Table 1.

Structure-activity relationships for N-(4-methoxybenzyl)-substituted aminopyrazoles, exploring variation of the resorcylate amide with methyl- and phenyl-substitution at R². Fold-selectivity > 5 for any compound is highlighted in red.

Entry	Compound	X	R2	C. neoformans EC50a (μM)	C. neoformans fold- selectivityb	C. albicans EC50c (μM)	C. albicans fold- selectivityb
1	20		CH3	0.040	0.8	0.011	0.9
2	21		Ph	0.877	2.5	0.511	2.2
3	22		CH3	0.087	1.2	0.184	0.4
4	23		Ph	0.142	4.0	0.068	6.2
5	24		CH3	0.063	1.7	0.157	0.5
6	25		Ph	0.121	2.7	0.063	3.9
7	26		CH3	0.109	0.6	0.117	0.4
8	27		Ph	0.787	2.2	1.089	1.2
9	28		CH3	0.592	0.1	0.054	0.5
10	29		Ph	0.705	2.7	1.043	1.3
11	30		CH3	1.330	5.8	> 9	-
12	31		Ph	> 9	-	> 9	-
13	32		CH3	0.096	1.0	0.171	0.4
14	33		Ph	0.146	0.8	0.023	1.8
15	34		CH3	0.086	1.2	0.115	0.7
16	35		Ph	0.091	0.8	0.014	1.7
17	36		CH3	0.115	0.9	0.143	0.6
18	37		CH3	4.814	1.6	> 6	0.0
19	38		Ph	0.464	2.1	0.282	1.2
20	39		Ph	>10	-	>10	-

EC₅₀ values were determined by FP-based equilibrium competition assay performed in 384-well format using whole cell lysates prepared from C. neoformans (a) and C. albicans (c) and serial compound dilutions. All determinations were performed in duplicate. To calculate fold-selectivity (b), the EC₅₀ value determined in human HepG2 cell lysate was divided by the EC₅₀ value determined in fungal cell lysate. The resulting ratio was then normalized to values determined in the same assay for the non-selective inhibitor geldanamycin using lysate of each cell type. Results for key selective compounds were confirmed by repeat assay (see Supplemental Table 1).