Mumtaz Iscan

The expression of cytochrome P450 enzymes in human breast tumours and normal breast tissue

Environmental chemicals are one of the risk factors in breast cancer genesis. Cytochrome P450 (CYP) enzymes play a major role in the activation of these chemicals. Using highly specific and sensitive reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, the expression profile of all major xenobiotic metabolizing CYP forms was screened in breast tumour and surrounding tumour free (control) breast tissue in a series of 20 sample pairs obtained from females with infiltrating ductal carcinoma. The levels of CYP1A1 mRNA were very low in both tumour and normal tissue. CYP1B1, CYP2B6, CYP2C, CYP2D6, CYP2E1, CYP4B1, and CYP11A1 expressions were positive in both tumours and control tissue. CYP2A6, CYP2A7, CYP2A13, CYP2F1, CYP3A4, CYP3A5, and CYP3A7 mRNAs were expressed neither in tumours nor in control tissue. These results show that several CYPs, responsible for the activation of a quite large number of procarcinogens and genotoxic estrogen metabolites, are expressed in breast tissue with a lack of qualitative differences in CYP expression at mRNA level between breast tumours and surrounding normal breast.

Interindividual variability of coumarin 7-hydroxylation in a Turkish population.

One hundred healthy Turkish volunteers (70 male, 30 female) aged from 19 to 56 years were given 5 mg coumarin p.o. after an overnight fast. Urine samples were collected before and 2, 4 and 8 h after drug administration. The extent and rate of formation of 7-OH-coumarin (7OHC) was determined by the urinary excretion of the metabolite as measured with the fluorometric method.On average, 80% of 7OHC formed was excreted in 2 h. The total amount of 7OHC formed was 59.8% (21.5%) (mean and SD, n=100, range 17–100%) of the given dose. The percentage of 7OHC excreted during the first 2 h compared with the 7OHC excretion at 8 h was a constant and stable individual characteristic for the rate of the formation of 7OHC (‘2 h coumarin test’).Although four individuals had relatively slow coumarin test values (34–40%), no clear-cut polymorphism in the rate of 7OHC formation was found. However, 7OHC formation was lower in males and in cigarette smokers.

Synthesis and Antioxidant Properties of Novel Benzimidazole Derivatives

Some novel benzimidazole derivatives carrying thiosemicarbazide and triazole moieties at the N1 position were synthesized and their in vitro effects on rat liver microsomal NADPH-dependent lipid peroxidation (LP) levels determined by measuring the formation of 2-thiobarbituric acid reactive substance. The free radical scavenging properties of the compounds were also examined in vitro by determining the capacity to scavenge superoxide anion formation and the interaction with the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). The compounds showed a significant effect in the above tests except to scavenge superoxide anion formation.

The Organochlorine Pesticide Residues and Antioxidant Enzyme Activities in Human Breast Tumors: Is There Any Association?

The levels of some organochlorine pesticides (OCP)s (hexachlorobenzene, HCB, α-hexachlorocyclohexane, α-HCH, β-HCH, γ-HCH, heptachlorepoxide, HE, bis (4-chlorophenyl)-1,1-dichloroethene, p.p′DDE, bis (4-chlorophenyl)-1,1,1-trichloroethane, p.p′ DDT and total DDT (Σ-DDT) and antioxidant enzyme activities namely Cu, Zn superoxide dismutase (SOD), catalase (CAT), selenium-dependent glutathione peroxidase (Se-GSH-Px), total glutathione peroxidase (T-GSH-Px), selenium independent glutathione peroxidase (GSH-Px II), glutathione reductase (GRd), level of reduced glutathione (GSH) and lipid peroxidation (LP), glutathione S-transferase (GST) activity toward several substrates including 1-chloro-2,4-dinitrobenzene (CDNB), 1,2-dichloro-4-nitrobenzene (DCNB), ethacrynic acid (EAA), 1,2-epoxy-3-(p-nitrophenoxy)-propane (ENPP) were measured in tumor and surrounding tumor free tissues of 24 female breast cancer patients and was evaluated whether there exist any association between the levels of OCPs and antioxidants. The mean levels of GSH, α-BHC, γ-BHC and HE, and activities of SOD, Se-GSH-Px, T-GSH-Px, GSH-Px II,GRd, GST CDNB, and GST DCNB were significantly higher in tumors than in controls. In tumors, significant correlations were noted between: SOD and γ-BHC; Se-GSH-Px and γ-BHC; T-GSH-Px and γ-BHC; GSH-Px II and α-BHC, γ-BHC; GSH and α-BHC, γ-BHC, HE; GRd and α-BHC; CDNB GST and α-BHC, γ-BHC. These results show that free-radical mediated oxidative stress is, at least partly, associated with some of these OCP residues in human breast tumors.

