Withania somnifera L. is widely used as a medicinal plant for its therapeutic properties. In this study, the impact of Chitosan as a biotic stimulus and exposure to light and UV rays as physical stimuli on cultured callus were investigated.
Compared to the control, the results showed that Chitosan significantly reduced callus fresh and dry weight (more than 70% decrease), while exposing the callus to UV rays for 60 minutes led to a significant increase in weights (18% increase). Six withanolide compounds were quantified in all treatments of callus cultures, using HPLC analysis. The production of these compounds was significantly enhanced through elicitation strategies. Substantially, Chitosan at 100 mg/l stimulated the biosynthesis of 27-OH-withanolide-A (52.0 µg/ml, 160% increase) compared to control, while 150 mg/l of Chitosan displayed optimal production of withanolide-B (96.3 µg/ml, 255% increase), and 27-OH-w
ithanolide-B (124.6 µg/ml, 40% increase). Continued light conditions (24 hours/day) increased the production of Withaferin-A and Withanone compounds (179.5 µg/ml, 82% increase, and 145.3µg/ml, 215% increase) respectively. While exposing the callus culture to UV rays for 60 minutes promoted the formation of withanolide-A (241.1 µg/ml, 99% increase), exposure for 90 minutes resulted in a high content of 27-OH-withanolide-B (124.8 µg/ml, 40% increase). In conclusion, the elicitors used in this study demonstrated their efficiency in stimulating the biosynthesis of withanolide compounds in the callus cultures of W. somnifera. These findings provide valuable insights for optimizing the production of therapeutic compounds in the Withania plant, which is widely used for its medicinal properties.