Antioxidant and Cytotoxic Activities of Myrtaceae Essential Oils Rich in Terpenoids From Brazil

This work analyzed the chemical compositions and evaluated the antioxidant and cytotoxic activities of essential oils (EO) of Eugenia patrisii (Epat), Eugenia stipitata (Esti), Myrcia splendens (Mspl), Myrcia sylvatica (Msyl), Psidium guajava (Pgua), and Psidium guineense (Pgui-1 and Pgui-2) from the Brazilian Amazon. Sesquiterpenoids were found in high concentrations in the oils of E. patrisii and M. splendens, which were rich in E-caryophyllene (32.0% and 45.8%); E. stipitata and M. sylvatica, which displayed germacrene D (11.8%) and germacrene B (24.5%); and P. guajava that showed epi-β-bisabolol (16.1%) as the main compound. However, P. guineense samples (Pgui-1 and Pgui-2) were rich in monoterpenoids such as limonene (Pgui-1: 30.2%; Pgui-2 30.4%) and α-pinene (Pgui-1: 22.5%; Pgui-2: 17.7%). The samples showed a weak and moderate antioxidant activities in the DPPH assay, displaying inhibition rates from 11.5% to 38.6% (at 10 mg/mL). All samples were cytotoxic against human cancer cells by the MTT method. Epat oil showed higher activity against melanoma (SKMEL-19, IC505.8 µg/mL), gastric (AGP01, IC503.2 µg/mL), and colon (HCT116, IC506.7 µg/mL). Meanwhile, the samples Pgua and Pgui were more active against breast cancer cells (MCF7, IC5012.4 µg/mL and 11.6 µg/mL, respectively).