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PubMed1992

Anticarcinogenic action of diallyl sulfide in hamster buccal pouch and forestomach.

The anticarcinogenic action of the garlic constituent diallyl sulfide (DAS), was examined in the hamster buccal pouch and forestomach. Groups of hamsters were topically treated, for up to 14 weeks, with a 0.5% solution of the buccal pouch and forestomach carcinogen 7,12-dimethylbenz[a]anthracene (DMBA). Prior to, during and after DMBA treatment, groups of hamsters were also treated, on alternate days, with a 1% solution of DAS. In addition to tumor formation, the induction of gamma-glutamyl transpeptidase (gamma GT) buccal pouch epithelial lesions served as an additional presumptive index of in vivo carcinogenesis/anticarcinogenesis. DAS resulted in a significant reduction in buccal pouch tumor frequency, buccal pouch tumor burden, buccal pouch gamma GT lesion frequency and forestomach tumor frequency. In a separate experiment, DAS also reduced the level of autoradiographically quantified unscheduled DNA repair synthesis (UDS) in pieces of hamster buccal pouch concurrently exposed in vitro to the potent buccal pouch carcinogen N-methyl-N-benzylnitrosamine (MBN). This study demonstrates that DAS is an effective anticarcinogenic agent in squamous mucosa of the hamster and suggests novel cost-effective strategies for the rapid identification of tissue-specific anticarcinogens and a quantitative assessment of their efficacy.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1996

Garlic and associated allyl sulfur components inhibit N-methyl-N-nitrosourea induced rat mammary carcinogenesis.

Our previous studies demonstrated that dietary garlic powder supplementation inhibits N-nitrosamine induced DNA alkylation in liver and mammary tissue. The present studies compared the impact of dietary supplementation with garlic powder or two garlic constituents, water-soluble S-allyl cysteine (SAC) and oil-soluble diallyl disulfide (DADS), on the incidence of mammary tumorigenesis induced by N-methyl-N-nitrosourea (MNU). Female Sprague-Dawley rats were fed semi-purified casein based diets with or without supplements of garlic powder(20g/kg), SAC (57 micromol/kg) or DADS (57 micromol/kg) for 2 weeks prior to treatment with MNU (15 mg/kg body wt). Garlic powder, SAC and DADS supplementation significantly delayed the onset of mammary tumors compared to rats receiving the unsupplemented diet. Tumor incidence 23 weeks after MNU treatment was reduced by 76, 41 and 53% in rats fed garlic, SAC and DADS, respectively, compared to controls (P<0.05). Total tumor number was reduced 81, 35 and 65% by these supplements, respectively (P<0.05). In a separate study the quantity of mammary DNA alkylation occurring 3 h after MNU treatment was reduced in rats fed garlic, SAC or DADS (P<0.05). Specifically, O(6)-methylguanine adducts were reduced by 27, 18 and 23% in rats fed supplemental garlic, SAC and DADS, respectively, compared to controls. N(7)-Methylguanine adducts decreased by 48, 22 and 21% respectively, compared to rats fed the control diet. These studies demonstrate that garlic and associated allyl sulfur components, SAC and DADS, are effective inhibitors of MNU-induced mammary carcinogenesis.

Allyl Compounds↗
PubMed1993

The effect of pergolide and MDL 72974 on rat brain CuZn superoxide dismutase.

It has previously been shown that both the dopamine receptor agonist, pergolide, and the monoamine oxidase inhibitor, (-)-deprenyl, can cause induction of CuZn superoxide dismutase in the rat striatum. We have now confirmed this effect of pergolide (0.04 mg/kg i.p.) as being localised to the striatum, but not the cerebellum, and shown it to take 3 weeks to develop. Furthermore, we have found that MDL 72974, a more specific monoamine oxidase inhibitor than (-)-deprenyl, failed to bring about such an induction either at a low selective monoamine oxidase B inhibitory dose, or at a higher non-selective dose.

Allyl Compounds↗
PubMed1980

Influence of hypoxia on the hepatotoxic effects of carbon tetrachloride, paracetamol, allyl alcohol, bromobenzene and thioacetamide.

Exposure of rats to a reduced oxygen tension (6% O2, 94% N2) for 6 h increased the serum enzyme and the histological lesions induced by carbon tetrachloride (CCl4). Hypoxia did not enhance the hepatotoxic response to paracetamol, allyl alcohol, bromobenzene or thioacetamide. No correlation was found between the changes in hepatotoxicity induced by hypoxia and those after treatment with ethanol. Hepatic hypoxia therefore was not the pathogenetic mechanism responsible for ethanol-induced enhancement of hepatotoxicity.

