Synthesis Characterization and Biological Activity Study of New Schiff and Mannich Bases and Some Metal Complexes Derived from Isatin and Dithiooxamide

Abdulghani, Ahlam J.; Abbas, Nada M.

doi:https://doi.org/10.1155/2011/706262

Bioinorganic Chemistry and Applications

On this page

Abstract Introduction Methods Results Conclusions References Copyright Related Articles

Research Article | Open Access

Volume 2011 | Article ID 706262 | https://doi.org/10.1155/2011/706262

Synthesis Characterization and Biological Activity Study of New Schiff and Mannich Bases and Some Metal Complexes Derived from Isatin and Dithiooxamide

Ahlam J. Abdulghani¹and Nada M. Abbas¹

Academic Editor: Zhe-Sheng Chen

Received06 Dec 2010

Revised05 Feb 2011

Accepted27 Feb 2011

Published15 May 2011

Abstract

Two new Schiff and Mannich bases, namely, 1-Morpholinomethyl-3(1′ -N-dithiooxamide)iminoisatin (L_IH) and 1-diphenylaminomethyl-3-1′-N-dithiooxamide)iminoisatin (L_IIH), were prepared from condensation reaction of new Schiff base 3-(1′-N-dithiooxamide)iminoisatin (SBH) with morpholine or diphenylamine respectively in presence of formaldehyde . The structures were characterized by IR, ¹HNMR, mass spectrometry, and CHN analyses. Metal complexes of the two ligands were synthesized, and their structures were characterized by elemental analyses, atomic absorption, IR and UV-visible spectra, molar conductivity, and magnetic moment determination. All complexes showed octahedral geometries except palladium complexes which were square planar. The biological activity of the prepared compounds and some selected metal complexes was tested against three types of bacteria and against cell line of human epidermoid larynx carcinoma (Hep-2).

1. Introduction

Various Mannich Schiff bases of isatin have been found to be of biological importance [1] and have shown anticonvulsant [2], antibacterial [3, 4], antimicrobial [5–7] and anti-HIV activities [8, 9]. Dithiooxamide (dto) is an effective flexidentate complexing agent with varied coordination chemistry. Due to the intense chromophoric character, dto can be used in an imaging processes [10], coordination polymers [11], histological agents, and as a source for duplicating processes [12]. The transition metal complexes of dto and its derivatives are characterized by semiconductor, magnetic, and spectroscopic properties [12–15]. The aim of this work is to synthesize and study the coordination behavior of the two new Schiff and Mannich base ligands L_IH and L_IIH shown in Scheme 1, from condensation reaction of a new Schiff base 3-(1′-N-dithiooxamide) iminoisatin (SBH) with morpholine or diphenylamine, respectively, in presence of formaldehyde in a mole ratio of (1 : 1 : 1), respectively, or from reaction of Mannich bases N-morpholinomethyl isatin (M_I) and N-diphenylaminomethyl isatin (M_II) [16] with dithiooxamide. The biological activity of the two ligands and some of their metal complexes was investigated against selected types of bacteria and against cancer cell line of human epidermoid larynx carcinoma (Hep-2).

2. Experimental/Materials and Methods

Melting points (uncorrected) were determined by using Gallenkamp MFB600–010f m.p apparatus. The purity of the synthesized compounds was checked by T.L.C. techniques using a mixture of chloroform and acetone (2 : 2 V/V) and various ratios of methyl acetate: acetone solvent mixture as eluents and iodine chamber for spot location. The HPLC of the Schiff base (SBH) and the derived two ligands were obtained by using HPLC (LKB), mobile phase CH₃CN : H₂O (80 : 20). Infrared spectra were recorded on a Perkin-Elmer 1310 IR spectrophotometer and Shimadzu corporation 200–91527 IR spectrophotometer using KBr and CsI disks. ¹H n.m.r spectra of the organic compounds were recorded on a 300 MHz n.m.r spectrophotometer (Joel) using TMS as internal reference. Mass spectra were recorded on a Joel 700 mass spectrometer. Elemental CHN analyses were obtained by using EA elemental analyzer (Fison Ision Instrument). Electronic spectra of the ligands and their metal complexes in the region 200–1100 nm were recorded on a Shimadzu UV-visible-160 spectrophotometer. The metal contents were determined by atomic absorption technique using a Varian-AA-775 atomic absorption instrument. Electrical conductivity of metal complexes was measured at room temperature in DMF (10⁻³ M) using Elkta Lictfahigkeit conductivity meter (SIMENS). Magnetic moments (μ_eff BM) for the solid metal complexes at room temperature were determined according to Faraday’s method by using Johnson Mattey magnetic balance system division. Chloride content of metal complexes was determined by potentiometric titration using 1686-titroprocessor-665 Dosinametrom (Swiss). All organic and inorganic materials were of high purity and used as received except ethanol, methanol, and DMF which were dried and distilled prior to use [17]. Palladium(II) chloride was converted to dichlorobis(benzonitrile)palladium(II) [18], and H₂PtCl₆·6H₂O was converted to potassium hexachloroplatinate(IV) hexahydrate [19] prior to use. Mannich bases N-morpholinomethylisatin (M_I) and N-diphenylaminomethyl isatin (M_II) were prepared according to methods mentioned in the literature [16]. Complex formation was studied in solutions to obtain the molar ratio of the ligand to metal ion (L : M) using ethanol, or DMSO as solvents. A series of solutions containing constant concentration of the metal ion (1 × 10⁻⁴M) were treated with various amounts of the same concentration of the ligand. The results of (L : M) ratio were obtained by plotting absorbance of solution mixtures at detected λ_max against [L]/[M].

