Amino Acid Schiff Base Research Articles

New amino acid-Schiff base derived from s-allyl cysteine and methionine alleviates carbon tetrachloride-induced liver dysfunction

In spite of the tremendous stride in modern medicine, conventional drugs used in the hepatotoxic management are mostly inadequate. The present study aims in the synthesis of novel Schiff base compound derived using s-allyl cystiene and methionine. The newly synthesized compound, 2-((2-((2-(allylthio)-1-carboxyethyl)imino)ethylidene)amino)-4-(methylthio)butanoic acid (ACEMB) was characterized using UV–visible spectrophotometer, FTIR, 1HNMR, and GC-MS. ACEMB showed potent in vitro antioxidant property. Chronic administration of ACEMB prior to CCl4 intoxication: i) attenuated the leakage of liver injury markers, such as, enzymes (AST, ALT, GGT, ALP and LDH) and biomolecules (bilirubin) into the blood circulation; ii) normalized the concentration of total proteins, albumin and globulin to control level; and iii) protected the liver against dyslipidemia. These effects of ACEMB show the preservation of endoplasmic reticulum function against CCl4 toxicity in the liver. The protective effect of ACEMB was due to its antioxidant property, which was revealed by reduced oxidative stress (TBARS and HP) and enhanced functions of the endogenous antioxidative system (SOD, catalase, GPx, GST, GSH, vitamin E and C) against CCl4 intoxication. Also, ACEMB protected the functional activities of the various mitochondrial tricarboxylic acid cycle and oxidative phosphorylation enzymes. The biochemical alterations are in concurrence with the histological observations, wherein ACEMB pretreatment prevented the vacuolation, degeneration of nuclei and necrosis of hepatocytes. In addition, in silico analysis reveals the interaction of ACEMB in the active site of cytochrome P450. ACEMB mediates hepatoprotective effect by substituting itself as an antioxidant and decreasing oxidative stress, thereby diminishing the intracellular organelle dysfunction against CCl4 toxicity in the liver.

Binding interactions of mixed ligand copper(II) amino acid Schiff base complexes with biological targets: Spectroscopic evaluation and molecular docking

AbstractThree mixed ligand copper(II) complexes [Cu(o‐vanillin‐l‐tryptophan Schiff base)(diimine)] (diimine =2,2′‐bipyridine (1), 1,10‐phenanthroline (2) and 5,6‐dimethyl‐1,10‐phenanthroline(3)) were synthesized and characterized using analytical and spectral methods. The molecular structures of 1–3 were optimized using density functional theory (DFT) at B3LYP/LanL2DZ levels in the gas phase. Spectral and DFT studies suggest a distorted square pyramidal geometry around the copper ion. Binding interactions of 1–3 with calf thymus DNA and bovine serum albumin protein were studied using UV–visible and fluorescence spectroscopies, viscometric titrations and cyclic voltammetry and also using molecular docking analysis. Studies of the binding of the complexes with calf thymus DNA reveal intercalation, which is supported by molecular docking simulation. The DNA cleavage nature of 1–3 with pUC19 DNA shows that the complexes can cleave DNA without any external agents, and the efficiency follows the order 1 > 3 > 2. Synchronous and three‐dimensional fluorescence spectral studies suggest that the secondary structures of the protein are altered by the complexes. Antioxidant studies reveal that the complexes have significant radical scavenging activity against DPPH. In vitro cytotoxic activity of the complexes was evaluated against breast cancer cells (MCF‐7), revealing that complex 2 exhibits higher cytotoxicity than the other complexes. Nuclear chromatin condensation and fragmentation were observed with DAPI staining assay. The mitochondrial membrane potential damage was studied by FITC staining assay. Flow cytometric analysis suggests that all the metal complexes induce cell apoptosis.

