Synthesis, Structure, SOD Activity And Interaction With Biomacromolecules Of Amino Acid Schiff Base Nickel Complexes

Schiff base compounds are a class of organic ligands with C=N structure formed by dehydration and condensation of amino groups with various kinds of aldehyde or ketone.As a kind of significant biological ligands, its transition metal complexes have many kinds of biological activity, such as antitumor, antibacterial, anti-cancer and so on. Nickel is the essential elements of life and it exist in many organism's enzymes, such as urease, nickel iron hydrogenase, superoxide dismutase.DNA is a carrier and passer of genetic information and it is also the main targets of many drugs. Serum albumin as a biological content is one of the most abundant protein in the body can store and transport protein of many endogenous and exogenous compounds.It plays a very important role on life activities. Studying the interaction between drugs or complexes and biological macromolecules such as DNA and BSA at the molecular level, is one of the important research projects in the direction of the biological inorganic. Ten new nickel?II? complexes have been synthesized and characterized by IR spectrum and elemental analyses. Their crystal structures have been determined by single crystal X-ray diffraction analysis. The interaction between the complexes and DNA or BSA were determined by UV absorption, fluorescence, circular dichroism?CD? spectra and viscosity measurement. SOD-like activity of the complex was determined by the modified photoreduction of NBT.1. Two L-Glutamine schiff base nickel?II? complexes, [Ni?o-van-L-Gln??phen??H₂O?]?1? and [Ni?sal-L-Gln??phen??H₂O?]?2??o-van-L-Gln = a Schiff base derived from o-vanillin and glutamine, sal-L-Gln = a Schiff base derived from salicylaldehyde and glutamine, phen = 1,10-phenanthroline?, have been synthesized and characterized by elemental analysis and IR spectra.The single crystal X-ray diffraction showed that?1? and?2? belong to monoclinic and Triclinic crystal system, P2?1?/c and P^-1 space group.The two complexes are all six-coordinated with Ni?II? centers and distorted octahedral configuration. The studies by spectra and viscosity measurement indicated that the twocomplexes binds to CT-DNA in an intercalative mode and the binding constants are Kb?1?=5.44×104 L·mol^-1 and Kb?2?=3.97×104 L·mol^-1and the quenching constants are Ksq?1?=1.28 and Ksq?2?=0.59. The complexes could bind to BSA protein at specific sites at the ratio of 1:1, and they can efficiently quench intrinsic fluorescence of BSA. And the quenching constants are Ksv?1?=6.34×104 L·mol^-1 and Ksv?2?=5.12×104 L·mol^-1. SOD-like activities of the complexes were determined by the modified photoreduction of NBT, the values of IC50?1? is 34.0 ?mol·L^-1and IC50?2? is 43.0 ?mol·L^-1.2. Two L-Histidine schiff base nickel?II? complexes, [Ni?sal-L-His??Phen?]H₂O?3? and[Ni?Sal-L-His??bipy?]₂ × 2CH₃ OH × 3H₂O?4??sal-L-His = a Schiff base derived from salicylaldehyde and histidine, phen = 1,10-phenanthroline, bipy=2,2'-bipyridine?, have been synthesized and characterized by elemental analysis and IR spectra.The single crystal X-ray diffraction showed that?3? and?4? belong to monoclinic and orthorhombic crystal system, P2?1?/c and C222?1? space group.The two complexes are all six-coordinated with Ni?II? centers and distorted octahedral configuration. The studies by spectra and viscosity measurement indicated that the two complexes binds to CT-DNA in an intercalative mode and the binding constants are Kb?3?=2.41×104L·mol^-1and Kb?4?=2.41×104L·mol^-1and the quenching constants are Ksq?3?=0.85 and Ksq?4?=0.72. The complexes could well binding affinity to specific sites of BSA protein in the form of one to one and quench their intrinsic fluorescence efficiently. And the quenching constants are Ksv?3?=6.78×104L·mol^-1and Ksv?4?=3.91×104 L·mol^-1. The Complex?3? had a better effect than complex?4?, the reason may be the planarity of phen is better than bipy. SOD-like activities of the complexes were determined by the modified photoreduction of NBT, the values of IC50?3? is 51.5 ?mol·L^-1and IC50?4? is 58.1 ?mol·L^-1.3. Two L-Tryptophan schiff base nickel?II? complexes, [Ni?naph-L-Trp??Phen??CH₃OH?]