Table 1.

Inhibitory activity of compounds 6a-m towards hHDAC1 and hHDAC6 (as IC₅₀, nM)^a.

Compound	R1	R2	R3	R4	hHDAC1 (IC50 nM)	hHDAC6 (IC50 nM)	HDAC1/6
(±)-6a				H	4290	73.2 ± 11.6	59
(±)-6b				H	3650	164.8 ± 30.7	22
(±)-6c				H	8100	110.6 ± 15.5	73
(±)-6d				H	4850	28.5 ± 3.8	170
(±)-6e				H	6160	141.9 ± 38.6	43
(±)-6f				H	7600	111.7 ± 19.4	68
(±)-6g	Me			H	18680	166.2 ± 31.3	112
(±)-6h	Me			H	5330	41.9 ± 6.0	127
(R)-(+)-6h	Me			H	16190	90.6 ± 15.5	178
(S)-(−)-6h	Me			H	3380	71.3 ± 8.4	47
(±)-6i	Me			OMe	5320	67.2 ± 15.3	79
(±)-6j	Me			H	6320	810.8 ± 59.6	8
(±)-6k	Me			H	1630	616.3 ± 40.7	3
(±)-61	Me			H	10790	61.1 ± 12.9	177
(±)-6m				H	8100	151.6 ± 26.4	53
Tubacin, 37	-	-	-	-	1400	4	350
SAHA, 47	-	-	-	-	33	33	1

^aEach value is the mean of at least three determinations; results are expressed with ±SD. When not specified, SD is <10% of the IC₅₀.