Patent ID: 7868185

Claim:
An acid of formula (II) or a pharmaceutically acceptable salt thereof, wherein R 1 is unsubstituted aryl or heteroaryl or aryl or heteroaryl substituted with alkyl, alkylamino, halogen, haloalkyl, carboxy, alkoxycarbonyl, hydroxy, N-morpholino, N-morpholinoalkyl, N-morpholinocarbonyl, N-methyl-N-piperazinyl, N-methyl-N-piperazinylalkyl, N-methyl-N-piperazinylcarbonyl or sulfo, and R 2 is phenyl substituted with a nitro, halogen, haloalkyl, carboxy, alkoxycarbonyl, hydroxy or sulfo group, with exclusion of 4-((1,5-dihydro-3-(4-nitrophenyl)-5-oxo-1-phenyl-4H-pyrazol-4-ylidene)-hydrazino)-benzenesulfonic acid and 4,4′-(4,5-dihydro-5-oxo-((4-sulfophenyl)-hydrazono)-1H-pyrazole-1,3-diyl)-bisbenzenesulfonic acid.