Effect of oligofucose derivatives on acetic acid-induced gastric ulcer in rats.

This study attempted to enhance the anti-ulcer activity of fucoidan from Cladosiphon okamuranus TOKIDA by chemical modification with a hydrophobic group. The suitable number of fucose residues in the effective compound was also clarified to obtain a compound of constant quality. Degraded fucoidans were coupled with several hydrophobic groups via Schiff bases, and their anti-ulcer activities were determined by acetic acid-induced ulcer models in rats. Size-fractionated oligofucose was also modified and assayed for anti-ulcer activity. Among the modified oligofucoses, only the oligofucose-dodecylaniline combination (OFDA) significantly promoted ulcer healing. The effective dose was 0.2 mg/kg/d. The most suitable number of fucose residues in the compound for the anti-ulcer activity was determined to be around 12. We succeeded in enhancing the anti-ulcer activity of Cladosiphon fucoidan by modification with dodecylaniline. The activity of this compound was comparable or greater than that of typical anti-ulcer agents. By determination of the optimal OF chain length for the anti-ulcer activity of OFDA, it became possible to obtain OFDA of constant quality.