(±)-5'-Chloro-5'-deoxy-ENBA

(±)-5'-Chloro-5'-deoxy-ENBA is a selective and high-affinity adenosine A1 receptor agonist with Ki values of 0.51 [1].
Adenosine A1 receptor mediated neuroand cardioprotection (an antiarrhythmic effect), reduction of lipolysis in adipose tissue and reduction of neuropathic pain [1].
In mice injected with formalin at doses between 1 and 2mg/kg, (±)-5'-Chloro-5'-deoxy-ENBA inhibited the first and the second phases of the nocifensive response induced by formalin [1]. In a mouse model of neuropathic pain (the Spared Nerve Injury (SNI) of the sciatic nerve), (±)-5'-Chloro-5'-deoxy-ENBA (0.5 mg/kg) reduced thermal hyperalgesia and mechanical allodynia 7 and 3 days post-SNI without significantly changed the motor coordination and arterial blood pressure. Also, (±)-5'-Chloro-5'-deoxy-ENBA chronic treatment reduced activated and hypertrophic microglia [2]. In a Parkinson's disease (PD) mouse model, (±)-5'-Chloro-5'-deoxy-ENBA prevented the increase in sIPSC frequency and eIPSC amplitude produced by SKF. In mice with unilateral DA denervation, (±)-5'-Chloro-5'-deoxy-ENBA reduced the development of abnormal involuntary movements induced by L-DOPA [3].
References:
[1]. Franchetti P, Cappellacci L, Vita P, Petrelli R, et al. N6-Cycloalkyl- and N6-bicycloalkyl-C5'(C2')-modified adenosine derivatives as high-affinity and selective agonists at the human A1 adenosine receptor with antinociceptive effects in mice. J Med Chem, 2009, 52(8): 2393-2406.
[2]. Luongo L, Petrelli R, Gatta L, et al. 5'-Chloro-5'-deoxy-(±)-ENBA, a potent and selective adenosine A(1) receptor agonist, alleviates neuropathic pain in mice through functional glial and microglial changes without affecting motor or cardiovascular functions. Molecules, 2012, 17(12): 13712-13726.
[3]. Mango D, Bonito-Oliva A, Ledonne A, et al. Adenosine A1 receptor stimulation reduces D1 receptor-mediated GABAergic transmission from striato-nigral terminals and attenuates l-DOPA-induced dyskinesia in dopamine-denervated mice. Exp Neurol, 2014, 261: 733-743.

5'-Chloro-5'-deoxy-(+/-)-ENBA, a potent and selective adenosine A(1) receptor agonist, alleviates neuropathic pain in mice through functional glial and microglial changes without affecting motor or cardiovascular functions.[Pubmed:23174891]

Molecules. 2012 Nov 22;17(12):13712-26.

This study was undertaken in order to investigate the effect of chronic treatment with 5′-chloro-5′-deoxy-(±)-ENBA, a potent and highly selective agonist of human adenosine A(1) receptor, on thermal hyperalgesia and mechanical allodynia in a mouse model of neuropathic pain, the Spared Nerve Injury (SNI) of the sciatic nerve. Chronic systemic administration of 5′-chloro-5′-deoxy-(±)-ENBA (0.5 mg/kg, i.p.) reduced both mechanical allodynia and thermal hyperalgesia 3 and 7 days post-SNI, in a way prevented by DPCPX (3 mg/kg, i.p.), a selective A(1) adenosine receptor antagonist, without exerting any significant change on the motor coordination or arterial blood pressure. In addition, a single intraperitoneal injection of 5′-chloro-5′-deoxy-(±)-ENBA (0.5 mg/kg, i.p.) 7 days post-SNI also reduced both symptoms for at least two hours. SNI was associated with spinal changes in microglial activation ipsilaterally to the nerve injury. Activated, hypertrophic microglia were significantly reduced by 5′-chloro-5′-deoxy-(±)-ENBA chronic treatment. Our results demonstrated an involvement of adenosine A(1) receptor in the amplified nociceptive thresholds and in spinal glial and microglial changes occurred in neuropathic pain, without affecting motor coordination or blood pressure. Our data suggest a possible use of adenosine A(1) receptor agonist in neuropathic pain symptoms.

Tremorolytic effect of 5'-chloro-5'-deoxy-(+/-)-ENBA, a potent and selective adenosine A1 receptor agonist, evaluated in the harmaline-induced model in rats.[Pubmed:28371468]

CNS Neurosci Ther. 2017 May;23(5):438-446.

AIM: The aim of this study was to examine the role of adenosine A1 receptors in the harmaline-induced tremor in rats using 5'-chloro-5'-deoxy-(+/-)-ENBA (5'Cl5'd-(+/-)-ENBA), a brain-penetrant, potent, and selective adenosine A1 receptor agonist. METHODS: Harmaline was injected at a dose of 15 mg/kg ip and tremor was measured automatically in force-plate actimeters by an increased averaged power in the frequency band of 9-15 Hz (AP2) and by tremor index (a difference in power between AP2 and averaged power in the frequency band of 0-8 Hz). The zif-268 mRNA expression was additionally analyzed by in situ hybridization in several brain structures. RESULTS: 5'Cl5'd-(+/-)-ENBA (0.05-0.5 mg/kg ip) dose dependently reduced the harmaline-induced tremor and this effect was reversed by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective antagonist of adenosine A1 receptors (1 mg/kg ip). Harmaline increased the zif-268 mRNA expression in the inferior olive, cerebellar cortex, ventroanterior/ventrolateral thalamic nuclei, and motor cortex. 5'Cl5'd-(+/-)-ENBA reversed these increases in all the above structures. DPCPX reduced the effect of 5'Cl5'd-(+/-)-ENBA on zif-268 mRNA in the motor cortex. CONCLUSION: This study suggests that adenosine A1 receptors may be a potential target for the treatment of essential tremor.

N6-Cycloalkyl- and N6-bicycloalkyl-C5'(C2')-modified adenosine derivatives as high-affinity and selective agonists at the human A1 adenosine receptor with antinociceptive effects in mice.[Pubmed:19317449]

J Med Chem. 2009 Apr 23;52(8):2393-406.

To further investigate new potent and selective human A(1) adenosine receptor agonists, we have synthesized a series of 5'-chloro-5'-deoxy- and 5'-(2-fluorophenylthio)-5'-deoxy-N(6)-cycloalkyl(bicycloalkyl)-substituted adenosine and 2'-C-methyladenosine derivatives. These compounds were evaluated for affinity and efficacy at human A(1), A(2A), A(2B), and A(3) adenosine receptors. In the series of N(6)-cyclopentyl- and N(6)-(endo-norborn-2-yl)adenosine derivatives, 5'-chloro-5'-deoxy-CPA (1) and 5'-chloro-5'-deoxy-(+/-)-ENBA (3) displayed the highest affinity in the subnanomolar range and relevant selectivity for hA(1) vs the other human receptor subtypes. The higher affinity and selectivity of 5'-chloro-5'-deoxyribonucleoside derivatives 1 and 3 for hA(1) AR vs hA(3) AR compared to that of the parent 5'-hydroxy compounds CPA and (+/-)-ENBA was rationalized by a molecular modeling analysis. 5'-Chloro-5'-deoxy-(+/-)-ENBA, evaluated for analgesic activity in the formalin test in mice, was found to inhibit the first or the second phases of the nocifensive response induced by intrapaw injection of formalin at doses ranging between 1 and 2 mg/kg i.p.