Atividades antioxidante e antitumoral de óleos essenciais contra linhagens celulares de câncer de pulmão: Uma Revisão

Abstract

Lung cancer is one of the malignant tumors with the highest incidence and lethality rates worldwide. Available treatments for this disease can cause serious adverse effects, are expensive and often ineffective, which makes the search for new therapeutic interventions essential. Essential oils are complex volatile substances with great therapeutic potential against several pathologies, including cancer. Due to the role of oxidative stress in carcinogenesis, the antioxidant and antitumor properties of essential oils provide them chemopreventive, chemotherapeutic and tumor suppression abilities. Thus, the aim of this review was to critically analyze and summarize information regarding such effects of essential oils on lung cancer cell lines, obtained by previous studies. We reviewed experimental in vitro studies published from 2005 to December 22, 2020, which investigated the antioxidant and/or antitumor effects of essential oils against lung cancer cell lines. Electronic searches were conducted in the databases Embase®, MEDLINE®/PubMed®, SciELO, Science Direct, Scopus® and Web of Science, using different combinations of keywords (essential/volatile oil; antioxidant/anticancer/antitumor/antitumor/ antineoplastic activity/capacity/effect/property; lung cancer/carcinoma cell line). To evaluate the quality of the selected studies, the impact factor and citescore of the journals were considered, as well as the average of citations per year of individual articles. Furthermore, a robustness score of the results was developed to analyze aspects such as the presence or absence of: control groups (negative and positive) in the implemented methodologies; calculation of IC50 or its equivalent; graphical/tabular representation of results; statistical analysis of the data; complementary methodology for corroborating results. Initially, 3,748 articles were identified and, after screening the titles/abstracts and full reading the pre-selected papers, 64 studies were included in this review. All of them evaluated the antitumor activity of essential oils, and 26 studies mentioned oils (n = 29) with strong antitumor potential against lung cancer cell lines, especially A549. And in 31 studies, the chemical antioxidant activity of essential oils was evaluated, from which 13 reported oils (n = 19) that showed strong activity, however, the diversity of methods used causes heterogeneity of outcomes, culminating in the absence of standardization and categorization of the results. Essential oils from Artemisia indica, Citrus sinensis, Graptophyllum pictum, Juniperus communis, Perilla frutescens, Senecio graciliflorus, Syzygium aromaticum and Thymus vulgaris showed strong antioxidant and antitumor activities against lung cancer cell lines. However, these results alone are not sufficient to establish a relation between both effects, which reflects a paradigm shift that essential oils with strong antioxidant activity necessarily have antitumor potential, and vice-versa. This is probably due to the different mechanisms of action of essential oils in the performance of these activities.