3. Preparation of Ligands

3.1. 3-(1′-N-dithiooxamide)iminoisatin (SBH)

A solution mixture of isatin (0.01 mole, 1.47 g) and dto (0.01 mole, 1.021 g) in dry ethanol (50 mL) containing 2-3 drops glacial acetic acid was heated under reflux for 8 h with continuous stirring. The mixture was then left at room temperature for 24 hs. A yellow precipitate was formed. The product was filtered, washed with warm ethanol, and crystallized from ethanol:dichloromethane solvent mixture (1 : 1). m.p. 190°C yield 60%; IR (KBr) ν(cm⁻¹): 3296, 3203 (NH₂); 3147 (NH-isatin); 1733 (C=O), 1614 (−C=N); 1540 (C–S + δNH, I); 1430 (C–N + C–S, II); 1197 (C–S, III); 835 (C=S, IV). ¹H n.m.r. δ(ppm) (CD₂Cl₂) 12.012 (1H, s, NH); 7.653–6.94 (4H, m, aromatic); 2.022 (2H, d, NH₂). MS, (m/z) (I%) (EI) calculated for C₁₀H₇N₃OS₂ m.wt 249 g/mole: 250 (10) [M+1]; 221 (3.2) [M–CO]; 207 (4) [M–NCO]; 162 (2); 119 (24); 90 (7.5).

3.2. 1-Morpholinomethyl-3-(1′-N-dithiooxamide)iminoisatin (L_IH) and 1-diphenylaminomethyl-3-1′-N-dithiooxamide)Iminoisatin (L_IIH)

(a) To a stirred solution of 3-(1′-N-dithiooxamide)iminoisatin (SBH) (0.01 mole, 2.49 g) and formaldehyde 37% (0.015 mole) in warm dry ethanol (20 mL) was added, drop by drop, (0.01 mole) of morpholine (L_IH) or diphenylamine (L_IIH). The mixture was heated under reflux for 3 h with continuous stirring, and then left to cool at room temperature. A solid precipitate was formed. The products were filtered, washed with warm ethanol, and then crystallized from ethanol : chloroform (1 : 1 v/v) mixture; yield 35 and 28.2%, respectively.

(b) To a solution of dto (5 mmole, 0.6 g) in warm ethanol (10 mL) containing 2-3 drops glacial acetic acid was added (5 mmole) of Mannich base N-Morpholinomethylisatin (M_I) or N-Diphenylaminomethyl isatin (M_II) [16] in ethanol (10 mL) with continuous stirring, and the mixture was heated under reflux for 10 h. After leaving the mixture at room temperature for 24 h a precipitate was formed. The products were filtered, washed with warm ethanol, and crystallized; yield 20.3 and 21%, respectively (m.p. 215 and 283°C, resp.).

1-Morpholinomethyle-3-(1′-N-dithiooxamide)iminoisa- tin (L_IH):
yellowish orange crystals, m.p. 162°C; IR (KBr). ν(cm⁻¹): 3203, 3138 (NH₂); 3030–3000 (arom CH); 2815–2364 (CH₂); 1730 (C=O); 1614 (−C=N); 1589 (C=C arom.); 1540 (νC=N, δNH, I); 1429 (C–N + C–S, II); 1195 (C–S, III); 835 (C=S, IV); 1149, 1328 (morpholine). ¹H n.m.r δ(ppm) (DMSO): 7.59-6.898 (4H, m, aromatic +NH); 4.09 (2H, d, N–CH₂N); 3.65 (4H, d, 2^”, 6^” CH₂ morph.); 2.33 (4H, d, 3^”, 5^” CH₂ morph.); 1.567 (1H, br, SH). MS (FAB) m/z (I%) calculated for C₁₅H₁₆N₄O₂S₂, m.wt 348.45 g/mole,: 349.1 (93) [M]; 320 (38) [M–CO]; 235 (100); 234 (80); 220 (15), 207 (40). 131 (43); 104 (78%); (EI) m/z (I%): 348.5 (84) [M]; 320 (25) [M–CO]; 234 (38); 207 (17); 130 (19); 117 (24); 104 (57); 90 (30); 78 (22%). CHN% Calculated for C₁₅H₁₆N₄O₂S₂ C, 51.67; H, 4.59, N, 16.07% found C, 50.69; H, 4.20; N, 15.75%; ν_max (cm⁻¹) (DMF) (ε_max mol⁻¹ cm⁻¹) 34013 (20030) ; 2415 (2980), (DMSO) 38461 (19519) .

Diphenylaminomethyl-3-(1′-N-dithiooxamide)Iminoisa tin (L_IIH):
yellow red crystals, m.p. 182, IR (KBr) ν(cm⁻¹): 3193, 3034 (NH₂); 1730 (C=O); 1614 (C=N); 1540, 1434, 1195, 833 (C–N + δNH, C–N + C–S, C–S, C=S I–IV, resp.). ¹H n.m.r (δ, ppm) (CD₂Cl₂): 7.59–6.89 (14H, m, aromatic); 4.83 (2H, d, CH₂); 2.17 (2H, b, NH₂). MS m/z (I%) (EI): calculated for C₂₃H₁₈N₄OS₂, m.wt 430.55 g/mol: 430.9 (5.5) [M]; 402 (2.5) [M–CO]; 235 (21); 129.2 (1.8); 104 (4.8); 89 (10.3); 78.1 (3.5%). CHN (%) calculated for C₂₃H₁₈N₄OS₂: C, 64.18, H, 4.21; N, 13.02% found: C, 64.02; H, 4.22; N, 13.52%. ν_max (cm⁻¹) (DMF) (_max, L mol⁻¹ cm⁻¹) 32258 (22970) ; 24509 (3530) ; (DMSO): 38461 (19540): 28571 (14120) .

