Total phenolics, resveratrol content and antioxidant activity of seeds and calluses of pinto peanut (Arachis pintoi Krapov. & WC Greg.)

Arachis pintoi is a peanut species native to Brazil, which is cultivated in many countries for animal forage, soil cover, landscaping, and recovery of degraded areas. Tissue culture studies for this species have been focused in plant production, whereas works on in vitro secondary metabolites production are scarce. The goal of the present work was to establish callus cultures from different seed explants of A. pintoi, aiming at evaluating the potential for metabolites production and antioxidant activity. Embryonic axes, leaflets, and cotyledons were cultured on solidified MS medium supplemented with picloram (PIC), 2,4-dichlorophenoxyacetic acid (2,4-D), thidiazuron (TDZ) or different combinations of 6-benzyladenine (BA) and alpha-naphthaleneacetic acid (NAA), under light or dark conditions. Friable calluses with a high biomass (4.3 +/- 0.3 g FW per callus) were obtained from embryonic leaflets cultured on medium supplemented with 17.6 A mu M BA plus 5.4 A mu M NAA, in the dark. Cotyledons and embryonic axes cultured in the presence of 4.4 A mu M BA combined with 10.8 A mu M NAA formed heterogeneous calluses with a compact base and a large friable surface. Trans-resveratrol and other stilbenes that were not found in seeds were detected in callus extracts, especially those originated from cotyledons, although these materials showed lower total phenolic contents (TPC) when compared with seeds with and without testa, as well as cotyledons. Extracts from seeds with testa and from calluses derived from cotyledons and embryonic axes showed the highest EC50 in DPPH assays. No correlation between TPC, trans-resveratrol and antioxidant activity was observed.