Table 2.

IC₅₀ values of heterocyclic derivatives against Hsp90α and Hsp90β determined using fluorescence polarization (FP) assay.

Entry	Compound	HSP90β [IC50 in μM]	HSP90α [IC50 in μM]	Selectivity
1	KUNB31 [a]	0.18 ± 0.01	9.55 ± 1.08	> 50
2	5	0.27 ± 0.09	> 100	> 370
3	18	> 100	> 100	NA
4	19	> 100	> 100	NA
5	20	> 100	> 100	NA
6	21	0.45 ± 0.15	2.22 ± 0.19	4.9
7	29a	> 100	> 100	NA
8	29 b	0.15 ± 0.04	0.79 ± 0.14	>5
9	31	5.23 ± 0.13	> 100	> 19.1
10	32a	8.29 ± 0.17	> 100	>12
11	32b	1.86 ± 0.11	> 100	> 53
12	40	8.83 ± 1.48	> 100	>11
13	41	> 100	> 100	NA
14	42	0.34 ± 0.01	2.42 ± 0.07	7.1
15	43	18.19 ± 1.3	> 100	>5
16	44	19.59 ± 2.2	> 100	>5
17	45	> 100	> 100	NA
18	46	> 100	> 100	NA
19	50	6.75 ± 0.01	43.13 ± 11.5	>5
20	51	> 100	> 100	NA
21	52	> 100	> 100	NA
22	59a	> 100	> 100	NA
23	59 b	> 100	> 100	NA

^[a]KUNB31 IC50 values were taken from Ref. [27].