Biofortification of broccoli seedlings with selenium: influence on bioactive compounds and in vivo toxicity

• Autor(a) principal: Bachiega, Patricia
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: http://www.teses.usp.br/teses/disponiveis/11/11141/tde-01112018-164508/
• topic: Brassica oleracea; Brassica oleracea; Alimentos funcionais; Functional foods; Micronúcleo; Micronucleus; Mutagenicidade; Mutagenicity; Selenato de sódio; Sodium selenate; Spray dryer; Spray dryer

The objective of this study was to evaluate the influence of biofortification with selenium in the bioactive compounds of broccoli; to test their toxicity and mutagenicity in vivo to prove their safety for consumption; to develop microparticles by the spray dryer technique and to evaluate its physicochemical properties. The broccoli seedlings were biofortified through the addition of 2 mL of 50 μM sodium selenate solution 15 days after sowing (DAS), and collected 30 DAS. The samples were analyzed by different methods for the quantification of selenium (ICP-MS, benchtop and handheld EDXRF). The energy-dispersive X-ray fluorescence spectrometry made either in bench or in a portable equipment presented a good performance for the quantification of selenium, together with low cost and less analysis time. The selenium biofortification technique increased the concentration of this micronutrient in broccoli seedlings. In addition, it also allowed a significant increase in bioactive compounds, such as chlorophyll (12%), phenolic (26%) and flavonoid (19%) compounds, vitamin C (32%) and sulforaphane (12%), the main bioactive compound with anticarcinogenic potential. The efficiency of biofortification with selenium in the culture was verified, and toxicity and mutagenicity studies were conducted in female and male mice treated with different doses of selenium-biofortified broccoli seedlings. After 40 consecutive days of treatment, broccoli seedlings with selenium at doses of 45 and 70 μg Se/kg body weight resulted in significant changes in the relative weights of vital (liver, spleen and kidneys) and reproductive organs (ovary/testis), with the presence of histological alterations in the kidneys and spleen in mice of both sexes. In male mice, the dose of 70 μg Se/kg body weight increased the frequency of micronucleated polychromatic erythrocytes. In females this increase was not observed, demonstrating greater sensitivity of males to the treatment. Finally, microparticles of ethanolic extracts of broccoli seedlings with and without selenium were developed through the spray drying microencapsulation technique. The samples presented low moisture (4-5%) and hygroscopicity (11-12 g of water absorbed 100/g of microparticle) and high solubility (99%). However, there was a significant reduction in the content of phenolic compounds and antioxidant activity after the microencapsulation process. The results of this study demonstrate the importance of biofortification of selenium as a strategy to increase the content of bioactive compounds in broccoli and that the dose of 15 μg Se/kg body weight had no significant toxic or mutagenic effects. In addition, microencapsulation has been shown to allow the elaboration of samples with good technological characteristics however, optimization studies should be conducted to increase the retention power of bioactive compounds and their antioxidant activity.