no. the Benazepril HCl isolated compound as geraldol, a flavonoid. Geraldol effectively blocked binding of NMO-IgG to AQP4 in immunofluorescence assays and decreased CDC in NMO-IgG/complement-treated FRTL-AQP4 Kcnc2 cells and primary astrocytes. Geraldol exhibited low cytotoxicity, with no effect on proliferation or apoptosis of FRTL-AQP4 cells and primary astrocytes. Permeability assays indicated Benazepril HCl that geraldol did not alter the water transport function of AQP4 in either cell system. The present study suggests the potential therapeutic value of geraldol for NMO drug development. Keywords: neuromyelitis optica, autoimmune disease, aquaporin-4, neuromyelitis optica-IgG, geraldol Introduction Neuromyelitis optica (NMO), also known as Devic’s syndrome, is a severe demyelinating disease of the central nervous system that causes recurrent seizures. NMO mainly affects the optic nerves and the spinal cord, but it can also affect the brain, to a lesser extent (1). NMO is difficult to distinguish clinically from multiple sclerosis (MS) as both disorders have similar characteristics in the early stages of disease. NMO was once considered a subtype of MS, and was even termed optica-spinal MS in Japan. However, a previous study has suggested that NMO is an independent clinical entity that is distinct from MS (2). NMO is caused by an autoimmune antibody (NMO-IgG) targeting aquaporin-4 (AQP4), a plasma membrane water transport channel expressed in the glia (3C5). Binding of NMO-IgG to AQP4 on astrocytes can cause complement-mediated and cell-mediated injury to astrocytes, triggering a series of inflammatory cascades that result in the release of cytokines, activation of microglia and accumulation of leukocytes. Together, these responses result in neuronal injury and cause the clinical symptoms of NMO (6C8). NMO remains to be an incurable disease. The goal of treating acute NMO events is to improve relapse Benazepril HCl symptoms and restore neurological functions, while the aim of long-term immunosuppression is to prevent further attacks (9C11). For long-term immunosuppression, patients usually receive either B cell-targeted therapies, such as intravenous rituximab or oral azathioprine, and/or prednisone (12C20). Other therapeutic options include mycophenolate mofetil (21), methotrexate (22) or mitoxantrone. Mitoxantrone can cause adverse effects, such as cardiotoxicity or leukemia, and is thus generally not considered for first-line treatment (11,23C28). A novel strategy for NMO treatment is blocking the binding of NMO-IgG to AQP4. Based on this strategy, a high-affinity, non-pathogenic monoclonal antibody (aquaporumab) was developed and exhibited positive effects in clinical trials (29). Aquaporumab can relieve NMO symptoms by competing with NMO-IgG to bind to AQP4 (29). However, monoclonal antibody drugs can also have disadvantages, for example, they may activate the complement system and cause pathological changes similar to those observed in NMO, or they may induce the production of autoimmune antibodies, thus reducing their protective effects (10). In this context, inhibitors that block binding between Benazepril HCl NMO-IgG and AQP4 may represent potential drug candidates for treating NMO. A previously established reporter cell-based high-throughput screening system identified a small molecule inhibitor (isotetrandrine, obtained from an extract of the herb was purchased from a commercial herb supplier (Hongjian Herb Store). The isolation procedures were performed as previously described (33). The aerial parts of were crushed and extracted using different solvents (petroleum, ethyl acetate, chloroform, n-butanol; all were 100%; purchased from Beijing Chemical Works) at room temperature to attain optimum solubility for the mark peak (bioactive small percentage). The ingredients (50 g) had been additional purified by high-speed countercurrent chromatography (HSCCC; TBE-300; Tauto Biotechnique Co., Ltd.), that was in conjunction with a UV detector (kitty. no..