NATURAL POLYSACCHARIDE DERIVATIVE SUBSTITUTED WITH SIALIC ACID AND FUNCTIONING AS CELL RECOGNIZING ELEMENT AND ITS PREPARATION

摘要

PURPOSE:To prepare a natural polysaccharide derivative having a cell recognizing property in vivo and a physiological activity, by introducing a sialic acid residue as a cell recognizing element into the sugar chain end of part of the sugar units which constitute pullulan, aminopectin, etc. CONSTITUTION:Primary hydroxyl groups on the carbon atom at the 6-position of 0.1-5 sugar units per 100 glucose units constituting pullulan, aminopectin, etc. which are natural polysaccharides, as shown by the formula (where phi is a sialic acid residue), so that the sialic acid residue which is a cell recognizing element is introduced into the sugar chain end of the polysaccharide, whereby the object natural polysaccharide derivative is obtained. When a medicine carrier such as liposome is coated with this polysaccharide derivative, a medicine contained in the medicine carrier can be prevented from flowing out spontaneously, and yet the rate of migration of the medicine carrier toward target cells can be improved by the action of the sialic acid residue as a cell recognizing element.