TCM Substances in Neuropsychopharmacotherapy: Basic Aspects with a Focus on Depression

Depression is one of the most common complexes of heterogeneous psychiatric disorders. Etiopathogenic factors of depression are deregulation of serotonin, noradrenaline and dopamine systems, increased activity of type A monoamine oxidase, deficit of brain-derived neurotrophic factor, and impaired neurogenesis in the hippocampus and neuroinflammation. Current antidepressant medicines, such as tricyclic antidepressants, selective serotonin, or noradrenaline reuptake inhibitors and monoamine oxidase inhibitors, are effective, but about one-third of the patients are resistant to the therapy. Traditional Chinese medicine, herb, and plant-derived phytochemicals are proposed as alterative therapeutic agents in depression. This review presents molecular mechanisms underlying antidepressant effects of diet habits, traditional herbs, St John’s wort, saffron, passion flower, lavender, valerian, kava, and Ginkgo biloba, and their phytochemical constituents. Phytochemicals have been proved to modify multiple pathogenic factors of depression and ameliorate the symptoms in preclinical models. The epidemiological and clinical intervention studies have presented some beneficial effects of herb and phytochemicals. However, the intensive rapid metabolism and poor bioavailability in the brain prevent the clinical application of phytochemicals. Synthesis of more effective and stable compounds based on phytochemical scaffold and establishment of effective delivery systems are discussed in order to develop novel therapeutic strategy for depressive disorders by use of phytochemicals.