Thermal degradation kinetics of isoflavone aglycones from soy and red clover

Abstract

Driven by their beneficial effects on human metabolism, isoflavonoids have gained considerable importance reflected by an increased number of isoflavone-rich foods, food supplements and pharmaceutical products on the market, mainly derived from soy and red clover. While it is well known that the genuine isoflavone pattern will be altered during processing, data on aglycone stability are rare. Therefore, a thorough study into the thermal sensitivities of biochanin A, daidzein, formononetin, flavone, genistein, glycitein and isoflavone was performed. Samples were heated at 150 degrees C over a period of 7 h at three different pH values, and degradation of the aglycones was monitored by HPLC-DAD analyses. Therefrom, structure-related stability characteristics could be established. While virtually no decay was observed at pH 7.0 and 5.6, degradation was most prominent at pH 3. 1. Individual aglycone retention was further dependent on heating time with daidzein being the most labile compound after any time interval. Curve fitting of the data revealed first-order degradation kinetics for flavone and glycitein, while the remaining aglycones exhibited a sigmoidal degradation pattern.

Evaluation of bioactive compounds and bioactivities of soybean dried by different methods and conditions

“…However, aglycones content in soybean dried at 150°C was lower than that in soybean dried at 130°C. Recent data revealed that aglycones exhibit higher degradation rates when heated at 150°C or higher (Chien et al, 2005;Stintzing, Hoffmann, & Carle, 2006;Xu et al, 2002). It is possible that the inter-conversion from several glucosides to the corresponding aglycones via hydrolysis occurred at lower extents compared to the thermal degradation of aglycones at the drying temperature of 150°C.…”

Surface molecularly imprinted silica for selective solid-phase extraction of biochanin A, daidzein and genistein from urine samples

“…Besides, considering the reports that isoflavones are sensitive to oxidation, particularly under basic conditions at elevated temperatures [41][42][43], the appropriate control experiments to study the template decomposition during synthesis process were performed. It concerned, the comparison of the chromatograms obtained from the analysis of the standard of biochanin A and methanol extracts of Soxhlet extraction, used for template removal.…”

Detection of Potential Chloroplastic Substrates for Polyphenol Oxidase Suggests a Role in Undamaged Leaves

“…The stability of biochanin and formononetin at 90°C for 5 min has previously been demonstrated (Stintzing et al, 2006). The freeze-dried leaf samples (50 ± 2.5 mg samples) were extracted x1 in 0.…”