Chlorophyll and bacteriochlorophyll derivatives, their preparation and pharmaceutical compositions comprising them

A compound of the formula

• X--CO--Y--A--R
• wherein
• X--CO-- is a C17-propionyl residue of a compound selected from the group consisting of a chlorophyll (Chl), a bacteriochlorophyll (Bchl), and a Chl and a Bchl in which the central Mg atom is substituted by a different divalent metal atom;
• Y is O, S or NH;
• A is a covalent bond or a straight or branched, saturated or unsaturated, substituted by one or more functional groups selected from the group consisting of OH, COOH, NH.sub.2, and CONH2, or unsubstituted hydrocarbon chain having from 2 to 20 carbon atoms and containing an end functional group selected from the group consisting of OH, COOH and NH.sub.2 ;
• or such a hydrocarbon chain interrupted by one or more heteroatoms selected from the group consisting of O, S or N, or by a phenyl ring;
• and
• R is a residue of a peptide or a protein that are cell-specific ligands.