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PubMed2006

In vivo treatment by diallyl disulfide increases histone acetylation in rat colonocytes.

Diallyl disulfide (DADS) is an organosulfur compound from garlic which exhibits various anticarcinogenic properties including inhibition of tumor cell proliferation. DADS antiproliferative effects were previously associated with an increase in histone acetylation in two human tumor colon cell lines, suggesting that DADS-induced histone hyperacetylation could be one of the mechanisms involved in its protective properties on colon carcinogenesis. The effects of DADS on histone H4 and H3 acetylation levels were investigated in vivo in colonocytes isolated from non-tumoral rat. Administrated by intracaecal perfusion or gavage, DADS increases histone H4 and H3 acetylation in colonocytes. Moreover, data generated using cDNA expression arrays suggest that DADS could modulate the expression of a subset of genes. These results suggest the involvement of histone acetylation in modulation of gene expression by DADS in normal rat colonocytes, which might play a role in its biological effects as well as in its anticarcinogenic properties in vivo.

Acetylation↗
PubMedDate not supplied

Microarray analysis of altered gene expression in diallyl trisulfide-treated HepG2 cells.

Diallyl trisulfide (DT) is a natural compound derived from garlic. Despite its reported lipid-lowering effects, the mechanisms of its actions are not clear yet. To further understand the molecular mechanisms of actions of this compound, microarray technology was used in the present study to investigate the lipid-lowering effects of DT on HepG2 cells. To optimize the concentration of DT treatment on HepG2 cells, a series of concentration of DT were incubated with HepG2 cells for 24 h. The data indicted that the concentrations of DT in the range from 20 to 50 microM were effective in lowering cellular total triglyceride and cholesterol, with no significant cytotoxicity. Using oligonucleotide microarrays and RT-PCR technology, the genes that were differentially regulated by DT were identified. The results showed that peroxisome proliferator activated receptor alpha (PPAR-alpha) and hepatocyte nuclear factor 4alpha (HNF-4alpha) mRNA were up-regulated, and CYP7A1 mRNA was down-regulated following DT treatment, suggesting that the lipid-lowering effects of DT may be at least in part mediated through the regulation of PPAR-alpha dependent pathways.

Allyl Compounds↗
PubMed1999

Low doses of diallyl disulfide, a compound derived from garlic, increase tissue activities of quinone reductase and glutathione transferase in the gastrointestinal tract of the rat.

Diallyl disulfide (DADS), a substance that is formed from the organosulfur compounds present in garlic, is known to increase tissue activities of the phase II detoxification enzymes quinone reductase (QR) and glutathione transferase (GT) in animals. In previous experiments, however, high doses of DADS were employed and only a limited range of tissues were examined. In the present studies, increased activities of QR and GT were recorded in the forestomach, glandular stomach, duodenum, jejunum, ileum, cecum, colon, liver, kidneys, spleen, heart, lungs, and urinary bladder of rats given DADS over a wide range of dose levels. Large variations in response were recorded among the different organs, with forestomach, duodenum, and jejunum being the most sensitive to enzyme induction by DADS. In these organs, significant increases in QR activity were observed at a dose of only 0.3 mg/kg/day. Such a dose level is close to that which may be achieved through human consumption of garlic, suggesting that induction of phase II enzymes may contribute to the protection that is afforded by this vegetable against cancer of the gastrointestinal tract in humans.

Allyl Compounds↗
PubMed1996

Novel anti-carcinogenic activity of an organosulfide from garlic: inhibition of H-RAS oncogene transformed tumor growth in vivo by diallyl disulfide is associated with inhibition of p21H-ras processing.

In this study, we report a novel anticarcinogenic activity of an organosulfur compound from garlic, diallyl disulfide (DADS). DADS treatment significantly inhibited the growth of H-ras oncogene transformed tumors in nude mice. As compared to controls, the appearance of tumors was also delayed markedly by oral administration of DADS. The inhibition of tumor growth by DADS treatment correlated with the inhibition of p21H-ras membrane association in the tumor tissue. The levels of membrane associated p21H-ras were markedly lower in the tumor tissues of DADS treated mice as compared to controls. An opposite trend, however, was evident for cytosolic p21H-ras. Furthermore, DADS treatment resulted in a significant inhibition of hepatic as well as tumoral 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. These results indicate that DADS suppresses the growth of H-ras oncogene transformed tumors in nude mice by inhibiting the membrane association of tumoral p21H-ras.

Allyl Compounds↗
PubMed2002

Antitumorigenic potential of diallyl sulfide in Ehrlich ascites tumor bearing mice.

OBJECTIVE: To study the effects of diallyl sulfide (DAS), an organosulfur compound present in garlic (Allium sativum), on the life span of ehrlich ascites (EA) tumor bearing Swiss albino mice, cytotoxicity and angiogenesis. METHODS: EA tumor cells were maintained by serial transplantation in peritoneal cavity of male Swiss albino mice. EA tumor cells were inoculated at concentrations of 1 x 10(6) EA cells, 2.5 x 10(6) EA cells and 5 x 10(6) EA cells. DAS was given in 0.2 ml normal saline i.p., daily for seven days followed one hour later by inoculation with EA cells in respective groups. RESULTS: The results revealed that administration of DAS increased the life span of EA tumor bearing animals by more than 25 percent. A significant dose dependant cytotoxic response of DAS was also observed on EA tumor cells. DAS was also found to inhibit the angiogenesis in EA tumor bearing mice in a dose dependent manner. CONCLUSION: It is suggested that DAS may exert its anticarcinogenic effects by more than one mechanism and is a useful chemopreventive and chemotherapeutic agent.

