Document Type : Review Article
Department of Chemistry, Federal University, Gashua, Yobe State, Nigeria
Depression has become burden to the society with millions of people suffering from annually. Symptoms of depression are including difficulties in concentration, sad mood, loss of interest, guilt, feeling of hopelessness, sleeping difficulty, restlessness, appetite loss, decreased energy, suicidal attempts among others. Therefore, the present work aimed to review the antidepressant activity of extracts from seventy six medicinal plants belonging to forty four plant families. Methodology such as open field test, force swim test, tail suspension test and beam walking assay were used for the determination of antidepressant activity in plants extracts. Different extraction techniques and solvents were utilized to extract phytochemicals from the plants materials. All information regarding the antidepressant medicinal plants in this research study were obtained from various research articles published in fifty nine Journals. The results indicated that the medicinal plants in this review possess significant antidepressant activity. These medicinal plants extracts may serve as a potential resource for natural psychotherapeutic agent against depression.
Over 121 million people in 2008 and 350 million people in 2012 from the world population suffered from mental disorder known as depression [1-2]. Depression has been described as the second leading psychiatric disorder with almost 21 % of the world population suffering from it . This disorder has become burden to the society and can affect any category of age group ranging from childhood to old age . In another report, the worldwide age group suffering from depression has noticeably decreased to age range of 25–35 years from 40–50 years . Resulting disorder from depression includes metabolic disorder, endocrine disorder, cardiovascular disease, inflammatory disorder, neurodegenerative disorder .
Selective serotonin reuptake inhibitors, tricyclic antidepressants, oxidase inhibitors, monoamine and specific serotonin-noradrenaline reuptake inhibitors are mostly the reported medications available for the treatment of depression, but do comes with side profile effect like loss of sex drive, sleep, losing body weight and cardiovascular problem [7-8].
Hence, the present work was aimed at reviewing the antidepressant activity of extracts of seventy six medicinal plants (Table 1) from forty four plants families (Figure 1).
Figure 1. Distribution of families of medicinal plants with antidepressants activity results
Plant materials have an important therapeutic role in the prevention and treatment of diseases of over 80% of the world’s population and have been portrayed to be better compliance of patients, less adverse reactions and good efficiency . Different plant extracts and some novel compounds isolated from medicinal plants have been reported to be effective against depressants [10-11].
In the present study, seventy six medicinal plants belonging to forty four plants’ families were reviewed for antidepressant activities (Table 1). The plants showed significant antidepressant-like effect in some of the test model (open field test, force swim test, tail suspension test and beam walking assay). These test models of depression are widely used for screening antidepressant drugs .
Table 1. Details of selected medicinal plants with antidepressants activity
Natural products having antidepressant activities are of major concern for many reasons. The current review has revealed the therapeutic importance of medicinal plants in the treatment of major depression (Table 1). The use of medicinal plants for curing depression have successfully lead to improvement of quality of life by normalizing mood, increasing awareness of personal pleasures and interests, reversing the functional and social disabilities associated with depression, as well as to reduce suicide rates .
Some flavonoids have been shown to be effective in the modulation of serotonergic activity by attenuating mitochondrial MAO-A activity in the brain and attenuate oxidative stress by interrupting the generation of hydrogen peroxide accompanying the MAO-A reaction .
Various plant alkaloids have been reported to have antidepressant effect.  reviewed the mechanisms of some alkaloids having antidepressant-like activities which include either decreasing plasma corticosterone level, increasing monoaminergic turnover, interfering with MAO-A and several cell-surface receptors, reducing the release of corticosterone, inhibiting 11-b-hydroxysteroid dehydrogenase, modulating monoamine transmitters, improving serotonergic system and inhibition of 5HT reuptake.
Terpenoids represent another group of phytochemicals that have been studied to produce antidepressant effects by induction of P-glycoprotein, influences hepatic cytochrome, improving the multidrug-resistant profile of cells, reduction of plasma concentration of immunosuppressant and interaction with indinavir .
Low levels of monoamines such as noradrenaline, dopamine and serotonin in the brain have been hypothesized to cause depression. Hence, saponins are reported to increase the levels of monoamine neurotransmitters in the brain. In addition, over-activity of hypothalamus pituitary adrenal (HPA) axis is ascribed to causes depression. However, some saponins are reported to normalization the level of the HPA .
The antidepressant activities of medicinal plants extracts reported in this study may be due to the presence of phytochemicals like saponins, flavonoids, phenols, alkaloids and tannins found to be present the in plants extracts.
This review has provided information on the basis of available literature and suggested that medicinal plants could play a potential role as natural antidepressants. Seventy six medicinal plants belonging to forty four plant families were extensively review for their potency as antidepressants agents. In conclusion, plant-based products and its metabolites can serve as leads for discovery of antidepressant drugs.