ABSTRACT
Stevia rebaudiana Bertoni is one of two species that contains steviol glycosides. Among steviol glycosides that extracted from leaves, stevioside and rebaudioside A are the two major and the sweetest glycosides that are about 200-300 times sweeter than sucrose with zero calories. The best method for stevia propagation is tissue culture. So, for investigation of nutrients in medium, we studied the effect of different concentrations of MS media (MS, 0.5 MS, 0.25 MS, 0 MS) on morphological traits, UGT74G1 and UGT76G1 genes expression and accumulation of steviol glycosides in stevia leaves. The best growth rate (0.472 mm/d) has occurred in plants grown in MS media. Also, the highest gene expression of UGT74G1 gene (1.000 Total lab unit) was seen under MS treatment. However, the highest expression level of UGT76G1 gene (1.701 Total lab unit) was observed at plants grown in 0 MS. The highest amount of both Stevioside and Rebaudioside A (14.23 and 8.12, respectively) were accumulated in plants under MS treatment. Obviously, dilution of MS media associated with decreasing in both expression of the intended genes and accumulation of steviol glycosides.
Subject(s)
Culture Media/pharmacology , Diterpenes, Kaurane/metabolism , Gene Expression/drug effects , Glucosides/metabolism , Stevia/drug effects , Gene Expression Regulation, Plant/drug effects , Genes, Plant/genetics , Plant Extracts/chemistry , Plant Leaves/chemistry , Stevia/genetics , Stevia/growth & development , Stevia/metabolism , Tissue Culture TechniquesABSTRACT
Interactions between efavirenz (EFZ) with calf thymus DNA (CT-DNA) were investigated in vitro under stimulated physiological conditions using multispectroscopic techniques, cyclic voltammetry viscosity measurement, and gel electrophoresis. Methylene blue and acridine orange dyes were used as spectral probes by fluorescence spectroscopy. Hypochromicity was observed in ultra-violet (UV) absorption band of EFZ. Considerable fluorescence enhancement of EFZ was observed in the presence of increasing amounts of DNA solution and the binding constants (Kf ) and corresponding numbers of binding sites (n) were calculated at different temperatures. Thermodynamic parameters including enthalpy change (ΔH) and entropy change (ΔS) were calculated to be -304.78 kJ mol(-1) and -924.52 J mol(-1) K(-1) according to the van 't Hoff equation, which indicated that reaction is predominantly enthalpically driven. In addition, UV/vis absorption titration of DNA bases confirmed that EFZ interacted with guanine and cytosine preferentially. Gel electrophoresis of DNA with EFZ demonstrated that EFZ also has the ability to cleave supercoiled plasmid DNA. Circular dichroism study showed stabilization of the right-handed B form of CT-DNA. All results suggest that EFZ interacts with CT-DNA via an intercalative mode of binding.
