency of the methodology for the long-term storage of these biotechnological materials. Histological analyzes performed during the different stages of the protocol showed structural damages in the cryopreserved materials, including high plasmolysis rates, which were reverted after transfer to recovery medium. No changes were observed in biosynthetic capacity of cryopreserved roots when compared to non-cryopreserved materials. The antibacterial potential of leaves and roots of in vitro plants of P. pohlii was also investigated and compared with those of other species of the genus. However, extracts of P. pohlii promoted an increase in the growth of the tested bacterial strains, unlike that observed in the materials of other species, especially those belonging to the Passiflora subgenus, which suggests a genotypic influence in the production of substances with antibacterial activity. The biotechnological strategies described in this work were successfully applied to the production and in vitro conservation of phenolic compounds with antioxidant activity of P. pohlii. In addition, the identification of the flavonoids present in leaf extracts was achieved for the first time for this species.