Extratos de Echinodorus grandiflorus, obtidos a partir de folhas secas por três técnicas diferentes, foram avaliados pelo ensaio de indução lisogênica bacteriana (Induteste), em relação às propriedades genotóxicas. As amostras foram previamente esterilizadas por vapor de água (autoclavação) ou luz ultravioleta. Somente os extratos preparados por infusão e esterilizados a vapor mostraram atividade genotóxica. A análise fitoquímica revelou a presença dos flavonóides isovitexina, isoorientina, swertisina e swertiajaponina. Isovitexina e isoorientina, isoladas de uma fração genotóxica, foram testadas separadamente e não apresentaram genotoxidade. O desenvolvimento de odor adocicado e escurecimento dos extratos submetidos ao calor motivaram a investigação quanto às substâncias precursoras da reação de Maillard no extrato. Ácidos aminados e açúcares redutores foram identificados e a presença de precursores da reação de Maillard no extrato foi confirmada por espectrofotometria no visível com a adição do inibidor bissulfito de sódio antes do aquecimento. Este é o primeiro relato de aparecimento de melanoidinas em uma técnica que pode ser usada para a preparação de fitoterápico. A atividade genotóxica de tais infusões preparadas ao calor implica em algum risco de desenvolvimento de doenças degenerativas com seu uso descontrolado e por longo prazo.

Extracts of Echinodorus grandiflorus obtained from dried leaves by three different techniques were evaluated by bacterial lysogenic induction assay (Inductest) in relation to their genotoxic properties. Before being added to test cultures, extracts were sterilized either by steam sterilization or ultraviolet light. Only the extracts prepared by infusion and steam sterilized have shown genotoxic activity. The phytochemical analysis revealed the presence of the flavonoids isovitexin, isoorientin, swertisin and swertiajaponin, isolated from a genotoxic fraction. They were assayed separately and tested negative in the Inductest protocol. The development of browning color and sweet smell in extracts submitted to heat, prompted further chemical analysis in search for Maillard's reaction precursors. Several aminoacids and reducing sugars were cast in the extract. The presence of characteristic Maillard's melanoidins products was determined by spectrophotometry in the visible region and the inhibition of this reaction was observed when its characteristic inhibitor, sodium bisulfite, was added prior to heating. Remarkably, this is the first paper reporting on the appearance of such compounds in a phytomedicine preparation under a current phytopharmaceutical procedure. The genotoxic activity of such heat-prepared infusions imply in some risk of developing degenerative diseases for patients in long-term, uncontrolled use of such phytomedicines.

Echinodorus macrophyllus, commonly known as chapéu-de-couro, is a medicinal plant used in folk medicine to treat inflammation and rheumatic diseases. In this work, we used short-term bacterial assays based on the induction of SOS functions to examine the genotoxicity and mutagenicity of an aqueous extract of E. macrophyllus leaves. Whole extract and an ethyl acetate fraction showed similar genotoxicity and caused an ~70-fold increase in lysogenic induction. The extract also gave a positive result in the SOS chromotest with an increase of 12-fold in β-Galactosidase enzymatic units. There was a strong trend towards base substitutions and frameshifts at purine sites in the mutations induced by the extract in Escherichia coli (CC103 and CC104 strains) and Salmonella typhimurium test strains (22-fold increase in histidine revertants in TA98 strain). Since reactive oxygen species may be implicated in aging process and in degenerative diseases, we used antioxidant compounds as catalase, thiourea and dipyridyl in the lysogenic induction test. All this compounds were able to reduce the induction factor observed in the treatment with chapéu-de-couro, thus suggesting that the genotoxicity and mutagenicity were attributable to the production of reactive oxygen species that targeted DNA purines.