Table 1. IC₅₀ values of initial compounds 4a–h.

	IC50 (μM)		IC50 (μM)
4a	54 ± 4	4e	23 ± 2
4b	42 ± 3	4f	49 ± 2
4c	37 ± 3	4g	>100
4d	26 ± 1	4h	>100