Two New Oxovanadium(IV) Compounds Containing Amino Acid Schiff Base and 1,10-Bathophenanthroline Ligands: Syntheses, Crystal Structures, and In Vitro Evaluation of the Anticancer Activities

Two new oxovanadium(iv) compounds containing 1,10-bathophenanthroline (Bphen) and amino Schiff base derivatives [VO(hnd-napha)(Bphen)] (1) and [VO(o-van-met)(Bphen)] (2) were synthesised (where hnd-napha and o-van-met are N-Schiff bases derived from the reaction of 2-hydroxy-1-naphthaldehyde with 3-(1-naphthyl)-l-alanine and o-vanillin with l-methionine, respectively). These compounds were characterised by elemental analysis, infrared spectroscopy, high-resolution mass spectrometry, and single-crystal X-ray diffraction (XRD). Both compounds showed low molar conductance values, indicating that they are non-electrolytes. The XRD results showed that the VIV atoms in both compounds existed in the VO3N3 coordination geometry with Schiff base and Bphen ligands. The in vitro anticancer activities of compounds 1 and 2 were evaluated against A549 human lung carcinoma and HepG2 human hepatoma cell lines using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the results revealed that both compounds were cytotoxic with half maximal inhibitory concentration (IC50) values in the range of 8.22 ± 1.0 to 94.89 ± 3.2 μmol L−1. Notably, compound 2 exhibited much better anticancer activity in vitro against A549 cells (8.22 ± 1 μmol L−1) than [VO(acac)2] (24 ± 6 μmol L−1) or any of our previously reported oxovanadium(iv) compounds, making it comparable in activity to cisplatin (3.1 ± 0.5 μmol L−1). These results therefore suggest that compound 2 could be used as a promising lead for the development of anticancer agents for the treatment of lung cancer.

Synthesis, Characterizations, Biological, and Molecular Docking Studies of Some Amino Acid Schiff Bases with Their Cobalt(II) Complexes

The synthesis and structural characterization of cobalt(II) complexes of amino acid Schiff bases was prepared from Salicylaldehyde and three amino acid (Valine, Leucine, and Isoleucine) in basic medium. The metal complexes was synthesized by treating an ethanolic solution of the ligand with appropriate amount of metal salts [1:2] [M:L] ratio. The synthesized Schiff bases and their metal complexes have been investigated on the bases of elemental chemical analysis, FTIR, electronic spectral, 1HNMR, 13CNMR, MS, molar conductance and magnetic susceptibility measurements. The electronic spectra of the metal complexes and their magnetic susceptibility measurements suggest octahedral structures are the probable coordination geometries for the isolated complexes. The Schiff bases and their metal complexes were preliminary scanned against various strains of microbes to study their biological effect.

Analysis of crystallographic structures of Ni(ii) complexes of α-amino acid Schiff bases: elucidation of the substituent effect on stereochemical preferences.

In this study, we performed critical analysis of 13 crystallographic structures of various Ni(ii) complexes of amino acid Schiff bases. The major finding of this work is the significance of a parallel displaced type of aromatic interactions between o-amino-benzophenone and Pro N-benzyl rings. The quality of these aromatic interactions was shown to control the steric environment around the amino acid side-chain, rendering variously substituted Ni(ii) complexes of different thermodynamic stabilities. The discovered structural trend holds true for aliphatic, aromatic and sterically bulky amino acids and can be used for the rational design of new and more efficient chiral ligands for general asymmetric synthesis of tailor-made α-amino acids.

GREEN SYNTHESIS OF NEW AMINO ACID SCHIFF BASES AND THEIR BIOLOGICAL ACTIVITIES

In this study, four new and two known amino acid Schiff base compounds derived from the condensation reaction of benzaldehyde, salicylaldehyde, pyrrole-2-carbaldehyde, pyridine-2-carbaldehyde, fluorene-2-carbaldehyde and terephthalaldehyde with 2-phenylglycine methyl ester hydrochloride have been synthesized by both conventional method and microwave irradiation protocol. The new compounds were characterized by FTIR, 1 H-NMR, LC-MS and electronic spectral studies. A comparative study between conventional heating and microwave irradiation has also been reported. Based on these results, with the microwave synthesis, the yield of the products was increased from 37% upto 96% as compared to conventional method. By microwave, reactions were completed within 5.5-8.5 minutes and the products were obtained in good to high yields, with reduced time, waste, and formation byproduct. DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging effect were performed to determine antioxidant activities of the new compounds. All of the compounds exhibited significant activities in DPPH radical scavenging.

