title: Study on the phosphorescence characterizations of palmatine chloride on the solid substrate and its interaction with ctDNA.
abstract: The spectroscopic characterizations of solid substrate room temperature phosphorescence (SS-RTP) of palmatine (Pal) have been studied. Strong RTP signal at 615nm can be induced on filter paper in the presence of TIAc. The interaction between calf thymus DNA (ctDNA) and Pal has been investigated at pH 6.90 using fluorescence, UV-vis, SS-RTP and cyclic voltammogram spectroscopy. Strong binding affinity of Pal with DNA is revealed from the absorption and fluorescence studies in the liquid state. With the addition of ctDNA, the fluorescence intensity of Pal is enhanced greatly and UV-vis spectra show no apparent hypochromicity and red shift, which indicates that Pal intercalates into ctDNA bases. However, this conclusion could not explain the phenomena from fluorescence polarization and denatured DNA measurements, which indicate that groove binding is at least the main binding mode. Binding constant and binding site size have been calculated to be 2.57x10(4)L/mol and 0.16 based on Scatchard plot from fluorescence titration data. Groove binding has also been supported by phosphorescence lifetime and anion quenching experiments. Above studies demonstrate that there should exist intercalative binding and groove binding in the interaction of Pal and DNA. Furthermore, cyclic voltammogram study suggests that electrostatic binding exists at the same time exactly. Taken together, the binding model obtained in this study is mixed-mode.
authors.affiliation: Department of Chemistry, Center of Environmental Science and Engineering Research, Shanxi University, Taiyuan, China.
authors.forename: Junfen
authors.initials: J
authors.lastname: Li
authors.forename: Shaomin
authors.initials: S
authors.lastname: Shuang
authors.forename: Chuan
authors.initials: C
authors.lastname: Dong
mesh_terms: D000818:Animals; D001600:Berberine Alkaloids / Q000032:analysis* / Q000737:chemistry*; D002417:Cattle; D004247:DNA / Q000032:analysis* / Q000737:chemistry*; D005374:Filtration; D006863:Hydrogen-Ion Concentration; D007287:Inorganic Chemicals / Q000737:chemistry; D008163:Luminescent Measurements; D015394:Molecular Structure; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013053:Spectrophotometry; D013379:Substrate Specificity
chemical_list: D001600:Berberine Alkaloids; D007287:Inorganic Chemicals; D004247:DNA; C427203:calf thymus DNA; C005413:palmatine