A compound having the general formula (I) or a pharmacologically acceptable salt thereof: X-NH-Y-NH-R1 (I)[whereinX represents R2-SO2- in which R2 represents an optionally substituted lower alkyl group or phenyl groupY represents a group selected from the group consisting of -R3-NH-R4-, -R5-NH-R6-NH-R7-, -R8-NH-R9-NH-R10-NH-R11- and -R12-NH-R13-NH-R14-NH-R15- in which R3 to R15 each independently represent a C3 to C5 alkylene group andR1 represents hydrogen or an optionally substituted lower alkyl group, with the proviso that the case where X represents a tosyl group, Y represents -(CH2)3-NH-(CH2)4-NH-(CH2)3- and R1 represents hydrogen is excepted].