4. Synthesis of Metal Complexes

To a solution of Schiff Mannich base ligand (2 mmole) in absolute ethanol (L_IH) or ethanol and dimethylsulfoxide (1 : 1 v/v) (L_IIH) (5 mL) was added an alcoholic solution (5 mL) of the metal salt (chlorides, nitrates, or acetates) (1 mmol), and the mixture was heated under reflux with continuous stirring for 3 h. Precipitation of products took place after heating time of 30 min for (Co(II)), Ni(II), and complexes of L_IH and L_IIH (C₂, C₃, C₈, and C₉, resp.), 1 h for (Mn(II), Cu(II), and Ir(III) complex of L_IH and Cd(II) complex of L_IIH (C₁, C₄, C₅, and C₁₂, resp.), 1.5 h for Pt(IV) complex of L_IH (C₇), 2 h for Pd(II) complex of L_IH and Pt(IV) complex of L_IIH (C₆ and C₁₁, resp.) and 3 h for Pd(II) complex of L_IIH (C₁₀). The products were filtered and purified from reactants by washing many times with ethanol and ether (C₁–C₇) or with DMSO, ethanol and ether (C₈–C₁₂), and vacuum dried. Purity of the products was detected by TLC, using silica gel as a stationary phase and a mixture of chloroform and acetone (2 : 2 V/V) or various ratios of methyl acetate: acetone solvent mixture as eluents.

5. Biological Activity Study

5.1. Antibacterial Action

Antibacterial activities of the prepared compounds were tested against three types of pathogenic bacteria, namely, Escherichia coli, Staphylococcus areus, and Proteus mirabilis using the antibiotic Ceftriaxone as a control. Bacterial cultures were prepared by streaking (0.1) mL of 10⁶ CFU/mL broth of indicator strain on the whole surface of nutrient agar plate. In each plate four wells (pores) were created on the nutrient agar layer using sterile cork porer. In each hole was injected 50 μL of 10⁻³ M of the studied compounds in DMSO by micropipette. The resulting cultures were incubated at 37°C for 24 h. The inhibition zones caused by each compound were measured, and the results were interpreted according to diameter measurements.

5.2. Cytotoxic Activity

A preliminary study of cytotoxic activity of some of the prepared compounds was performed against human epidermoid larynx carcinoma cell lines (Hep-2) of 52-year-old patient. Hep-2 monolayer cell lines were prepared by subculturing cell line into (RPMI-1640) medium supplemented with 10% heat deactivated fetal bovine serum. The resulting media were incubated at 37°C for 48 h until confluent layer was achieved. Four concentrations of investigated compounds were prepared: 62.5, 125, 250, and 500 μg/mL using dimethyl sulfoxide (DMSO) as a diluent. Hep-2 cell line was plated into 96-well microtiter plates. Then 0.2 mL of each tested compound was added to each well in triplicates, and incubation was carried out for 48 h. Cultures were stained with 50 μL/well Neutral Red (NR) solution. The stained cultures were left in the incubator for further 2 h, washed with phosphate buffered saline solution followed by (0.1 mL) ethanol phosphate buffered solution (NaH₂PO₄ : ethanol (1 : 1), vehicle ethanol). The cytotoxic effects of the applied compounds were measured in terms of optical density of viable cells at nm using a Micro ELISA reader.

6. Results and Discussions

6.1. Synthesis

The synthesis of the two new ligands has been achieved by following two different pathways A and B as is illustrated by Scheme 2. Pathway A involves the synthesis of Schiff base precursor of isatin (SBH) followed by condensation with the secondary amine, morpholine or diphenylamine, in presence of formaldehyde to form L_IH and L_IIH, respectively. Pathway B involves the formation of Mannich base precursor of isatin (M_I and M_II) followed by condensation reaction with dithiooxamide. The second method showed lower yield and longer reaction time.

The ¹H n.m.r spectrum of the Schiff base precursor SBH in CD₂Cl₂ (Figure 1) is characterized by the appearance of chemical shift related to the NH₂ protons of dto moiety at δ2.022 ppm [11, 20, 21] and the appearance of NH proton of isatin ring at δ12.012 ppm [5–7, 22–25] which is quite agreeable with the suggested structure of SBH. The ¹H n.m.r spectrum of L_IIH in CD₂Cl₂ exhibited chemical shifts of NH₂ protons at 2.17 ppm while that of L_IH in DMSO (Figure 2) gave chemical shifts at δ1.567 ppm. This was attributed to tautomerism of L_IH in DMSO to iminosulfhydryl structure in equilibrium with dithioamide structure, as a result of solvent polarity [26, 27]. Such behavior was confirmed by the appearance of the signal assigned to imino NH group at lower field. The spectrum of L_IIH (Figure 3) exhibited chemical shifts of aromatic protons of isatin ring and diphenylamine at δ6.89–7.11 and at δ7.68–7.59, respectively, while those of methylene group appeared at high fields [22–24].

