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Origanum vulgare ssp. hirtum has been used as medicinal herbs promoting antioxidant, anti-inflammatory, antimicrobial, and neuroprotective activities. We investigated the protective effects and the mechanism of O. vulgare ssp. hirtum essential oil (OEO) on cognitive impairment and brain oxidative stress in a scopolamine (Sco)-induced zebrafish (Danio rerio) model of cognitive impairment. Our results show that exposure to Sco (100 µM) leads to anxiety, spatial memory, and response to novelty dysfunctions, whereas the administration of OEO (25, 150, and 300 µL/L, once daily for 13 days) reduced anxiety-like behavior and improved cognitive ability, which was confirmed by behavioral tests, such as the novel tank-diving test (NTT), Y-maze test, and novel object recognition test (NOR) in zebrafish. Additionally, Sco-induced brain oxidative stress and increasing of acetylcholinesterase (AChE) activity were attenuated by the administration of OEO. The gas chromatography–mass spectrometry (GC-MS) analyses were used to elucidate the OEO composition, comprising thymol (38.82%), p-cymene (20.28%), and γ-terpinene (19.58%) as the main identified components. These findings suggest the ability of OEO to revert the Sco-induced cognitive deficits by restoring the cholinergic system activity and brain antioxidant status. Thus, OEO could be used as perspective sources of bioactive compounds, displaying valuable biological activities, with potential pharmaceutical applications.

Thymus vulgaris L. is an aromatic herb used for medicinal purposes such as antimicrobial, spasmolytic, antioxidant, anti-inflammatory, antinociceptive, antitumor, and may have beneficial effects in the treatment of Alzheimer&rsquo, s disease. The present study aimed to investigate whether Thymus vulgaris L. essential oil enhances cognitive function via the action on cholinergic neurons using scopolamine (Sco)-induced zebrafish (Danio rerio) model of memory impairments. Thymus vulgaris L. essential oil (TEO, 25, 150, and 300 &micro, L/L) was administered by immersion to zebrafish once daily for 13 days, whereas memory impairment was induced by Sco (100 &mu, M), a muscarinic receptor antagonist, delivered 30 min before behavioral tests. Spatial memory was assessed using the Y-maze test and novel object recognition test (NOR). Anxiety and depression were measured in the novel tank diving test (NTT). Gas Chromatograph-Mass Spectrometry (GC-MS) analysis was used to study the phytochemical composition of TEO. Acetylcholinesterase (AChE) activity and oxidative stress response in the brain of zebrafish were determined. TEO ameliorated Sco-induced increasing of AChE activity, amnesia, anxiety, and reduced the brain antioxidant capacity. These results suggest that TEO may have preventive and/or therapeutic potentials in the management of memory deficits and brain oxidative stress in zebrafish with amnesia.

Aims: This study was undertaken in order to evaluate the anxiolytic, antiamnesic and antioxidant potential of the Rosmarinus officinalis essential oil (25,150 and 300 µl/L) using a scopolamine (100 µM) - induced a zebrafish model of dementia. Methods: The essential oil chemical composition was evaluated by GC-MS. Also, the anxiety-like behavior and memory formation were assessed by novel tank diving test (NTT), the Y-maze and the T-maze tests. The essential oil (25,150 and 300 µl/L) was administered by immersion for 61 days period. Also, the scopolamine (100 µM) was delivered by immersion 30 minutes before the behavioral tests to induce anxiety and mild dementia. A Logitech HD Webcam C922 Pro Stream camera recorded zebrafish behavior, and the videos analyzed using ANY-maze®software (Stoelting CO, USA). The in vivo antioxidant effects of the essential oil were determined through antioxidant enzymes activity (SOD. CAT and GPX) levels, total content of reduced GSH and lipid peroxidation products (MDA) from the brain homogenates. Also, the acetylcholinesterase activity was evaluated. Results: Our data demonstrated that the essential oil reverted the anxiety and amnesic responses as a result of scopolamine administration that parallel with decreasing of brain oxidative stress and lipid peroxidation products. Conclusions: In summary, our essential oil could be considered as a good candidate for improving memory via antiacetylcholinesterase inhibitory effect and reducing brain oxidative stress.