Studies on soybean isoflavones usually express the total concentration of these components as aglycones, since conjugated forms are hydrolysed to aglycones during intestinal absorption in humans (Murphy
et al., 1997). Total isoflavone find more aglycones ranged between 11.2 and 52.0 mg/kg, with a mean content of 42.5 mg/kg. There is a wide range of contents of isoflavones in soy-based infant formulas reported in the literature. Knight et al. (1998) and Kuo and Ding (2004) reported slightly lower contents of aglycone isoflavones in soy-based infant formulas, ranging from 6.5 to 13 mg/kg, in comparison to our findings. Murphy et al., 1997, Setchell et al., 1997, Irvine et al., 1998 and Garrett et al., 1999 and Genovese and Lajolo (2002) reported higher contents of aglycone isoflavones in comparison to those of the present study, ranging from 78 to 205 mg/kg. The distribution of isoflavones among β-glycosilated, malonylglycosilated, acetylglycosilated and aglycones in infant formula samples are shown in Fig. 1A. In general, these results were in accordance to data previously published in the literature (Genovese and Lajolo, 2002, Murphy et al., 1997 and Setchell et al., Smad inhibitor 1997). β-Glycosylated isoflavones (genistin, daidzin and glycitin) were the most abundant, corresponding
to a mean of 51.6% of total isoflavones, followed by malonylglycosilated isoflavones and aglycones (genistein, daidzein and glycitein), which accounted for 19.4% and 16.6%, respectively. Acetylglycosilated isoflavones were the least abundant, corresponding to a mean of only 12.4% of total isoflavones. Aptamil 1, Aptamil 2 and Nan Soy presented little variation regarding the distribution of isoflavones. Amino acid Isomil 1 showed a lower relative content of β-glycosylated (39.1%) and a higher relative content of acetylglycosilated (28.4%) isoflavones in relation to the three above-mentioned samples. This profile indicated that the soy protein used to produce Isomil 1 was probably submitted to milder heating conditions, since β-glycosylated isoflavones are formed as a consequence of thermal degradation of malonylglycosilated
isoflavones (Wang & Murphy, 1996). AlergoMed presented higher relative contents of β-glycosylated (63.8%) and aglycone (21.9%) isoflavones, as well as lower relative contents of malonyl (6.8%) and acetylglycosilated (7.5%) isoflavones. This profile is consistent with soy protein that has been extensively processed, since aglycones are produced as a consequence of hydrolysis of conjugated isoflavones Wang & Murphy, 1994 (Wang & Murphy, 1996). In fact, AlergoMed was produced with hydrolysed soy protein, probably explaining its high relative content of aglycones. Considering that isoflavones are hydrolysed during intestinal absorption and thus aglycone cores are responsible for isoflavones potential bioactivity (Murphy et al.