1 Changes in non Enzymatic Antioxidants and Ajmalicine Production in Catharanthus roseus with Different Soil Salinity Regimes

Abstract: Here the experiment was carried out with different concentrations of sodium chloride (NaCl) in alba and rosea varieties of Catharanthus roseus (L.) G. Don. to determine the changes that occurring in antioxidant potentials and to evaluate the possibility of increasing the anti-hypertension alkaloid, ajmalicine, present in the roots. The two varieties were evaluated by using four different concentrations of NaCl (25, 50, 100 and 200 mM) treatment in pot culture, which were repeated in four different stages of growth like 30, 45, 60 and 75 days after sowing (DAS). The plants were uprooted randomly on 90 DAS and the non-enzymatic [ascorbic acid (AA), reduced glutathione (GSH),-tocopherol (-toc)] and ajmalicine content were analysed. High salinity caused an enhancement in total AA contents. GSH content decreased insignificantly only at NaCl concentration of 25 mM and increased at higher concentration treatments. The-toc content had no significant change under 25 mM NaCl but increased under high salinity regimes. NaCl treatment significantly increased the content of root alkaloid ajmalicine in both the varieties. The increase in ajmalicine content was resulted from the increased secondary metabolite production in the plant under salinity stress. Therefore it can be concluded that, C. roseus is an ideal plant for cultivation in salt affected areas in order to obtain maximum amount of secondary metabolites. Key words: Abiotic stress Antioxidants Ajmalicine Catharanthus roseus Medicinal plan