Cultura de tecidos, análise fitoquímica e determinação da atividade antioxidante de extratos de sementes, plantas in vivo e materiais obtidos in vitro de Arachis pintoi Krapov. & W.C. Greg.

Abstract

Pinto peanut (Arachis pintoi Krapov. & W.C. Greg) is a herbaceous perennial species native from Brazil, used as forage and plant cover for the control of erosion and recovery of degraded areas. Although several studies with A. hypogaea (groundnut) have revealed the presence of metabolites of interest, studies on phytochemistryl and biological activities for other species of the genus are still limited. The goal of this study was to establish tissue culture systems for A. pintoi cv. Amarillo MG-100, using different types and concentrations of plant growth regulators, to perform phytochemical analysis and to determine the potential antioxidant activity of different extracts. Cotyledons, embryonic axes and leaflets explants from seeds, as well as leaflets, nodal and internodal segments from in vitro growth plants formed mixed and friable calluses in response to combinations of BA and NAA, and mucilaginous calluses in response to PIC. Shoot formation was obtained from all explants, except embryonic and in vitro grown plants leaflets, in response to 2,4-D, TDZ or BA and NAA combinations. Adventitious roots development was obtained from cotyledons in response to IAA, IBA and combinations of 0.44 μM BA with NAA. Root cultures were established in different types of systems, and multiplication was obtained in liquid medium supplemented with IBA under agitation, as well as in liquid medium supplemented with IBA or NAA, using a bead system. Phytochemical analysis of extracts from roots formed in the presence of 54 μM NAA, 57 μM IAA and 14.7 μM IBA, seeds, cotyledons, and organs of in vivo and in vitro plants (stems, roots and leaves) was performed by TLC and HPLC. Different constituents were observed in specific conditions for the detection of saponins and triterpenes by TLC, in addition to a great variety of phenolic compounds. HPLC analysis revealed 49 peaks, including resveratrol, which was found in all extracts. A strong antioxidant activity was found in extracts from leaves of in vivo grown plants (EC50 = 0.91 mg of crude extract/ml of DPPH solution), corresponding to 0.2 mg of quercetin equivalents. In vitro studies will be continued in order to establish other callus cultures and to optimize the adventitious root cultures. Other chromatographic methods will be utilized to define the compounds detected by TLC and HPLC.