Essential oil of Citrus lumia Risso: Phytochemical profile, antioxidant properties and activity on the central nervous system

Citrus lumia Risso Essential oil Antioxidant properties Anti-cholinesterase activity Cytotoxicity Neuroactive effects 1. Introduction Plants that produce essential oils (EOs) represent a large part of natural flora and an important resource in various fields such as pharmaceutical, food and cosmetic industries, due to their flavor, fra- grance and biological activity (Swamy et al., 2016). EOs play a pivotal role in the growth and colonization of plants, giving color and scent to reproductive organs, attracting pollinators, favoring seed dispersion (Sharifi-Rad et al., 2017), and defending the plant against abiotic (light, temperature, etc.) and biotics (herbivores, harmful insects and pa- thogen microbes) stressors (Sharifi-Rad et al., 2017). More than 250 types of essential oils are commercialized annually on the international market, some of which are used since ancient times in popular medi- cines (Jarić et al., 2015; Mahboubi, 2015), in aromatherapy, and as a therapeutic aid in the treatment of various pathologies including car- diovascular and neurological diseases, as well as diabetes and cancer (Swamy et al., 2016; Lillehei and Halcon, 2014; Solórzano-Santos and ABSTRACT The use of essential oils (EOs) is known since long time in traditional medicine and aromatherapy for the management of various oxidative stress-related disorders and has been further increased recently for their neuroprotective and anti-aging potentials as well as for reducing anxiety and stress. The purpose of this work was to evaluate, for the first time, the chemical composition of Citrus lumia Risso EO and its antioxidant, anti-cholinesterase, and neuroactive properties by cell-free and cell-based assays. The EO has shown strong antioxidant and free radical scavenging properties, particularly in hydrogen atom transfer based assays (β-carotene bleaching and ORAC, IC50 22 μg/mL and 46 μg/mL, respectively), that can be attributed to the high content of monoterpenes, especially D-Limonene (48.905%), and Linalool (18.245%). Furthermore, the EO has shown an interesting anti-acetylcholinesterase activity (IC50 258.25 μg/mL). Data from MTT analysis indicate that the cytotoxicity of EO, evaluated on L929 mouse fibroblasts, is very low, with an IC50 higher than 500 μg/mL at 48 h. Rat neuronal networks subjected to EO showed a concentration-dependent in- hibition of spontaneous electrical activity. Results indicate that C. lumia EO could be an important source of natural antioxidants suggesting an im- portant preventive role in the onset of oxidative stress-related pathologies.