The mass spectra of the two Mannich and Schiff base ligands as well as SBH are shown in Figures 4, 5, and 6, respectively. The EI mode of mass spectrum displayed by SBH (Figure 6) gave a peak at m/z = 250 which was assigned to [M+1], while the two Mannich base ligands displayed peaks corresponding to [M⁺] molecular ions. Smaller fragments were also observed and were characteristic of isatin behavior of other compounds [1, 22, 26, 28–34]. The FAB and EI modes of L_IH (Figures 4(a) and 4(b)) showed different intensities of common fragments ions.

(a)

(b)

The IR spectra of the three organic compounds exhibited the disappearance of stretching modes assigned to C-3 carbonyl of isatin ring and appearance of stretching modes of azomethine group of Schiff base products at 1614 cm⁻¹ [35]. Stretching vibrations of C-2 carbonyl group of isatin ring for SBH and the two Mannich Schiff base ligands were observed at 1733–1730 cm⁻¹ [35]. The presence of bands assigned to NH₂ asymmetric symmetric stretching vibrations indicates that the formation of Schiff bases was through one NH₂ group only. Both ligands exhibited the absence of stretching vibrations assigned to NH of isatin ring, and instead vibrational modes of N–CH₂ groups were observed at 2813–2304 cm⁻¹ [35]. Bands observed at 1149, 1328 in the spectrum of L_IH were attributed to C–O–C and C–N–C vibration of morpholine ring, respectively [35–38].

6.2. Physical Properties and Analytical Data of Metal Complexes

The color, melting points, yields, and elemental analyses of the prepared metal complexes of isatin Schiff Mannich base ligands are described in Table 1. Most results were in agreement with the suggested formula. Some deviations in elemental analyses may be attributed to incomplete combustion of the complexes. The low yield resulted from extensive purification of products from the starting materials as was indicated from TLC results.

6.3. Infrared Spectra

The important stretching vibrations of L_IH and L_IIH metal complexes are described in Table 2. The Mn(II), Co(II) and Ni(II) complexes of L_IH (C₁–C₃, resp.) and Co(II) complex of L_IIH (C₈) exhibited shifts of the thioamide groups to lower frequencies indicating the involvement of thiocarbonyl sulfur atoms in coordination with these metal ions [39, 40]. The spectra of C₁ and C₂ demonstrated further shift of NH₂ group vibrational modes to lower frequencies as a result of bonding. On the other hand the spectra of Cu(II), Ir(III), and Pt(IV) complexes of L_IH (C₄, C₆, C₇, resp.) and Pd(II), Pt(IV), and Cd(II) complexes of L_IIH (C₁₀–C₁₂, resp.) displayed the disappearance of the stretching mode of thioamide NH₂ group and the shift of C-S band to lower frequencies. This refers to the bonding of metal ion to the deprotonated group of the ligand in the form of 706262.tab.001 as in C₄, C₆, and C₉ or in the form of 706262.tab.002 anion as in the case of C₅, C_7, and C₁₀–C₁₂. The appearance of stretching modes assigned to NH and C=N of −C=NH groups was observed at 3371–3100 and 1640–1620 cm⁻¹, respectively [15, 35, 39, 41]. The stretching vibrations of azomethine group of the Schiff base ligands were shifted to lower frequencies in all spectra except those of C₆, C₁₀, and C₁₂, whereas stretching vibrations of carbonyl group were shifted to lower frequencies in all spectra except C₁, C₄, C₆, and C₁₀ indicating additional coordination of metal ions to C=N and C=O groups [36–38]. Bands related to coordinated water vibrations were observed in the spectra of C₁, C₄, and C₁₂ at (3490, 756, 640), (3480, 800, 730), and (3500, 864, 710) cm⁻¹, respectively, and to lattice water vibrations at frequency range 3519–3464 cm⁻¹ in the other complexes. The bands related to nitrate ions were observed in the spectra of C₂and C₃ at (1522, 1478), (1765, 1641) cm⁻¹ and were assigned to monodentate and free ion behaviors, respectively, whereas that of C₈appeared at 1750–1660 and 1406–1380 cm⁻¹ showing monodentate and bidentate behaviors, respectively [42]. Bands attributed to acetate group vibrations were observed in the spectra of C₉ and C₁₂ at (1645, 1340) and (1590, 1465) cm⁻¹, respectively, indicating monodentate and bidentate bridging behaviors, respectively [42]. Additional bands were observed at lower frequencies (600–250 cm⁻¹) and were attributed to M–N, M–O, M–S, and M–X (X = acetate, NO₃⁻, Cl⁻) stretching modes [42].

6.4. Thermal Analysis

Steps of thermal decomposition of the Co(II) and Ir(III) complexes of L_IH (C₂, C₆) following TG and DTG curves under nitrogen atmosphere and heating range 50–800°C are described in Table 3, and their thermographs are shown in Figures 7 and 8, respectively. At low temperatures, the initial weight losses were determined from TG curves referred to loss of water of crystallization [43–45]. The final stage of thermal decomposition of C₂ gave the metal oxide whereas the Ir complex (C₆) gave the free metal as a final residue [43–45].

6.5. Electronic Spectra and Suggested Structures

Table 4 describes the energies of bands observed in the spectra of metal complexes and their assignments together with magnetic moments and molar conductivity in DMF (10⁻³ M). The spectral parameters 10 Dq, , , and as well as energies of unobserved ligand field bands were obtained by applying observed band energies and band ratios on Tanabe-Saugano diagrams of the specified metal ion [46–48]. All metal complexes exhibited spectra related to octahedral arrangement of ligand atoms around the metal ions except those of palladium(II) as they gave square planar geometries. The high values of magnetic moments of Co(II), Ni(II), and Cu(II) complexes are attributed to spin-orbital coupling [49]. All complexes were of high-spin octahedral geometries except Pt(IV), Ir(III), and Cd(II) complexes which were diamagnetic and so were Pd(II) complexes.

