Table 2. Structures and in vitro inhibitory potencies of compounds 54–59 against the β5i subunit of human iCP.

Compound	R	RA (%) at 10 μM or IC50 for β5i (nM)
54		62 ± 3
55		IC50 = 1830 ± 380
56		101 ± 7
57		111 ± 16
58		99 ± 9
59		102 ± 9