Anxiolytic effect of Anthemis nobilis L. (roman chamomile) and Citrus reticulata Blanco (tangerine) essential oils using the light-dark test in zebrafish (Danio rerio)

The anxiety disorders are the most prevalent mental health condition, and anxiety is considered the sixth cause of disability surpassing diabetes mellitus, chronic obstructive pulmonary disease, and osteoarthritis. Besides, the COVID-19 pandemic provided an increase in the number of psychiatric diseases diagnosis in all social layers around the world. About 55%-94% of patients diagnosed with anxiety disorders are treated with benzodiazepines, meanwhile benzodiazepines can promote several adverse effects. In this way, alternative therapies, such as essential oils may offer significant benefits in the treatment of patients with anxiety disorders. However, the anxiolytic effect of these essential oils must be proper evaluated appropriate as well as the suitable dosage and side effect need further research.The aim was to evaluate the anxiolytic effect of Roman chamomile (Anthemis nobilis L.) and tangerine (Citrus reticulata Blanco) essential oils using the light-dark test in adult zebrafish (Danio rerio).Both essential oils were analyzed by GC-MS and the major compounds were identified. The anxiolytic effect was evaluated by light-dark test in adult zebrafish.The results showed that roman chamomile essential oil has anxiolytic effect in adult zebrafish, whereas tangerine essential oil tends to reduce anxiety The major compounds of tangerine essential oil were limonene and γ-terpinene, and the major compounds of roman chamomile were pentadecyl-3-methyl-2-butenoate, hexadecyl-3-methyl-2-butenoate, 1-piperidinol and trans-1-ethyl-3-methyl-cyclopentane.The present study demonstrated that this anxiolytic effect may be attributed to the synergistic effect of the compounds present in roman chamomile essential oil, particularly the major compounds. The roman chamomile essential oil at the highest concentration showed anxiolytic effect. The tangerine essential oil showed a tendency to reduce anxiety, but it was not statistically significative. In addition, roman chamomile and tangerine essential oils did not cause cause alteration in locomotion activity and exploratory ability of the fish.