Material and methods: EOCC composition was determined by GC-MS. Direct antimicrobial activity was tested by determination of Minimal Inhibitory Concentration (MIC). Mutagenic potential was assessed by the Ames test using Salmonella typhimurium strains TA98 and TA100. Cytotoxicity was evaluated in vitro against human non-cancer fibroblast cell line (WI38) by MTT assay and pulmonary toxicity was assessed by administration of a single dose of 0.125 and 0.5% of EOCC with broncho-alveolar lavage after 24h.

Results: Citral (83.29%) was detected as major compound. The results confirmed the antimicrobial activity of EOCC against streptococcus and haemophillus strains (MIC from 0.25 to 0.5%v/v). Also, EOCC is not mutagenic on Salmonella typhimurium strains at the highest concentration tested (200μg/plate) and had a low cytotoxicity (IC50: 49.39±9.65µg/mL). Single doses of 0.125 or 0.5%v/v did not induce inflammation, cell recruitment or cytotoxicity in lungs 24h after administration, suggesting safety at these concentrations. This is the first report of pulmonary toxicity of EOCC by this technique.

Conclusion: Taking together, these results provide a scientific basis for the use of EOCC as a treatment for sore throat.