Biosynthesis and accumulation of a medicinal compound, Picroside-I, in cultures of Picrorhiza kurroa Royle ex Benth (original) (raw)

2009, Plant Cell, Tissue and Organ Culture (PCTOC)

Establishment of callus cultures and plant regeneration from different explants coupled with estimation of Picrosides in morphogenetically different developmental stages showed that Picroside-I accumulates in shoot cultures of Picrorhiza kurroa with no detection of Picroside-II. The Picroside-I content was 1.9, 1.5, and 0.04 mg/g in leaf discs, stem and root segments, respectively. The Picroside-I content declined to almost non-detectable levels in callus cultures derived from leaf discs, stem segments with no change in Picroside-I content in root segments or calli derived thereof. The biosynthesis and accumulation of Picroside-I started in callus cultures differentiating into shoot primordia and reached to the concentrations comparable to original explants of leaf discs and stem segments in fully developed shoots with contents of 2.0 and 1.5 mg/g, respectively. The shoots formed from root-derived callus cultures were relatively slow in growth as well as the amount of Picroside-I content was comparatively low (1.0 mg/g) compared to shoots derived from callus cultures of leaf and stem segments, respectively. The current study concludes that the biosynthesis and accumulation of Picroside-I is developmentally regulated in different morphogenetic stages of P. kurroa tissue cultures. Keywords Shoots Á Callus Á Regeneration Á Morphogenesis Á Picroside Á Indirect organogenesis Abbreviations IBA Indole-3-butyric acid 2,4-D 2,4 Dichlorophenoxyacetic acid KN Kinetin BA 6-Benzyladenine Picrorhiza kurroa Royle ex Benth (Family: Scrophulariaceae) is a medicinal herb, mainly found in the NorthWestern Himalayan regions of India at altitudes of 3,000-4,300 m. P. kurroa is a well-known herb in the Ayurvedic system of medicine and has traditionally been used to treat disorders of the liver and upper respiratory tract, reduce fevers, and to treat dyspepsia, chronic diarrhea, and scorpion sting. The active constituents are obtained from the shoots, roots and rhizomes of plant. P. kurroa is a high value medicinal herb due to rich source of hepatoprotective metabolites, Picroside-I and Picroside-II and other metabolites like Picroside-III, Picroside-IV, Apocynin, Androsin, Catechol, Kutkoside, etc. (Weinges et al. 1972; Stuppner and Wagner 1989). The medicinal importance of P. kurroa is due to its pharmacological properties like hepatoprotective (Chander et al. 1992), antioxidant (particularly in liver) (Ansari et al. 1988), antiallergic and antiasthamatic (Dorch et al. 1991), anticancerous activity particularly in liver (Joy et al. 2000) and immunomodulatory (Gupta et al. 2006). A hepatoprotective drug formulation, Picroliv has been prepared from the extracts of P. kurroa (Ansari et al. 1991; Dwivedi et al. 1997). Picroside-I is the major ingredient of Picroliv and, therefore, makes this compound a highly valued secondary metabolite of P. kurroa. The P. kurroa plants have been recklessly collected from its natural habitat, thereby, reducing its populations and putting it under the