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PubMed2006

Detection of benzopyrene-deoxyguanosine adducts by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

A method for the detection of BPDE-d guanosine adducts using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is described and illustrated. The results indicate that MALDI is capable of detecting two other DNA benzopyrene adducts, which are trace products formed during the synthesis of BPDE-d guanosine. This MALDI-TOFMS method offers the potential for the detection of DNA adducts in human tissue using very limited sample purification and preparation.

Benzopyrenes↗
PubMed1976

Prevention of 3,4-benzopyrene carcinogenesis in presence of putrescine.

The 3,4-Benzopyrene (3,4-BP) carcinogenesis can be postponed or even completely inhibited in the presence of Putrescine (P). A single s.c. injection of 2.52 mg 3,4-BP in 0.5 ml tricaprylin on female mice (NMRI-strains, 4--5 weeks old, 20--25 g of body weight) induced locally malignant tumors (sarcomas and carcinomas) up to 97% of the animals treated. (132 mice with tumors from 136 animals treated). Animals injected with 3,4-BP plus 10 mg putrescine showed a considerable reduction of tumor incidence. Only three from 38 mice treated developed tumors (8%). The prevention of tumor could not be further improved with higher putrescine amounts, for example 15 mg and 20 mg P. These concentrations were moreover toxic to the animals. Histologically, the tumors developed in the presence of putrescine were rather poor in malignant cells and mitoses were also rare, in contrast to the usual 3,4-BP tumors which were rich in polymorph cells and mitoses.

Animals↗
PubMed1976

Experimental investigations on the influence upon the chemical carcinogenesis. IInd communication: studies with 3,4-benzopyrene.

After subcutaneous application of 0.5 mg 3,4-benzopyrene (BP) to Sprague-Dawley-rats on the 2nd day of life, 50% of the animals developed local fibrosarcomas after 250 +/- 70 days. Additional treatment with immunostimulating (BCG, albumin, vitamin A-acid) or immunodepressive agents (hydrocortisone, cyclophosphamide, methotrexat) which was started 6 days after birth and maintained throughout life, did not influence carcinogenesis with respect to tumor incidences and induction periods of tumors.

Animals↗
PubMed1993

Effect of four plant phenols, beta-carotene and alpha-tocopherol on 3(H)benzopyrene-DNA interaction in vitro in the presence of rat and mouse liver postmitochondrial fraction.

The modulatory effect of beta-carotene, alpha-tocopherol and the four plant phenols eugenol, hydroxychavicol, curcumin and catechin on mouse and rat liver postmitochondrial fraction (S9 mix)-mediated 3(H)benzopyrene (B(a)P)-DNA interaction in vitro was studied. All the plant phenolics significantly inhibited 3(H)B(a)P-DNA interaction in the presence of both mouse and rat liver S9 fractions. In contrast, alpha-tocopherol proved to be ineffective in the presence of both types of S9 mix, whereas beta-carotene inhibited only mouse S9 mix-mediated 3(H)B(a)P-DNA interaction.

Animals↗
PubMed1982

Effects of protein-degradation inhibitors on the inactivation of tyrosine aminotransferase, tryptophan oxygenase and benzopyrene hydroxylase in isolated rat hepatocytes.

The following three potent inhibitors of hepatocytic proteolysis were investigated to see if they would inhibit the intracellular inactivation of enzymes: chymostatin and leupeptin (proteinase inhibitors) and methylamine (a lysosomotropic weak base). Chymostatin inhibited the inactivation of two of the three enzymes tested: tyrosine aminotransferase (EC 2.6.1.5) and tryptophan oxygenase (tryptophan 2,3-dioxygenase, EC 1.13.11.11). Leupeptin had no effect on any of the enzymes, whereas methylamine had only a weak inhibitory effect on tyrosine aminotransferase inactivation. Apparently proteolytic cleavage (probably by a non-lysosomal proteinase, since only chymostatin is effective) is involved in the inactivation of tyrosine aminotransferase and tryptophan oxygenase. The third enzyme, benzopyrene hydroxylase (flavoprotein-linked mono-oxygenase, EC 1.14.14.1), is probably inactivated by a non-proteolytic mechanism.

