Tetraclinis Articulata Essential Oil Mitigates Cognitive Deficits and Brain Oxidative Stress in an Alzheimer's Disease Amyloidosis Model

Background: Tetraclinis articulata is used in traditional medicine and has been reported to possess antibacterial, antifungal, cytotoxic, anti-inflammatory and antioxidant properties.

Purpose: This study investigated the effects of T. articulata essential oil on memory and brain oxidative stress in amyloid-β peptide 1-42 (Aβ1-42)-induced an Alzheimer's disease amyloidosis model. Moreover, the underlying mechanism for memory enhancement and antioxidant activity was investigated, thus supporting its traditional use with scientific evidence for further studies.

Methods: T. articulata essential oil was administered by inhalation to male Wistar rats once daily for 15 min period at doses of 1% and 3% for 21 days after the intracerebroventricular administration of Aβ1-42 right-unilaterally to induce memory deficits. The chemical composition of the essential oil was done by GC-MS and GC-FID. Spatial memory of rats was tested using Y-maze and radial arm maze tests. The possible underlying mechanism for memory improvement exhibited by T. articulata essential oil was investigated by in vivo brain antioxidant effect and acetylcholinesterase (AChE) inhibitory effect. In vitro, experimental evaluations were assessed through DPPH and ABTS tests.

Results: The GC-MS and GC-FID data showed that the essential oil has a high percent of monoterpene hydrocarbons. Also, we demonstrated the essential oil reversed the Aβ1-42-induced decreasing of the spontaneous alternation in the Y-maze test and the Aβ1-42-induced increasing of the working and reference memory errors in the radial arm maze test. Furthermore, the Aβ1-42-decreased the acetylcholinesterase activity and the oxidant-antioxidant status in the rat hippocampus was retrieved by the treatment with the essential oil.

Conclusion: The study demonstrates that the essential oil could be a potent pharmacological agent against dementia by modulating cholinergic activity and promoting antioxidant action in the rat hippocampus.