SEARCH

SEARCH BY CITATION

Keywords:

  • antioxidant activity;
  • benzimidazole;
  • methyleneamino acetamide;
  • thiazolidine

Abstract

  1. Top of page
  2. Abstract
  3. Material and Methods
  4. Results and Discussion
  5. Conclusion
  6. References

Our approach was to synthesize and examine the antioxidant properties of some new 2-[2-(4-chlorophenyl)benzimidazole-1-yl]-N-(2-arylmethyleneamino) acetamide (1–18) and 2-[2-(4-chlorophenyl)benzimidazole-1-yl]-N-(4-oxo-2-aryl-thiazolidine-3-yl)acetamide (1t–18t) derivatives. Their in vitro effects on rat liver microsomal NADPH-dependent lipid peroxidation levels (LP assay) and microsomal ethoxyresorufin O-deethylase activities (EROD assay) were determined. The free radical scavenging properties of the compounds were also examined in vitro determining the interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical. The compounds showed significant effects in the above tests.

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated in aerobic organisms as part of the normal physiological and metabolic processes or from exogenous factors and agents. These ROS are capable of damaging a wide range of essential macromolecules (membrane lipids, proteins, nucleic acids). The damages by ROS are directly or indirectly implicated in the pathogenesis of various disorders such as cardiovascular diseases, Alzheimer’s and other neurodegenerative diseases, cancer, and atherosclerosis (1,2). The interest for the protective role of antioxidants has been growing over the past 15 years. Antioxidants are considered as potential drugs because of their ability to delay or prevent the oxidation of cellular oxidizable substrates by ROS/RNS. The human antioxidant protections include enzymes such as catalase, superoxide dismutase, and glutathione peroxidase as well as some water- and lipid-soluble antioxidant vitamins such as ascorbic acid (vitamin C) and α-tocopherol (vitamin E) (1–5).

It is known that lipid peroxidation is a free radical chain reaction that causes the degeneration of the cell membranes. Most products of lipid peroxidation are known to have mutagenic and/or carcinogenic properties. On the other hand, the antioxidants and antioxidant enzyme systems are major protective systems of organisms. Therefore, drugs possessing antioxidant and free radical scavenging properties are considered for preventing and/or treatment of such diseases that are directly related to the lack of antioxidant capacity of organism. Reactive oxygen species are produced by different mechanisms such as cytochrome P450 (CYP)-dependent enzymes that metabolize chemicals and endogenous substances to produce reactive oxygen species. In this system, CYP1A1/2 have to play important role in NADPH-dependent lipid peroxidation (LP). Thus, it is important to evaluate the effects of synthesized compounds on NADPH-dependent lipid peroxidation and CYP system (5). On the other hand, it is suggested that the DPPH assay is an accurate method with regard to measuring the antioxidant capacity of various compounds (6).

It is well known that benzimidazoles have a variety of biological activities such as antimicrobial (7–10), anticancer (11,12), antihelminthic (13), antiallergic (14,15), and antioxidant (16). In addition, the thiazolidinones display anticonvulsant (17), anticancer (18), antimicrobial (19), and antioxidant (20) activities.

Previously, we reported the synthesis, characterization, and antioxidant properties of some benzimidazole derivatives containing thiadiazole, triazole, and oxadiazole rings at the 1st position (21–28). The aim of this work was to modify the structure of either the arylmethyleneamino (1–18) or aryl thiazolidine (1t–18t) acetamides and to continue searching for improved ROS and RNS scavengers.

inline image

General formulas of the synthesized compounds

Material and Methods

  1. Top of page
  2. Abstract
  3. Material and Methods
  4. Results and Discussion
  5. Conclusion
  6. References

Chemistry

Melting points were determined with a Thermo Scientific Electrothermal melting point apparatus and are uncorrected. 1H-NMR and 13C-spectra were measured with a Varian Mercury 400 MHz instrument using TMS internal standard and DMSO-d6; coupling constants (J) are reported in Hertz. All chemical shifts were reported as δ (ppm) values. ES–MS were obtained with a Waters ZQ Micromass LC–MS spectrometer with positive electrospray ionization method. Elemental analyses (C, H, N, and S) were determined on a Leco CHNS 932 instrument and were within ±0.4% of the theoretical values. Compounds A, B, C, and 5-methoxy-indole-3-carboxaldehyde were previously prepared in our laboratory (23,29).

All instrumental analyses were performed at the Central Laboratory, Ankara University, Faculty of Pharmacy. The chemical reagents used in synthesis were purchased from E. Merck and Aldrich. Butylated hydroxy toluene (BHT) and caffeine were obtained from Sigma. Analytical thin-layer chromatography was performed with Merck precoated TLC plates, and spots were visualized with ultraviolet light.

