Prophylactic or therapeutic drug for renal diseases

A method for tbe prophylaxis or treatment of diabetic nephropathy or glomerulonephritis in a mammal comprising the step of administering a pharmaceutically effective amount of a compound or salt thereof represented by formula (I′)

• wherein R1 stands for H or a lower (C1-C4) alkyl, R2 stands for a group represented by the formula —CO—D″ where D″ stands for hydroxy or a lower (C1-C4) alkoxy group, the alkyl moiety of which optionally is substituted with hydroxy, amino, halogen, lower (C2-C6) alkanoyloxy, lower (C4-C7) cycloalkanoyloxy, lower (C1-C6) alkoxyearbonyloxy, lower (C3-C7) cycloalkoxycarbonyloxy or lower (C1-C4) alkoxy, R3 stands for a tetrazolyl, carboxyl group or a group represented by the formula:
• where i stands for —O— or —S— and j stands for >C═O, >C═S or >S(O)m where m is 0, 1 or 2;
• ring A stands for a benzene ring;
• Y stands for O, N(H) or S, to a mammal in need threreof.