Reduction of cardiotoxicity of an antitumor agent using manganese compound

A method of reducing the cardiotoxicity of an anti-tumor agent administered to a human or non-human animal body, said method comprising administering to said body an anti-tumor agent and simultaneously, separately or sequentially a compound of formula I:

• ##STR5## or a metal chelate thereof or salt of a metal chelate thereof wherein in formula I
• each R.sup.1 independently represents hydrogen or --CH.sub.2 COR.sup.5 ;
• R.sup.5 represents hydroxy, optionally hydroxylated alkoxy, amino or alkylamido;
• each R.sup.2 independently represents a group XYR.sup.6 ;
• X represents a bond, or a C.sub.1-3 alkylene or oxoalkylene group optionally substituted by a group R.sup.7 ;
• Y represents a bond, an oxygen atom or a group NR.sup.6 ;
• R.sup.6 is a hydrogen atom, a group COOR.sup.8, an alkyl, alkenyl, cycloalkyl, aryl or aralkyl group optionally substituted by one or more groups selected from COOR.sup.8, CONR.sup.8.sub.2, NR.sup.8.sub.2, OR.sup.8, =NR.sup.8, =O, OP(O)(OR.sup.8)R.sup.7 and OSO.sub.3 M;
• R.sup.7 is hydroxy, an optionally hydroxylated, optionally alkoxylated alkyl or aminoalkyl group;
• R.sup.8 is a hydrogen atom or an optionally hydroxylated, optionally alkoxylated alkyl group;
• M is a hydrogen atom or one equivalent of a physiologically tolerable cation;
• R.sup.3 represents a C.sub.1-8 alkylene group, a 1,2-cycloalkylene group, or a 1,2-arylene group;
• and
• each R.sup.4 independently represents hydrogen or C.sub.1-3 alkyl.