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| Other names | 3-(3-Hydroxypropyl)-7-methyl-8-(3-methoxystyryl)-1-propargylxanthine |
| Drug class | Adenosine A2A receptor antagonist |
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| Chemical and physical data | |
| Formula | C21H22N4O4 |
| Molar mass | 394.431 g·mol−1 |
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MSX-2 is a selective adenosine A2A receptor antagonist used in scientific research. [1] It is a xanthine and a derivative of the non-selective adenosine receptor antagonist caffeine. [1] [2]
The affinities (Ki) of MSX-2 for the human adenosine receptors are 5.38 to 14.5 nM for the adenosine A2A receptor, 2,500 nM for the adenosine A1 receptor (172- to 465-fold lower than for the A2A receptor), and >10,000 nM for the adenosine A2B and A3 receptors (>690-fold lower than for the A2A receptor). [3] [4]
MSX-2 has poor water solubility, which has limited the use of MSX-2 itself. [1] [5] Water-soluble ester prodrugs of MSX-2, including MSX-3 (a phosphate ester prodrug) and MSX-4 (an amino acid ester prodrug), have been developed and used in place of MSX-2. [1] [5] MSX-3 is best-suited for use by intravenous administration, whereas MSX-4 can be administered by oral administration. [5] [6]
MSX-3 and MSX-4 reverse motivational deficits in animals and hence have the capacity to produce pro-motivational effects. [7] [8] [9]
MSX-2 and MSX-3 were first described in the scientific literature by 1998. [10] [11] Subsequently, MSX-4 was developed and described by 2008. [5] [6]