Cultura de tecidos, análise fitoquímica e avaliação do potencial antioxidante de Passiflora setacea DC cv “BRS Pérola do Cerrado”

Abstract

The genus Passiflora occurs mainly in tropical climate regions, with Brazil being an important center of diversity. Passion fruit, as the species of the genus are known, are of great ornamental interest, mainly due to the beauty and exuberance of their flowers. Furthermore, they can be used for food and medicinal purposes, due to the various recognized pharmacological activities, mainly as anxiolytic. In vitro culture systems allow the modulation of the production of metabolites of interest by modifying culture conditions. The cultivar P. setacea BRS Pérola do Cerrado was developed by the genetic improvement program of Embrapa Cerrados aiming to increase the productivity and size of the fruit, which is rich in mineral salts and antioxidant substances. Therefore, the general objective of this work was to establish in vitro culture systems, characterize the phytochemical profile and evaluate the antioxidant potential of this cultivar. Friable calluses were induced from stem and leaf segments in MSM medium supplemented with picloram (PIC) at different concentrations (4.14, 20.7 and 41.4 μM) and kept in the dark, white fluorescent light or different types of LEDs (blue, red, white and blue + red). Callus formation was observed in response to all treatments, with frequencies between 81.6 and 100%. Phytochemical analysis of leaves of plants in vivo and in vitro, as well as calluses was performed by Thin-Layer Chromatography (LCD), High Performance Liquid Chromatography (HPLC) and HPLC- UV coupled to mass spectrometry. The flavonoids vicenin-2 and schaftoside were identified as major constituents in both leaf extracts. On the other hand, chromatographic analyzes indicated that blue LED induced greater production of bioactive substances in callus extracts. All samples showed low antioxidant activity by the DPPH assay, but high capacity to chelate iron ions. In addition, the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) was performed. Although no differences in SOD and CAT activity were observed, the specific activity of APX was increased in leaf extracts from micropropagated plants. Calluses obtained from internodal segments under red LED showed higher activity of the three enzymes. This is the first work evaluating the influence of lighting conditions in in vitro culture systems, on the production of bioactive substances in P. setacea BRS Pérola do Cerrado. In general, the efficiency of callogenesis, biomass accumulation and activity of antioxidant enzymes were influenced by the red LED and the production of substances of biotechnological interest was influenced by the blue LED.