Part Two: Evaluation of N-methylbupropion as a Potential Bupropion Prodrug

Molybdenum bupropion combined neurotoxicity in rats

Heavy metal toxicity is a common foodborne problem in Egypt, especially in combination. Molybdenum toxicity has been studied as a model of the heavy metal toxicity. Molybdenum could promote toxicity via oxidative-inflammatory mechanisms. Bupropion is a well-known antidepressant that has anti-oxidant mechanisms. It exerts a cytoprotective action against molybdenum induced metal toxicity. The aim of the study is to evaluate the effects of combined bupropion and molybdenum in a toxic animal model. The results showed that the combination of bupropion and high doses of molybdenum was extremely toxic with an evident animal fatality. Bupropion showed a clear anti-oxidant/anti-inflammatory profile detected by the ELISA assay of malondialdehyde (MDA), reduced glutathione, and interleukin -6 (IL-6), and real-time gene expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and tumor necrosis factor-α (TNF-α). The immunohistochemistry of nuclear factor Kappa Beta (NF-κB) showed that bupropion reduced the inflammatory response induced by the molybdenum neurotoxicity. Despite the improved laboratory profile, the animals were extremely intoxicated with recorded fatalities raising the question about other pathways and mechanisms explaining the drug metal interaction. Furthermore, Bupropion even in normal doses was toxic to the animals. Choroid plexus hyperplasia was reported in the histological examination of the animal brain loaded with bupropion, and choroid plexus papilloma was recorded in the combined drug metal group. More wide-scale studies are needed to verify the safety of the current antidepressant medications for the long-term therapy. It is important to focus on drug metal interaction as a possible cause of neuropathology.

Development of a sensitive and quantitative capillary LC-UV method to study the uptake of pharmaceuticals in zebrafish brain

The present study explores the potential of 10-day-old zebrafish (Danio rerio) as a predictive blood-brain-barrier model using a set of 7 pharmaceutical agents. For this purpose, zebrafish were incubated with each of these 7 drugs separately via the route of immersion and the concentration reaching the brain was determined by applying a brain extraction procedure allowing isolation of the intact brain from the head of the zebrafish larvae. Sample analysis was performed utilizing capillary ultra-high performance liquid chromatography (cap-UHPLC) on a Pepmap RSLC C18 capillary column (150 mm × 300 μm, d_p = 2 μm) coupled to a variable wavelength UV detector. Gradient separation was performed in 28 min at a flow rate of 5 μL/min and the optimal injection volume was determined to be 1 μL. The brain extraction procedure was established for the zebrafish strain TG898 exhibiting red fluorescence of the brain, allowing control of the integrity of the extracted parts. Quantitative experiments carried out on pooled samples of six zebrafish (n = 6) demonstrated the selective semipermeable nature of the blood-brain barrier after incubating the zebrafish at the maximum tolerated concentration for the investigated pharmaceuticals. The obtained brain-to-trunk ratios ranged between 0.3 for the most excluded compound and 1.2 for the pharmaceutical agent being most accumulated in the brain of the fish. Graphical abstract Workflow of brain extraction to study the uptake of pharmaceuticals in the brain of zebrafish larvae.