Acetaminophen↗
PubMed1984

Disposition of [14C]2,3-dichloropropene in Fischer-344 rats after oral or intraperitoneal administration.

2,3-Dichloropropene (2,3-DCP), a component of commercial fumigants and nematocides, was mixed with [14C]2,3-DCP and given to rats by peroral (p.o.) or intraperitoneal (i.p.) administration. Urine, feces, and expired air were collected over 72 h. Excretion of radioactivity in urine predominated over other routes, with 66% to 75% of the dose excreted in 72 h. Feces contained from 13% to 21% of dose. 8% of the dose was exhaled as 14CO2. At the end of 72 h, only 2% to 3% of the dose remained in the carcass with the highest concentrations of 14C in liver, kidney, testes, and lung. Approx. 91% of the p.o. dose was absorbed from the gastrointestinal (GI) tract.

Administration, Oral↗
PubMed1992

Alterations in hepatic phase I and phase II biotransformation enzymes by garlic oil in rats.

Studies were conducted to examine the effect of a single and repeated administrations of garlic oil (diallyl sulfide) on Phase I and Phase II biotransformation enzymes in rats. Adult, male Sprague-Dawley rats treated with a single dose of garlic oil (500 mg/kg i.p.) showed a significant depression of hepatic cytochrome P-450, aminopyrine N-demethylase and aniline hydroxylase while microsomal protein content, cytochrome b5, NADPH-cytochrome c reductase, benzphetamine N-demethylase and cytosolic glutathione, S-transferase remained unaffected 24 h following the treatment. Although certain microsomal enzymes were depressed, there was no liver damage caused by garlic oil as judged by the putative serum enzyme test. On the other hand, daily administration of garlic oil (50 mg/kg i.p. for 5 days) produced a significant increase in hepatic cytochrome P-450, aminopyrine N-demethylase and benzphetamine N-demethylase activities, but not in the rest of the aforementioned parameters of biotransformation reactions. These data indicate that the effect of garlic oil on the hepatic drug-metabolizing enzyme system is dose-dependent.

Allyl Compounds↗
PubMed1987

Gas chromatography-mass spectrometry of monohydroxyeicosatetraenoic acids as their methyl esters trimethylsilyl, allyldimethylsilyl and tert.-butyldimethylsilyl ethers.

The gas chromatographic and mass spectrometric properties of the monohydroxy acids 5-hydroxyeicosatetraenoic acid (5-HETE), 12-hydroxyeicosatetraenoic acid (12-HETE) and 15-hydroxyeicosatetraenoic acid (15-HETE) as their methyl ester trimethylsilyl, methyl ester allyldimethylsilyl and methyl ester tert.-butyldimethylsilyl ethers were investigated. The gas chromatographic properties of the trimethylsilyl and tert.-butyldimethylsilyl derivatives were found to be excellent while the allyldimethylsilyl derivative required a well deactivated column. The mass spectra of these silyl derivatives with the exception for 12-HETE did not exhibit particularly intense ions in the upper mass region. A quantitative analysis by selected-ion monitoring of the most intense ion in the upper mass region of respective mass spectrum demonstrated that a detection limit in the low picogram range could only be obtained for 12-HETE. Since the mass spectra indicated that the double bonds exerted a strong influence on the fragmentation pattern, the trimethylsilyl, allyldimethylsilyl and tert.-butyldimethylsilyl ethers of the methyl esters of the reduced analogues of the monohydroxy acids were prepared. The saturation of the double bonds completely altered the fragmentation patterns and very intense ions carrying a high percentage of the total ion abundance were found in all of the mass spectra. The developed technique was utilized for measurements of 5-HETE in lung tissue samples from patients with lung cancer.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1991

Determination of an irreversible inhibitor of monoamine oxidase B (MDL 72974A) in human plasma and urine by gas chromatography-positive-ion chemical ionization mass spectrometry.

A sensitive and specific assay has been developed for the quantitative measurement in human plasma and urine of the irreversible inhibitor of monoamine oxidase B [(E)-4-fluoro-beta-fluoromethylenebenzene-butanamine HCl salt] (MDL 72974A) (I). This assay is based on gas chromatography-mass spectrometry with ammonia as the chemical ionization reagent gas. After addition of 1-fluoro-2-(4-chlorobenzene)-ethanamine HCl salt (MDL 71946A) as the internal standard, plasma (1 ml) and urine (100 microliter) samples were extracted using an automated solid-liquid extraction procedure on CN columns. The eluent was dried with a stream of nitrogen, and the residue was derivatized with pentafluoropropionic anhydride. Selected-ion monitoring of the [MNH4]+ ions m/z 361 (I) and 351 (internal standard) was used for quantification. The method yielded a linear response over the concentration range 0.25-100 pmol/ml in plasma with a limit of quantitation of 0.25 pmol/ml. The within-day reproducibility at a concentration of 5 pmol/ml was 4.6% and at a concentration of 50 pmol/ml was 1.3%. The day-to-day reproducibility was 5.2 and 7.0% at concentrations of 10 and 30 pmol/ml, respectively. The method was applied to the quantification of I in plasma and urine after the administration of 12-mg doses of I to a healthy male volunteer.

