Myrtus communis L. subsp. communis Seeds Exhibit Potent Antioxidant Capacity, Enzyme Inhibition, and Selective Cytotoxicity Against Lung, Breast, Prostate, and Liver Human Cancer Cells

Background and Aims: Myrtle (Myrtus communis L.) has been used as a food and folk medicine since ancient times. The aim of this study was to determine the antioxidant capacity, inhibition of tyrosinase enzyme, and cytotoxicity of 12 extracts from the fruit, seed, leaves, and twigs of Myrtus communis L. subsp. communis. Methods: The cytotoxic effects on human lung (A549), liver (Hep3B), prostate (PC-3) and breast (MCF7) cancer cells and healthy L929 cells were determined using the MTT method. Tyrosinase enzyme inhibition was investigated using L-tyrosine as the substrate. The antioxidant capacity was determined using the DPPH, TEAC and CUPRAC methods. Results: It was found that the extracts did not affect the viability of healthy cells but showed concentration-dependent toxic effects on cancer cells. The ethyl acetate sub-extracts of the plant parts showed a higher cytotoxic effect on all cell lines, and the ethyl acetate sub-extract of the seed was the most effective with 72.6% proliferation inhibition against the Hep3B. The methanol extract and ethyl acetate sub-extract of the seed showed the highest inhibition against tyrosinase and the values were 388.6 and 412.8 mg KAE/ g extract, respectively. While all extracts showed significant antioxidant activities in all methods, the ethyl acetate sub-extract of seeds showed the highest. Conclusion: This is the first comparative study to investigate the antiproliferative effects of extracts from various parts of Myrtus communis L. subsp. communis. The results show that seeds in particular can be a promising, effective and recyclable resource that can be safely used in the pharmaceutical and cosmetic industries.