Antiviral sulfated chitosan derivatives

A compound of formula II:

• or a pharmaceutically acceptable salt thereof, wherein:
• each of R1, R2 or R3 independently represents H or −SO3M;
• with the proviso that total sulfation degree of compound expressed by Z is of between 0.05 and 3, and wherein Z is calculated in base to elemental analysis of compound according to this general formula:
• Z= (S%/32.06)/(N%/14.01);
• wherein S % and N % represent the percentage of each element by weight
• M represents a monovalent cation, preferably pyridinium cation, an ammonium cation or an alkali metal cation;
• R4 represents —CO—(CH2)7—CH═CH—(CH2)7—CH3;
• m represents from 0 to 1760 repeating units;
• n represents from 1 to 1100 repeating units;
• and
• o represents from 1 to 2100 repeating units,
• for use in the treatment and/or prevention of a viral infections.