In vitro culture and production of syringin and rutin in Saussurea involucrata (Kar. et Kir.) - an endangered medicinal plant

Background: Saussurea involucrata (Kar. et Kir.) commonly known as 'snow lotus' or 'Xue Lian' is an important plant in the traditional Chinese system of medicine. The plant contains flavonoids such as syringin and rutin. These compounds have been reported to be anti-rheumatic, anti-inflammatory and dilate blood vessels, lower blood pressure, prevent cardiovascular diseases, enhance immunity, and act as anti-aging, anti-cancer, and anti-fatigue agents. The species has become endangered due to the excessive collection of S. involucrata plants in the wild, slower plant growth and ecological destruction of natural habitats. There is a severe shortage of plant material, while the market demand is ever increasing. Hence, it is very important to apply tissue culture technique for plant propagation and production of the bioactive compounds of this species. Results: Multiple shoot induction and proliferation in shoot base explants derived from in vitro raised seedlings of S. involucrata was achieved on 3/4 strength of Murashige and Skoog's (MS) basal medium (MSBM) supplemented with 1.0 mg/L-1 BA and 1.5 mg/L-1 NAA. Rooting was induced in 100 % shoots cultured on 1/2X MSBM supplemented with 1.0 mg/L-1 IBA for one week and then transfer to auxin free medium. The plantlets could be acclimatized successfully by sachet technique and established in the greenhouse. Maximum callus induction and proliferation in leaf segments was achieved on 1/2X MSBM supplemented with 0.5 mg/L-1 BA, 0.5 mg/L-1 NAA, 0.4 % gelrite and on incubation at 20 degrees C. Container closures had an influence on the quality and quantity of callus and production of the active compounds. The HPLC analysis showed much higher syringin content in in vitro shoots and callus as compared to commercially available market crude drug. Conclusion: The present study describes an in vitro culture protocol of Saussurea involucrata. The bioactive compounds, syringin and rutin could be produced through tissue culture technique without sacrificing the endangered Saussurea involucrata plants in the wild.