N
H
N
H
OH
O
N
N
O
N
ricolinostat
15
HDAC6 IC 50 4.7 nM
HDAC1 1C 50 58 nM
18
HDAC6 IC 50 0.3 nM
HDAC1 1C 50 440 nM
N
H
OH
O
H
N
O
O
N
NH
O
O
N
N
S
HN
O
N
H
O
OH
17
HDAC6 IC 50 160 nM
HDAC1 1C 50 7300 nM
N
H
OH
O
N
N
N
O
O
marbostat-100
19
HDAC6 IC 50 0.7 nM
HDAC1 1C 50 360 nM
N
H
N
H
OH
O
N
N
O
N
citarinostat
16
HDAC6 IC 50 2.6 nM
HDAC1 1C 50 35 nM
Cl
Fig. 8 Examples of HDAC6 selective hydroxamic acid inhibitors
Table 3 The IC 50 values of
quisinostat against individual
HDAC isoforms with
vorinostat as a reference,
based on data provided in
reference [40]
Isoform
Vorinostat IC 50 (nM)
Quisinostat IC 50 (nM)
HDAC1
62
0.1
HDAC2
240
0.3
HDAC3
260
5.0
HDAC8
210
4.0
HDAC4
150
0.6
HDAC5
100
3.7
HDAC7
>1,000
120
HDAC9
180
32
HDAC6
20
77
HDAC10
150
0.5
HDAC11
100
0.4
N
H
O
OH
22
HDAC4 IC 50 10 nM
HDAC5 1C 50 10 nM
HDAC7 1C 50 30 nM
HDAC9 1C 50 60 nM
N
N
F
F
N
H
OH
O
N
MeO
PCI-34051
20
HDAC8 IC 50 10 nM
N
H
OH
O
N
N
N
21
HDAC8 IC 50 0.8 nM
Fig. 9 Examples of HDAC8 and class IIa selective HDAC inhibitors
10
A. Ganesan