β-Glycosidase Activity toward Different Glycosidic Forms of Isoflavones

Isoflavones, a group of soybean components that significantly contribute to human health and disease prevention, exist in various chemical forms. The enzyme activity can be very sensitive to molecular structure; thus, the profile of the isoflavones can affect their rate of hydrolysis. The objective of this work was to study the beta-glycosidase activities toward isoflavone beta-glycosides and their conjugated forms. Hydrolysis experiments were conducted where beta-glycosides and their conjugates were treated with beta-glycosidase. Results confirmed that beta-glycosidase can hydrolyze nonconjugated beta-glycosides into aglycones. However, when the enzyme amount and/or activity were limited, significant differences in enzyme activity toward the beta-glycosides were observed. On the other hand, beta-glycosidase was not effective in hydrolyzing the conjugated glycosides to their respective aglycones, even with increased levels of the enzyme and with prolonged incubation. The transformation of conjugated glycosides into their respective beta-glycosides will most likely result in increased hydrolysis rates and better absorption.