The spectrum of the Cd(II) complex (C₁₂) exhibited charge transfer bands only, which is a common phenomenon for d¹⁰ metal complexes where d-d transitions are excluded [47, 48]. Conductivity measurement of metal complexes in DMF solution (10⁻³ M) showed nonelectrolytic nature of Mn(II), Co(II), and Pt(IV) complexes of L_IH (C₁, C₂, and C₇, resp.) and Co(II), Ni(II), Pd(II), and Cd(II) complexes of L_IIH (C₈–C₁₀ and C₁₂, resp.) [50]. Electrolytic nature of 1 : 1 was exhibited by Pd(II), Ir(III) complexes of L_IH (C₅ and C₆) and Pt(IV) complex of L_IIH (C₁₁), 1 : 2 by Ni(II) complex of L_IH (C₃) and 1 : 3 by Cu(II) complex of L_IH (C₄) [50]. According to the above-mentioned data and those of elemental analyses and i.r. spectra, the structures of the metal complexes can be suggested as illustrated in Scheme 3.

7. Biological Activity

7.1. Antibacterial Activity

The growth inhibition of the prepared Schiff and Mannich base ligands and some selected metal complexes were studied against three types of pathogenic bacteria, namely, Proteus mirabilis, Escherichia coli, and Staphylococcus aureus by using DMSO as a solvent and the antibiotic Ceftriaxone as a control. Cultures were incubated at 37°C for 24 h. The inhibition zones were measured, and results are described in Table 5. The Schiff base precursor (SBH) and L_IH were potent against all types of bacteria with the latter being more active than Ceftriaxone, while L_IIH was inactive. Complexes of L_IH with Co(II), Ni(II), Pd(II), and Ir(III) ions (C₂, C₃, C₅, C₆) showed no activity while the Pt(IV) complex (C₇) was as active as the original ligand against all types. Among the selected metal complexes of L_IIH, the Pd(II) complex (C₁₀) was highly potent against all bacterial cultures. These results indicate that the degree of growth inhibition is highly dependent on the structure of ligands, metal complexes, and type of metal ion [51, 52]. Although the inhibition zones of L_IH, C₇ and C₁₀ were larger than that caused by Ceftriaxone, other categories, like toxicity of these compounds, still have to be studied in detail.

7.2. Cytotoxic Effect

Preliminary cytotoxicity tests of the Schiff base (SBH) and its Mannich base ligands (L_IH and L_IIH) with some selected metal complexes were performed in triplicate against cancer cell line of human epidermoid larynx carcinoma (Hep-2) using concentrations of 62.5, 125, 250, and 500 μg/mL in DMSO with exposure time of 48 h using ELISA spectrophotometer. The three organic compounds showed high toxic activities at 125, 250, 250 μg/mL, respectively, causing cell death as was confirmed by the drop in optical absorbance of NR in the treated cells compared with the controls which refers to complete disruption of cell functions [53]. The cytotoxic effect of metal complexes of L_IH was found to increase in the order of Pt(IV) < Pd(II) << Ir(III) as is shown in Figure 9. The Pt(IV) complex (C₇) was much less active than the parent ligand, and its performance was found to decrease with concentration that it was totally inactive at 500 μg/mL.

(a)

(b)

The Pd(II) complex (C₅) followed the same trend of concentration as the Pt(IV) complex but it was toxic enough to cause cell death. The Ir(III) complex (C₆) was exceptionally active, and its cytotoxic activity was found to increase with concentration. Figure 10 illustrates the difference in dye distribution in the tissue culture sections of Hep-2 before and after treatment with this complex in comparison with the control. Both the Pd(II) and Cd(II) complexes of L_IIH (C₁₀ and C₁₂) were less toxic than the parent ligand, and their activity slightly increased with concentration. The Cd(II) complex (C₁₂) caused 30–60% decrease of ligand activity. The complex was similarly inactive against growth of the three bacterial cultures although Cd⁺⁺ ion is well known as an environmental carcinogen at very low concentrations in human and animals [54]. This indicates that the toxicity of Cd⁺⁺ ion can be decreased on complexation with some ligands.

(a)

(b)

The present study describes a narrow scope of the cytotoxic activity of the studied compounds. Extension of this study, in future work to involve other cancer cell lines and other metal complexes, using normal human cell lines as control, may reveal more important data.

8. Conclusions

Condensation of dithiooxamide with isatin or its N-Mannich bases occurred from one amino end of the compound which allowed for tautomerism of the resulted compound in solutions as was confirmed by ¹H.n.m.r spectrum of the product and from the IR spectra of some of its coordination compounds. The potent chelating behavior of the two new Mannich and Schiff bases led to the formation of bi- and polynuclear metal complexes. The preliminary study of biological activity showed some controversy in performance between bacterial growth inhibition and cytotoxic activities against Hep-2 cell line. The Ir(III) complex of L_IH which showed the highest cytotoxic effect was almost inactive against bacterial growth.

