Synthesis and antitumor activity of conjugates of 5-fluorouracil and chito-oligosaccharides involving a hexamethylene spacer group and carbamoyl bonds.

With the object of providing an oligomeric prodrug of 5-fluorouracil (5FU) with reduced side-effects, affinity for tumor cells and high antitumor activity, 5FU was covalently attached to three chito-oligosaccharides (COS) through hexamethylene spacer groups via carbamoyl bonds. The ability of these conjugates to prolong the life of lymphocytic leukemia mice (following their intraperitoneal administration) and their tumor-inhibitory effects on Meth-A fibrosarcoma or MH-134 hepatoma mice (following their subcutaneous administration) were assessed. The conjugates caused a significant increase in the survival time of the p-388 leukemia mice, and higher growth-inhibitory effects against the solid tumor than either 5FU, COS, or blends of 5FU and COS. At the highest dose levels, the conjugates did not cause acute toxicity, and did not cause rapid decrease in body weight.