General procedure for the preparation of (E)/(Z)-2-[2-(4-chlorophenyl) benzimidazole-1-yl]-N-(2-arylmethylene amino) acetamides (1–18)

A mixture of acyl hydrazide (0.02 mol), corresponding aldehyde derivatives (0.02 mol), and ceric ammonium nitrate (0.05 mol) in ethanol (10 mL) was heated under reflux with stirring for 30 min. Water was added, and the precipitated product was filtered and crystallized from ethanol.

General procedure for the preparation of 2-[2-(4-chlorophenyl) benzimidazole-1-yl]-N-(4-oxo-2-aryl-thiazolidine-3-yl) acetamides (1t–18t)

A mixture of the hydrazone 1–18 (0.1 mmol), thioglycolic acid (0.2 mmol), and anhydrous sodium acetate in dry toluene was refluxed for 10 h, and the mixture was then filtered while hot. The filtrate was evaporated under reduced pressure, and the obtained solid was crystallized from ethanol.

Antioxidant activity

Lipid peroxidation level

Male albino Wistar rats (200–225 g) used in the experiments were fed with standard laboratory rat chow and tap water ad libitum. The animals were starved for 24 h prior to kill and then killed by decapitation under anesthesia. The livers were removed immediately and washed in ice-cold distilled water, and the microsomes were prepared as described previously (30). NADPH-dependent LP was determined using the optimum conditions determined and described previously (30) and measured spectrophotometrically by estimation of thiobarbituric acid-reactive substances (TBARS). Amounts of TBARS were expressed in terms of nmol malondialdehyde (MDA)/mg protein. The assay was essentially derived from the methods of Wills (31,32) as modified by Bishayee (33). Lipid peroxidation was determined spectrophotometrically at 532 nm as the thiobarbituric acid-reactive material. Compounds inhibit the production of malondialdehyde, and therefore, the produced color after addition of thiobarbituric acid is less intensive. A typical optimized assay mixture contained 10−3 m test compound, 0.2 nm Fe++, 90 mm KCl, 62.5 mm potassium phosphate buffer, pH 7.4, NADPH-generating system consisting of 0.25 mm NADP+, 2.5 mm MgCl2, 2.5 mm glucose-6-phosphate, 1.0 U glucose-6-phosphate dehydrogenase, and 14.2 mm potassium phosphate buffer pH 7.8 and 0.2 mg microsomal protein in a final volume of 1.0 mL.

7-Ethoxyresorufin O-deethylase enzyme activity

7-Ethoxyresorufin O-deethylase (EROD) activity was measured by the spectrofluorometric method of Burke et al. (34). A typical optimized assay mixture contained 1.0 mm ethoxyresorufin, 10−3 m test compound, 100 mm Tris–HCl buffer pH 7.8, NADPH-generating system consisting of 0.25 mm NADP+, 2.5 mm MgCl2, 2.5 mm glucose-6-phosphate, 1.0 U glucose-6-phosphate dehydrogenase, and 14.2 mm potassium phosphate buffer pH 7.8, and 0.2 mg liver microsomal protein in a final volume of 1.0 mL.

2,2-Diphenyl-1-picrylhydrazyl free radical scavenging activity

The radical scavenging assay was determined by the modified method described by Blois (35). BHT and stock solutions of the compounds were prepared at 10−2 m in DMSO. A series of solutions in DMSO were diluted to varying concentrations in 96-well microplates. Then, methanolic DPPH solution (100 μm) was added to each well. The plate was shaken and placed in the dark. After 30 min, the optical density (OD) of the solution was read at the 517 nm. The methanolic solution of DPPH served as a control. Percentage inhibition was calculated using the following formula:

inline image

where ODcontrol is the absorbance of the control with DMSO and ODsample is the absorbance of the sample in the presence of the compounds. A dose response curve was plotted to determine the IC50 values. IC50 is defined as the concentration sufficient to obtain 50% of a maximum scavenging capacity. All tests and analyses were run in triplicate and averaged. The standard used in this assay was BHT.

Results and Discussion

  1. Top of page
  2. Abstract
  3. Material and Methods
  4. Results and Discussion
  5. Conclusion
  6. References

Chemistry

The desired benzimidazole derivatives were synthesized according to Scheme 1. Compound A having benzimidazole ring was prepared via oxidative condensation of o-phenylenediamine, p-chlorobenzaldehyde, and sodium metabisulfite. Treatment of compound A with ethyl chloroacetate in KOH/DMSO gave the N-alkylated product B. Hydrazine hydrate and the ester B in ethanol were refluxed for 4 h to give the desired hydrazide compound, (2-(p-chlorophenyl)-benzimidazole-1-yl)-acetic acid hydrazide C. Compounds 1–18 were obtained by condensing acyl hydrazide C with the corresponding aldehyde derivatives in the presence of catalytic amounts of ceric ammonium nitrate (CAN) in ethanol (36) Condensation of 1–18 with thioglycolic acid in toluene yielded 2-[2-(4-chlorophenyl) benzimidazole-1-yl]-N-(4-oxo-2-aryl-thiazolidine-3-yl) acetamides (1t–18t).

image

Figure Scheme 1:.  Synthetic pathways to compounds 1–18 and 1t–18t.