Allyl Compounds↗
PubMedDate not supplied

Role of cytochrome P4502E1 in alcoholic liver disease pathogenesis.

The intragastric tube feeding model is ideal for the study of the role of dietary factors and the effect of drugs on experimental alcoholic liver disease (ALD), since the model allows us to study the effect of a single variable in the diet on the pathology of liver where the blood alcohol level (BAL) is maintained over 150 mg%. By varying the dietary fatty acid composition we showed that the pathology was worsened by increasing linoleic acid or polyunsaturated fatty acids (PUFAs) in the diet where cytochrome P4502E1 (CYP2E1) was increased posttranslationally by high BAL. Concomitant with the increase in CYP2E1 there was evidence for an increase in lipid peroxidation (LP) by microsomes. Protein adducts of the products of LP were increased in the blood. Isoniazid (INH) enhanced this process and the pathology of ALD when INH was fed at therapeutic levels with ethanol. Preliminary studies show that diallyl sulfide, which inhibits and destroys liver CYP2E1 selectively, also modified the pathologic effects of ethanol. Thus we postulate that CYP2E1 induction plays a central role in the pathogenesis of ALD.

Allyl Compounds↗
PubMed2004

Diallyl sulfide induces heme oxygenase-1 through MAPK pathway.

Diallyl sulfide (DAS), is protective against chemically induced heptotoxicity, mutagenesis, and carcinogenesis. The mechanism of its protective effects is not fully understood. In this study, we found that DAS can induce the expression of heme oxygenase-1 (HO-1), which plays a critical role in the cell defense system against oxidative stress. DAS causes a dose- and time-dependent increase of HO-1 protein and mRNA level without toxicity in HepG2 cells. DAS-induced HO-1 protein expression is dependent on newly synthesized mRNA and newly synthesized protein. DAS increases Nrf2 protein expression, nuclear translocation, and DNA-binding activity. The MAP kinase ERK is activated by DAS. Both ERK and p38 pathways play an important role in DAS-induced Nrf2 nuclear translocation and ho-1 gene activation. DAS stimulates a transient increase of reactive oxygen species (ROS). N-Acetyl-cysteine blocked this increase of ROS production as well as DAS-induced ERK activation, Nrf2 protein expression and nuclear translocation, and ho-1 gene activation. The increase in HO-1 produced by DAS protected the HepG2 cells against toxicity by hydrogen peroxide or arachidonic acid. These results suggest that DAS induces ho-1 through production of ROS, and Nrf2 and MAPK (ERK and p38) mediate this induction. Induction of ho-1 may play a role in the protective effects of DAS.

Allyl Compounds↗
PubMed2006

Cadmium induced mitochondrial injury and apoptosis in vero cells: protective effect of diallyl tetrasufide from garlic.

Oxidative stress and mitochondrial injury has been implicated in cadmium-induced apoptosis. In this study, we examined the protective effect of diallyl tetrasulfide from garlic on cadmium induced oxidative stress and apoptosis in vero cells. Exposure of vero cells to cadmium (10 microM) for 18 h showed the apoptotic events such as loss of cell viability, alterations in nuclear morphology and decreased mitochondrial membrane potential with significantly increased levels of reactive oxygen species (super oxide anion and hydrogen peroxide). Treatment of vero cells with cadmium (10 microM) and diallyl tetrasulfide (5-50 microg/ml) showed that diallyl tetrasulfide attenuated the cadmium-induced suppression of cell viability in a dose dependent manner and highly significant effect was observed at 40 microg/ml. The nuclei morphological analysis with 4',6-diamidino-2-phenylindole staining confirmed that diallyl tetrasulfide at 40 microg/ml prevented the Cd (10 microM) induced apoptosis. Flow cytometric analysis with 2',7'-dichlorofluorencein diacetate showed that the inhibitory effect of diallyl tetrasulfide (10-40 microg/ml) on reactive oxygen species generation parallel with its effect on cell viability. In addition, diallyl tetrasulfide (40 microg/ml) remarkably reduced the cadmium-induced accumulation of superoxide radical and hydrogen peroxide with in cells. Further, diallyl tetrasulfide significantly protected the cadmium-induced decrease in mitochondrial membrane potential, an indicator of mitochondrial function. Our study suggest that diallyl tetrasulfide affect the reactive oxygen species generation induced by cadmium, and possesses a novel protective effect on the cytolethality associated with mitochondrial injury, which contributes to the antiapoptotic effect of diallyl tetrasulfide against cadmium.

