BSA Binding Properties Of Schiff Bases And Their Transition Metal Complexes Constructed Through Derivatives Of Salicylaldehydes Thiosemicarbazone

Schiff base constructed through derivatives of salicylaldehydes and their metalcomplexes have become one of the hotspots in recent years, because of their biologicalactivities, such as antimicrobial, anticancer and antitumor. Schiff base constructed throughderivatives of salicylaldehydes thiosemicarbazone and their metal complexes weresynthesized，and the interaction with bovine serum albumin were studied simply.（1） In this paper, firstly, three derivatives of salicylaldehyde were synthesized withsalicylaldehyde as the raw material, including3-nitrosalicylaldehyde,5-nitrosalicylaldehydeand3,5-diiodosalicylaldehyde. Secondly, five derivatives of thiosemicarbazide weresynthesized with ammonia and carbon bisulfide as the starting materials, includingN（4）-hydroxyethylthiosemicarbazide, N（4）-phenylthiosemicarbazide, N（4）-o-tolylthiosemicar-bazide, N（4）-m-tolylthiosemicarbazide and dithiocarbohydrazon. All of them werecharacterized by melting point, IR spectra and UV spectra after purified.（2） Twelve new salicylaldehydes thiosemicarbazone schiff bases were synthesized,including3-nitrosalicylaldehyde-N（4）-phenylthiosemicarbazone（HL₁）,3-nitrosalicylaldehyd-e-N（4）-m-tolylthiosemicarbazone（HL₂）,3-nitrosalicylaldehyde-N（4）-o-tolylthiosemicarbazon-e（HL₃）,3-nitrosalicylaldehyde-N（4）-hydroxyethylthiosemicarbazone（HL₄）,5-nitrosalicylald-ehyde-N（4）-m-tolylthiosemicarbazone（HL₅）,5-nitrosalicylaldehyde-N（4）-o-tolylthiosemicar-bazone（HL₆）,5-nitrosalicylaldehyde-N（4）-hydroxyethylthiosemicarbazone（HL₇）,3,5-diiodos-aliylaldehyde-N（4）-phenylthiosemicarbazone（HL₈）,3,5-diiodosalicylaldehyde-N（4）-m-tolylt-hiosemicarbazone（HL₉）,3,5-diiodosalicylaldehyde-N（4）-hydroxyethylthiosemicarbazone(HL₁₀),3-nitrosalicylaldehyde-dithiocarbohydrazon(HL₁₁),3,5-diiodosalicylaldehyde-dithio-carbohydrazon(HL₁₂). All the schiff bases were characterized and confirmed by melting point,IR spectra, UV spectra and HNMR analysis after purified. And the structures of HL4and HL7were determined by X-ray diffraction analysis. And twenty four complexes of transition metalwith the purified ligands have been synthesized. They were characterized by IR spectra, UVspectra, TG-DTA and elementary analysis. The possible structures of the complexes wereestimated on the basis of these characterizations.（3）At the same time, the binding reaction between some complexes and bovine serumalbumin （BSA） was studied by fluorescence spectroscopy combined with UV-Vis absorption measurements under imitated physiological conditions. The results indicated that itscombination reaction is mainly a static quenching process. The binding constants, bindingsites and the corresponding thermodynamic parameters （ΔG, ΔH and ΔS） of the interactionsystem were calculated at different temperatures, and the average number of binding sites wasabout1. According to F ster non-radiation energy transfer theory, the binding distance rbetween the donor BSA and acceptor for the complexes at298K is less than7nm, whichaffirms that the complexes have partly inserted into the hydrophobic pocket of BSA.