Table 1. Results for Tautomerase Inhibition (K_i) from the HPP Assay and for Binding (K_d) from the Fluorescence Polarization Assay^a.

compd	X	Y	Z	Ki (μM)	Kd (μM)b
1a	–	–	OH	37	30% (25 μM)
2a	–	–	OH	8.8	1.75
3a	H	H	OH	0.59	0.260
3b	AEOEO	H	OH	0.77	0.348
3c	AEOEO	H	3-F,4-OH	0.33	0.163
3d	MOEO	H	F	8.9	(>1.5)
3e	MOEO	H	OMe	NA	NA
3f	MrEOEO	H	OH	0.41	0.211
3g	MrEOEO	H	3-F,4-OH	0.15	0.152
3h	H	5-p-COOH-OPh	3-F,4-OH	0.11	0.110
3i	H	5-m-COOH-OPh	3-F,4-OH	0.057	0.071
3j	O(CH2)3COOH	H	3-F,4-OH	0.034	0.063
4a	H	H	OH	1.48	0.347
5a	OCH3	–	–	1.90	1.71
5b	COOH	–	–	1.70	1.15
Orita-13	–	–	–	17	20% (100 μM)
(R)-ISO-1	–	–	–	24	24
NVS-1	cyclohexyl	–	–	0.569	0.456
NVS-2	p-OMe-Ph	–	–	0.027	0.055
NVS-6	p-OH-Ph	–	–	0.185	0.159
4-IPP	–	–	–	(4.5)c,d	(0.446)c
PSB	–	–	–	ND	49% (200 μM)

^aMOEO = methoxyethoxy; AEOEO = aminoethoxyethoxy; Mr = N-morpholinyl. NA = not active.

^bK_d or % bound at indicated concentration in parentheses.

^cCovalent inhibitor: result is time-dependent.

^dIC₅₀ from ref (9).