Styrene derivatives

A styrene derivative of the following formula (I):

• ##STR146## wherein R.sup.1 represents a cyano group;
• R.sup.2 represents --CONR.sup.9 R.sup.10 wherein R.sup.9 and R.sup.10 independently each represent a hydrogen atom or ##STR147## (in which n represents 0 or an integer of from 1 to 5, and X.sup.l, X.sup.2 and X.sup.3 independently each represent a hydrogen atom, halogen atom, C.sub.1 -C.sub.5 alkyl group, C.sub.1 -C.sub.5 alkoxy group, hydroxy group, nitro group or cyano group), with the proviso that R.sup.9 and R.sup.10 don't represent hydrogen atom at the same time;
• R.sup.3 represents & hydrogen atom, C.sub.1 -C.sub.5 alkyl group or hydroxy group;
• and
• R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 independently each represent (1) a hydrogen atom, (2) hydroxy group, (3) halogen atom, (4) C.sub.1 -C.sub.5 alkoxy group, (5) nitro group, (6) cyano group, (7) --NR.sup.12 R.sup.13 wherein R.sup.12 and R.sup.13 independently each represent a hydrogen atom, C.sub.1 -C.sub.5 alkyl group or benzoyl group, (8) --SOpR.sup.14 wherein p represents 0, 1 or 2, and R.sup.14 represents a C.sub.1 -C.sub.5 alkyl group or phenyl group, (9) --COR.sup.15 wherein R.sup.15 represents a hydrogen atom, C.sub.1 -C.sub.5 alkyl group, C.sub.1 -C.sub.5 alkoxy group, hydroxy group, phenyl group, phenoxy group or --NHR.sup.16 (in which R.sup.16 represents a C.sub.1 -C.sub.5 alkyl group or phenyl group), or (10) a C.sub.1 -C.sub.5 alkyl group optionally substituted by a halogen atom;
• with the proviso that at least one of R.sup.4 to R.sup.8 is a hydroxy group, and that when R.sup.3 is a hydrogen atom and R.sup.4 to R.sup.8 independently each represent a hydrogen atom, hydroxy group, C.sub.1 -C.sub.5 alkoxy group, --NR.sup.12 R.sup.13 (in which R.sup.12 and R.sup.13 are as defined above), or C.sub.1 -C.sub.5 alkyl group, then R.sup.2 represents --CONR.sup.9 R.sup.10 wherein R.sup.9 represents a hydrogen atom and R.sup.10 represents ##STR148## (in which Z represents a C.sub.1 -C.sub.5 alkyl group, halogen atom, nitro group or cyano group),
• or a pharmaceutically acceptable salt thereof.