Table 5. Binding Activity of 4′-Truncated (N)-Methanocarba Derivatives at hORs, hA₃AR and TSPO and Transporters; 4′-Truncated (N)-Methanocarba 7-Deaza-adenosine Derivatives^a.

compound	R2=	R3=	DOR,bKi, nM	KOR,bKi, nM	MOR,bKi, nM	TSPO,bKi, nM	A3AR binding Ki, nM (species),c or % of control at 10 μM
54a	phenyl-ethynyl	CH3	d	1120 ± 220	2670 ± 280	e	85.6 ± 12.0 (h), 11 ± 1% (m)
55a	phenyl-ethynyl	(CH2)2-Ph	3660 ± 1330	1370 ± 180	4020 ± 890	2120 ± 230	217 ± 65 (h), 29 ± 2% (m)
56	phenyl-ethynyl	CH(cPr)2	2550 ± 660	d	1440 ± 750	4210 ± 1840	178 ± 32 (h)
57	5-Br-thienyl-ethynyl	CH(cPr)2	>10 000	3020 ± 90	>10 000	>10 000	2440 ± 430 (h)
58	I	CH(cPr)2	e	e	e	e	5310 ± 1310 (h)

^aDAT and NET binding inhibition is <50% at 10 μM, unless noted. 54: DAT, −58%; 55: NET, K_i = 5.56 μM.

^bBinding assays performed as specified in Table 1, unless noted. Values are expressed as the mean ± SEM (n = 2–4). Values are expressed as the mean ± SEM of N = 2–4 assays performed in duplicate.

^cA₃AR binding data from Tosh et al.^{2,3,6,34,35,37} Representative binding K_i values at hA₁AR (nM): 55, 1300 ± 290; 56, 650 ± 71; determined as reported.³⁷ Values are expressed as the mean ± SEM of N = 3 assays performed in duplicate.

^d30–50% inhibition of radioligand binding at 10 μM.

^e<30% inhibition of radioligand binding at 10 μM.