Sulfonamide derivatives

The present invention provides a method for inhibiting tubulin polymerization and for treating rheumatism by administering to individuals in need thereof an effective amount of sulfonamide derivatives represented by the general formula (1):wherein R1 and R2 may be the same or different and each independently represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a nitro group, a hydroxy group; each R3, R4, R5 and R6 represents a hydrogen atom; A represents any group of (1) 5-membered heterocyclic group which is optionally substituted by a lower alkyl group or phenyl group, whose ring members include at least 1 nitrogen atom and may include any atom(s) selected from the group consisting of nitrogen atom, oxygen atom, and sulfur atom, (2) an alicyclic group which is optionally substituted by a lower alkyl group or phenyl group, and (3) an alicyclic group whose ring members include at least 1 nitrogen atom and may include any atom(s) selected from the group consisting of nitrogen atom, oxygen atom, and sulfur atom, or pharmaceutically acceptable salts thereof together with a pharmaceutically acceptable excipient or carrier. The sulfonamide derivatives have low toxicity and a potent effect of inhibiting tubulin polymerization.