A study on the antioxidant capacities of some benzimidazoles in rat tissues

Seven benzimidazole compounds were synthesized and their in vitro effects on rat liver, lung and kidney microsomal NADPH-dependent lipid peroxidation (LP) levels were determined. The significant decrease in male rat liver microsomal LP level was noted only by the compound 4 at 10(-4) M (20%) and 10(-3) M (40%) concentrations whereas the other compounds were ineffective. In lung, only the compound 6 at 10(-4) M concentration exhibited significant alteration, i.e. 56% increase, in LP level. In kidney, however, apart from the compound 4, all the compounds increased LP level (35-52%) significantly. The classical antioxidant, butylated hydroxy toluene (BHT), at 10(-4) M concentration, significantly decreased LP level about 70%, in all the tissues studied. To clarify the effects of compounds 4 and 6 on LP, the responses of some CYPs, which are active in producing reactive oxygen species, to these compounds were also investigated. The compound 4 at 10(-4) and 10(-3) M concentrations inhibited the hepatic microsomal ethoxyresorufin O-deethylase (EROD) (37 and 65%) and pentoxyresorufin O-depenthylase (PROD) (14 and 62%) enzyme activities significantly. However, it did not alter the hepatic microsomal NADPH-cytochrome P450-reductase activity. BHT, at 10(-3) M concentration, significantly inhibited hepatic microsomal EROD (73%), PROD (62%) and NADPH-cytochrome P450 reductase (17%) enzyme activities. Caffeine (10(-3)M) and SKF 525A (10(-3)M), which are specific inhibitors of EROD and PROD enzyme activities, significantly decreased the enzyme activities 33 and 77%, respectively. Caffeine was unable to alter hepatic microsomal NADPH-cytochrome P450 reductase enzyme activity whereas SKF 525A significantly inhibited (80%) it. In lung and kidney, the compound 6 at 10(-4)M concentration significantly increased EROD (44 and 19%) and PROD (103 and 86%) enzyme activities. However, the elevation of PROD enzyme activity in both tissues was observed to be more pronounced than that of EROD enzyme activity. This compound was ineffective on lung and kidney microsomal P450-reductase enzyme activity. These results reveal that the synthesized benzimidazoles have variable tissue dependent in vitro effects on LP due to their distinct effects on CYP activities but not on NADPH-cytochrome P450 reductase activity in rats.

DNA single-strand breakage in rat lung, liver and kidney after single and combined treatments of nickel and cadmium

Single-strand breaks were observed in rat lung and kidney after acute treatment of animals with CdCl2 (4 mg/kg body weight) injected intraperitoneally and NiCl2, (44.4 mg/kg body weight) injected subcutaneously. In the rat liver, no single-strand breakage was evident with those doses in single and combined metal treatments. The most susceptible tissue in rats to cadmium or nickel chloride treatment was the lung tissue. The single-strand breaks were higher in cadmium treatment than in nickel treatment in the rat lung. Also the response to cadmium treatment was obtained earlier than nickel. Rat kidney was also responsive to cadmium treatment. However, the response, although statistically significant, was much lower than the one obtained in rat lung. The combined treatment, which was done by administrating cadmium prior to nickel administration, reduced the number of single-strand breaks significantly and reversed them to control values in rat lung and kidney. This study confirms that cadmium and nickel create single-strand breaks when administered alone in the rat lung. This effect, which was seen in the single metal treatments, was reduced in the combined treatments.

Synthesis, antifungal and antioxidant screening of some novel benzimidazole derivatives

Some novel benzimidazole derivatives were synthesized and their in vitro effects on rat liver microsomal NADPH-dependent lipid peroxidation (LP) level, ethoxyresorufin O-deethylase (EROD) and antifungal activities were determined. A significant decrease in male rat liver microsomal LP level was noted by compounds 4c (52%), 4e (58%) and 4h (43%) at 10− 3 M concentration. Compounds 4c (100.0%), 4h (100.0%), 5c (98.0%) and 5h (100.0%) inhibited the microsomal ethoxyresorufin O-deethylase (EROD) enzyme activity better than that of the specific inhibitor caffeine (85%). Among these compounds, only compounds 4b and 4h exhibited moderate activity against C.albicans whereas the others had weak effects.