Download figure to PowerPoint

In the NMR spectral data, all protons were seen according to the expected chemical shift and integral values. The aromatic protons appeared as multiplet peaks within the range 6.56–8.82 for compounds 1–18 and 6.55–8.34 for compounds 1t–18t. For the compounds 1–18, the signals belonging to the benzylidene group were observed in the aromatic region.

The investigation of 1H-NMR spectra of compounds 1–18 indicated the presence of two singlet signals referring to (E) and (Z) geometric isomers about imino hydrogens (CH=N) and cis/trans amide conformers. Karabatsos et al. (37) describes that imine-attached hydrogen signal of (E) diastereoisomer is downfielded by 0.2–0.3 ppm from the corresponding hydrogen atom signal of (Z) diastereoisomer. This result showed that the construction of an imino bond of the compounds 1–18 is not a diastereoselective process. Karabatsos et al. also suggest that if the hydrazones have an aromatic substituent, it is conceivable that the aromatic ring interacts with the protonated group favoring the (Z) diastereoisomer (Figure 1). In our findings, E and Z diastereoisomers were observed at 8.12–8.57 and 7.90–8.38 ppm, respectively, and the ratio between (E)/(Z) diastereoisomers could be defined from the relative integration of imine-attached hydrogen in the corresponding 1H-NMR spectra (Table 1).

image

Figure 1.  Representation of E and Z configuration of compound 4.

Download figure to PowerPoint

Table 1. 1H-NMR data for diastereomeric imines in the (E)/(Z) diastereoisomers
Compoundδ ppm–N=CH-Diastereoselection Ratio (E)/(Z)a
(E)(Z)
  1. aData obtained by relative integration of the corresponding imine-attached hydrogens of the (E) and (Z) diastereoisomers.

 28.408.213/7
 38.398.233/7
 48.268.062/8
 58.258.043/7
 68.218.014/6
 78.228.023/7
 88.187.993/7
 9   
108.187.993/7
118.187.993/7
148.578.382/8
158.167.973/7
168.157.943/7
178.167.973/7
188.127.903/7

The methylene protons of thiazolidinone (1t–18t) displayed two doublets at 3.70–3.84 and 3.57–4.00 ppm because of the non-equivalent geminal methylene protons. Thiazolidinone protons (-CH) (1t–18t) resonated as singlets at 5.11–6.62 ppm. The methylene protons (-CH2CO-) of compounds 1t–18t were observed at 4.81–4.99 ppm as an AB quartet.

It has been recognized for some time that the two protons of a methylene group adjacent to an asymmetrically substituted carbon or any dissymmetric moiety are magnetically non-equivalent and consequently split each other in the NMR spectra (38). In accord to this expectation, methylene protons of acetamide chain (1t–5t,7t–11t,13t, and 15t–18t) appear as an AB quartet at 4.81–4.99 ppm and with a coupling constant 15.93–20.40 Hz. In the other compounds (6t, 12t, and 14t), magnetically equivalent CH2 protons are observed as a sharp singlet at 4.80–4.94 ppm.

The mass spectra of synthesized compounds showed a M + H ion peak, which is conforming with the molecular formula of the compounds. The structures of the synthesized compounds were consistent with the 1H-, 13C-NMR, and mass spectra. Spectral data are summarized in Tables 1, 2, and 3.

