Benzamide analogs useful as PARP (ADP-ribosyltransferase, ADPRT) DNA repair enzyme inhibitors

A 3-substituted benzamide compound having the formula I ##STR51## or a pharmaceutically acceptable salt thereof where:

• (i) Y is hydrogen, and
• X is --CH.sub.2 --Z
• wherein
• Z represents an optionally substituted aralkyl group, --C.dbd.CHR (where R is H, alkyl or an optionally substituted phenyl group), cyclohexyl, or a group having the structural formula III ##STR52## where R.sub.1 is selected from H, alkoxy, NO.sub.2, N.sub.3, NH.sub.2, NHCOR.sub.3 (R.sub.3 being alkyl or aryl), CO.sub.2 R.sub.4 (R.sub.4 being H or alkyl), alkyl, hydroxyalkyl, CW.sub.3 or W (W being halide), and CN,
• and where
• R.sub.2 is H,
• or where R.sub.1 and R.sub.2 together represent a group --O--CHR.sub.5 --O-- bridging adjacent ring C's with R.sub.5 being H, alkyl or an optionally substituted aralkyl or aryl group or
• (ii) Y is hydrogen, and
• X is --(CH.sub.2).sub.n --Z
• wherein n is in the range of 5 to 12, and
• Z is a purin-9-yl moiety.