Antioxidant Activities of Plants Used in Traditional Medicine in Turkey

Ethanol extracts from 6 species representing six different families, used in traditional medicine in Turkey were evaluated for their antioxidant activities. The inhibition of superoxide anion formation and lipid peroxidation levels of Ononis spinosa, Centranthus longiflorus, Lythrum salicaria, Plantago major, Juglans regia and Teucrium polium extracts were tested using in vitro standard procedures and IC50 values were determined. In vitro tests included superoxide anion radical scavenging activity and lipid peroxidation. All ethanol extracts of plants showed concentration-dependent superoxide anion radical scavenging activity. The results of the superoxide anion formation assay showed that the ethanol extract of Centranthus longiflorus was found to be most potent inhibitor (IC50 0.77 mg/ml) and followed by Plantago major (IC50 1.21 mg/ml), Juglans regia (IC50 1.39 mg/ml), Ononis spinosa (IC50 1.35 mg/ml), Teucrium polium (IC50 3.10 mg/ml) and Lythrum salicaria (IC50 5.00 mg/ml). All the extracts, excluding Ononis spinosa and Teucrium polium, showed concentration-dependent inhibitory effect on lipid peroxidation. IC50 values of the effective ethanol extracts of plants on lipid peroxidation were as follows: Juglans regia (IC50 3.3 mg/ml), Plantago major (IC50 3.4 mg/ml), Centranthus longiflorus (IC50 3.9 mg/ml) and Lythrum salicaria (IC50 5.3 mg/ml). The results showed that Centranthus longiflorus, Plantago major and Juglans regia extracts had the highest antioxidant capacities among the six species examined.

Combined effects of cadmium and nickel on testicular xenobiotic metabolizing enzymes in rats

When male rats were given a single dose of cadmium (Cd) (3.58 mg CdCl2·H2O/kg, ip) 72 hr prior to sacrifice, the testicular 7-ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities toward the substrates 1-chloro-2,4-dinitrobenzene (CDNB), 1,2-dichloro-4-nitrobenzene (DCNB), ethacrynic acid (EAA), 1,2-epoxy-3-(p-nitrophenoxy)-propane (EPNP), and cumene hydroperoxide (CHPx) decreased significantly as compared to controls. Cd also inhibited reduced glutathione (GSH) level while increasing the lipid peroxidation (LP) level significantly. When the animals were given a single dose of nickel (Ni) (59.5 mg NiCl2·6H2O/kg, ip) 16 hr prior to sacrifice, significant decreases were observed in EROD and GST activities toward CDNB, EAA, EPNP, and CHPx, and GSH level. No significant alterations were noted in DCNB GST activity and LP level by Ni. For the combined treatment, rats received the single dose of Ni 56 hr after the single dose of Cd and were killed 16 hr later. In these animals, lesser depressions were observed on EROD activity and LP level than those of Cd alone. The combination of metals significantly inhibited GST activities and GSH level but not to a greater degree than noted by Cd or Ni alone. Plasma testosterone levels of Cd-, Ni-, and combination-treated rats decreased significantly compared to controls. The strongest depression was achieved by Cd alone. Cd, both alone and in combination with Ni, increased the tissue Ni uptake significantly. Ni, however, did not produce such an effect on the tissue uptake of Cd in either case. Cd treatment caused interstitial edema and coagulation necrosis in seminiferous tubules and also caused fibrinoidal necrosis in vascular endothelium. Ni treatment did not produce any pathological testicular alterations compared to controls. Combined treatment produced fewer pathological alterations (i.e., only interstitial edema) than that of Cd treatment. These results reveal that the combination of Cd and Ni does not have a synergistic effect on testicular xenobiotic metabolizing enzymes, and in contrast, Ni has an ameliorating effect on pathological disturbances caused by Cd alone in the rat testis.

In vivo effects of 3-methylcholanthrene, phenobarbital, pyrethrum and 2,4,5-t isooctylester on liver, lung and kidney microsomal mixed-function oxidase system of guinea-pig: A comparative study

The optimum conditions (pH, microsomal protein amount and substrate concentration) of guinea-pig liver, lung and kidney microsomal aniline 4-hydroxylase, ethylmorphine N-demethylase and benzo[a]pyrene hydroxylase activities were determined. Male guinea-pigs weighing 500-700 g were administered 3-methylcholanthrene (25 mg/kg, i.p. 3 days), phenobarbital (75 mg/kg, i.p. 3 days), pyrethrum (120 mg/kg, i.p. 2 days) and 2,4,5-T isooctylester (200 mg/kg, i.p. 3 days). 3-Methylcholanthrene treatment caused significant increases in liver microsomal benzo[a]pyrene hydroxylase and kidney microsomal aniline 4-hydroxylase activities. However, with phenobarbital treatment the only significant increase was observed in liver microsomal ethylmorphine N-demethylase activity. Pyrethrum treatment decreased kidney microsomal ethylmorphine N-demethylase activity significantly. 2,4,5-T isooctylester treatment increased liver microsomal aniline 4-hydroxylase and lung microsomal ethylmorphine N-demethylase activities significantly. Liver microsomal NADPH-cytochrome c reductase activity was increased significantly by phenobarbital and pyrethrum treatment. The other treatments did not cause any significant changes in microsomal NADPH-cytochrome c reductase activities of liver, lung and kidney. Cytochrome P-450 content of guinea-pig liver microsomes were increased significantly about 2.5-fold and 2-fold by treatment with 3-methylcholanthrene and phenobarbital, respectively. 3-Methylcholanthrene also caused 1 nm spectral shift in the absorption maxima of CO difference spectrum of the dithionite-reduced liver microsomal cytochrome P-450, forming P-449.