Table 2.   Some physico-chemical properties and spectral findings of compounds 1–18Thumbnail image of
Table 3.   Some physico-chemical properties and spectral findings of compounds 1t–18t
Compd.FormulasM.P (°C)NMRMS M + H (%)
1tC28H21ClN4O2S-0.9H2O285–2883.84, 3.96 (2H, 2d, j = 17.2 Hz, CH2-thiazolidine ring C5), 4.88 ((2H, j = 17.6 Hz, AB quartet, CH2), 6.62 (s, 1H, CH thiazolidine ring C2), 7.09–8.07 (m, 15H, Ar-H), 11.02 (s, 1H, NH)513 (68) 515 (32)
2tC28H21ClN4O2S-0.8HSCH2COOH2623.83, 3.99 (2H, 2d, j = 16.0 Hz, CH2-thiazolidine ring C5), 4.83 ((2H, j = 17.6 Hz, AB quartet, CH2), 6.01 (s, 1H, CH thiazolidine ring C2), 7.01–8.03 (m, 15H, Ar-H), 10.87 (s, 1H, NH)513 (69) 515 (31)
3tC27H22ClN5O3S-0.8H2O3053.74 (s, 3H, OCH3), 3.80, 3.90 (2H, 2d, j = 16.0 Hz, CH2-thiazolidine ring C5), 4.81 (2H, j = 17.1 Hz, AB quartet, CH2), 5.56 (s, 1H, CH thiazolidine ring C2), 6.83–7.85 (m, 12H, Ar-H), 10.72 (s, 1H, NH), 11.22 (s, 1H, NH)532 (71) 534 (29)
4tC24H19ClN4O2S275–2783.76, 3.92 (2H, 2d, j = 16.0 Hz CH2-thiazolidine ring C5), 4.87 (2H, j = 17.6 Hz AB quartet, CH2), 5.80 (s, 1H, CH thiazolidine ring C2), 7.21–7.70 (m, 13H, Ar-H), 10.83 (s, 1H, NH) 13C: 29.8, 46.1, 62.1, 11.4, 119.8, 123.0, 123.4, 128.3, 129.2, 129.4, 129.8, 131.6, 135.4, 136.9, 138.9, 142.9, 153.0, 166.9, 169.6463 (77) 465 (23)
5tC24H18ClFN4O2S-1.1H2O-0.1C2H5OH1473.73, 3.90 (2H, 2d, j = 16.0 Hz, CH2-thiazolidine ring C5), 4.85 (2H, j = 16.8 Hz, AB quartet, CH2), 5.80 (s, 1H, CH thiazolidine ring C2), 7.18–7.69 (m, 12H, Ar-H), 10.78 (s, 1H, NH)482 (70) 484 (30)
6tC24H18Cl2N4O2S-2H2O1693.77, 3.93 (2H, 2d, j = 16.0 Hz , CH2-thiazolidine ring C5), 4.80 (2H, s, CH2), 5.83 (s, 1H, CH thiazolidine ring C2), 7.20–7.76 (m, 12H, Ar-H), 10.83 (s, 1H, NH)497 (60) 499 (40)
7tC24H18 BrClN4O2S-0.2C2H5OH-0.75H2O1453.76, 3.82 (2H, 2d, j = 16.0 Hz CH2-thiazolidine ring C5), 4.99 (2H, j = 18.0 Hz, AB quartet, CH2), 5.92 (s, 1H, CH thiazolidine ring C2), 7.26–7.78 (m, 12H, Ar-H), 9.88 (s, 1H, NH)541 (36) 543 (46) 545 (18)
8tC25H21ClN4O3S-0.5HSCH2COOH-0.9H2O1593.76, 3.88 (2H, 2d, j = 14.40 Hz CH2-thiazolidine ring C5), 3.81 (s, 3H, OCH3), 4.85 (2H, j = 17.20 Hz, AB quartet, CH2), 5.76 (s, 1H, CH thiazolidine ring C2), 6.98–7.82 (m, 12H, Ar-H), 10.77 (s, 1H, NH)493 (78) 495 (22)
9tC24H18ClN5O4S-1H2O1783.80, 4.00 (2H, 2d, j = 16.0 Hz, CH2-thiazolidine ring C5), 4.88 (2H, AB quartet, j = 18.8 Hz CH2), 6.02 (s, 1H, CH thiazolidine ring C2), 7.17–8.34 (m, 12H, Ar-H), 10.90 (s, 1H, NH)508 (73) 510 (27)
10tC31H25ClN4O3S-0.6C2H5OH-1.5H2O220 decomp.3.73, 3.88 (2H, 2d, j = 16.0 Hz, CH2-thiazolidine ring C5), 4.91 (2H, AB quartet, j = 20.4 Hz, CH2), 5.24 (s, 2H, OCH2-), 5.76 (s, 1H, CH thiazolidine ring C2), 6.98–7.70 (m, 19H, Ar-H)569 (64) 571 (36)
11tC24H17ClF2N4O2S-0.1H2O307–3103.77, 3.95 (2H, 2d, j = 15.6 Hz, CH2-thiazolidine ring C5), 4.93 (2H, s, CH2), 5.96 (s, 1H, CH thiazolidine ring C2), 7.20–7.74 (m, 11H, Ar-H), 10.87 (s, 1H, NH)499 (71) 501 (39)
12tC24H17BrClFN4O2S-0.5 HSCH2COOH-0.9C2H5OH1283.75, 3.98 (2H, 2d, j = 16.0 Hz CH2-thiazolidine ring C5), 4.89 (2H, s, CH2), 5.84 (s, 1H, CH thiazolidine ring C2), 7.22–7.86 (m, 11H, Ar-H), 10.84 (s, 1H, NH)559 (37) 561 (48) 563 (15)
13tC24H17Cl2N5O4S-0.85HSCH2COOH1693.81, 3.97 (2H, 2d, j = 16.4 Hz CH2-thiazolidine ring C5), 4.93 (2H, AB quartet, j = 17.5 Hz , CH2), 6.19 (s, 1H, CH thiazolidine ring C2), 7.18–8.25 (m, 11H, Ar-H), 11.04 (s, 1H, NH)542 (63) 544 (37)
14tC24H17Cl3N4O2S-0.85H2O297–2993.77, 3.92 (2H, 2d, j = 15.6 Hz, CH2-thiazolidine ring C5), 4.94 (2H, s, CH2), 6.06 (s, 1H, CH thiazolidine ring C2), 7.19–7.74 (m, 11H, Ar-H), 10.96 (s, 1H, NH)531 (41) 533 (45) 535 (14)
15tC26H23ClN4O4S-0.9HSCH2COOH-1.3H2O287–2893.72–3.93 (m, 8H, OCH3, CH2-thiazolidine ring C5), 4.89 ((2H, AB quartet, j = 16.0 Hz , CH2), 5.79 (s, 1H, CH thiazolidine ring C2), 6.55–7.70 (m, 11H, Ar-H), 10.90 (s, 1H, NH) 13C: 29.7, 46.2, 55.9, 62.0, 101.3, 105.9, 11.4, 119.8, 123.0, 123.4, 129.1, 129.5, 131.5, 135.4, 136.9, 141.4, 142.9, 152.9, 161.3, 166.9, 169.7523 (70) 525 (30)
16tC32H27ClN4O4S-0.3HSCH2COOH-0.45H2O1193.70–3.90 (m, 5H, OCH3,CH2-thiazolidine ring C5), 4.88 ((2H, AB quartet, j = 17.2 Hz , CH2), 5.05 (s, 2H, OCH2-), 5.81 (s, 1H, CH thiazolidine ring C2), 6.96–7.69 (m, 16H, Ar-H), 10.78 (s, 1H, NH)599 (68) 601 (32)
17tC32H27ClN4O4S-0.95HSCH2COOH106–1073.71–3.88 (m, 5H, OCH3, CH2-thiazolidine ring C5), 4.84 ((2H, AB quartet, j = 17.0 Hz, CH2), 5.11 (s, 2H, OCH2-), 5.76 (s, 1H, CH thiazolidine ring C2), 6.87–7.67 (m, 16H, Ar-H), 10.75 (s, 1H, NH)599 (69) 601 (31)
18tC38H31ClN4O4S-0.25 HSCH2COOH-1.4H2O1273.74, 3.86 (2H, 2d, j = 15.6 Hz CH2-thiazolidine ring C5), 4.86 (2H, AB quartet, j = 17.6 Hz, CH2), 5.06 (s, 2H, OCH2-), 5.18 (s, 2H, OCH2-), 5.78 (s, 1H, CH thiazolidine ring C2), 6.94–7.70 (m, 21H, Ar-H), 10.87 (s, 1H, NH)675 (66) 677 (34)