References

S. N. Pandeya, S. Smitha, M. Jyoti, and S. K. Sridhar, “Biological activities of isatin and its derivatives,” Acta Pharmaceutica, vol. 55, no. 1, pp. 27–46, 2005.
View at: Google Scholar
S. K. Sridhar, S. N. Pandeya, J. P. Stables, and A. Ramesh, “Anticonvulsant activity of hydrazones, Schiff and Mannich bases of isatin derivatives,” European Journal of Pharmaceutical Sciences, vol. 16, no. 3, pp. 129–132, 2002.
View at: Publisher Site | Google Scholar
S. K. Sridhar, M. Saravanan, and A. Ramesh, “Synthesis and antibacterial screening of hydrazones, Schiff and Mannich bases of isatin derivatives,” European Journal of Medicinal Chemistry, vol. 36, no. 7-8, pp. 615–625, 2001.
View at: Publisher Site | Google Scholar
R. W. Daisley and V. K. Shah, “Synthesis and antibacterial activity of some 5-nitro-3-phenyliminoindol-2(3H)-ones and their N-mannich bases,” Journal of Pharmaceutical Sciences, vol. 73, no. 3, pp. 407–408, 1984.
View at: Google Scholar
J. Borysiewicz and B. Lucka-Sobstel, “The effect of certain Mannich N-bases, derivatives of isatin beta-thiosemicarbazone, on the replication of vaccinia virus in in vitro studies,” Acta Microbiologica Polonica, vol. 27, no. 2, pp. 111–121, 1978.
View at: Google Scholar
S. N. Pandeya, D. Sriram, G. Nath, and E. De Clercq, “Synthesis and antimicrobial activity of Schiff and Mannich bases of isatin and its derivatives with pyrimidine,” Farmaco, vol. 54, no. 9, pp. 624–628, 1999.
View at: Publisher Site | Google Scholar
D. Maysinger, M. Movrin, and M. M. Saric, “Structural analogues of isatin and their antimicrobial activity,” Pharmazie, vol. 35, no. 1, pp. 14–16, 1980.
View at: Google Scholar
S. N. Pandeya, D. Sriram, E. DE. Clercq, C. Pannecouque, and M. Witvrouw, “Anti-HIV activity of some Mannich bases of Isatin derivatives,” Indian Journal of Pharmaceutical Sciences, vol. 60, no. 4, pp. 207–212, 1998.
View at: Google Scholar
S. K. Sridhar, S. N. Pandeya, and E. De Clercq, “Synthesis and anti-HIV activity of some isatin derivatives,” Bollettino Chimico Farmaceutico, vol. 140, no. 5, pp. 302–305, 2001.
View at: Google Scholar
Q. Y. Ye, Y. Nakano, G. R. Frauenhoff, D. R. Whitcomb, F. Takusagawa, and D. H. Busch, “Tetradentate dithiooxamide ligands and their nickel complexes. Synthesis, characterization, and crystal structure of a mononuclear neutral complex, Ni(c-C₅H₉)NHC(S)N(CH₂)₂NC(S) C(S)NH(c-C₅H₉),” Inorganic Chemistry, vol. 30, no. 7, pp. 1503–1510, 1991.
View at: Google Scholar
P. J. Werkman, A. Schasfoort, R. H. Wieringa, and A. J. Schouten, “Langmuir-Blodgett films of a polymerisable N,N'-disubstituted dithiooxamide coordination compound,” Thin Solid Films, vol. 323, no. 1-2, pp. 243–250, 1998.
View at: Google Scholar
M. R. Green, N. Jubran, B. E. Bursten, and D. H. Busch, “Transition-metal complexes of dithiooxamide ligands. Vibrational fine structure in the electronic spectra of symmetrically N,N′-disubstituted dithiooxamides and their divalent nickel ion complexes,” Inorganic Chemistry, vol. 26, no. 14, pp. 2326–2332, 1987.
View at: Google Scholar
J. A. Lekstrom and R. D. Koons, “Copper and nickel detection on gunshot targets by dithiooxamide test,” Journal of Forensic Sciences, vol. 31, no. 4, pp. 1283–1291, 1986.
View at: Google Scholar
A. Castiñeiras, M. C. F. Vidal, J. Romero et al., “Synthesis, characterization, and magnetic behaviour of dinuclear nickel(II) complexes of N,N'-substituted dithiooxamides derived from α-amino acids,” Zeitschrift fur Anorganische und Allgemeine Chemie, vol. 627, no. 7, pp. 1553–1559, 2001.
View at: Google Scholar
L. Stoicescu, M. Negoiu, R. Geogescu, and T. Rosu, “Pd(II), Pt(II), and Cu(II) complexes of N,N'-bis(methoxy-ylethyl)ethandithioamide synthesis and spectroscopic studies,” in Proceedings of the 12th Romanian Conference of Chemistry and Chemical Engineering, Bucharest, Romania, December 2001.
View at: Google Scholar
M. Jansersca and B. Stojceva, “Synthesis of Isatin N-Mannich Bases,” Glas Hem Technol Make donya, vol. 2, no. 1-2, pp. 53–58, 1977.
View at: Google Scholar
A. I. Vogel, A Text Book of Practical Organic Chemistry, Longmans, London, UK, 3rd edition, 1972.
E. G. Rochow, Inorganic Synthesis, vol. 4, McGraw-Hill, New York, NY, USA, 1960.
J. Catt and M. L. Seak, Inorganic Synthesis, vol. 5, Wiley, New York, NY, USA, 1957.
L. H. Kalbus and G. E. Kalbus, “Potentiometric determination of silver with dithiooxamide,” Analytica Chimica Acta, vol. 39, pp. 335–340, 1967.
View at: Google Scholar
O. V. Mikhailov and A. I. Khamitova, “Mild template synthesis of (2,8-dithio-3,7-diaza-5-oxanonanedithioamido-1,9)aquohydroxocobalt(III) in the KCoFe(CN)₆ gelatin-immobilized matrix systems,” Russian Journal of Coordination Chemistry, vol. 24, no. 11, pp. 807–810, 1998.
View at: Google Scholar
E. G. Mesropyan, G. B. Ambartsumyan, A. A. Avetisyan, M. G. Sarkisyan, and G. S. Amazaspyan, “Synthesis of isatin and 5-bromoisatin derivatives,” Russian Journal of Organic Chemistry, vol. 37, no. 10, pp. 1476–1477, 2001.
View at: Publisher Site | Google Scholar
R. C. Elderfield and J. R. Wood, “Synthesis of potential anticancer agents. XV. Nitrogen mustards from indole derivatives,” Journal of Organic Chemistry, vol. 27, no. 7, pp. 2463–2465, 1962.
View at: Google Scholar
S. N. Pandeya, D. Sriram, G. Nath, and E. De Clercq, “Synthesis, antibacterial, antifungal and anti-HIV activities of norfloxacin Mannich bases,” European Journal of Medicinal Chemistry, vol. 35, no. 2, pp. 249–255, 2000.
View at: Publisher Site | Google Scholar
M. C. Pirrung and S. V. Pansare, “Trityl isothiocyanate support for solid-phase synthesis,” Journal of Combinatorial Chemistry, vol. 3, no. 1, pp. 90–96, 2001.
View at: Publisher Site | Google Scholar
N. P. Peet and R. J. Barbuch, “Mass spectral fragmentation and rearrangement of isatin derivatives,” Organic Mass Spectrometry, vol. 19, no. 4, pp. 171–175, 1984.
View at: Google Scholar
P. W. West and L. R. M. Pitombo, “Microdetermination of copper using dithiooxamide crayons and the ring-oven technique,” Analytica Chimica Acta, vol. 37, pp. 374–378, 1967.
View at: Google Scholar
