Neuropharmacology and the applications of herbal extracts found within Sri Lankan traditional anxiety remedies

Background: Sri Lankan traditional medicine/medical (STM) therapies to treat neuropsychiatric disorders include herb-based formulations. However, the medicinal plants, phytochemicals and their possible mechanisms of action have not been extensively reviewed before. Purpose: This review aims to evaluate the neuropharmacological potential and applications of the medicinal plant extracts used in STM in alleviating anxiety. Study design: This study compiles in vitro, in vivo and in silico studies that have been conducted on neuromodulatory STM plant extracts to evaluate their anxiolytic potential, anxiolytic phytochemicals, target receptors, mechanism of action, and their possible commercial value. Methods: The keyword “unmada roga chikitsa”, was used to screen STM literature for neuromodulatory medicinal plant extracts. Next, the anxiolytic potential of the plant extracts, their putative phytochemicals, target neurotransmitter systems, were evaluated within the available scientific literacture. Finally a patent search was carried out to identify any patented formulations containing the identified plant extracts, to treat neuropsychiatric disorders, especially anxiety. Results: A total of 89 medicinal plants found within STM formulations with possible anxiolytic properties were identified. Published in vivo studies and clinical trials further demonstrated that 45 plants within these formuations exhibit anxiolytic properties. Moreover, these plant extracts contain 22 known anxiolytic phytochemicals. Additionally, 43 plants appeared in patented formulations related to anxiety. Conclusion: STM offers many plant based formulations that could alleviate neuropsychiatric disorders such as anxiety. However, further studies are required to identify novel anxiolytic phytochemicals, their synergistic effects, molecular mechanisms of action at target receptors and pharmacodynamics and pharmacokinetics of these plant based therapies.