Improvement of antioxidant and antimicrobial activity of soy isoflavones extracts bioconverted with ?-glucosidase / Melhoria da atividade antioxidante e antimicrobiana de extratos de isoflavonas de soja bioconvertidos com ?-glucosidase

Jefferson J. Teixeira, Rafael Conrado, Laura Gonçalves, Patrícia L. N. de Carvalho, Helia H. Sato, Ruann J. S. de Castro, Joelise de A.F. Angelotti


Soybean is largely produced in Brazil being one of the main Brazilian Agricultural crop, achieving 223 million tons produced in 2017. The consumption of soy products increased in recent years due to the association with healthy benefits in oxidative stress and chronic diseases. The researches have been pointing that the isoflavones presenting in soy are the responsible compounds for alleviating these symptoms. The main purpose of this work were use of ?-glucosidase enzyme to convert glucoside isoflavones to aglycone form in isoflavone soy extract, and then evaluate the antioxidant and antimicrobial activity against some pathogens. The isoflavones were obtained according to Aguiar (2004) with modifications. The soy flour (65 mesh) was defatted with hexane (1:10 w/v) and the extraction of isoflavones was performed using 80% aqueous methanol solution under 100 rpm stirring for 1 hour at room temperature. The mixture was then filtrated, and the supernatant recovered. The extract was used for the bioconversion of glycosyl isoflavones from soy into aglycones isoflavones using ?-glucosidase enzyme. According to recent researches the aglycon form has greater absorption by organism and higher antioxidant activity than the glucoside form. According the results all antioxidant methods presented higher activity to bioconverted extract. The bioconverted extract (1060.73 mg Trolox equivalent) presented near 9 times superior antioxidant activity measured by DPPH method than raw extract (123.21 mg Trolox equivalent).  The Total phenolic content presented similar behavior being higher to bioconverted extract than in raw extract. The antimicrobial activity of the isoflavones extracts raw and bioconverted against S. aureus, C. albicans and E. coli were higher than 1600 ?g/mL in the range studied 0.78 to 1600 ?g/mL.


soybean, isoflavones, ?-glucosidase.

Full Text:



Benzie, I. F. F.; Strain, J. J. 1996. The ferric reducing ability of plasma (FRAP) as a measure of antioxidant power the FRAP assay. Analytical Biochemistry, 239, 70–76.

BOUGATEF, A. et al., 2009. Antioxidant and free radical-scavenging activities of smooth hound (Mustelus mustelus) muscle protein hydrolysates obtained by gastrointestinal proteases. Food Chemistry, v. 114, p. 1198–1205.

Chen, K., Lo, Y., Liu, C., Yu, R., Chou, C., & Cheng, K., 2013. Enrichment of two isoflavone aglycones in black soymilk by using spent coffee grounds as an immobilizer for ??glucosidase. Food Chemistry, 139, 79–85.

Eason, R. R., Till, S. R., Velarde, M. C., Geng, Y., Chatman, L., Gu, L., … Simmen, R. C., 2005. Uterine phenotype of young adult rats exposed to dietary soy or genistein during development. Journal of Nutritional Biochemistry, 16, 625–632.

FAO, 2018. Food and agricultural commodities production: Country rank in the world, by commodity.

Kudou, S., Fleury, Y., Welti, D., et al., 1991. Malonyl isoflavone glycosides in soybean seeds (Glycine max Merrill). Agric. Biol. Chem., 55(9):2227-2233.

Lima, F. S., Ida, E. I., 2014. Optimisation of soybean hydrothermal treatment for the conversion of ??glucoside isoflavones to aglycones. LWT ? Food Science and Technology, 56, 232–239.

Mallek-Makhfakh, H., Fakhfakh, J., Walha, K., Hassairi, H., Gargouri, A., Belghith, H., 2017. Enzymatic hydrolysis of pretreated alfa fibers (stipa tenacissima) using ?-D-Glucosidase and xylanase of talaromyces thermophilus from solid-state fermentation , Int. J. Biol. Macromol., 103.

Matsuura, M., Obata, A., 1993. ?-Glucosidases from soybeans hydrolyze daidzin and genistin. J. Food Sci., 58(1):144-147.