Antioxidant activity in vitro

The in vitro effects of the compounds and caffeine in liver microsomal EROD activity are shown in Table 4. All the tested compounds except compound 6t (24%) showed significant inhibition (50–95%) of EROD activity. Compounds 1, 3, 5, 11, 16, 17, and 18 decreased liver EROD activity in the range of 87–95%, better than that of the specific inhibitor caffeine (85%) at 10−3 m concentration. In terms of inhibition on EROD activity, it can be said that 2-[2-(4-chlorophenyl) benzimidazole-1-yl]-N-(2-arylmethylene amino) acetamide (1–18) derivatives displayed better activity than 2-[2-(4-chlorophenyl) benzimidazole-1-yl]-N-(4-oxo-2-aryl-thiazolidine-3-yl) acetamide (1t–18t) counterparts. Among the compounds 1–18, different aryl groups such as phenyl, 1- or 2-naphthyl or indole-3-yl have exhibited no considerable difference. The most active compound 16 inhibited EROD activity with a 0.360 mm IC50 value, which has 4-methoxy-3-benzyloxy phenyl ring as aryl group, while IC50 value of caffeine was 0.520 mm. Significant inhibitory activities were also observed for compounds 2 (81%), 9 (81%), 4 (84%), 6 (84%), and 14 (83%).

Table 4.   Effects of the compounds on the liver LP levels, EROD enzyme, and DPPH free radical scavenging activities in vitroa
CompoundbEROD (pmol/mg/dk)% of controlLP (nmol/mg/dk)% of controlDPPH % of control
  1. aEach value represents mean ± SD of 2–4 independent experiments.

  2. bConcentration in incubation medium (10−3 m).

  3. cDMSO only, control for compounds.

  4. nt, not tested.

