Withania somnifera (L.) Dunal or Ashwagandha root has a long traditional history of usage in ayurvedic medicine and remains widely used. Phytochemical characterization studies have highlighted the complexity of this plant with the identification of numerous alkaloids, withanolides and sitoindosides. The phytochemical profile of the withanolides in different chemotypes of Withania somnifera varies considerably [1]. Reports of HPLC analysis of Withania somnifera typically detect and quantify only 2–4 withanolides [2,3]. A routine HPLC-PDA method was developed and validated (using linearity, accuracy, precision, limit of detection, limit of quantification, robustness, stability of standards and test solutions criteria) for the analysis of withanolide content in Withania somnifera raw materials and product samples. This assay uses routine methodologies and permits identification of several key withanolides – Withaferin A, 12-Deoxywithastramonolide, Withanolide A, Withanolide B, Withanoside IV and Withanoside V. The HPLC-PDA method developed enables chemotype differentiation and this together with the ability to quantitatively assess these key withanolides ensures a consistent therapeutic product using Withania somnifera.
References: [1] Bassalie, R. et al. (1987) J. Chrom. 389: 195–210. [2] Ganzara, M. et al. (2003) Fitoterapia 74: 68–76. [3] Khajuria, R. et al. (2004) J. Sep. Sci. 27: 541–546.