Animals↗
PubMed1995

Inhibition of benzopyrene-induced forestomach tumors by field bean protease inhibitor(s).

Protease inhibitors (PIs), particularly the soybean-derived Bowman-Birk inhibitor, have proved to be powerful blockers of carcinogenesis in many in vitro and animal model systems. However, so far an ability of PIs to suppress gastric carcinogenesis has not been demonstrated, because of the anticipated 'hostile' acidic gastric environment for the PI to exert its action. We therefore examined the ability of a purified PI from the Indian legume the field bean (FBPI), when administered by gavage, to subdue benzopyrene (BP)-induced neoplasia of the forestomach of mice. Forestomach tumors were produced in female Swiss albino mice by oral administration of BP at a dose of 1 mg twice weekly for 4 weeks. Groups of mice were treated per os with an aqueous solution of FBPI for 3 months or more at a dose of 20 mg/kg once daily, six times a week, either from the initiation of carcinogenesis or after completion of the carcinogen treatment. Another group was treated likewise with autoclaved inactive FBPI. Mice of both the FBPI-treated groups showed statistically significant (P < 0.001) reductions in the multiplicity of gastric tumors, with the tumor incidence being unaffected. However, the suppression of tumor multiplicity was appreciably (P < 0.01) more in the group that received FBPI treatment concomitantly with the carcinogen. The mice that were treated with heat-inactivated FBPI showed similar tumor multiplicity to the BP-treated group, indicating that the oncopreventive activity of FBPI is related to its protease inhibitory capacity. These observations point to the potential of PIs as effective chemoprotectors against gastric cancer in animals and, possibly, in humans as well.

Animals↗
PubMed1987

Proteolytic enzymes as new tumor markers in rats with benzopyrene sarcoma.

Proteolytic enzymes may facilitate tumor invasion by histolysis of the surrounding tissue and inhibit tumor growth in the course of host defense reactions. Using chromogenic peptide substrates, we looked for proteolytic activities related to carcinogenesis in serum and tumor extracts of rats with benzopyrene sarcomas. The enzymatic hydrolysis of two substrates (Boc-(Ala)2-p-nitroanilide and Bz-Lys-p-nitroanilide) was significantly decreased in the sera of tumor-bearing animals (P less than 0.01). This loss of proteolytic activity was highly correlated to tumor growth, so these enzymes might become useful as new tumor markers. In the tumor extracts, we found the Boc-(Ala)2-p-nitroanilide cleaving activity increased with tumor weight, whereas the Bz-Lys-p-nitroanilide cleaving activity did not exhibit any correlation to tumor growth. Studies on the potential use of these results for cancer patients are indicated.

Aminopeptidases↗
PubMed1987

[Determination of benzopyrene-hydroxylase (cytochrome P-450) activity in patients with lung cancer].

The study was concerned with comparison of inducibility index (ii) for benzopyrene-hydroxylase in mitogen-activated lymphocytes in patients with primary cancer of the lung, other cancers (breast, stomach, lower lip, rectum, skin and thyroid gland) and in lymphocytes of blood donors. The highest ii values were registered in bronchogenic carcinoma patients. Smokers, both lung cancer patients and healthy donors, revealed high values (80.0 and 83.3%, respectively). A modified "lymphocytic test" to assess the risk factor for primary lung cancer is suggested.

Adult↗
PubMed1982

[The presence of 3,4-benzopyrene in plants I. Methods].

Purification methods of vegetable extracts have been experienced during our researches on the possible presence of the aromatic polycyclic hydrocarbons (particularly 3,4 benzopyrene) in vegetables. The validity of different methods has been determined by IR spectrophotometric analysis using special apparatus (IR-DATA-STATION). Vegetables extracts have been purified efficaciously by column chromatography, saponification and special methods (Grimmer's method). The described method eliminates, nearly entirely, the polluting substances that could alternate the chemical analysis of the vegetable extracts.

Benzo(a)pyrene↗
PubMed1982

Reactivity of free and coordinated radicals in biology and chemical carcinogenity. I. Coordinated phenoxy radicals generated by hydrogen transfer from hydroxy derivatives of 3,4-benzopyrene.

