Herbal plants for mental disorders in Sri Lanka

Mental disorders, often referred to as psychiatric disorders or mental illnesses, are characterized by disturbances in cognition, emotional regulation, or behavior. Factors such as genetics, environment, and psychological influences play a key role in the onset and development of these disorders, which include anxiety, depression, bipolar disorder, schizophrenia, and neurodevelopmental conditions. According to a 2019 survey by the Institute of Health Metrics and Evaluation, around 970 million people globally, or one in every eight individuals, were living with a mental disorder, with anxiety and depression being the most common types.

While modern medicine has made significant advances, the use of herbal medicines continues to be relevant due to their perceived efficacy, fewer side effects, accessibility, and cultural significance. Particularly in Sri Lanka, the Ayurvedic system of medicine has incorporated herbal plants for centuries to treat mental disorders. Herbal remedies are often sought either as alternatives or adjunct therapies to conventional treatments due to their synergistic effects. This review focuses on identifying and analyzing the therapeutic potential of 24 traditional medicinal plants used in Sri Lanka, emphasizing their phytochemicals, mechanisms of action, and benefits in treating mental disorders​.

The Role of Ayurveda in Mental Health Management

Sri Lanka, a biodiversity hotspot, is home to over 1,200 medicinal plant species, 174 of which are unique to the island. Ayurvedic practices in Sri Lanka have traditionally relied on these plants for both physical and mental health treatments. The growing concern about mental health in Sri Lanka is mirrored in the increasing number of patients seeking treatment for conditions such as anxiety disorders (4.53%), depression (30.44%), bipolar disorder (5.2%), schizophrenia (7.72%), and disruptive behavior disorders (1.73%).

Key Ayurvedic herbs like Bacopa monnieri, Centella asiatica, Withania somnifera, and Valeriana wallichii have long been used to treat mental disorders, particularly anxiety and depression. Other plants, including Ginkgo biloba, Hypericum perforatum, and Rhodiola rosea, are utilized to address bipolar disorder, disruptive behavior, and schizophrenia. Despite their extensive traditional use, many herbal plants’ therapeutic mechanisms, particularly for more complex mental disorders, remain insufficiently explored​.

Methodology and Data Collection

The data for this review were gathered from traditional Ayurvedic texts such as "Medicinal Plants Used in Ceylon," "Atlas of Ayurvedic Medicinal Plants," and "Sinhala Waidya Widya," housed at the Faculty of Indigenous Medicine at the University of Colombo and the Pallekale Provincial Ayurvedic Hospital in Kandy, Sri Lanka. These texts served as foundational resources for systematically identifying 24 medicinal plants with a history of treating mental disorders. The review examined the scientific names, plant parts used, their distribution within Sri Lanka, pharmacological properties, and the phytochemicals identified in these plants. Additionally, a literature review from databases such as PubMed, Google Scholar, and Web of Science from 2001 to 2023 was conducted to enhance the understanding of these plants and their therapeutic potential​.

Phytochemicals and Their Mechanisms of Action

Phytochemicals found in traditional medicinal plants have been shown to possess antioxidant, anti-inflammatory, and neuroprotective properties, making them valuable in treating mental disorders. For example, trigonelline from Abrus precatorius seeds has demonstrated antioxidant activities that may help reduce oxidative stress and enhance cognitive function, potentially protecting against neurodegenerative disorders like Alzheimer’s disease. Meanwhile, bacosides from Bacopa monnieri regulate neurotransmitter levels and provide both antioxidant and anti-inflammatory effects, which help alleviate anxiety and depression.

Other notable compounds include asiaticoside and asiatic acid from Centella asiatica, which have exhibited antidepressant, anxiolytic, and neuroprotective activities by regulating neurotransmitter function and reducing brain inflammation. Luteolin-7-O-glucoside from Eclipta alba and quercetin from Ginkgo biloba have similar effects, influencing neurotransmitters such as serotonin and dopamine, which are central to mood regulation​.

Shogaol, a compound found in the rhizome of Zingiber officinale (ginger), has stress-reduction properties, protecting brain cells from oxidative damage and promoting relaxation. These bioactive phytochemicals have demonstrated promise in treating conditions ranging from depression and anxiety to more complex neurodegenerative diseases.

Ayurvedic Polyherbal Formulations: Their Benefits and Challenges

In Ayurvedic practice, polyherbal formulations that combine different plant parts—leaves, roots, stems, flowers, and seeds—are commonly used due to the biochemical diversity inherent in each part. This allows for a wider therapeutic range and a lower incidence of toxicity compared to conventional pharmaceuticals. For instance, plants such as Abrus precatorius, Asparagus falcatus, Eclipta prostrata, and Foeniculum vulgare are used together in Ayurvedic blends to treat mental health conditions, particularly in polyherbal preparations targeting disorders like ‘Olmada sanni’​.

However, despite their widespread use, there are challenges associated with these formulations. Issues such as contamination during storage, the difficulty of removing harmful metals, and insufficient scientific validation of these plants' efficacy and safety profiles need to be addressed. Moreover, certain plants may induce toxicity in various organs, making rigorous scientific investigation and standardization crucial to their continued use​.

Conclusions

The review of herbal plants used in Sri Lanka’s Ayurvedic system for treating mental disorders highlights the significant therapeutic potential of these remedies, particularly due to the antioxidant, anti-inflammatory, and neuroprotective properties of their phytochemicals. While compounds such as trigonelline, bacosides, asiaticoside, asiatic acid, and quercetin show promise in treating disorders like anxiety, depression, and neurodegenerative diseases, further research is required to validate their clinical effectiveness​.

Preserving these traditional remedies and integrating them into modern clinical practice requires extensive scientific research to isolate and standardize bioactive compounds. The current review of 24 medicinal plants provides a valuable starting point, but future studies should explore a broader range of species and more in-depth evaluations of their mechanisms of action. Establishing their safety and efficacy will be crucial in addressing the growing global burden of mental health disorders.

Full text:

https://www.xiahepublishing.com/2835-6357/FIM-2024-00024

The study was recently published in the Future Integrative Medicine.

Future Integrative Medicine (FIM) publishes both basic and clinical research, including but not limited to randomized controlled trials, intervention studies, cohort studies, observational studies, qualitative and mixed method studies, animal studies, and systematic reviews.

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