Study of the mechanism of action of Melissa officinalis L. extracts in inhibiting the growth of human tumor cellular lines

Melissa officinalis L., commonly known as "lemon balm" is a perianal herbaceous plant from the family Laminaceae, native in Europe particularly in the Mediterranean region. Rosmarinic acid, the most abundant phenolic compound derived from caffeic acid, and some flavonoids such as luteolin-7-O-glucoside are described as responsible for its antimicrobial properties, antiinflammatory, antioxidant and even anti-tumor activities. Previous studies have investigated the antitumor effects of M. officinalis extracts, including aqueous, ethanolic and hydro-alcoholic extracts, in various human tumor cell lines. However, to our knowledge, the mechanism of action of the extracts has never been investigated. Therefore, the aims of this project are to: i) investigate if 5 different extracts of Melissa officinalis, prepared with different extraction methods, have cell growth inhibitory activity in three human tumor cell lines: NCI-H460 (non-small cell lung cancer), MCF-7 (breast adenocarcinoma) and AGS (gastric adenocarcinoma) and ii) study the mechanism of action of the most potent extract. Results showed that all the extracts decreased cell growth in all tumor cell lines, in a concentration-dependent manner. The ethanolic extract was the most potent one, presenting a 50% growth inhibition concentration (GI50) of approximately 100.9 μg/mL in the NCI-H460 cells (most sensitive cell line). Current work is confirming the effect of this extract on cell cycle and apoptosis.N/