8-Cyclopentyl-1,3-dimethylxanthine

8-Cyclopentyl-1,3-dimethylxanthine (CPT) is an adenosine A₁ receptor antagonist (K_i = 10.9 nM).¹ It is selective for adenosine A₁ over A₂ receptors (K_i = 1,440 nM). CPT inhibits hypoxia-induced depression of evoked synaptic potentials in rat hippocampal slices in a concentration-dependent manner.² It increases secondary after-discharge duration in electrically induced seizures in rats when administered at doses of 2.5 mg/kg or higher.³ CPT increases the response rate under a fixed-interval schedule of stimulus-shock termination in squirrel monkeys (ED₅₀ = 2.5 μmol/kg), indicating psychomotor stimulant effects.⁴

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1. Jacobson, K.A., Kiriasis, L., Barone, S., et al. Sulfur-containing 1,3-dialkylxanthine derivatives as selective antagonists at A₁-adenosine receptors. J. Med. Chem. 32(8), 1873-1879 (1989).

2. Gribkoff, V.K., Bauman, L.A., and VanderMaelen, C.P. The adenosine antagonist 8-cyclopentyltheophylline reduces the depression of hippocampal neuronal responses during hypoxia. Brain Res. 512(2), 353-357 (1990).

3. Dragunow, M., and Robertson, H.A. 8-Cyclopentyl 1,3-dimethylxanthine prolongs epileptic seizures in rats. Brain Res. 417(2), 377-379 (1987).

4. Spealman, R.D. Psychomotor stimulant effects of methylxanthines in squirrel monkeys: Relation to adenosine antagonism. Psychopharmacology (Berl.) 95(1), 19-24 (1988).