Medicinal Plants as Potential Antidepressants: A Comprehensive Review of Experimental Evidence

Depression is a common and serious mental disorder marked by persistent low mood, lack of interest or pleasure, reduced energy, and impaired concentration. The pathophysiology of depression is mainly associated with increased activity of monoamine oxidase-A (MAO-A) and reduced levels of neurotransmitters such as noradrenaline (NA) and serotonin (5-HT). Clinical manifestations include loss of pleasure, feelings of worthlessness or excessive guilt, disturbed sleep, reduced appetite and libido, fatigue, and recurrent thoughts of death or suicide. Although several synthetic antidepressant drugs are available for the management of depression, their therapeutic effectiveness is often limited by adverse effects and poor patient compliance. Consequently, there has been a growing interest in traditional systems of medicine such as Ayurveda, Siddha, and Unani, which emphasize the use of natural remedies. Medicinal plants have gained significant attention due to their potential antidepressant activity and better safety profile. Numerous experimental and clinical studies have been reported on plant-based antidepressants; however, the available data remain insufficient to establish definitive therapeutic outcomes. Therefore, the present review aims to compile and critically analyze existing research on medicinal plants with antidepressant potential, highlighting the need for further scientific validation.