Iridoid glycosides from Picrorhiza genus endemic to the Himalayan region: phytochemistry, biosynthesis, pharmacological potential and biotechnological intercessions to boost production

Abstract

Iridoid glycosides are monoterpenoids synthesized in several plant species known to exhibit a diverse range of pharmacological activities. They are used as important bioactive ingredients in many commercially available drug formulations and as lead compounds in pharmaceutical research. The genus Picrorhiza comprises two medicinally important herbs endemic to the Himalayan region viz. Picrorhiza kurrooa Royle and Picrorhiza scrophulariiflora Hong. The medicinal properties of these two species are mainly due to iridoid glycosides present in their root, rhizome, and leaves. Unregulated harvesting from the wild, habitat specificity, narrow distribution range, small population size and lack of organized cultivation led to the enrolling of these species in the endangered category by the International Union for Conservation of Nature and Natural Resources (IUCN). Therefore, there is a need for immediate biotechnological and molecular interventions. Such intercessions will open up new vistas for large-scale propagation, development of genomic/transcriptomic resources for understanding the biosynthetic pathway, the possibility of genetic/metabolic manipulations, and possible commercialization of iridoid glycosides. The current review article elucidates the phytochemistry and pharmacological importance of iridoid glycosides from the genus Picrorhiza. In addition, the role of biotechnological approaches and opportunities offered by next-generation sequencing technologies in overcoming challenges associated with the genetic engineering of these species are also discussed.

Keywords:

• Iridoid
• medicinal plant
• endangered
• picroside
• Himalaya
• biosynthesis
• Picrorhiza

Acknowledgements

We are thankful to CSIR for supporting this study.

Author’s contribution

TS wrote the first draft of the manuscript. Anmol incorporated phytochemistry. US incorporated phytochemistry and finalized the manuscript. SK conceptualized, planned the whole study, and finalized the manuscript.

Disclosure statement

The authors report no declarations of interest.

Additional information

Funding

We are thankful to CSIR for supporting this study. TS is grateful to Department of Health Research (DHR), Young Scientist Scheme under the Human Resource Development (File no. R.12014/11/2022-HR; CSIR-IHBT/ GAP-0314), India for financial support. Anmol thanks DST-INSPIRE for senior research fellowship.