Electroanalytical Studies on the Interaction Of l-Serine-Based Schiff Base, HHDMP, with Copper in Sulphuric Acid

Amino acids and its Schiff bases have been widely recognized as green corrosion inhibitors primarily due to its non-toxic nature and biodegradable properties. Considering its unique nature and significant contribution in corrosion chemistry, studies were undertaken with an objective to find out the inhibitory effect of l-serine based Schiff base HHDMP on copper in 0.5, 1.0 and 1.5 M of sulphuric acid at 303, 308 and 313 K. Various techniques such as weight loss method, electrochemical impedance spectroscopy, potentiodynamic polarization (Tafel), basic computational calculations and adsorption studies were employed in the present investigations. Results revealed that Schiff base HHDMP do offer attractive inhibition efficiency in all concentrations of sulphuric acid. The inhibition effect advanced with the increased concentration of the inhibitor. However, with the increased concentration, the inhibition efficiency showed decline trend. Such behaviour of the amino acid Schiff base HHDMP on copper in sulphuric acid may be due to surface adsorption of the inhibitor molecules on the metal, which contributes to decrease in the double-layer capacitance and increase in the polarization resistance.

Synthesis, crystal structures, and antibacterial studies of silver(I) complexes with reduced Schiff base amino acid ligands

Three Ag(I) complexes of reduced Schiff base amino acid ligands, [Ag2(Hshis)2]·3H2O (1), Ag(Hcgly) (2), and Ag(cala) (3) (H2shis = N-(2-hydroxybenzyl)-l-histidine, H2cgly = N-(2-hydroxy-5-chlorobenzyl)-glycine, Hcala = N-(4-chlorobenzyl)-d,l-alanine), have been synthesized and characterized by X-ray crystallography. Complex 1 shows a dimeric structure, while complex 2 shows one-dimensional zigzag chains, which are extended into a two-dimensional supramolecular sheet by hydrogen bonds. Complex 3 exhibits a 2D sheet structure with dangling arms. The antimicrobial activities of the complexes have been investigated.

Syntheses, crystal structures and in vitro anticancer activities of oxovanadium(IV) complexes of amino acid Schiff base and 1,10-phenanthroline ligands

Four oxovanadium(IV) complexes, namely [VO(desa-met)(phen)]·MeOH·2H2O (1) (desa-met = Schiff base derived from 4-(diethylamino)salicylaldehyde and dl-methionine, phen = 1,10-phenanthroline), [VO(o-van-met) (phen)]·MeOH·CH2Cl2·3H2O (2) (o-van-met = Schiff base derived from o-vanillin and dl-methionine), [VO(dtbs-napa)(phen)]·2H2O (3) (dtbs-napa = Schiff base derived from 3,5-di-tert-butyl salicylaldehyde and 3-(1-naphthyl)-l-alanine) and [VO(hyna-napa)(phen)]·1.5H2O (4) (hyna-napa = Schiff base derived from 2-hydroxy-1-naphthaldehyde and 3-(1-naphthyl)-l-alanine), were synthesized and characterized by IR, HRMS, UV–vis spectra, molar conductance and single-crystal X-ray diffraction (XRD). X-ray structural analysis showed that the V(IV) atoms in all four complexes are six-coordinated in a distorted octahedral environment. In the crystals of complexes 1 and 2, π–π stacking interactions together with hydrogen bonds connect the molecular units into 2D networks. Meanwhile, CH–π stacking interactions are observed between the aromatic rings in the crystals of 1 and 4, while the π–π stacking interactions between aromatic rings in the crystals of 2 and 3 are arranged with a face-to-face mode. The in vitro anticancer activities of these complexes against A-549 and HeGp2 cells were tested by MTT assay.

Synthesis and antimicrobial activities of new higher amino acid Schiff base derivatives of 6-aminopenicillanic acid and 7-aminocephalosporanic acid

Novel β-lactam derivatives (1c-3c) (1d-3d) were produced by using 6-aminopenicillanic acid (6-APA), 7-aminocephalosporanic acid (7-ACA) and the higher amino acid Schiff bases. The synthesized compounds were characterized by elemental analysis, IR, 1H/13C NMR and UV–vis spectra. Antibacterial activities of all the higher amino acid Schiff bases (1a-3a) (1b-3b) and β-lactam derivatives were screened against three gram negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Acinetobacter baumannii RSKK 02026), three gram positive bacteria (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 07005, Bacillus subtilis ATCC 6633) and their drug-resistant isolates by using broth microdilution method. Two fungi (Candida albicans and Candida krusei) were used for antifungal activity.

