Table 1.

Structure-activity relationship of DUB inhibition.

Cmpd	R1	R2	R3	R4	EC50 (μM)
C1	H	H	H	H	>150 a
C2	H	OMe	H	OMe	>150 a
C3	H	H	H	CH2NHBoc	>150 a
C4	H	H	H	CH2NH2	210 ± 40 [250 ± 70]
C5	H	H	H	CH2NH-4-ClBn	300 ± 100
C31	H	Me	H	Me	>150 a
C11	F	H	H	CH2NH2	300 ± 100
C12	CH3	H	H	CH2NH2	250 ± 20
C13	CH3O	H	H	CH2NH2	260 ± 40
C14	Cl	H	H	CH2NH2	30 ± 10 [50 ± 10]
C15	Br	H	H	CH2NH2	30 ± 10 [40 ± 10]
C16	H	H	Cl	CH2NH2	60 ± 20
C17			H	CH2NH2	20 ± 10
C18	H			CH2NH2	40 ± 20
C23	Cl	H	H	CH2NHBoc	>150 a
C19			H	CH2NHBoc	>150 a
C20			H	CH2NH-neo-Pent	30 ± 10
C21			H	CH2NH-i-Bu	70 ± 10
C22			H	CH2-NH-(C=NH)NH2	50 ± 20
C6					>500
Cmpd	X	Y	R	EC50 (μM)
C8	O	NH	CH2NH2	>150 a
C7	NH	O	CH2NH2	>150 a
C10	O	CH2	CH2NH2	>150 a
C9	CH2	O	CH2NH2	>150 a

The values of EC₅₀ for the inhibition of the decomposition of high molecular weight ubiquitinated proteins (HMW-Ub) in lysates prepared from HEK 293T cells expressing HA-Ub. The values of EC₅₀ are the mean ± s.e.m. of at least 3 independent experiments (see Figure 2 for representative experiment). Brackets denote the values of EC₅₀ for the inhibition of the decomposition of HMW-Ub in lysates prepared from Cos-1 cells expressing HA-Ub.

^a.No effect was observed at 150 μM, the highest concentration tested (the solubility limit).