EFFECTS OF A DAIDZEIN‐RICH ISOFLAVONE AGLYCONE EXTRACT ON DIET‐INDUCED OBESITY IN AN OVARIECTOMIZED MOUSE MODEL

Abstract

SUMMARY 1 Obesity is the most common nutritional disorder in affluent societies and an increasingly important health problem in developing countries. Soy protein and soy isoflavone genistein have been investigated for their effects on reduction of bodyweight gain and on modulation of lipid metabolism, and the results have been inconclusive. Conversely, daidzein has been shown to have biological activities that are related to beneficial lipid profiles. 2 The aim of the present study was to evaluate the effects of a daidzein-rich isoflavone aglycone extract (AglyMax; Nichimo Co. Ltd, Tokyo, Japan) on reduction of bodyweight gain and modulation of lipid metabolism in an oestrogen-deficient female mouse model. Six-week-old female C57BL/6 mice were either ovariectomized (OVX) or sham operated. After 1 week recovery, mice were housed individually and OVX mice were randomly assigned into four of five experimental groups and consumed corresponding experimental diets for 8 weeks: (i) Sham: the high fat (HF; 45% calorie from fat) diet; (ii) OVX: the HF diet; (iii) OVX-Low AglyMax: the HF diet with addition of 0.12% AglyMax; (iv) OVX-High AglyMax: the HF diet with addition of 0.6% AglyMax; and (v) OVX pair-fed: the HF diet consumed at the same amount as that in the OVX-High AglyMax group. 3 Mice treated with AglyMax at 0.6% of the diet significantly reduced food intake by 18.2% (P < 0.001), final bodyweight gain by 63.5% (P < 0.001), white adipose tissue (WAT) mass by 44.1% (P < 0.001) and adipocyte size by 42.9% (P < 0.001) compared with the OVX mice. Mice treated with AglyMax (0.6% of the diet) further reduced bodyweight gain by 39.0% (P < 0.05), WAT mass by 37.3% (P < 0.01) and adipocyte size by 29.1% (P < 0.001) compared with the pair-fed mice. Mice treated with 0.6% AglyMax also had significantly reduced hepatic triglycerides and fecal bile acids excretion, by 41.0% (P < 0.01) and 58.5% (P < 0.05), respectively, compared with the pair-fed mice. 4 The results suggest that AglyMax may be further investigated for its application in the control of bodyweight gain and modulation of lipid metabolism preferentially in a subgroup of subjects with low oestrogen status.