Studies on Browning Reaction Products from Reducing Sugars and Amino Acids

The browning reaction products prepared by heating a mixture of D-xylose (2M) and glycine (2M) at 100°C for 2 hr. were fractionated into melanoidins and low molecular reductones by gelfiltration with Sephadex G15. Strong antioxidative activities were found in the melanoidin fractions. When these fractions were refractionated by G50, antioxidative activities were distributed in a wide molecular range of melanoidins. From the results of the paper partition chromatography and the antioxidative activities of these melanoidins, relatively low molecular melanoidin was used to further fractionation by gel filtration with G100. When the antioxidative activity of each fraction was compared at same color leve1, its activity was found to be distributed to all over the colored fractions. The melanoidin fraction by G100, Which exhibited a strong antioxidative activity, was further separated into three bands by thin Iayer chromatOgraphy with cellulose powder. Each band was named as melanoidin A, B and C. Of those three melanoidins, melanoidin B was considered to be pure on paper electrophoretical and ultracentrifugal patterns. The melecular weight of melanoidin B was about 4500. In comparison of antioxidative activities of those three melanoidins, C showed the weaker inhibitory effect on oxidation of linoleic acid than A and B which exhibited almost the same antioxidative activity each other.