Abstract
Equol, one of the intestinal microflora metabolites of daidzein, has gained much attention for having greater bioactivity than its precursor (daidzein and daidzin) and seeming to be promoted by hydrogen gas. The effects of lactulose on the equol-producing capacity and liver antioxidant status of barrows treated with daidzein were investigated in this study. Male castrated piglets (barrows) of Landrace×Duroc, aged 40 days, were randomly divided into the following three groups: control group (C, n = 12, fed an isoflavones-free basic diet), daidzein group (D, n = 12, fed an isoflavones-free basic diet with 50 mg/kg of daidzein supplementation) and daidzein+lactulose group (D+L, n = 12, fed an isoflavones-free basic diet with 1% of lactulose and 50 mg/kg of daidzein supplementation). After 20 days, the profile of short-chain fatty acids in the colon digesta showed that lactulose significantly increased the fermented capacity in the gastrointestinal tract of the barrows. First-void urinary equol concentrations were significantly higher in the D+L group than in the D group (3.13±0.93 compared to 2.11±0.82 μg/ml, respectively). Furthermore, fecal equol levels were also significantly higher in the D+L group than in the D group (12.00±2.68 compared to 10.00±2.26 μg/g, respectively). The population of bacteroidetes and the percentage of bacteroidetes to bacteria in feces were higher in the D+L group than in the D group. The DGGE profiles results indicate that lactulose might shift the pathways of hydrogen utilization, and changing the profiles of SRB in feces. Moreover, the D+L group had weak enhancement of T-SOD and CuZn-SOD activities in the livers of barrows treated with daidzein.
Highlights
Daidzein, the main isoflavones found in soybeans and most soy foods, can be transformed to equol [1]
For the colon digesta samples, the results showed that there was no influence on the Shannon diversity of the DGGE profile for bacteria, MPB, and Sulfate-reducing Bacteria (SRB), and that the DGGE band numbers for bacteria and SRB were of significant difference (Table 3)
Our previous studies showed that 1% (10g/L) of lactulose was able to improve equol production in vitro [13]
Summary
The main isoflavones found in soybeans and most soy foods, can be transformed to equol [1]. Equol is exclusively produced by intestinal microflora [2] and may be superior to all other isoflavones in terms of its antioxidant [3] and antiinflammatory properties [4]. Equol producers are advantageous in terms of enhancing health benefits, and gained much attention since the postulation of the equol hypothesis [6]. There is conflicting evidence available regarding the potential health benefits associated with the ability to produce equol, there is a growing interest in dietary applications that might enhance equol production in humans and animals. Hydrogen gas was reported to stimulate equol production in an equol-producing mixed culture (EPC4), likely by acting as an electron donor in the formation of equol [7]. A stronger decrease was observed with increasing amounts of EPC4 and constant equol production, suggesting daidzein to act partly as a hydrogen sink
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