Synthesis, structure elucidation, biological screening, molecular modeling and DNA binding of some Cu(II) chelates incorporating imines derived from amino acids

Three tridentate Schiff bases amino acids were prepared by direct condensation of 3-methoxysalicylaldehyde (MS) or 4-diethylaminosalicylaldehyde (DS) with α-amino acid ligands [l-phenylalanine (P), l-histidine (H) and DL-tryptophan (T)]. The prepared Schiff bases amino acids were investigated by melting points, elemental analysis, 1HNMR and 13CNMR, IR, UV–Vis spectra, conductivity and magnetic measurements analyses. Subsequently, copper was introduced and Cu(II) complexes formed. These complexes were analyzed by thermal and elemental analyses and further investigated by FT-IR and UV/Vis spectroscopies. The experimental results indicating that all Cu(II) complexes contain hydrated water molecules (except DSPCu complex) and don't contain coordinated water molecules. The kinetic and thermal parameters were extracted from the thermal data using Coast and Redfern method. The molar conductance values of the Schiff base amino acid ligands and their Cu(II) complexes were relatively low, showing that these compounds have non-electrolytic nature. Magnetic susceptibility measurements showed the diamagnetic nature of the Schiff base amino acid ligands and paramagnetic nature of their complexes. Additionally, a spectrophotometric method was determined to extract their stability constants. It was found that the complexes possess 1:2 (M:L) stoichiometry. The results suggested that 3-methoxysalicylaldehyde and 4-diethylaminosalicylaldehyde amino acid Schiff bases behave as monobasic tridentate ONO ligands and coordinate Cu(II) ions in octahedral geometry according to the general formula [Cu(HL)2]·nH2O. To further understanding the structural and electronic properties of these complexes, Density Functional Theory (DFT) calculations were employed and provided a satisfactory description. The optimized structures of MST Schiff base ligand and its complex were calculated using DFT. The antimicrobial activity of the Schiff base ligands and their complexes were screened against some types of bacteria such as Bacillus subtilis (+ve), Escherichia coli (−ve) and Micrococcus luteus (+ve) and some types of fungi such as Asperagillus niger, Candida glabrata and Saccharomyces cerevisiae. The results of these studies indicated that the metal complexes exhibit a stronger antibacterial and antifungal efficiency compared to their corresponding ligands. The complexes were screened for antiviral activity against a panel of DNA and RNA viruses. Minimum cytotoxic and minimum virus inhibitory concentrations of these complexes were determined. The mode of interaction between complexes and CT-DNA was monitored using absorption spectra, viscosity measurements and gel electrophoreses.

Spectroscopic characterization of some new coordination compounds of titanium(IV) with Schiff bases of amino acids

Spectroscopic characterization of some new coordination compounds of titanium(IV) with Schiff bases of amino acids

Water soluble and efficient amino acid Schiff base receptor for reversible fluorescence turn-on detection of Zn2+ ions: Quantum chemical calculations and detection of bacteria

An amino acid Schiff base (R) capable of recognizing Zn2+ ions selectively and sensitively in an aqueous medium was prepared and characterized. Upon addition of Zn2+ ions, the receptor exhibits fluorescence intensity enhancements (~40 fold) at 460nm (quantum yield, Φ=0.05 for R and Φ=0.18 for R–Zn2+) and can be detected by naked eye under UV light. The receptor can recognize the Zn2+ (1.04×10−8M) selectively for other metal ions in the pH range of 7.5–11. The Zn2+ chelation with R decreases the loss of energy through non-radiative transition and leads to fluorescence enhancement. The binding mode of the receptor with Zn2+ was investigated by 1H NMR titration and further validated by ESI-MS. The elemental color mapping and SEM/EDS analysis were also used to study the binding of R with Zn2+. Density functional theory calculations were carried out to understand the binding mechanism. The receptor was applied as a microbial sensor for Escherichia coli and Staphylococcus aureus.

