Avaliação fitoquímica e de atividades biológicas de sementes e sistemas in vitro de Arachis pintoi Krapov. & W.C. Greg.

Abstract

Arachis pintoi Krapov. & W.C. Greg is an herbaceous perennial peanut species from Brazil, used as forage and also as green cover for erosion control and recovery of degraded areas. Despite the existence of several studies demonstrating the presence of metabolites, such as resveratrol, in peanuts used for human consumption (A. hypogaea L.), studies on phytochemistry and biological activities of other species of the genus are still limited. The aim of this work was to investigate the antitumor potential of seed extracts as well as the in vitro induction of adventitious roots from cotyledons, in addition to evaluating the phytochemical profile and the presence of resveratrol by High Performance Liquid Chromatography (HPLC) in roots and callus from seeds. Ethanolic and hexanic seed extracts and the combined fractions 34-40 and 41 of the hexanic extract showed cytotoxicity against tumor (MCF-7, PC3 and A549) and leukemic (Jurkat and K562) cell lines. K562 cell line was the most sensitive and showed 71% and 73% reduction in cell viability by the MTT assay in response to fractions 34-40 and 41, respectively. Hexanoic, palmitic, 13-cis-octadecanoic and linoleic acids were detected in fraction 41. For root multiplication, root segments induced from cotyledons explants in response to auxins in absence of light were cultured in liquid media under filter paper bridge, obtaining the best result with 2 cm length in response to 0.49 μM indole-3-butyric acid (IBA). The histological analysis revealed the swelling of the proximal region of the cotyledons with the formation of root primordium, whose vascular tissue did not show connection to that of the explant. HPLC analysis of extracts from adventitious roots produced in response to IBA, α-naphthaleneacetic acid (NAA) and indole-3-acetic acid (IAA) evidenced similarity among the peaks present in the samples. Both the root and callus samples displayed a higher number of peaks between tR 7 and 9 min, similar to that of resveratrol (9.11 min). The total phenolic content observed by the Folin-Ciocalteu assay was higher in extracts from seeds and cotyledons than in those from calluses. On the other hand, resveratrol was detected only in extracts from calluses (obtained from cotyledons, embryonic axes and leaflets) and roots from plants maintained in natural conditions, being the highest content observed in calluses from cotyledons (8.37 μg/g fresh weight). The highest antioxidant activity obtained by the DPPH assay was detected in in vivo-plant roots (EC50 = 0.99 mg/mL). The activity of extratcs from seeds with coat was almost three times higher than the ones from seeds without coat or cotyledons, being similar to that of materials produced in vitro. These results indicate that the cultures evaluated in this work may constitute new sources of antioxidant compounds, whose synthesis could be optimized by the use of elicitors.