Análise dos teores de isoflavonas e minerais em cultivares de soja transgênicas e comerciais

Abstract

The increased consumption of genetically modified organisms and the discovery of biologically active compounds have been constant subjects in academia. This study combines these two subjects aiming to evaluate the composition differences between conventional soybeans traded in Belo Horizonte and genetically modified soybeans harvested in Minas Gerais in 2011. We focused on the analysis of isoflavones profile and the mineral fraction, questioning the substantial equivalence of conventional and genetically modified organisms. In order to check whether GM declaration on labels agrees to transgenic content within grains, we used traditional methods to evaluate labeling combined with modern methods of transgenic assessment (PCR Real-time). It was not found presence of the 35S promoter indicating the absence of transgene insertion. Regarding minerals analysis, the chosen method was ICP-OES because of its scope and possibility of multi-element analysis. Quantification of isoflavones done by High Performance Liquid Chromatography - HPLC led to greater precision of quantification as well as better stratification of their groups. Statistical difference was found between conventional and transgenic soybean groups regarding isoflavone levels and mineral composition. Potassium, the main mineral component, was quantified in higher concentrations in conventional soybeans, while GM presented higher concentrations of iron. Genistein, the more bioactive aglycone, was found in significantly higher quantities in conventional soybeans, however the total content of isoflavones was higher in transgenic samples. Results call attention to the lack of substantial equivalence among organisms, whatever conventional or GM origins. Although the pairing between groups was not done in the traditional format, which compares conventional soybeans and its almost isogenic, the design represent the reality experienced by consumers in the state of Minas Gerais, in relation to what is produced and consumed.