Rapid and Convenient Detection of Urinary Equol by Thin-Layer Chromatography

Equol, a metabolite of daidzein for some intestinal microflora, is known to retain highly estrogenic activity and is of wide interest in relation to human health. However, not all humans can produce equol. In this study, detection of urinary equol using thin-layer chromatography (TLC) was performed to distinguish between equol producers and non-producers. After 36 h of soy food intake, urine, collected from 7 volunteers, was hydrolyzed, purified by reverse phase silica gel column and applied to normal phase TLC. Consequently, equol was clearly separated from the urine samples and discriminated the equol producers in this system. The detection limit of equol was at least 20 ng.