The present invention relates to a compound of formula I, or a pharmaceutically acceptable salt thereof, wherein Z is OR 1 or NR 1 R 2 wherein each of R 1 and R 2 is independently H, or a hydrocarbyl group；X is an alkylene, alkenylene, or alkynylene group, each of which may be optionally substituted by one or more substituents selected from alkyl, COOH, CO 2 -alkyl, alkenyl, CN, NH 2 , hydroxy, halo, alkoxy, CF 3 and nitro； Y is a polar functional group selected from OH, NO 2 CN, COR 3 , COOR 3 , NR 3 R 4 , CONR 3 R 4 , SO 3 H, SO 2 -R 3 , SO 2 NR 3 R 4 and CF 3 , where each of R 3 and R 4 is independently H or a hydrocarbyl group； A is an aryl or heteroaryl group, each of which may be optionally substituted； and B is (CH 2 ) n where n is 0, 1, 2, 3, 4 or 5； with the proviso that: (i) when A is phenyl, n is 0, and Z is OH, X-Y is other than meta -C‰¡C-(CH 2 ) 2 CO 2 H, meta -C‰¡C-(CH 2 ) 2 OH, meta -C‰¡C-(CH 2 ) 2 CO 2 Me, meta- (CH 2 ) 4 CO 2 H, ortho -CH 2 CO 2 H, ortho -(CH 2 ) 2 CO 2 H and ortho -(CH 2 ) 4 CO 2 H； and (ii) when A is phenyl, n is 0, and Z is OMe, X-Y is other than meta -C‰¡C-(CH 2 ) 4 OH. Further aspects of the invention relate to the use of such compounds in the preparation of a medicament for the treatment of a muscular disorder, a gastrointestinal disorder, or for controlling spasticity or tremors.
