ACE inhibitory activity and bioconversion of isoflavones by Lactobacillus in soymilk supplemented with B‐vitamins

Abstract

PurposeThe aim of this study is to examine the bioactive properties of lactobacilli‐fermented B‐vitamin soymilk, namely the in‐vitro antihypertensive property and bioconversion of isoflavone glucosides to aglycones.Design/methodology/approachLactobacillus acidophilus BT 1088, L. fermentum BT 8219, L. acidophilus FTDC 8633 and L. gasseri FTDC 8131 were investigated for their bioactive potential and enhanced bioconversion of isoflavones in soymilk supplemented with individual B‐vitamins at a concentration of 1 mg/L.FindingsThe supplementation of thiamine, riboflavin, niacinamide, calcium pantothenate, biotin and folic acid enhanced the ACE‐inhibitory activity of lactobacilli in soymilk accompanied by a lower IC50 value compared to the control (P<0.05). The β‐glucosidase specific activity of lactobacilli was also enhanced on supplementation of B‐vitamins, leading to increased bioconversion of isoflavones in soymilk. The concentration of genistein was decreased, accompanied by an increased concentration of genistein on fermentation in the presence of thiamine, niacinamide, biotin, calcium pantothenate and folic acid. Additionally, the supplementation of niacinamide, calcium pantothenate, biotin and folic acid also led to lower concentrations of malonyl daidzin, indicating increased hydrolysis of malonyl daidzin to daidzin. Results from the present study indicated that the supplementation of B‐vitamins could enhance the bioactive potential and bioconversion of isoflavones in lactobacilli‐fermented soymilk.Originality/valueThis work has shown that the supplementation of B‐vitamins in lactobacilli fermented soymilk has exerted in vitro ACE‐inhibitory activity and increased the accumulation of bioactive isoflavone aglycones. To the authors' knowledge, this is the first evaluation reporting on such aspects.

Ultraviolet radiation enhanced growth of lactobacilli and their bioconversion of isoflavones in biotin-supplemented soymilk

“…Soymilk fermented by UVB treated lactobacilli has also been found to contain significantly lower (P < 0.05) concentration of malonyl-and b-glucosides compared to that of the control and other UV radiation studied. This was attributed to higher doses of UVB treatment on lactobacilli that had led to enhance b-glucosidase enzyme and cleavage of b-1,6-glucosidic linkage to release bioactive aglycones during the fermentation of soymilk (Ewe et al, 2011).…”

“…The isoflavones from fermented soymilk was extracted and analyzed according to the method of Ewe et al (2011). Concentrations of isoflavones were determined using high performance liquid chromatography (HPLC).…”

“…Intracellular b-glucosidase activity of bacterial cells was assayed as described previously (Ewe, Wan-Abdullah, & Liong, 2011). The crude enzyme extract from bacterial cells was extracted in cold sodium citrate buffer (50 mmol/l, pH 5.5) by sonication in an icebath for 30 min.…”

“…Fermented soymilk has been reported to contain higher amounts of aglycones than glucosides conjugates of isoflavones via bioconversion by microorganisms. We have demonstrated that the supplementation of B-vitamins particularly biotin had significantly promoted the growth and b-glucosidase enzyme activity of lactobacilli in soymilk (Ewe, Wan-Abdullah, & Liong, 2010), which subsequently enhanced the bioconversion of isoflavone glucosides to aglycones during the fermentation of soymilk (Ewe et al, 2011). Biotin is an essential micronutrient required by various lactic acid bacteria for normal cellular function, growth and development.…”

Bioconversion of Isoflavones and the Probiotic Properties of the Electroporated Parent and Subsequent Three Subcultures of Lactobacillus fermentum BT 8219 in Biotin-Soymilk

“…It has been found that the β-glucosidases possessing intestinal microbiota, such as lactobacilli, are involved with the hydrolysis of glucose moiety from glucoseconjugated isoflavones, producing aglycone configurations that are more bioavailable and biologically active [44]. The fermentation of soymilk with β-glucosidases-possessing lactobacilli has been reported to contain higher amounts of aglycones than glucosides conjugates of isoflavones [12].…”