The Isoxazole Ring and Its N-Oxide: A Privileged Core Structure in Neuropsychiatric Therapeutics

Mental disorders are neuropsychiatric conditions that are marked by unusual or irregular thinking, feelings, or behavior, and lead to distress and/or impaired functions. Major psychiatric conditions are depression, anxiety, and psychoses of various types. Their etiopathogeneses, of a primary or secondary origin, are associated with genetic and environmental factors. They are commonly treated with psychoactive drugs (also known as psychotropics), which target serotonin, dopamine, norepinephrine, glutamate, and nuclear receptors (NRs), including retinoic acid receptor-related orphan receptors (RORs) and other receptors in the central nervous system (CNS). Herein we present a diverse array of isoxazole derivatives, among which are some prominent marketed drugs. Some of the derivatives and forms, including N-oxides, are under either (pre)clinical evaluation or patent protection as new generation of psychotropics, and a few have effective blood-brain barrier (BBB) permeability. Various drug-like isoxazol(in)es and their structural features and efficiency, modified through scaffold hopping, are described and discussed in the context of treating neuropsychiatric conditions.