Table 4. Enzyme Inhibition Data of Compounds 9a-d.

	HDAC1*	HDAC6*	Selectivity Index
Compounds	IC50 (μM)	IC50 (μM)	HDAC1/HDAC6
9a	6.0 +/- 2.9	0.93 +/-0.75	6.5
9b	3.7 +/- 1.7	0.13 +/- 0.07	28.4
9c	0.92 +/- 0.16	0.22 +/- 0.04	4.3
9d	0.90 +/- 0.45	0.13 +/- 0.02	9.6
a Tubastatin A	16.4+/-2.6	0.015+/-0.001	1093
b TSA	0.0060+/-0.0025	0.0086+/-0.0014	1.4

^aTaken from ref. [31]

^bTaken from ref. [32].

* Indicated are the mean values of at least three independent experiments.