Anticancer Effect of Solid-Lipid Nanoparticles Containing Mentha longifolia and Mentha pulegium Essential Oils: In Vitro Study on Human Melanoma and Breast Cancer Cell Lines

Breast cancer and melanoma are common cancers with several treatments such as surgery, radiotherapy, chemotherapy, and their side effects. Therefore, new drugs using plant-derived substances (especially essential oils) have received more attention in recent years; however, they are generally less effective than synthetic drugs. Therefore, the preparation of essential oil-based nanoformulations is considered a promising approach to improving their efficiency. In this study, ingredients of Mentha longifolia and Mentha pulegium essential oils were first identified by GC-MS analysis. Their anticancer effects were then evaluated against one melanoma cell line (A-375) and two breast cancer cell lines (MDA-MB-468 and MCF-7). The cytotoxic effect of the essential oil on all cell lines at even the highest concentration, 1200 µg/mL, was not proper (viability > 55%). After that, solid lipid nanoparticles containing each essential oil with particle sizes of 107 ± 9 (PDI 0.274) and 191 ± 8 (PDI 0.174) nm and zeta potential -7.10 and -4.81 mV were prepared. Interestingly, both prepared nanoformulations reduced the viability of all three cell lines to around 10% at half the mentioned concentration, 600 µg/mL. Thus, the prepared nanoformulations could be introduced as proper candidates for investigation in-vivo research and supplementary medicine.