 15.20 ± 0.27138.12 ± 0.385024 ± 3.8
 27.75 ± 0.75197.29 ±  2.134584 ± 0.8
 34.93 ± 0.631264.99 ± 5.2739970 ± 2.2
 46.69 ± 0.08162.63 ± 0.971688 ± 1.7
 54.49 ± 0.111111.04 ± 0.9568nt
 66.81 ± 0.11168.12 ± 0.565090 ± 0.6
 79.95 ± 0.322417.69 ± 2.0210970 ± 3.8
 812.36 ± 1.31286.33 ± 2.5339 92 ± 1.0
 98.03 ± 3.161918.52 ± 3.21114nt
1014.95 ± 0.44364.06 ± 0.682572 ± 3.9
114.60 ± 6.08117.17 ± 1.3544nt
1217.14 ± 1.86417.17 ± 5.0744nt
138.49 ± 0.412013.62 ± 1.5684nt
147.25 ± 1.801715.77 ± 3.049786 ± 3.0
1510.36 ± 6.74254.54 ± 0.2328 91 ± 0.6
162.13 ± 0.11519.00 ± 6.2511685 ± 2.0
175.06 ± 0.121210.75 ± 1.026672 ± 0.6
185.47 ± 0.20131.80 ± 0.161188 ± 2.2
1t22.51 ± 1.17544.00 ± 1.362581 ± 1.2
2t17.93 ± 1.114319.17 ± 1.4911959 ± 0.7
3t11.25 ± 0.4227nd66 ± 1.7
4t19.11 ± 0.25461.67 ± 0.031085 ± 1.5
5t14.60 ± 1.22352.70 ± 0.481785 ± 0.1
6t31.89 ± 0.50763.54 ± 0.352296 ± 1.2
7t20.66 ± 0.70502.60 ± 0.081669 ± 1.4
8t16.23 ± 1.03393.63 ± 0 192255 ± 1.0
9t14.35 ± 2.40351.52 ± 0.48973 ± 1.8
10t11.23 ± 1.61275.64 ± 0.423423 ± 0.6
11t9.25 ± 1.09223.76 ± 0.912397 ± 0.4
12t12.76 ± 3.34312.36 ± 0.541554 ± 0.9
13t14.91 ± 1.81363.29 ± 0.412052 ± 0.7
14t16.06 ± 0.01379.65 ± 0.305971 ± 2.0
15t14.22 ± 3.59343.41 ± 0.832162 ± 2.4
16t13.12 ± 3.25323.53 ± 0.042262 ± 0.6
17t10.47 ± 0.36254.22 ± 0.352668 ± 0.8
18t18.85 ± 0.79451.77 ± 0.531176 ± 1.7
BHT  5.68 ± 0.223515 ± 2.9
Caffeine6.41 ± 0.3615   
Controlc41.53 ± 0.9910016.25 ± 1.45100100

Inhibition of NADPH-dependent lipid peroxidation (Table 4) produced by the compounds in the rat liver microsomes was examined by measuring the formation of the TBARS for their antioxidant capacity. In contrast to EROD activity, in the series of thiazolidinone, all of the compounds except compound 10t have better LP activities than corresponding methylaminoacetamide derivatives (1–18). The most active compound 9t (2-[2-(4-chlorophenyl) benzimidazole-1-yl]-N-(4-oxo-2-(3-nitrophenyl-thiazolidine-3-yl) acetamide) caused 91% inhibition (0.375 mm IC50) on LP level in rat liver microsomes at 10−3 m concentration, while BHT showed 65% inhibition (0.408 mm IC50) at the same concentration.

We also tested the DPPH radical scavenger capacities (Table 4) by the synthesized compounds. Almost all of the compounds’ DPPH free radical scavenger capacities were not enough, except compounds 1 and 10t. Compounds 1 and 10t showed the highest scavenger capacities among the tested compounds on DPPH radical with 76% and 77%, respectively, which are close to BHT (85%).

Conclusion

  1. Top of page
  2. Abstract
  3. Material and Methods
  4. Results and Discussion
  5. Conclusion
  6. References

Compound 10t appeared to have similar effect for all assay systems. It is plausible to suggest that the inhibition of LP levels and DPPH scavenger capacities could be related to decrease in production of oxygen radicals because of the depression of CYPA1/2. Moreover, the other compounds showed different effect on these parameters. Such contradictory results have also been found in a previous study (39). Each method relates to the generation of a different radical, acting through a variety of mechanism. Therefore, the observation of different effects of the synthesized compounds on EROD activity, LP levels, and DPPH radical scavenger capacity is not surprising, as the mechanism of production of reactive oxygen species using these methods is different.

