Patent ID: 8633335

Claim:
A compound or salt thereof represented by the following formula (I): wherein: (a) R 1 , R 4 and R 5 are hydrogen atoms, and R 2 and R 3 are bond to each other to form a 5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalene ring together with the benzene ring to which R 2 and R 3 are bound, or (b) R 1 , R 3 and R 5 are hydrogen atoms, and R 2 and R 4 are trimethylsilyl groups; X represents —NH—CO— or —CO—NH; and Z represents —CH 2 —COOH or —CH 2 —CH 2 —COOH; and wherein X and Z are at para positions with respect to each other on the benzene ring to which X and Z are bound.