Assessment of compounds and cytotoxicity of Citrus deliciosa Tenore essential oils: From an underexploited by-product to a rich source of high-value bioactive compounds

Essential oil (EO) from the peels of Citrus deliciosa fruits are underexploited among Citrus EO by the food and cosmetic industries. The aims of this study were to evaluate the biological effects of EO from C. deliciosa fruit peels at different stages of maturation in an adenocarcinoma cell line and propose the use of this by-product as a new source for the extraction of bioactive compounds. The fruits were collected at the immature (IM), intermediate (INT), and mature (MAT) stages. A total of 15, 17, and 14 components were measured using GC-MS in the EO at the IM, INT, and MAT stages, respectively. The main components were limonene and gamma-terpinene at all the stages. The in vitro antioxidant activity was evaluated using ABTS. assay, and EO INT showed the greatest activity with an IC50 value of 0.264 +/- 0.004 mg/mL. The cytotoxic effect was evaluated against HT-29 cells, in which EO MAT showed significant cytotoxic activity with an IC50 of 110 + 10 mu g/mL. It was found that the presence of citronellol and beta-linalool favors the antioxidant activity; however, their presence suggested a decrease in the cytotoxic activity, when associating the phytochemical profile with the evaluated activities. The results showed that secondary compounds at trace concentrations were associated with differences in biological activities. C. deliciosa fruit peel, a by-product of food juice industry, might be used as a source for the extraction of bioactive compounds with promising biological activities.