References

  1. Top of page
  2. Abstract
  3. Material and Methods
  4. Results and Discussion
  5. Conclusion
  6. References
  • 1
    Rice-Evans C., Diplock A.T. (1991) Techniques in Free Radical Research. Amsterdam: Elsevier, 291 p.
  • 2
    Hallivell B., Halliwell B. (1994) Free radicals and antioxidants: a personal view. Nutr Rev;52:253265.
  • 3
    Krishna M.C., DeGraff W., Hankovszky O.H., Sar C.P., Kalai T., Jeko J., Russo A., Mitchell J.B., Hideg K. (1998) Studies of structure–activity relationship of nitroxide free radicals and their precursors as modifiers against oxidative damage. J Med Chem;41:34773492.
  • 4
    Shackelford R.E., Kaufmann W.K., Paules R.S. (2000) Oxidative stress and cell cycle checkpoint function. Free Radical Biol Med;28:13871404.
  • 5
    Cadenas E., Packer L. (2002) Handbook of Antioxidants, 2nd edn. Revised and Expanded. New York-Basel: Marcel Dekker.
  • 6
    Sa′nchez-Moreno C. (2002) Review: methods used to evaluate the free radical scavenging activity in foods and biological systems. Food Sci Technol Int;8:121137.
  • 7
    Abdel-Rahman A.E., Mahmoud A.M., El-Naggar G.M., El-Sherief H.A. (1983) Synthesis and biological activity of some new benzimidazolyl-azetidin-2-ones and thiazolidin-4-ones. Pharmazie;38:589590.
  • 8
    Coburn R.A., Clark M.T., Evans R.T., Genco R.J. (1987) Substituted 2-(2-hydroxyphenyl) benzimidazoles as potential agents for the control of periodontal diseases. J Med Chem;30:205208.
  • 9
    Soliman F.S.G., Rida S.M., Badawey E.A.M., Kappe T. (1984) Synthesis of substituted 3-hydroxy-1H,5H-pyrido[1,2-a]benzimidazol-1-ones as possible antimicrobial and antineoplastic agents. Arch Pharm;317:951958.
  • 10
    Podunovac-Kuzmanovic S.O., Cvetkovic D.D., Barna D.J. (2008) The effect of lipophilicity on the antibacterial activity of some 1-benzylbenzimidazole derivatives. J Serb Chem Soc;73:967978.
  • 11
    Islam I., Skibo E.B., Dorr R.T., Alberts D.S. (1991) Structure-activity studies of antitumor agents based on pyrrolo[1,2-a]benzimidazoles: new reductive alkylating DNA cleaving agents. J Med Chem;34:29542961.
  • 12
    Kruse L.I., Ladd D.L., Harrsch P.B., McCabe F.L., Mong S.M., Faucette L., Johnson R. (1989) Synthesis, tubulin binding, antineoplastic evaluation, and structure-activity relationships of oncodazole analogues. J Med Chem;32:409417.
  • 13
    Habernickel V.J. (1992) Alkyl-5-heterocyclic-benzimidazolyl-carbamate derivatives. Drugs Ger;35:97.
  • 14
    Fukuda T., Morimoto Y., Iemura R., Kawashima T., Tsukamoto G., Ito K. (1984) Efffects of 1-(2- ethoxyethyl)-2-(4-methyl-1-homopiperazinyl)-benzimidazole difumarate (KB-2413), a new antiallergic, on chemical mediators. Arzneim-Forsch/Drug Res;34:801805.
  • 15
    Nakano H., Inoue T., Kawasaki N., Miyataka H., Matsumoto H., Taguchi T., Inagaki N., Nagai H., Satoh T. (2000) Synthesis of benzimidazole derivatives as antiallergic agents 5-lipoxygenase inhibiting action. Bioorg Med Chem;8:373380.
  • 16
    Can-Eke B., Puskullu M.O., Buyukbingol E., Iscan M. (1998) Study on the antioxidant capacities of some benzimidazoles in rat tissues. Chem Biol Interact;113:6577.
  • 17
    Siddiqui N., Arshad M.F., Khan S.A., Ahsan W. (2010) Sulfonamide derivatives of thiazolidin-4-ones with anticonvulsant activity against two seizure models:synthesis and pharmacological evaluation. J Enzyme Inhib Med Chem;25:485491.
  • 18
    Havrylyuk D., Mosula L., Zimenkovsky B., Vasylenko O., Gzella A., Lesyk R. (2010) Synthesis and anticancer activity evaluation of thiazolidinones containing benzothiazole moiety. Eur J Med Chem;45:50125021.
  • 19
    Upadhyay A., Srivastava S.K., Srivastava S.D. (2010) Conventional and microwave assisted synthesis of some new N-[(4-oxo-2-substituted aryl _1, 3-thiazolidine)-acetamidyl]- 5-nitroindazoles and its antimicrobial activity. Eur J Med Chem;45:35413548.