Kinetic Screening for the Acid‐Catalyzed Hydrolysis of Some Hydrophobic Fe(II) Schiff Base Amino Acid Chelates and Reactivity Trends in the Presence of Alkali Halide and Surfactant

ABSTRACTKinetics of acid‐catalyzed hydrolysis of some high‐spin Fe(II) Schiff base amino acid complexes were followed spectrophotometrically at 298 K under pseudo–first‐order conditions. The studied ligands were derived from the condensation of 5‐bromosalicylaldehyde with different four amino acids (phenylalanine, aspartic acid, histidine, and arginine). The acid hydrolysis reaction was studied in aqueous media and in the presence of different concentrations of the alkali halide (KBr) and cationic surfactant (cetyl‐trimethyl ammonium bromide, CTAB). The general rate equation was suggested to be rate = kobs[complex], where kobs = k2[H+]. The increase in [KBr] enhances the reactivity of the reaction, and the addition of CTAB to the reaction mixture accelerates the reaction reactivity. The obtained kinetic data were used to determine the values of δmΔG# (the change in the activation barrier) for the studied complexes when transferred from “water to water containing different [KBr]” and from “water to water containing altered [CTAB].”

Albumin Conjugating Amino Acid Schiff-Base Metal Complexes for Scavenging Superoxide Anion Radical

Superoxide anion radical (O 2 •− ) is a toxic reactive oxygen species (ROS). Schiff-base metal complexes have been widely studied as synthetic antioxidants to scavenge ROS. However, it is toxic and shows poor water solubility. In this work, a kind of novel water-soluble biopolymer/metal complex conjugate (HO-SAM@BSA) was prepared by binding the 4-hydroxy-salicylaldehyde amino acid Schiff-base metal complexes (HO-SAM, M = Cu, Zn, Co) with water-soluble biopolymer bovine serum albumin (BSA). The conjugates were characterized using IR, UV–Vis, circular dichroism spectra (CD), and polyacrylamide gel electrophoresis (PAGE). The results show that the structure of BSA is maintained when the binding rate (nHO-SAM: nBSA) of amino acid Schiff-base metal complexes is 10. In addition, the O 2 •− scavenging activities of resultant conjugates were determined via nitrobule tetrazolium assay method. After combining HO-SAM into BSA, the poor water-solubility of HO-SAM is improved, and the O 2 •− scavenging activity of BSA increases dramatically. The conjugation HO-SCCu@BSA displays excellent O 2 •− scavenging activity. When the EC50 value was 0.10 μmol/L, the analog quantity reached 41 % of natural SOD. Therefore, it can act as a bifunctional mimic of enzyme, which has a great application prospect in antioxidant drug.

Synthesis of monosodium salts of N-(5-nitro-salicylidene)-D-amino acid Schiff bases and their iron(III) complexes: spectral and physical characterizations, antioxidant activities

Amino acid Schiff bases, [NaL]·nH2O (L = N-(2-hydroxy-5-nitrobenzylidene)alaninate, N-(2-hydroxy-5-nitrobenzylidene)valinate, and N-(2-hydroxy-5-nitrobenzylidene)phenylalaninate), were synthesized as monosodium salts (L1Na–L3Na). The structures of the monosodium salts were confirmed on the basis of elemental analysis, conductivity measurements, UV–vis, FT-IR, and 2D NMR (HMQC) spectroscopies. L1Na was also structurally determined by single-crystal X-ray diffraction. Hydrogen bond between the amino N(2)–H and phenolate O(1) of the salicylidene part of the molecule played important roles in stabilizing the zwitterion crystal structure. The ranges of the D–H…A angles and those of the H…A and D…A distances indicated the presence of short hydrogen bonds in the structure. In addition, the monosodium salts have been evaluated for in vitro antioxidant activity. Iron(III) complexes (L1Fe–L3Fe) have been obtained by reaction of the appropriate ligand with iron(III) chloride in a 2 : 1 M ratio. Fe(III) complexes were characterized by elemental and thermal analysis, conductivity and magnetic susceptibility measurements, UV–vis, FT-IR, and X-ray photoelectron spectroscopy methods.

Kinetics of acid hydrolysis and reactivity of some antibacterial hydrophilic iron(II) imino-complexes

Kinetic study of acid hydrolysis of some hydrophilic Fe(II) Schiff base amino acid complexes with antibacterial properties was performed using spectrophotometry. The Schiff base ligands were derived from sodium 2-hydroxybenzaldehyde-5-sulfonate and glycine, L-alanine, L-leucine, L-isoleucine, DL-methionine, DL-serine, or L-phenylalanine. The reaction was studied in aqueous media under conditions of pseudo-first order kinetics. Moreover, the acid hydrolysis was studied at different temperatures and the activation parameters were calculated. The general rate equation was suggested as follows: rate = k obs [Complex], where k obs = k 2 [H+]. The evaluated rate constants and activation parameters are consistent with the hydrophilicity of the investigated complexes.

