From ancient times, plants have been regarded as therapeutic agents, in addition to their usage as food. Plants are rich sources of antioxidant and phenolic compounds. Lavandula angustifolia and Melissa officinalis are medicinal herbs rich in antioxidant compounds. The aim of this study was to compare the antioxidant and anticancer properties of Lavandula angustifolia and Melissa officinalis extracts using aqueous, ethanol and methanol solvents, to select the best extraction methods and solvents and to evaluate the cytotoxic effect of the extracts on HeLa, OVCAR-3 and MCF-7 cancer cell lines. Methanol, aqueous and ethanol extracts were obtained from the dried leaves of the plants and the antioxidant activities of each extract were measured by DPPH and FRAP methods. Finally, the anticancer effects of the extracts on HeLa, OVCAR-3 and MCF-7 cancer cell lines were evaluated by MTT assay in order to identify the most efficient extract. Comparing the results of total antioxidant assay showed that the highest amount belonged to the ethanol extract of Melissa officinalis and Lavandula angustifolia methanol extracts using lyophilization method. The IC50 value of ethanol extract of Melissa officinalis was equal to 0.028 mg/ml on OVCAR-3 cells, which was the best result obtained in comparison with other solvents, and the ethanol extract of Lavandula angustifolia with IC50 = 2.07 mg/ml on MCF-7 cells was the most effective extract among the others. In HeLa cell-line, methanol extract of Lavandula angustifolia with IC50 = 7.36 mg/ml showed the highest cytotoxicity. In this study, for the first time, the effects of different extracts of Lavandula angustifolia and Melissa officinalis on MCF-7, OVCAR-3 and HeLa cancer cells were evaluated and the results showed that ethanol and methanol extracts of these plants had better toxic effect on cancer cells.
