Rosmarinus officinalis L. extract inhibits human melanoma cell growth

Abstract

Products able to inhibit reactive oxygen species (ROS) and reactive nitrogen species (RNS) production by UV-R could be used in the prevention of skin cancer [1]. Rosmarinus officinalis L. (rosemary) is used as a folk medicine around the world, as well as in cosmetics. In medicine, the extract is receiving increasing attention due to its anti-inflammatory and antioxidative constituents [2]. The antioxidant properties of rosemary have been well documented, and there are several reports that have established carnosic acid as the major phenolic diterpenoid present in rosemary leaves with antioxidant activity [2]. Recently, this phenolic compound has attracted wide interest as a potential therapeutic agent against several diseases, and researches showed that it has chemopreventive, anti-neoplastic and antimutagenic effects [2]. Our recent studies evidenced that R. officinalis extract, containing 31.7% of carnosic acid, was able to contrast deleterious effects of UV-R, protecting plasmid DNA by hydroxyl radical generated by UV-A [2]. In this work, we evaluated the effect of this extract on pBR322 DNA cleavage induced by nitric oxide, and the growth inhibitory activity against two human melanoma cell lines (M14 and A375). The results obtained indicate that our sample at 200–800µg/ml concentrations, like carboxy-PTIO (1 mM), an NO trapping agent, was able to reduce the NO-induced plasmid DNA damage, and at non toxic concentrations (20–80µg/ml) for normal human fibroblast cells, was able to reduce significantly (p<0.001) the growth (MTT assay) of both melanoma cell lines. In addition, our results seem to indicate that apoptotic cell demise appears to be induced in M14 and A375 cells. In fact, no statistically significant increase in LDH release was observed in melanoma cells, correlated to a fragmentation of genomic DNA, determined by COMET assay.