The present invention aims to provide a novel compound for measuring cellular cytotoxicity or cell proliferation capacity accurately with high reproducibility, conveniently and rapidly, and a measurement method of cellular cytotoxicity or cell proliferation capacity by using the compound. The present invention relates to a compound represented by the formula (I): wherein R1 is a substituent, R2 and R3 are each an optionally substituted hydrocarbon group, or an optionally substituted heterocyclic group, Y is a substituent, n is an integer of 0-3, Z is a single bond, —O—, —S—, —SO—, —SO2—, or —NR4— (R4 is a hydrogen atom or a substituent), and A is an optionally substituted C1-6 alkylene group) or a salt thereof.