Methods for the treatment of conditions related to hydrogen sulfide

A method comprising, treating a neurodegenerative disease that is associated with decreased activity of H2S in an animal in need thereof, by orally administering to the animal, an effective amount of a compound of formula (I)

• wherein:
• R1 represents a (1-6C)alkoxycarbonyl group or a (1-6C)alkanoyl group that may bear one, two or three substituents selected from hydroxy, (1-6C)alkoxy, (1-6C)alkanoyloxy, carboxy and (1-6C)alkoxycarbonyl;
• R2 represents a hydroxyl group, a (1-6C)alkoxy group, NRaRb (wherein each Ra and Rb is independently H or (1-6C)alkyl), or a residue of an amino acid;
• and
• R3 represents a (1-6C)alkanoyl group that may bear one, two or three substituents selected from hydroxy, (1-6C)alkoxy, (1-6C)alkanoyloxy, carboxy and (1-6C)alkoxycarbonyl;
• or
• a compound of formula (III)
• wherein:
• R8 represents a (1-6C)alkoxycarbonyl group or a (1-6C)alkanoyl group that may bear one, two or three substituents selected from hydroxy, (1-6C)alkoxy, (1-6C)alkanoyloxy, carboxy and (1-6C)alkoxycarbonyl;
• and
• R9 represents a hydroxyl group, a (1-6C)alkoxy group that may bear one, two or three substituents selected from hydroxy, (1-6C)alkoxy, (1-6C)alkanoyloxy, amino, (1-6C)alkylamino, di-(1-6C)alkylamino, carboxy and (1-6C)alkoxycarbonyl, NRaRb (wherein each Ra and Rb is independently H or (1-6C)alkyl), or a residue of an amino acid;
• or
• a compound of formula (IV)
• wherein:
• R10 represents a hydrogen atom, a (1-6C)alkoxycarbonyl group or a (1-6C)alkanoyl group that may bear one, two or three substituents selected from hydroxy, (1-6C)alkoxy, (1-6C)alkanoyloxy, carboxy and (1-6C)alkoxycarbonyl;
• and
• one of R11 and R12 represents a (1-6C)alkoxy group, NRaRb (wherein each Ra and Rb is independently H or (1-6C)alkyl), or a residue of an amino acid, and the other of R11 and R12 represents a hydroxy group, a (1-6C)alkoxy group, NRaRb (wherein each Ra and Rb is independently H or (1-6C)alkyl), or a residue of an amino acid.