6-[(1-NaphthalenylMethyl)thio]-9H-purine

PU 02 is an antagonist of the serotonin (5-HT) receptor subtype 5-HT₃ with IC₅₀ values ranging from 0.36 to 1.3 μM for human 5-HT_3A, 5-HT_3AB, 5-HT_3AC, and 5-HT_3AE in a FLIPR membrane potential assay using HEK293 cells expressing human recombinant receptors. It is selective for 5-HT₃ over other Cys-loop containing receptors with IC₅₀ values >100 μM for mouse, rat, and human nicotinic (nACh), human GABA_A, and human glycine (Gly) receptors. PU 02 inhibits currents induced by 5-HT in COS-7 cells expressing human 5-HT_3A (IC₅₀ = 0.49 μM). PU 02 also reduces growth of HepG2 cells in a dose-dependent manner via induction of cell cycle arrest at the G₂/M phase and apoptosis.