N. Usami, K. Kitahara, S. Ishikura, M. Nagano, S. Sakai, and A. Hara, “Characterization of a major form of human isatin reductase and the reduced metabolite,” European Journal of Biochemistry, vol. 268, no. 22, pp. 5755–5763, 2001.
View at: Publisher Site | Google Scholar
M. C. F. Vidal, I. Lens, A. Castiñeiras, A. Matilla Hernández, J. M. Tercero Moreno, and J. Niclós-Gutiérrez, “N,N' -substituted dithiooxamides derived from alkyl-α-amino acids or from glycylglycine: acid dissociation properties in aqueous solution and crystal and molecular structures of N,N' -bis(carboxymethyl) dithiooxamide (GLYDTO) and N,N' -bis(1-carboxyethyl) dithiooxamide (ALADTO),” Polyhedron, vol. 18, no. 25, pp. 3313–3319, 1999.
View at: Google Scholar
M. Unger, W. Jacobsen, U. Holzgrabe, and L. Z. Benet, “Quantitative liquid chromatography-mass spectrometry determination of isatin in urine using automated on-line extraction,” Journal of Chromatography B, vol. 767, no. 2, pp. 245–253, 2002.
View at: Publisher Site | Google Scholar
D. Wang, Y.-D. Shang, F. Quin, L. Fang, and P. Grong, “Synthesis and in Vitro Antivaral Activities of Some New 2-Arylthiomethyl-4-tertiarylaminomethyl substituted derivatives of 6-Bromo-3-ethoxycarbonyl-5-hydroxyindoles,” Chinese Chemical Letters, vol. 15, no. 1, pp. 19–22, 2004.
View at: Google Scholar
J. B. Jensen, H. Egsgaard, H. Van Onckelen, and B. U. Jochimsen, “Catabolism of indole-3-acetic acid and 4- and 5-chloroindole-3-acetic acid in Bradyrhizobium japonicum,” Journal of Bacteriology, vol. 177, no. 20, pp. 5762–5766, 1995.
View at: Google Scholar
M. Yoneda, K. Tsujimoto, M. Ohashi, M. Shiratsuchi, and Y. Ohkawa, “Structures of [M-44]⁺ ions in the electron impact and fast atom bombardment mass spectra of the b-blocker nipradilol with nitrate ester group,” Organic Mass Spectrometry, vol. 25, no. 3, pp. 146–150, 1990.
View at: Google Scholar
V. Yaylayan, J. R. J. Paré, R. Laing, and P. Sporns, “Formation of β-carboline from 1-[1'-carboxy-2'-indole-3-yl-ethyl)amino]-1-deoxy-D-fructose under electron impact conditions,” Organic Mass Spectrometry, vol. 25, no. 2, pp. 141–145, 1990.
View at: Google Scholar
R. M. Silverstein and F. X. Webster, Spectrometric Identification of Organic Compounds, John Wiley and Sons, New York, NY, USA, 6th edition, 1997.
N. Raman, S. Ravichandran, and C. Thangaraja, “Copper(II), cobalt(II), nickel(II) and zinc(II) complexes of Schiff base derived from benzil-2,4-dinitrophenylhydrazone with aniline,” Journal of Chemical Sciences, vol. 116, no. 4, pp. 215–219, 2004.
View at: Google Scholar
M. Singh and R. Nayan, “Synthesis and characterization of nickel(II) complexes with some tetraaza macrocyclic ligands,” Indian Journal of Chemistry. Section A, vol. 35, no. 3, pp. 239–242, 1996.
View at: Google Scholar
J. R. Allan, J. G. Bonner, A. R. Werninck, H. J. Bowley, and D. L. Gerrard, “Thermal studies on itaconic acid compounds of some transition metal ions,” Thermochimica Acta, vol. 122, no. 2, pp. 295–303, 1987.
View at: Google Scholar
G. L. Van De Cappelle and M. A. Herman, “Dissociation constants of n,n'-bis(2-carboxyethyl)dithiooxamide,” Analytica Chimica Acta, vol. 43, pp. 89–94, 1968.
View at: Google Scholar
H. O. Desseyn, W. A. Jacob, and M. A. Herman, “Infra-red absorption spectra of complexes of dithio-oxamides,” Spectrochimica Acta Part A, vol. 25, no. 10, pp. 1685–1692, 1969.
View at: Google Scholar
H. C. Hofmans, H. O. Desseyn, R. A. Dommisse, P. Van Nuffel, and A. T. H. Lenstra, “Determination of the crystal structure and the spectroscopic data of Pd(N, N' -dicyclopentyldithiooxamide),” Transition Metal Chemistry, vol. 9, no. 6, pp. 213–217, 1984.
View at: Publisher Site | Google Scholar
K. Nakamato, Infrared and Ramman Spectra of Inorganic and Coordination Compounds, John Wiley and Sons, New York, NY, USA, 5th edition, 1997.
X. Weimiad, W. Shurong, and L. Zhiyong, “Synthesis of rare earth coordination compounds of salicylalde-hyde-β-alanine schiff base and their thermal behaviours I,” Thermochimica Acta, vol. 133, pp. 377–382, 1988.
View at: Google Scholar
C. Duval, Inorganic Thermogravimetric Analysis, Elsevier, London, UK, 2nd edition, 1963.
J. R. Allan, A. Renton, W. E. Smith, D. L. Gerrard, and J. Birnie, “Thermal studies on pyridine-3,4-dicarboxylic acid compounds of cobalt, nickel and copper,” Thermochimica Acta, vol. 161, no. 1, pp. 111–118, 1990.
View at: Google Scholar
D. Sutton, Electronic Spectra of Transition Metal Complexes, McGraw-Hill, New York, NY, USA, 1968.
A. B. . Lever, Inorganic Electronic Spectroscopy, Elsevier, Amsterdam, The Netherlands, 1968.
B. N. Figgis, Introduction to Ligand Fields, John Wiely and Sons, New York, NY, USA, 1966.
K. Bruger, Coordination Chemistry, Experimental Methods, Butterworth, London, UK, 1967.
W. J. Geary, “The use of conductivity measurements in organic solvents for the characterisation of coordination compounds,” Coordination Chemistry Reviews, vol. 7, no. 1, pp. 81–122, 1971.
View at: Google Scholar
A. A. Khandar, K. Nejati, and Z. Rezvani, “Syntheses, characterization and study of the use of cobalt (II) Schiff-Base complexes as catalysts for the oxidation of styrene by molecular oxygen,” Molecules, vol. 10, no. 1, pp. 302–311, 2005.
View at: Google Scholar
N. Nawar, M. A. Khattab, M. M. Bekheit, and A. H. El-Kaddah, “Synthesis and spectral studies of manganese(II), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II) and mercury(II) complexes of 4-oxo-4H-1-benzopyran-3-carboxaldehyde hydrazone derivatives,” Indian Journal of Chemistry. Section A, vol. 35, no. 4, pp. 308–312, 1996.
View at: Google Scholar
A. Ravid, D. Rocker, A. Machlenkin et al., “1,25-Dihydroxyvitamin D enhances the susceptibility of breast cancer cells to doxorubicin-induced oxidative damage,” Cancer Research, vol. 59, no. 4, pp. 862–867, 1999.
View at: Google Scholar
S. S. Roy, S. Mukherjee, S. Mukhopadhyay, and S. K. Das, “Differential effect of cadmium on cholinephosphotransferase activity in normal and cancerous human mammary epithelial cell lines,” Molecular Cancer Therapeutics, vol. 3, no. 2, pp. 199–204, 2004.
View at: Google Scholar

