A role for amylase and peroxidase-linked polymerization in phenolic antioxidant mobilization in dark-germinated soybean and implications for health

Abstract

Consumption of soybeans has been linked a reduced risk of coronary heart disease and the development of certain cancers. Soybeans are a rich source of phenolic antioxidants, the majority of which occur naturally bound to carbohydrates. Free phenolic antioxidants have higher antioxidant activity than their carbohydrate-bound forms. Hypothesizing that increasing the phenolic aglycone content in soybean may increase its nutritional functionality, we investigated whether carbohydrate-cleaving enzymes have a role in phenolic mobilization in sprouted soybean. Total phenolic content, glucosidase, amylase and glucuronidase activities were measured in extracts of a dark-germinated soybean. Additionally, antioxidant activity and peroxidase activity were measured. Phenolic content and antioxidant activity correlated to amylase and glucuronidase activities, but not to glucosidase activity. Peroxidase activity suggested possible utilization of amylase-mobilized phenolics. Optimization of phenolic antioxidant content based on this metabolic understanding could have benefits for increasing the nutritional functionality of soybean for improving carbohydrate metabolism-linked overall health and wellness.