Suppressive Effect of Wheat-bran Hemicellulose on Blood Pressure in Spontaneously Hypertensive Rats

Abstract

It has been reported that wheat water-soluble hemicellulose (WSH) has a suppressive effect on blood pressure, and also reported that WSH consists of two arabinoxylans (AX-1 and AX-2) that differ in their characteristics and structure. In order to clarify the hemicellulose component responsible for this effect, each of the arabinoxylans was separated and puhfied from WSH, and their suppressive effect on blood pressure in SHR (spontaneouly hypertensitive rats) was investigated. AX-1, characterized as an arabinoxylan consisting of a main chain of 1, 4-linked-β-D-xylopyranose residues having only a few L-arabinofuranosyl branches and few uronic acid moieties, which was separated by 50% ethanol precipitation from WSH, had no suppressive effect on blood pressure. On the other hand, AX-2, an arabinoxylan consisting of a main chain with many arabinofuranosyl branches, some uronic acid moieties and a proteinaceous portion, which was prepared by ultrafiltration following enzymatic treatment with cellulase Onozuka, was found to suppress blood pressure. Compared with control SHR fed no hemicellulose, SHR fed AX-2 showed increased excretion of sodium in thier feces, while SHR fed AX-1 showed no difference from the control. It is suggested that only AX-2 in WSH is the component responsible for the suppressive effect on blood pressure, due probably to its unique structure and ion-exchange ability through its uronic acid and/or proteinaceous portion.