Introduction: Plant cells produce two sets of compounds: primary metabolites and secondary metabolites. Alkaloids are the most important products of secondary metabolism in plants. Some alkaloids are used as medicine. For example, the structure of vinbelastine and vincristine is used for similar synthesis of two important drugs for vinflunine and vinorelbine cancers. Catharanthus roseus has three varieties: Alba, Roseus, Acillata. This plant, as a rich source of alkaloid chemical compounds (Indole Alkaloids) contains more than 130 known secondary metabolites which are present in parts of the plant. These metabolites are secologanine, triptamine, strictozidin, serpentine, catarantine, ajmalicine, vindoline, vincristine, vinbelastine, and …. Some of these compounds have pharmacological effects. Vinbelistine is the most important alkaloids in the leaves of Catharantus Roseus plant. It is used to heal the diseases like: testicle and breast cancers, lymphoma, neuroblastoma, hodgkin and nonhodgkin’s lymphoma, Mycosis fungoides, histiocytosis and kaposi’s sarcoma. It also controls mitotic activity by stopping the cells in metaphase through nonreturnable connection to tuboline.The mechanism of the effect of vincristine is like vinbelastine.
Heavy metals are the metals which have the density more than 5 grams/1cm3 in the Alternative Table. The stress of heavy metals leads to change in the synthesis of secondary metabolites of plants, and increase or decrease of these compounds. Succena et al. (2003), investigating the effect of different treatments of Nickel on Hypericumperforatum secondary metabolites, found that in densities of 0, 25, and 250 milli-molars, the amount of Hipricine in experimental group increases 15 to 20 times more than control group. Studies have shown that the change in planting conditions can increase the amount of Catharanthus Roseus alkaloids, especially Vinbelastine and Vincristine. In order to investigate the effect of Nickel on Catharanthus Roseus plant, in densities of 0, 2.5, 5, 10, 25, and 50 mili-molar of Nickel chloride, an experiment was conducted with factorial design, repeated three times in Faculty of Sciences, University of Arak. The purpose of the research was to investigate the production amount of alkaloids.
Methods: The Catharanthus Roseus healthy seeds of pink variety were sterilized and Planted in vases. They were watered with Hoagland solution of 1/2. The 45-day-year-old plants were exposed to Nickel chloride with densities of 0, 2.5, 5, 10, 25, 50 milli-molars for 96 hours. For obtaining of Alkaloid, the Plant Essence was prepared and then The Total Amount of Alkaloid in Herbal Essence was read. In using the TLC plates, The amount of RF of each spot was compared with RF of vinbelastine and vincricistine standards. After observing the TLC plates by UV, they were sprayed by Dragendorf reagent.
The statistical design of the experiment was totally random. In order to analyze the measured factor, SPSS Software was applied.
Results: When the density of Nickel increases, the total amount of alkaloid significantly increases (p<0.05) in Catharantus Roseus leaves. Investigating qualitative changes of alkaloids following TLC method, it was observed that there was serpentine alkaloid in all densities, and ajmalicine alkaloid in all densities except in control group and the treatment of 2.5 milli-molars. By increasing the density of the treatment, the color of RF=0.19 becomes dark. it is because of the existence of vincristine alkaloid. The band related to RF=0.31 is observed when the density is 10 or more milli-molars which refers to vinbelastine. Nickel treatment has a significant effect (p<0.05) on the amount of total alkaloid of the plant root. Investigating the TLC plates, it was observed that there were serpentine, vindoline, vincristine alkaloids in all densities. the band of RF=0.19 is observed in the density of 10 milli-molars, and becomes darker gradually. By increasing the density of the treatment, the color of RF=0.4 gradually becomes dark. it is because of the existence of vinbelastine alkaloid.
Conclusion: The results of studies showed that the production amount of ajmalicine alkaloid, and tryptophan and tryptamine aminoacids increases remarkably, which leads to the noticeable increase of vincristine and vinbelastine alkaloids.
The obtained data showed that under the Nickel treatment, the degree of qualitative and quantitative changes of alkaloids is remarkable. The degree of total alkaloid in the leaf and root of the plant increased significantly by the increase in the density of Nickel treatment.
Keywords: Catharantus Roseus, Nickel heavy metal, indole alkaloids, TLC plates