In vitro and in vivo toxicological evaluations of methyl ferulate, methyl p-coumarate, and pulegone 1,2-epoxide

Context: Toxicological screening of natural compounds for medicinal purposes. Objectives: The objective of this study is to evaluate the toxicity of methyl ferulate (MF), methyl p-coumarate (MpC), and pulegone 1,2-epoxide (PE) with in vitro and in vivo assays. Materials and methods: The in vitro toxicity of MF, MpC, and PE was assessed at a concentration of 10mg/ml with the Ames assay using two strains of Salmonella typhimurium TA98 and TA100. Human red blood cells (RBC) were used to determine the hemolytic activity of these compounds. The cytotoxicity of above compounds was determined with brine shrimp lethality bioassay (BSLB) at the concentrations of 0.1-20mg/ml. While dermal and ocular irritation studies were conducted on healthy rabbits (n=8) for 96 and 12h post-topical application of test compounds, respectively. Results: PE produced 6-8% hemolysis of RBCs at all the tested concentrations while MF and MpC produced 10-5% hemolysis up to 20mg/ml, and 50-85% hemolysis at concentrations of 40 and 80mg/ml, respectively. The Ames assay indicated that MF, MpC, and PE were non-mutagenic as the test values were not significantly higher as compared with background values of the assay. BSLB suggested the lethal concentration (LC50) values of MF, MpC, and PE as 4.38, 6.74, and 25.91mg/ml, respectively. In vivo ocular and dermal irritation scores of MF, MpC, and PE were comparable with ethanol (control) in rabbits indicating the non-irritant nature of these natural compounds. Conclusion: The present studies suggest that these compounds are non-toxic/non-irritant and might be used for medicinal purposes.