Withania somnifera Dunal is one of the most commonly used plants in Ayurvedic and indigenous system of medicine in India for over thousands of years. In view of its varied therapeutic potential, the plant has also been the subject of considerable scientific attention. The major chemical constituents of the Withania genus, the withanolides, are a group of naturally occurring C28-steroidal lactones built on an intact or rearranged ergostane framework, in which C22 and C26 are oxidized to form a six-member lactone ring. In recent years, numerous pharmacological investigations have been carried out utilizing W. somnifera extracts and several patents have been filed on pharmacological and medicinal importance of withanolides and extracts of W. somnifera, individually or in combination. Considering the immense importance of withanolides for medicinal purposes, the establishment of strategies to improve withanolides yield are highly desirable. Under natural conditions, W. somnifera possesses restricted levels of withanolides then, alternatives for obtaining withanolides in better yields are imperative. In vitro approaches followed by metabolic engineering could be attractive tools to achieve this goal. Therefore, we present here an overview of the development of various protocols for in vitro tissue regeneration from W. somnifera and in vitro secondary metabolite production as well. The review also gives an account of selected patents on various important activities of phytochemicals and extracts of W. somnifera.
Keywords: Agrobacterium mediated transformation, Ashwagandha, callus cultures, hairy roots, In vitro tissue culture, multiple shoot cultures, cell suspension cultures, root cultures, rhizogenesis, triterpenoids, Withania somnifera, withanolides.