POSSIBLE LOCALITY OF AFFINITIVE SITE(S) ON CELLULOSE FOR PRESERVATION OF STABLE RED COLOR OF CARTHAMIN

To search for the specific binding site(s) of cellulose to form a stable coloured complex with carthamin, interaction between carthamin and four different glucosyl polymers was studied as a function of pigment adsorbability to respective test polymers in an acidic buffer solution. A possible action site in the interaction was suggested to be primary alcoholic hydroxyl group(s) on the glucose units of the macromolecules examined. An equivalent amount of carthamin was fixed with cellulose and the resultant carthamin-cellulose complex subjected to spectroscopic analyses. In the complex, there were characteristic changes in the spectrophotometric patterns in the regions of 1630 cm-1 (infra-red) and 2260 nm (near infra-red), indicating that hydrogen bonding(s) exists between carthamin and cellulose. The above results are finally discussed in relation to the stable red colour expression of carthamin on cellulose. © 1990.