Withania somnifera plantlets were produced in vitro from the shoot-tip of aseptically germinated seedlings. Culture conditions were optimized using different plant growth regulators which gave rise to 120 shoots from a single bud. The plantlets were then transferred to pots and maintained in greenhouse for 4 months. 90% of these in vitro propagated plantlets survived and showed normal growth. Leaves from these plants were used for isolation of the withanolides. Methanolic extract of leaves from plantlets growing in tissue culture and those transferred to the greenhouse were evaluated for immunomodulatory activity. While the extract from greenhouse samples showed potent immunosuppressive activity, those from tissue cultures samples did not show any activity. Fractionation and characterization of withanolides, using HPLC, NMR, MS methods revealed the presence of withaferin A in the greenhouse samples. Our results indicate that Withania species may require longer time and better differentiation and also natural environment for the production of withaferin A.

In vitro cultivated plant cells and tissues were found to synthesize polyisoprenoids. Taxus baccata suspension cell cultures accumulated polyisoprenoids of the same pattern as the parental tissue; methyl jasmonate or chitosan treatment almost doubled their content. All the root cultures studied accumulated dolichols as predominant polyisoprenoids. Roots of Ocimum sanctum grown in vitro accumulated approx. 2.5-fold higher amount of dolichols than the roots of soil-grown plants. Dolichols dominated over polyprenols in all Triticum sp. tissues studied.