Withania somnifera (L.) Dunal (Ashwagandha): A comprehensive review on ethnopharmacology, pharmacotherapeutics, biomedicinal and toxicological aspects

Withania somnifera (L.) Dunal (Solanaceae) has been used as a traditional Rasayana herb for a long time. Traditional uses of this plant indicate its ameliorative properties against a plethora of human medical conditions, viz. hypertension, stress, diabetes, asthma, cancer etc. This review presents a comprehensive summary of the geographical distribution, traditional use, phytochemistry, and pharmacological activities of W. somnifera and its active constituents. In addition, it presents a detailed account of its presence as an active constituent in many commercial preparations with curative properties and health benefits. Clinical studies and toxicological considerations of its extracts and constituents are also elucidated. Comparative analysis of relevant in-vitro, in-vivo, and clinical investigations indicated potent bioactivity of W. somnifera extracts and phytochemicals as anti-cancer, anti-inflammatory, apoptotic, immunomodulatory, antimicrobial, anti-diabetic, hepatoprotective, hypoglycaemic, hypolipidemic, cardio-protective and spermatogenic agents. W. somnifera was found to be especially active against many neurological and psychological conditions like Parkinson's disease, Alzheimer's disease, Huntington's disease, ischemic stroke, sleep deprivation, amyotrophic lateral sclerosis, attention deficit hyperactivity disorder, bipolar disorder, anxiety, depression, schizophrenia and obsessive-compulsive disorder. The probable mechanism of action that imparts the pharmacological potential has also been explored. However, in-depth studies are needed on the clinical use of W. somnifera against human diseases. Besides, detailed toxicological analysis is also to be performed for its safe and efficacious use in preclinical and clinical studies and as a health-promoting herb.