Characterization of Phenolic Compounds and Antiproliferative Effects of and Extracts.

The phenolic compounds of methanolic extracts of and were identified by liquid chromatography tandem mass spectrometry. Carnosic acid and its metabolite carnosol were the most abundant terpene phenolic compounds of , while they were completely absent in . The main terpene phenolic constituent of was 12--methylcarnosic acid and its mass/mass fragmentation pathway was explained. The detailed mechanism of carnosic acid oxidation to carnosol was suggested. The effects of extracts and/or carnosic acid, the main diterpene phenolic component of , on the proliferation and cell cycle of two melanoma cell lines (A375, Mel JuSo) and human fibroblast cell line (HFF) were investigated by MTT assay, PI-exclusion assay and flow cytometry cell cycle analysis. Extract of more efficiently than extract reduced the proliferation of the human melanoma cells. Carnosic acid showed the most significant effect. The first evidence that carnosic acid affects microtubule dynamics and arrests the cell cycle in the G2/M phase was provided. Collectively, our results demonstrate that these two species are plants of medicinal interest with perspective for further investigation. Carnosic acid could be the compound responsible for the biological activities of extracts.