Abstract: AIM: To evaluate the cytotoxicity of anovelanticholinergic drug penehyelidine hydrochloridle(PHC) and its four optical isomers R-1, R-2, S-1, and S-2. METHODS: Two in vitro assays. MTT assay andneutral red uptake 198ay, were used to evaluate the cyto-toxicity following PHC and its isomers exposure to HepG2cells at different concentrations. RESULTS: PHC and itsisomers induced decreases of viability of HepG2 ceils in aconcentration-dependent manner. Comparison of the cyto-toxicity of the five anticholinergic agents with 50% inhibi-tory concentration (ICg) values indlicated that the orderof potency was PHC> R-2> R-1> S2> S-1 for MTTassay, and R-2> PHC ≈ R-1> S2> S-1 for neutral reduplake assay. CONCLUSION: With respect to the cyto-toxicity of the four isomers on HepG2 cells, the config-uration was more potent than the S configuration, and R-2 was the most potent isomer whereas S-! was the leastpotent isomer among the four optical isomers.

Key words: anticholinergic drug, penehyclidine hydnochloride, opieal isomers, cytotoxicity