Copyright

Copyright © 2011 Ahlam J. Abdulghani and Nada M. Abbas. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies

Views

5245

Downloads

2472

Citations

Bioinorganic Chemistry and Applications

Synthesis Characterization and Biological Activity Study of New Schiff and Mannich Bases and Some Metal Complexes Derived from Isatin and Dithiooxamide

Abstract

1. Introduction

2. Experimental/Materials and Methods

3. Preparation of Ligands

3.1. 3-(1′-N-dithiooxamide)iminoisatin (SBH)

3.2. 1-Morpholinomethyl-3-(1′-N-dithiooxamide)iminoisatin (LIH) and 1-diphenylaminomethyl-3-1′-N-dithiooxamide)Iminoisatin (LIIH)

4. Synthesis of Metal Complexes

5. Biological Activity Study

5.1. Antibacterial Action

5.2. Cytotoxic Activity

6. Results and Discussions

6.1. Synthesis

6.2. Physical Properties and Analytical Data of Metal Complexes

6.3. Infrared Spectra

6.4. Thermal Analysis

6.5. Electronic Spectra and Suggested Structures

7. Biological Activity

7.1. Antibacterial Activity

7.2. Cytotoxic Effect

8. Conclusions

References

Copyright

3.2. 1-Morpholinomethyl-3-(1′-N-dithiooxamide)iminoisatin (L_IH) and 1-diphenylaminomethyl-3-1′-N-dithiooxamide)Iminoisatin (L_IIH)