Culturas de raízes de Cleome dendroides Schult & Schult f. e caracterização química de materiais obtidos in vitro e coletados a campo

Abstract

Plants are an important source of bioactive molecules whose synthesis usually occurs at low concentrations. The need to use large amounts of plant material for the commercial exploitation of these molecules makes the process less efficient and can compromises species conservation. This issue can be minimized by the application of plant tissue culture techniques through which in vitro production of metabolites of interest is possible. Among these techniques, the adventitious root cultures have great potential for bioactive´s production because roots are constituted by differentiated cells. This study aims to: (1) evaluate the effect of different physical and chemical factors on in vitro root multiplication, and (2) to perform the chemical characterization of Cleome dendroides, an endemic herbaceous species of the Atlantic forest. As source of explants were used in vitro propagated plants. The parameters tested were: explant size (0.5; 1.0; 1.5 cm), light (dark and 16:8 hrs photoperiod), the medium total mineral salts (MS1/4; MS1/2; MS; 2MS), the sucrose concentration (10; 20; 30; 50; 70 ; 90 g.L-1), the culture medium pH (5.0; 5.8, 6.0, 6.5 and 7.2) and agitation speed (60; 110; 130; 160 rpm). The explants were cultured in MS medium without hormone supplementation (MS0) or in the presence of 3.0 mg.L-1 of IBA. The accumulation of biomass was quantified by measuring the dry weight after 45 days in culture. The chemical characterization was performed with in vitro materials (plants and root cultures) and field-grown plants, considering two methodologies of extraction (dynamic maceration and ultrasound-accelerated maceration) and chromatographic analyses. The results showed that the supplementation with AIB increased the production of roots when compared to cultures kept in MS0. Size of the explants influenced root proliferation only for cultures kept in the dark. However, the presence of light favored root multiplication. Considering the results obtained in these first assays, for the continuation of studies were selected explants with 0.5 cm cultured on medium supplemented with 3.0 mg.L-1 AIB in the presence of light. The reduction in the total minerals salt concentration has a positive effect in root multiplication, mainly on MS1/4. The same response was observed when the sucrose concentration was raised to 70 g.L-1. The increase of the initial pH value of the culture medium to 6.5, as well as maintenance of cultures under a speed agitation of 130 rpm, also favored the process of roots multiplication. The use of the best conditions described above in a single culture protocol proved an efficient strategy to maintain the multiplication capacity of roots over time in culture. Considering the chemical characterization, for most of the extracts evaluated, the dynamic maceration was more effective. The CCD analyses suggested the presence of saponins and flavonoids. The analyses in HPLC showed, mainly, the presence of flavonoids. The results demonstrated the feasibility in the production of in vitro root cultures of C. dendroides using in vitro propagated plants as source of explants. In addition showed its chemical profile, important information for studies related to the medicinal potential of the species