Chemical composition and antiproliferative effect of essential oils of four Solidago species (S. canadensis, S. gigantea, S. virgaurea and S.× niederederi).

There is a growing interest in the research of natural products with potent activity in the prevention and treatment of diseases. Thereby, essential oil phytochemicals have demonstrated broad bioactivities. This study highlights the chemical composition of essential oils obtained from the leaves and inflorescences of diverse species of the genus Solidago (Solidago canadensis, Solidago gigantea, Solidago virgaurea and Solidago × niederederi), also known as Goldenrod, through GC-MS analysis, and their antiproliferative activity on three human tumour cell lines (MDA-MB 231, A375 and HCT116) by the MTT assay. The most represented chemical classes in the essential oils were oxygenated sesquiterpenes, sesquiterpene hydrocarbons, oxygenated monoterpenes and monoterpene hydrocarbons, with a remarkable contribution of compounds such as germacrene D (3.89-19.51%), a-pinene (3.59-18.82%), bornyl acetate (3.30-12.73%) and caryophyllene oxide (3.07-9.18%). Chemical quali- and quantitative differences were noticed between the leaves and flowers of the same species, as well as between the studied species. The MTT assay showed that the essential oils from the leaves were more active than those from the flower ones. The essential oil having the highest impact on cell viability was that from S. × niederederi (IC50 = 12.93, 6.72, and 6.82 µg/ml), followed by S. virgaurea (IC50 = 13.39, 7.96, and 8.36 µg/ml) and finally S. gigantea (IC50 = 18.04, 5.94, and 8.10 µg/ml) on MDA-MB 231, A375 and HCT116 cell lines, respectively. The essential oil from S. canadensis showed the lowest activity (IC50 = 29.33, 12.63, and 18.03 µg/ml, respectively). Taken together, these findings highlight the Solidago species as good sources of cytotoxic compounds. Further studies are encouraged on the in vivo effects and safety of these products.