Tricyclic indoles and (4,5-dihydro) indoles

A compound of the formula (I):

• wherein the ring A represents a fused heterocycle of the formula II, IIb, III or IV:
• R1 represents hydrogen atom or an optionally substituted group selected from alkyl, cycloalkyl, alkenyl, alkynyl, heterocyclyl, aryl, heterocyclyloxy-alkyl and alkoxycarbonyl group;
• R2 is hydrogen or halogen atom or a group of formula —COOR5 or —CONHR5, wherein R5 represents one of the meanings above defined for R1, or an optionally substituted aryl or heterocyclyl group;
• R3 is hydrogen atom or a group of formula —CHO, —COOR5 or —CONHR5, wherein R5 is as defined above;
• R4 is hydrogen atom or NHR6, wherein R6 is hydrogen atom or an optionally substituted alkyl, aryl or heterocyclyl group;
• means either simple or double Carbon-Carbon bond (—CH2—CH2— or —CH═CH—);
• or a pharmaceutically acceptable salt thereof;
• with the provisos that
• if R2 is hydrogen or halogen atom or an optionally substituted aryl or heterocyclyl group, then R3 is not hydrogen atom, and
• if the ring A is a fused heterocycle of the formula III, R3 and R4 are hydrogen atoms, and means double Carbon-Carbon bond (—CH═CH—), then R2 is not COOH, COOMe or COOEt and
• the compound 1H-pyrrolo[2,3-f]isoquinoline-3-carboxaldehyde is excluded.