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. Author manuscript; available in PMC: 2014 Jan 7.
Published in final edited form as: Handb Exp Pharmacol. 2011;(200):10.1007/978-3-642-13443-2_6. doi: 10.1007/978-3-642-13443-2_6

Table 1.

Adenosine receptor affinities of 8-unsubstituted xanthine derivatives

Ki (nM)a
A1 A2A A2B A3
Natural xanthine (X) derivatives
1 Caffeine (1,3,7-TrimethylX) 10,700 (h)1
44,900 (h)2
41,000 (r)3
44,000 (r)4
47,000 (gp)5
44,000 (c)5 		23,400 (h)2
9,560 (h)1
45,000 (r)4
32,500 (r)6
48,000 (r)1 		33,800 (h)7
10,400 (h)8
20,500 (h)9
30,000 (r)10
13,000 (m)10 		13,300 (h)1
>100,000 (r)11
2 Theophylline (1,3-DimethylX) 6,770 (h)12
14,000 (r)13
8,740 (r)1
7,060 (gp)14
4,710 (rb)14
9,050 (s)14
6,330 (c)14 		1,710 (h)12
6,700 (h)1
22,000 (r)13
25,300 (r)1 		9,070 (h)8
74,000 (h)9
15,100 (r)8
5,630 (m)15
11,000 (gp)16
17,700 (rb)15
38,700 (d)15 		22,300 (h)1
86,400 (h)12
>100,000 (r)11
85,000 (r)17
>100,000 (d)18
3 Theobromine (3,7-DimethylX) 105,000 (r)13
83,400 (r)19 		>250,000 (r)13
187,000 (r)19 		130,000 (h)19 >100,000 (r)11
4 Paraxanthine (1,7-DimethylX) 21,000 (r)13 32,000 (r)13 4,500 (h)20 >100,000 (r)11
Mono-substituted xanthine derivatives
5 1-MethylX 36,000 (r)13
11,400 (r)19 		47,000 (r) 13
36,200 (r)19 		6,600 (h)19 >100,000 (r)11
6 1-PropylX 13,000 (r) 13 33,000 (r) 13 360 (h)8
1,880 (r)8 		2,370 (h)8
7 1-ButylX 9,000 (r) 13 61,000 (r) 13 421 (h)8 4,610 (h)8
8 1-BenzylX 2,800 (r) 13 22,000 (r) 13 nd nd
9 3-MethylX >100,000 (r) 13
35,000 (r) 21 		59,000 (r) 13 87,000 (h)20 >100,000 (r)11
10 Enprofylline (3-PropylX) 156,000 (h)22
42,000 (h)1
32,000 (r)13
29,100 (r)19
>100,000 (d)18 		32,000 (h)22
81,300 (h)1
137,000 (r)13
103,000 (r)19 		7,000 (h)22
4,730 (h)8
19,800 (h)23
26,000 (r)24
5,630 (m)15
5,840 (rb)15
6,960 (d)15 		92,600 (h)1
65,000 (h)22
93,000 (r)1
>100,000 (d)18
11 7-MethylX 33,000 (r) 13 59,000 (r) 13 97,000 (h)20 >100,000 (r)11
12 7-PropylX 18,000 (r) 13 >200,000 (r) 13 nd nd
13 9-MethylX >250,000 (r) 13 >250,000 (r) 13 >1,000,000 (h)20 >100,000 (r)11
14 9-PropylX >250,000 (r) 13 >250,000 (r) 13 nd nd
Di- and trisubstituted xanthine derivatives
15 Doxofylline ca. 100,00025 ca. 100,00025 nd nd
16 1,3-DipropylX 700 (r)13
450 (r)19
1,310 (gp)5
340 (c)5 		6,600 (r)13
5,160 (r)19 		1,110 (h)8
680 (h)20 		1,940 (h)1
17 IBMX 3-Isobutyl-1-methylX 7,000 (r)13
2,460 (r)19
8,600 (gp)5
4,400 (c)5 		16,000 (r)13
13,800 (r)19 		3,500 (h)19 nd
18 3-Methyl-1-propargylX 820 (r) 13
5,830 (r)8 		4,800 (r) 13
33,600 (r)8 		511 (h)8
2,150 (r)8 		10,900 (h)8
19 7-Methyl-1-propargylX 22,000 (r) 13 16,000 (r) 13 nd nd
20 DMPX 3,7-Dimethyl-1-propargylX 45,000 (r)4
11,000 (r)5
25,800 (gp)5
16,400 (c)5 		16,000 (r)4
5,600 (r)6 		4,130 (h)8 >10,000 (r)26
21 DBXR 4,190 (r)11 19,500(r)11 nd 6,030 (r)11,b
22 DBXRM 37,300 (r)27 >100,000 (r)27 nd 229 (r)27,c
a

h = human; c = cow; d = dog; gp = guinea pig; m= mouse; r = rat; rb = rabbit; a few A2B data are from functional (cAMP) studies; nd = no data available

b

partial agonist;

c

full agonist