The tautomeric keto form of 6-, 7- and 8-hydroxy-3,4-benzopyrene (BP) prevails in nonpolar solvents at laboratory temperature, in contrast with the enol form of 9-HO-BP and 3-HO-BP, as it was shown according to the ESR study of H-transfer reactions initiated by tert. butyl peroxy radicals coordinated upon the hydroxy derivative of cobalt(III)-acetylacetonate [HO-Co(acac)2]. A further hydroxylation of the keto form of 6-HO-BP, mainly in the position 3, in the thermal interval 40-60 degrees C and the presence of oxygen was observed. Because of lack of steric hindrance in the neighborhood of the position 3 or 9 the primarily formed phenoxy radical after H-abstraction remains stabilized as sigma-coordinated radical on CoIII. Such a radical complex can be destroyed after addition of polar solvents (e.g. methanol). During autooxidation of BP in aerated solutions, similarly as during enzymatic oxidation, a relatively great concentration of high-stable radicals accumulates in nonpolar solvents and in the absence of peroxides. The paramagnetic species is interpreted as a radical pair of two nondissociated semiquinones. In discussion of the carcinogenic activity of oxidative products of BP, not only the enzymatically formed, but also the randomly formed radical intermediates in the first steps of autooxidation must be taken into consideration, which reactivity to biological targets is mediated with the polarity of the biological medium.

Animals↗
PubMed1983

Reactivity of free and coordinated radicals in biology and chemical carcinogenesis. II. Electron transfer from 3,4-benzopyrene to molecular oxygen and to peroxides, and interpretation of ESR signals of the intermediate radicals of oxidation.

Already a trace of oxygen mediates the one-electron transfer from 3,4-benzopyrene (benzo(a)pyrene, BP) to hydrogen peroxide or to tert. butyl hydroperoxide (ROOH), leading in this way to generation of highly reactive HO X, HO2 X or RO X and RO2 X radicals in nonpolar solvents at biological temperatures. At slightly higher concentration of O2 in solution and at moderately elevated temperature (40-60 degrees C) a stable radical pair (HO-BPO X)2 in equilibrium with its diamagnetic dimer of quinone-hydroquinone type is formed. The paradiamagnetic equilibrium of this redox system is reversibly shifted with temperature. At low temperature (up to -40 degrees C) the paramagnetism disappears. The precursor of the radical pair, which can be decomposed, applying a polar solvent, is the keto form of the hydroxy derivative (6-HO-BP) at ambient temperature. According to the study of highly resolved ESR spectra of the primary temporarily formed ion radical pair [BP+ X O-2 X] of BP oxidation in the dark, of the secondary radical pair (HO-BPO X)2 and of the coordinated unhindered phenoxy radicals of hydroxy derivatives BPO X CoIII, the mechanisms of one-electron or of hydrogen-atom transfer from radical intermediates of BP to potential biological targets is discussed.

Animals↗
PubMed1983

Selective immunosuppression resulting from exposure to the carcinogenic congener of benzopyrene in B6C3F1 mice.

B6C3F1 mice were exposed to two congeners of benzopyrene, either the carcinogen benzo(a)pyrene (B(a)P) or the non-carcinogen benzo(e)pyrene (B(e)P. Exposure of mice to B(a)P resulted in a reduced number of IgM and IgG antibody plaque forming cells (PFC) to the T-dependent (TD) antigen SRBC and IgM PFC's to the T-independent (TI) antigen LPS. The IgM response to hapten conjugated TI antigens was examined using TNP-LPS for reactivity of less mature B cells (B1) and TNP-Ficoll for more mature B cells (B2). Exposure to B(a)P severely depressed the TNP-Ficoll PFC response by up to 77% without altering the TNP-LPS response. These data indicated that exposure to B(a)P alters differentiation and antibody production in mature B cells to both TD and B2 TI antigens. No change in PFC was observed following exposure to B(e)P. Mishell-Dutton co-cultures confirmed that B cells were affected and that T helper cells or suppressor Mphi were not involved. Parameters of cell-mediated immunocompetence including delayed cutaneous hypersensitivity to KLH, allograft or tumour cell rejection and susceptibility to Listeria monocytogens were unaltered in B(a)P treated mice.

Animals↗