Phytochemical profiling and neuroprotective activity of Callistemon subulatus leaves against cyclophosphamide-induced chemobrain.

Cyclophosphamide (CPA) is a chemotherapeutic drug used for various types of cancers. However, patients receiving CPA for long periods suffer cognitive impairment associated with difficulties in learning, decreased concentration, and impaired memory. Chemotherapy-induced cognitive impairment, known as chemobrain, has been attributed to enhanced oxidative stress and inflammatory response. The current study aimed to identify the phytoconstituents of Callistemon subulatus extract (CSE) using HPLC-ESI/MS-MS analysis and evaluate its neuroprotective activity against CPA-induced chemobrain in rats. Fourteen compounds were identified following HPLC analysis including, five phlorglucinols, four flavonol glycosides, a triterpene, and a phenolic acid. Forty rats were divided into five groups treated for ten days as follows; group I (control group), group II received CPA (200 mg/kg, i.p.) on the 7th day, groups III and IV received CSE (200 and 400 mg/kg respectively, orally) for ten days and CPA (200 mg/kg, i.p.) on the 7th day, and group V received only CSE (400 mg/kg, orally) for ten days. The administration of CSE effectively ameliorated the deleterious effects of CPA on spatial and short-term memories, as evidenced by behavioral tests, Y-maze and passive avoidance. Such findings were further confirmed by histological examination. In addition, CSE counteracted the effect of CPA on hippocampal acetylcholinesterase (AChE) activity enhancing the level of acetylcholine. Owing to the CSE antioxidant properties, it hindered the CPA-induced redox imbalance, which is represented by decreased catalase and reduced glutathione levels, as well as enhanced lipid peroxidation. Therefore, CSE may be a promising natural candidate for protection against CPA-induced chemobrain in cancer patients.