TTT20171 is an SDHC inhibitor that demonstrates nanomolar-level inhibition of CII; however, it shows limited efficacy within cellular environments. In cell assays, the most responsive cells, 22Rv1 prostate cancer cells, exhibit an IC50 of 5.4 µM, which significantly exceeds both the suggested usage concentration of 2 µM and the chemical probe quality standard of 1 µM.