Table 2.

Binding affinity of a series of (N)-methanocarba adenosine derivatives at three subtypes of mARs.

Compd	Affinity (Ki, nM) or % inhibitiona
	mA1	mA2A	mA3
3b	15.3±5.8	10,400±1,700	1.49±0.46
4b	7.32±1.5	5,350±860	0.80±0.14
6b	45.6±7.9	(41%)i	0.85±0.08
7b	1390±430	(42%)i	6.06±1.21
8b	55.3±6.0	20,400±3,200	49.0±3.9
13	(29±2%)	(0%)	37.7±1.1
14	(55±5%)	(2±1%)	37.2±2.0
27	(50±5%)	(2±1%)	1.23±0.14
28	(65±3%)	(7±2%)	2.38±0.04
29	(51±12%)	(19±3%)	2.64±0.22
30	(35±3%)	(55%)	2.39±0.38
31	(14±3%)	(27±2%)	3.08±0.23
32	261±19	(5±2%)	0.82±0.06
33	(18±3%)	(22%)	3.66±0.25
34	(41±6%)	(6±1%)	10.8±0.93
35	(8±2%)	(64%)	47.6±4.6

^aCompetition radioligand binding assays using [¹²⁵I]54 (A₁ and A₃ARs) and [³H]53 (A_2AAR) were conducted with membranes prepared from HEK293 cells expressing recombinant mA₁, A_2A, or A₃ARs. The data (n = 3–4) are expressed as K_i values. A percent in parentheses refers to inhibition of radioligand binding at 10 μM.

^bValues from Melman et al.²¹