Efeito do 24-epibrassinolídeo na modulação do perfil de constituintes voláteis e nas atividades biológicas e antioxidante dos óleos essenciais das folhas de Mentha pulegium e de Mentha piperita (Lamiaceae)

Abstract

Some essential oils have antimicrobial, antioxidant and antiproliferative activities against tumor cell lines. Increases in the concentrations of chlorophyll, evidenced after administration of brassinosteroids (hormones that regulate plant development) may lead to higher rates of photosynthesis, which may result in increases in the number of essential oils, suggesting a possible role of this hormone in the biosynthetic activity of secondary metabolites plants, including mono-and sesquiterpenes track of isoprene derivatives which are important constituents of the essential oils. Were used in the study Mentha piperita and Mentha pulegium, as are species with essential oils widely used in Brazil for food, cosmetic and medical (antimicrobial activity reports, antioxidant and cytotoxic against some tumor cell lines). The 24-epibrassinolide was applied in a single concentration (10 -7 M) on the substrate where the plants were grown and leaves were collected for analysis 15 and 52 days after application of brassinosteroid. The essential oils from M. pulegium leaves of plants of the group receiving the 24-epibrassinolide demonstrated better results in the essential oils of the plants 15 days' analysis, which presented low MIC values for the indicator strains susceptible to oil essential and can be associated to the synergistic effect of the action of the main constituents (such as pulegone and menthol) with minority which had a higher percentage share in the oil composition (limonene and with menthyl acetate), these constituents with documented antimicrobial effect literature. On the other hand, treatment led to changes in the profile of volatile constituents of essential oils, both at 15 and at 52 days after treatment, likely related to higher antibacterial activity. The antiproliferative activity against tumor cell lines was also enhanced in the essential oil of plant M. pulegium receiving 24-epibrassinolide. The essential oils from leaves of M. piperita demonstrated effective improvement in the yield of oil from plants treated with the 24-epibrassinolide. The oil obtained from plants treated with the 24epibrassinolide, compared to the essential oil of the control group, presented results indicating greater antibacterial activity, increased antioxidant capacity and greater antiproliferative activity against tumor cell lines. This behavior was observed mainly for samples 52 days of analysis for the essential oil of M. piperita leaves subjected to 24-epibrassinolide in the control group, which presented low values of CIM, TGI and higher value of antioxidant capacity ORACFL the test, and the biological effect may be due to the synergistic effect of different chemical constituents of essential oil. It is concluded that the use of 24-epibrassinolide presented in modulating effect profile of volatile constituents in the antimicrobial and antioxidant activity and antiproliferative activities of essential oil from M. pulegium and M. piperita leaf for some strains of microorganisms, some tumor cell lines. However, the modulator...