Table 1 Affinities of key ammonium salts tested.

From: Simple ammonium salts acting on sigma-1 receptors yield potential treatments for cancer and depression

Ammonium salt

σ-1 R affinity

pKi ± SEM (n)

σ-1 R affinity

(µM)

σ-2 R affinity

pKi ± SEM (n)

σ-2 R affinity

(µM)

σ-1 R Ki/σ-2 R Ki

Octyl

6.1 ± 0.3 (4)

0.80

5.2 ± 0.2 (3)

6.2

0.13

Decyl

6.5 ± 0.4 (4)

0.32

5.41 ± 0.07 (3)

3.9

0.081

Dipropyl

5.6 ± 0.2 (6)

2.6

4.10 ± 0.07 (3)

79

32

Dibutyl

6.9 ± 0.4 (6)

0.14

5.64 ± 0.07 (3)

2.3

18

Dipentyl17

7.4 ± 0.5 (6)

0.043

6.9 ± 0.2* (3)

0.12

3.2

Dihexyl

6.8 ± 0.6 (6)

0.14

7.58 ± 0.06* (3)

0.026

0.17

Dioctyl

10.3 ± 0.2 (6)

0.000050

7.9 ± 0.5 (3)

0.014

0.0040

Tributyl

6.9 ± 0.1 (6)

0.13

5.5 ± 0.2* (3)

3.0

0.040

Tripentyl

7.8 ± 0.2 (6)

0.015

6.1 ± 0.1 (3)

0.78

0.020

Trihexyl

8.1 ± 0.4 (6)

0.009

6.63 ± 0.03 (3)

0.23

0.034

Bis(2-ethylhexyl)

4.5 ± 0.3* (5)

29

4.0 ± 0.2* (3)

91

0.29

Triisobutyl

5.1 ± 0.6 (6)

7.9

5.46 ± 0.06 (3)

3.5

2.3

Triisopentyl

4.1 ± 0.4* (6)

79

6.40 ± 0.09* (3)

0.40

200

Tetrapropyl

2.5 ± 0.1 (3)

3,200

3.5 ± 0.2* (3)

310

10

Tetrabutyl

2.8 ± 0.1 (3)

1,600

4.22 ± 0.08* (3)

60

25

  1. Affinities for the sigma-1 and sigma-2 receptors (σ-1 R and σ-2 R, respectively) are shown as pKi and Ki (µM) values from competition binding assays. Hill slopes were determined as unity for all salts tested, except those labelled *. σ-1 R Ki/σ-2 R Ki shows the ratio between Ki values. Sigma-1 receptor affinity has been previously published17. These data are reproduced from the PhD theses by J.M. Brimson44 and H. Abbas45.
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