₂×2CH₃OH?5? and [Ni?o-van-L-Trp??Phen??CH₃OH?]×CH₃OH?6?(naph-L-Trp = a Schiff base derived from 2-hydroxy^-1-napthaldehyde and tryptophan, o-van-L-Trp = a Schiff base derived from o-vanillin and tryptophan, phen = 1,10-phenanthroline), have been synthesized and characterized by elemental analysis and IR spectra.The single crystal X-ray diffraction showed that?5? and?6? belong to monoclinic crystal system, P2?1? andP2?1?/c space group.The two complexes are all six-coordinated with Ni?II? centers and distorted octahedral configuration. The studies by spectra and viscosity measurement indicated that the two complexes binds to CT-DNA in an intercalative mode and the binding constants are Kb?5?=1.64×104L × mol^-1 and Kb?6?=9.47×103L × mol^-1and the quenching constants are Ksq?5? = 1.02 and Ksq?6? = 1.01. The complexes could well binding affinity to BSA protein and quench their intrinsic fluorescence efficiently. And the quenching constants are Ksv?5?=3.71?105 L×mol^-1 and Ksv?6?=1.57?105L×mol^-1?4. One L-Methionine schiff base nickel?II? complex, [Ni?o-van-L-Met??phen??CH₃OH?]?7??o-van-L-Met = a Schiff base derived from o-vanillin and methionine, phen =1,10-phenanthroline?, has been synthesized and characterized by elemental analysi and IR spectra.The single crystal X-ray diffraction showed that?7? belong to Triclinic crystal system, P^-1 space group.The complex is six-coordinated with Ni?II? centers and distorted octahedral configuration. The studies by spectra and viscosity measurement indicated that the complex binds to CT-DNA in an intercalative mode and the binding constant is Kb?7?=4.73×104 L × mol^-1and the quenching constants are Ksq?7? = 1.49. The complexes could bind to BSA protein at specific sites at the ratio of 1:1, and they can efficiently quench intrinsic fluorescence of BSA. And the quenching constant is Ksv?7? =9.92?104L×mol^-1.5. One L-leucine schiff base nickel?II? complex, [Ni?naph-L-Leu??phen??CH₃OH?] × 2CH₃OH?8?(naph-L-Leu = a Schiff base derived from 2-hydroxy^-1-napthaldehyde and leucine, phen = 1,10-phenanthroline), has been synthesized and characterized by elemental analysis and IR spectra.The single crystal X-ray diffraction showed that?8? belong to Triclinic crystal system, P^-1 space group.The complex is six-coordinated with Ni?II? centers and distorted octahedral configuration. The studies by spectra and viscosity measurement indicated that the complex binds to CT-DNA in an intercalative mode and the binding constant is Kb?8?=1.0×104 L×mol^-1and the quenching constant is Ksq?8? = 0.80. The complex could well binding affinity to BSA protein and quench their intrinsic fluorescence efficiently. And the quenching constant is Ksv?8? =8.1 ? 104 L × mol^-1. SOD-like activities of the complex were determined by the modifiedphotoreduction of NBT, the value of IC50?8? is 42.5 ?mol·L^-1.6. Two D-Alanine schiff base nickel?II? complexes, [Ni?naph-D-Ala??Phen??CH₃OH?]?9? and [Ni?o-van-D-Ala??Phen?]₂×3H₂O?10?(naph-D-Ala = a Schiff base derived from 2-hydroxy^-1-napthaldehyde and alanine, o-van-D-Ala = a Schiff base derived from o-vanillin and alanine, phen = 1,10-phenanthroline), have been synthesized and characterized by elemental analysis and IR spectra.The single crystal X-ray diffraction showed that?9? and?10? belong to monoclinic and orthorhombic crystal system, P2?1?/c and P2?1?2?1?2?1? space group.The two complexes are all six-coordinated with Ni?II?centers and distorted octahedral configuration. The studies by spectra and viscosity measurement indicated that the two complexes binds to CT-DNA in an intercalative mode and the binding constants are Kb?9?= 2.41×104 L·mol^-1 and Kb?10?=1.89×104 L·mol^-1 and the quenching constants are Ksq?9? = 1.01 and Ksq?10? = 0.85. The complexes could well binding affinity to BSA protein and quench their intrinsic fluorescence efficiently. And the quenching constants are Ksv?9?=2.3?105L×mol^-1 and Ksv?10?=1.3?105L×mol^-1. SOD-like activities of the complexes were determined by the modified photoreduction of NBT, the values of IC50?9? = 48.0 mmol·L^-1 and IC50?10? = 55.0 mmol·L^-1.