The optimization of tissue culture and phytochemical study of insulin plant (Costus pictus D. Don)

Costus pictus D. Don, commonly known as insulin plant, is used for the treatment of diabetes in southern India. In recent years this plant is cultivated in some greenhouses in Iran and is propagated by cutting. Therefore, the present study was carried out to optimization of tissue culture and evaluation of phytochemical compounds in this plant. Among different explants including leaf, node and internode and different hormone treatments, the best results were observed for node explants and treatments with BA (3.5 mg/l) and NAA (0.5 mg/l). To access phytochemical properties of in vivo and in vitro leaves, the contents of photosynthetic pigments, soluble sugar, phenol, flavonoid and protein were measured. The results showed that all of these parameters with the exception of phenol and protein in in vivo leaves were significantly higher than in vitro leaves. Also, phytochemical analyses of in vivo leaves and rhizomes revealed that leaves were rich in flavonoid, soluble sugar, caffeic acid and quercetin whereas rhizomes were rich in phenol and protein. Mineral elements analyses indicated that the concentrations of Ca, K, Mn and Sr of leaves were higher while higher concentrations of Al, Fe, Na, Cr and Zn were observed in rhizomes. In conclusion, presented micropropagation protocol in this study, in addition to accelerate large scale multiplication and conservation of C. pictus, would be important economically. Also, leaves of this plant, are rich in quercetine (an antidiabetic compound), could be considered as a potential candidate for phytochemical and medical studies.