Comparative Pharmacognostic Study of Different Parts of Withania somnifera and its Substitute Ruellia tuberosa

Abstract

Withania somnifera (L.) Dunal. (Solanaceae) is a therapeutically important medicinal plant widely used in Ayurveda and traditional systems of medicine in all over the world. Since this valuable plant is not commercially cultivated in Sri Lanka, traditional practitioners use Ruellia tuberosa L. (Acanthaceae) as a substitute for Withania somnifera. However, use of R. tuberosa as a substitute without scientifically proven data on important quality standards might adversely affect on the therapeutic properties of herbal drugs. Present study investigates the important pharmacognostic aspects of W. somnifera and R. tuberosa. Comparative quality parameters on morphological, anatomical, powder microscopical, phytochemical, physicochemical and brine shrimp toxicity of different parts of (leaf, bark and roots) W. somnifera and R. tuberosa by using established protocols. Results demonstrated that all major phytochemical groups tested were present in leaves, bark and roots of both plants. Physicochemical analysis exhibited the higher total ash, water soluble ash and acid insoluble ash in all parts of R. tuberosa. However, TLC profiles exhibited the higher number of spots in all 3 parts for W. somnifera over R. tuberosa. Potent of brine shrimp toxicity was increased as leaf>bark>roots for R. tuberosa and bark>root>leaf for Withania somnifera. Therefore, W. somnifer acould be differentiated from R. tuberosaby comparing polymorphic macroscopic, microscopic, phytochemical, physicochemical characters either singularly or as a whole. The presence of certain similarities in major phytochemical groups, and in brine shrimp toxicity of W. somnifera and R. tuberosa partially justifies the use of R. tuberosa as a substitute for W. somnifera in traditional systems of medicine in Sri Lanka which needs to be confirmed after further clinical trials.