A Systematic Review of Withania somnifera (Ashwagandha): Delineating Classical Dravyaguna Attributes from Modern Evidence for Stress and Immunomodulation

Background: Withania somnifera (L.) Dunal (Ashwagandha) is a preeminent Rasayana (rejuvenative) herb in Ayurveda. Its therapeutic profile is codified in Dravyaguna Vijnana through specific attributes (Rasa, Guna, Virya, Vipaka). Separately, a body of modern research investigates its pharmacological effects. Objective: This systematic review aims to critically delineate the classical Dravyaguna profile of Ashwagandha from contemporary scientific evidence pertaining to its anti-stress and immunomodulatory properties, without conflating the two epistemological frameworks. Methods: A systematic search was conducted following a predefined protocol. Classical data were sourced from authoritative Ayurvedic texts. Modern scientific literature was retrieved from PubMed, Scopus, and Web of Science until May 2024. Clinical trials and preclinical studies elucidating mechanisms of action on the HPA axis, neurobiology, and immune function were included. Results: The classical profile describes Ashwagandha as having Tikta-Kashaya-Madhura Rasa, Guru-Snigdha Guna, Ushna Virya, and Madhura Vipaka, indicating its use for conditions of debility (Daurbalya) and compromised immunity (Ojakshaya). Modern evidence, from over 40 included studies, independently demonstrates significant cortisol reduction in stressed adults, GABA-mimetic activity, and promotion of neurite outgrowth. Immunological data reveal enhanced proliferation of immune cells and potent inhibition of the NF-κB pathway by withanolides such as withaferin A. Conclusion: The traditional Dravyaguna framework and modern pharmacological research provide two distinct, yet convergent, validation pathways for Ashwagandha's use in stress and immune disorders. The classical system offers a holistic, predictive profile, while modern science provides reductionist, mechanistic evidence. This parallel analysis underscores the plant's therapeutic value and highlights the utility of traditional knowledge as a guide for scientific inquiry.