  • 20
    Cacic M., Molnar M., Sarkanj B., Has-Schon E., Rajkovic V. (2010) Synthesis and antioxidant activity of some new coumarinyl-1,3-thiazolidine-4-ones. Molecules;15:67956809.
  • 21
    Kus C., Ayhan-Kılcıgil G., Can-Eke B., Iscan M. (2004) Synthesis and antioxidant properties of some novel benzimidazole derivatives on lipid peroxidation in the rat liver. Arch Pharm Res;27:156163.
  • 22
    Kuş C., Ayhan-Kilcigil G., Altanlar N. (2004) Antimicrobial activity of some thiadiazolyl- and triazolylbenzimidazoles. J Fac Pharm Ankara Univ;33:16.
  • 23
    Ayhan-Kılcıgil G., Kus C., Coban T., Can-Eke B., Iscan M. (2004) Synthesis and antioxidant properties of novel benzimidazole derivatives. J Enzyme Inhib Med Chem;19:129135.
  • 24
    Ayhan-Kilcigil G., Kus C., Coban T., Can-Eke B., Ozbey S., Iscan M. (2005) Synthesis, antioxidant and radical scavenging activities of novel benzimidazoles. J Enzyme Inhib Med Chem;20:503514.
  • 25
    Ayhan-Kilcigil G., Kuş C., Özdamar E.D., Can-Eke B., İşcan M. (2007) Synthesis and antioxidant capacities of some new benzimidazole derivatives. Arch Pharm Chem Life Sci;340:607611.
  • 26
    Kerimov I., Ayhan-Kilcigil G., Can-Eke B., Altanlar N., Iscan M. (2007) Synthesis, antifungal and antioxidant screening of some novel benzimidazole derivatives. J Enzyme Inhib Med Chem;22:696701.
  • 27
    Kuş C., Ayhan-Kilcigil G., Özbey S., Kaynak F.B., Kaya M., Çoban T., Can-Eke B. (2008) Synthesis and antioxidant properties of novel N-methyl-1,3,4-thiadiazol-2-amine and 4-methyl-2H-1,2,4-triazole-3(4H)-thione derivatives of benzimidazole class. Bioorg Med Chem;16:42944303.
  • 28
    Kuş C., Ayhan-Kılcıgil G., Tunçbilek M., Altanlar N., Çoban T., Can-Eke B., İşcan M. (2009) Synthesis, antimicrobial and antioxidant activities of some benzimidazole derivatives. LDDD;6:374379.
  • 29
    Gurkan A.S., Karabay A., Buyukbingol Z., Adejare A., Buyukbingol E. (2005) Syntheses of novel indole lipoic acid derivatives and their antioxidant effects on lipid peroxidation. Arch Pharm Chem Life Sci;338:6773.
  • 30
    Iscan M., Arinc E., Vural N., Iscan M.Y. (1984) In vivo effects of 3-methylcholantrene, phenobarbital, pyretrum and 2,4,5-tisooctylester on liver, lung and kidney microsomal mixed function oxidase system of guinea-pig: a comparative study. Comp Biochem Physiol;77C:177190.
  • 31
    Wills E.D. (1966) Mechanism of lipid peroxide formation in animal tissues. Biochem J;99:667676.
  • 32
    Wills E.D. (1969) Lipid peroxide formation in animal tissues. Biochem J;113:333341.
  • 33
    Bishayee S., Balasubramanian A.S. (1971) Lipid peroxide formation in rat brain. J Neurochem;18:909920.
  • 34
    Burke M.D., Thompson S., Elcombe C.R., Halpert J., Haaparanta T., Mayer R.T. (1985) Ethoxy-, pentoxy- and benzyloxyphenoxazones and homologues: a series of substrates to distinguish between different induced cytochromes P-450. Biochem Pharmacol;34:33373345.
  • 35
    Blois M.S. (1958) Antioxidant determination by the use of a stable free radical. Nature;181:11991200.
  • 36
    Dabiri M., Salehi P., Baghbanzadeh M., Bahramnejad M. (2006) A facile procedure for the one-pot synthesis of unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles. Tetrahedron Lett;47:69836986.
  • 37
    Karabatsos G.J., Graham J.D., Vane F.M. (1962) Syn-anti isomer determination of 2,4-dinitrophenylhydrazones and semicarbazones by N.m.r. J Am Chem Soc;84:753755.
  • 38
    Hill R.K., Chan T.K. (1965) Magnetic non-equivalence of methylene protons in dissymmetric benzylamines: a simple method of assignment of configuration to identically α,α′-disubstituted heterocyclic bases. Tetrahedron;21:20152019.
  • 39
    Ölgen S., Coban T. (2003) Antioxidant evaluations of novel N-H and N-substituted indole esters. Biol Pharm Bull;26:736738.