Natural Polyphenols And Terpenoids For Depression Treatment: Current Status

Major depression is a worldwide psychiatric disorder associated with high levels of disability and various comorbidities. Despite the wide range of antidepressants available, they all share similar mechanisms of action and are only marginally effective in patients. In addition, these compounds need several weeks of treatment to cause the remission of depressive symptoms and are associated with multiple side effects. These factors contribute to the lack of adhesion to treatment by a significant percentage of depressive patients. In contrast, plant-derived agents are comparatively more tolerable and possess fewer side effects. Hence, the interest in phytochemicals with antidepressant potential is increasing in an effort to establish novel strategies for the management of this psychiatric disorder. This chapter reviews evidence on the antidepressant effects elicited by natural compounds belonging to polyphenol and terpenoid classes and their mechanisms of action. Polyphenols (flavonoids, nonflavonoids such as resveratrol, curcumin, coumarin, and phenolic acids) have antioxidant and neuroprotective properties, which make them suitable as complementary medicinal compounds for the treatment of psychiatric disorders. Terpenoids (such as carvatrol, genipin, hyperforin, and ursolic acid) constitute another large category of phytochemicals that have been shown to produce antidepressant effects in preclinical studies. This chapter also presents the current status of clinical studies testing the effects of supplementation with polyphenols and/or terpenoids in the treatment of depressive disorders.