Assessment of the Inhibition of AChE and BChE by Carthamus caeruleus Essential Oil and Carline Oxide: Neuroprotective Effects and In Vivo Toxicity Assessment for the Management of Alzheimer’s Disease

Background: Alzheimer’s disease is associated with dysfunction of the cholinergic system, making the inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) a promising therapeutic approach. Objective: This study aimed to evaluate the neuroprotective effects and toxicity of essential oil (EO) and carlina oxide from Carthamus caeruleus in mice, assessing their potential for Alzheimer’s disease treatment. Methods: The chemical composition of the essential oil extracted from the roots of Carthamus caeruleus was analyzed using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The main component, carlina oxide, was isolated via column chromatography. The inhibitory activities of AChE and BChE were evaluated in vitro for both the essential oil and carlina oxide. Additionally, in vivo, toxicity was assessed in laboratory mice. Results: Chemical analysis identified carlina oxide (81.6%) as the major constituent, along with minor compounds such as 13-methoxycarlin oxide and hexadecanoic acid. Both the essential oil and its main component, carlina oxide, exhibited significant inhibitory activity against AChE and BChE, enzymes associated with Alzheimer’s disease. The essential oil demonstrated promising IC50 values, with stronger anti-BChE activity compared to the reference drug, galantamine. Toxicity tests in mice revealed no adverse effects at lower doses (0.2-0.5 g/kg). However, higher doses (1.0-2.0 g/kg) resulted in mild to significant toxicity, including weight loss and mortality. Discussion: The essential oil and carlina oxide demonstrated potent BChE inhibition, particularly relevant in advanced Alzheimer's disease. While effective at low doses, signs of toxicity were observed at higher concentrations, highlighting the importance of dose optimization. These findings suggest that C. caeruleus may serve as a natural source of cholinesterase inhibitors, pending further in vivo studies and clinical validation. Conclusion: Carthamus caeruleus essential oil and carlina oxide show promising inhibitory effects on AChE and BChE, suggesting their potential as neuroprotective agents. However, their toxicity at higher doses highlights the need for cautious use and further investigation.