Allyl Compounds↗
PubMed2004

Evolution of enzymatic activity in the tautomerase superfamily: mechanistic and structural studies of the 1,3-dichloropropene catabolic enzymes.

The use of the soil fumigant Telone II, which contains a mixture of cis- and trans-1,3-dichloropropene, to control plant-parasitic nematodes is a common agricultural practice for maximizing yields of various crops. The effectiveness of Telone II is limited by the rapid turnover of the dichloropropenes in the soil due to the presence of bacterial catabolic pathways, which may be of recent origin. The characterization of three enzymes in these pathways, trans-3-chloroacrylic acid dehalogenase (CaaD), cis-3-chloroacrylic acid dehalogenase (cis-CaaD), and malonate semialdehyde decarboxylase (MSAD), has uncovered intriguing catalytic mechanisms as well as a fascinating evolutionary lineage for these proteins. Sequence comparisons and mutagenesis studies revealed that all three enzymes belong to the tautomerase superfamily. Tautomerase superfamily members with known structures are characterized by a beta-alpha-beta structural fold. Moreover, they have a conserved N-terminal proline, which plays an important catalytic role. Mechanistic, NMR, and pH rate studies of the two dehalogenases, coupled with a crystal structure of CaaD inactivated by 3-bromopropiolate, indicate that they use a general acid/base mechanism to catalyze the conversion of their respective isomer of 3-chloroacrylate to malonate semialdehyde. The reaction is initiated by the conjugate addition of water to the C-2, C-3 double bond and is followed by the loss of HCl. MSAD processes malonate semialdehyde to acetaldehyde, and is the first identified decarboxylase in the tautomerase superfamily. The catalytic mechanism is not well defined but the N-terminal proline plays a prominent role and may function as a general acid catalyst, similar to its role in CaaD and cis-CaaD. These are the first structural and mechanistic details for tautomerase superfamily members that catalyze either a hydration or a decarboxylation reaction, rather than a tautomerization reaction, in which Pro-1 serves as a general acid catalyst rather than as a general base catalyst. The available information on the 1,3-dichloropropene catabolic enzymes allows speculation on the possible evolutionary origins of their activities.

Allyl Compounds↗
PubMed2006

Stereoselective allyl transfer to chiral alpha-methoxycarbaldehydes: a model study related to the C-9/C-15 fragment of geldanamycin.

The enantiomerically pure alpha-methoxycarbaldehyde 3 was prepared from l-leucine in five steps and 31% overall yield. The aldehyde was subjected to a diastereoselective BF3-mediated crotylation with silane 4 and to various reagent-controlled addition reactions. The configuration of aldol addition products 19 and 20 was proven by single crystal X-ray crystallography. Based on these data spectral comparison allowed an unambiguous assignment of the desired anti,syn-crotylation product 2b and of the syn,syn-crotylation product 2a. Unexpectedly, product 2a of the BF3-mediated crotylation is formally the product of chelation-control. The anti,syn-crotylation product 2b, which is a model for the C-9/C-15 fragment of geldanamycin, was obtained by a reagent-controlled crotylation with the chiral (Z)-crotylborane 23.

Aldehydes↗
PubMed2004

[3H]-MRE 2029-F20, a selective antagonist radioligand for the human A2B adenosine receptors.

MRE 2029-F20 [N-benzo[1,3]dioxol-5-yl-2-[5-(2,6-dioxo-1,3-dipropyl-2,3,6,7-tetrahydro-1H-purin-8-yl)-1-methyl-1H-pyrazol-3-yloxy]-acetamide] is a selective antagonist ligand of A2B adenosine receptors. For use as a radioligand, 1,3-diallyl-xanthine, the precursor of [3H]-MRE 2029-F20, was synthesized, and tritiated on the allyl groups. [3H]-MRE 2029-F20 bound to human A2B receptors expressed in CHO cells showed a KD value of 1.65+/-0.10 nM and Bmax value of 36+/-4 fmol/mg protein. [3H]-MRE2029-F20 represents a useful tool for the pharmacological characterization of human A2B adenosine receptor subtype.

Acetamides↗