Silver(I) complexes of 2,4-dihydroxybenzaldehyde-amino acid Schiff bases-Novel noncompetitive α-glucosidase inhibitors.

A series of silver(I) complexes of 2,4-dihydroxybenzaldehyde-amino acid Schiff bases were designed and tested for α-glucosidase inhibition. Our results indicate that all the silver complexes (4a-18a) possessed strong inhibitory activity at μmolL(-1) level, especially glutamine (12a) and histidine (18a) Schiff base silver(I) complexes exhibited an IC50 value of less than 0.01μmolL(-1). This series of compounds exhibited noncompetitive inhibition characteristics in kinetic studies. In addition, we investigated the mechanism of inhibition and the structure-activity relationships of the amino acid Schiff base silver complexes. Our results reveal that Schiff base silver complexes may be explored for their therapeutic potential as alternatives of α-glucosidase inhibitors.

Novel Schiff base amino acid as corrosion inhibitors for carbon steel in CO2-saturated 3.5% NaCl solution: experimental and computational study

AbstractThe corrosion inhibition and adsorption behavior of some novel Schiff bases based on amino acids on carbon steel in CO2-saturated 3.5% NaCl solution at 50°C was investigated using gravimetric, potentiodynamic polarization, linear polarization resistance corrosion rate, and scanning electron microscope (SEM)/energy-dispersive X-ray spectroscopy analysis (EDAX) techniques. Results show that the inhibition efficiency increases when the inhibitor concentration increases. Potentiodynamic polarization curves reveal that the used Schiff bases are mixed-type inhibitors. Experimental data indicate that these Schiff base inhibitors adsorb at the carbon steel/solution interface according the Langmuir adsorption isotherm. SEM/EDAX was used to examine the surface morphology of carbon steel samples in the absence and presence of the inhibitors. Quantum chemical calculations were further applied to explain the experimental results.

Tailoring, physicochemical characterization, antibacterial and DNA binding mode studies of Cu(II) Schiff bases amino acid bioactive agents incorporating 5-bromo-2-hydroxybenzaldehyde

Five novel Cu(II) complexes derived from the condensation between 5-bromosalicylaldehyde (bs) and α-amino acids (L-alanine, l-phenylalanine, L-aspartic acid, L-histidine and L-arginine) were synthesized and characterized by their elemental analyses, thermogravimetric analysis, IR, mass and electronic spectra, conductance and magnetic measurements. Moreover, the stoichiometry and the stability constants of the prepared complexes have been determined spectrophotometrically using continuous variation and molar ratio methods. The obtained results indicated that the Schiff bases of the amino acids: L-alanine, L-phenylalanine, L-histidine and L-arginine behave as tridentate ligands. The ligands are coordinating with the Cu(II) via azomethine nitrogen, deprotonated carboxylate oxygen and phenolic oxygen. However, in the case of L-aspartic, the ligand acts as tetradentate due to the coordination of the second carboxylate group. Based on the studies of magnetic moments and electronic spectra, a square planar geometry has been proposed for all Cu(II) complexes except bromsalicylaldehydine aspartate complex which has a distorted tetrahedral structure. The representative Schiff bases and their Cu(II) complexes were tested in vitro for their antibacterial activity against two Gram-positive bacteria (Micrococcus luteus and Bacillus cereus) and one Gram-negative bacteria (Pseudomonas aeruginosa). All the complexes showed activity against the organisms more than the free Schiff base ligands and the activity increases with the increase in concentration of test solution containing the new complexes. Moreover, the interaction of the prepared Schiff base amino acid Cu(II) complexes with calf thymus DNA has been investigated by absorption spectra, viscosity and gel electrophoresis measurement and the mode of CT-DNA binding to the complexes has been explored. The investigated complexes exhibit cooperative binding and presumably intercalate into DNA and follow the trend: bsarc>bshc>bsalc>bsphalc>bsasc.