Allyl Compounds↗
PubMed2003

Protective effect of diallyl sulfide on oxidative stress and nephrotoxicity induced by gentamicin in rats.

Gentamicin (GM) is an antibiotic whose clinical use is limited by its nephrotoxicity. Experimental evidences suggest a role of reactive oxygen species in GM-induced nephrotoxicity. In this work we explored the effect of diallyl sulfide (DAS), a garlic-derived compound with antioxidant properties, on GM-induced nephrotoxicity. Four groups of rats were studied: (1) Control, treated intragastrically with olive oil as a vehicle, (2) GM, treated subcutaneously with GM (125 mg/kg/day for 4 days), (3) DAS, treated intragastrically with DAS (50 mg/kg/day for 4 days), and (4) GM + DAS. Nephrotoxicity was made evident by: (1) the increase in creatinine and blood urea nitrogen in serum, (2) the increase in urinary excretion of N-acetyl-beta-D-glucosaminidase and total protein, and (3) necrosis of proximal tubular cells. These functional and structural alterations were prevented or ameliorated by DAS treatment. In addition, GM increased levels of renal oxidative stress markers nitrotyrosine and protein carbonyl groups which were also ameliorated by DAS in GM + DAS group. The mechanism by which DAS has a protective effect on GM-induced nephrotoxicity may be related, at least in part, to the decrease in oxidative stress in renal cortex.

Acetylglucosaminidase↗
PubMed1997

Hydroxyl and peroxyl radical trapping by the monoamine oxidase-B inhibitors deprenyl and MDL 72,974A: implications for protection of biological substrates.

We have examined in vitro radical trapping by the monoamine oxidase-B (MAO-B) inhibitor deprenyl and compared it to the specific MAO-B inhibitor MDL 72,974A. The capacity for the compounds to prevent .OH-mediated oxidation of biological substrates was examined by determining their ability to inhibit oxidation of 2-deoxyribose and phosphatidylcholine liposomes using the thiobarbituric acid reactive substances (TBARS) assay. MDL 72,974A gave a dose-dependent inhibition of 2-deoxyribose oxidation, while deprenyl generated a strong false positive TBARS reaction with both the sugar and the liposomes. When lipid peroxidation was monitored by conjugated diene formation, deprenyl inhibited oxidation while MDL 72,974A was without effect suggesting that trapping of .OH was not responsible for activity. Deprenyl inhibited liposomal peroxidation initiated with the water-soluble peroxyl radical generator 2,2'-azobis (2-amidinopropane) (ABAP) with an IC50 of 78 microM as compared to 4.2 mM for MDL 72,974A. A similar difference was observed using the lipophilic peroxyl radical generator 2,2'-azobis (2,4-dimethylvaleronitrile) (AMVN). The data indicate that radical trapping by the MAO-B inhibitors provides differential protection against biological substrates and may involve trapping of secondary peroxyl radicals rather than .OH.

Allyl Compounds↗
PubMed2004

Modulation of altered hepatic foci induction by diallyl sulphide in Wistar rats.

Diallyl sulphide (DAS) is a sulphur-containing volatile compound present in garlic (Allium sativum). It has been shown to inhibit a number of chemically induced forms of cancer in experimental animals. The present study demonstrates the inhibitory effect of DAS on the development of diethylnitrosamine (DEN) initiated and 2-acetyl-aminofluorene (2-AAF) promoted preneoplastic altered hepatic foci (AHF) in Wistar rats. AHF were scored and analysed by quantitative stereology using the Image Analysis system from frozen liver sections stained for biological markers, namely glutathione S-transferase, placental form (GST-P), gamma-glutamyl transpeptidase (GGT), adenosine triphosphatase (ATPase), glucose-6-phosphatase (G6 Pase) and alkaline phosphatase (AlkPase). DAS-supplemented rats were found to restore the near-normal levels of enzymes GST-P and GGT when exposed to DEN and 2-AAF. DAS administration following DEN and 2-AAF exposure led to the restoration of enzymic activity of ATPase, G6 Pase and AlkPase, as evident by number and area of the foci. These findings suggest the protective role of DAS in rat hepatocarcinogenesis, by suppressing DEN- and 2-AAF-induced AHF development.

Allyl Compounds↗
PubMed1998

Antitumor activity of diallyl sulfide in two-stage mouse skin model of carcinogenesis.

It has been reported that diallyl sulfide (DAS), a sulfur-containing volatile compound in garlic (Allium sativum), exerts anticarcinogenic activity in various rodent tumor models. In the present study, the antitumor property of DAS was tested in Swiss albino mice in the two stage initiation-promotion mouse skin carcinogenesis. Skin cancers were initiated topically with a single subcarcinogenic dose (52 micrograms) of 7, 12-dimethyl benz (a) anthracene (DMBA). Promotion was performed by twice weekly applications of 12-O-tetradecanoyl phorbol-13-acetate (TPA) at a dose of 5 micrograms/animal for 32 weeks. DAS was applied topically (250 micrograms/animal) thrice weekly for 3 weeks for anti-initiating and 1 h prior to each promotion treatment for anti-promoting studies. The results showed that the treatment schedule of DAS can effectively delay the onset of tumorigenesis and reduce the cumulative number of tumors and the average number of tumors per mouse. In groups in which DAS applied prior to initiation or promotion, a significant population of the animals remained tumor-free till the termination of experiment. These findings suggest that DAS can effectively inhibit chemically induced mouse skin carcinogenesis.

Administration, Topical↗
PubMed2006

Chemoprevention of rat prostate carcinogenesis by diallyl disulfide, an organosulfur compound of garlic.

Diallyl disulfide (DADS), an important component of garlic (Allium sativam) has been demonstrated to exert a potential chemopreventive activity against human cancers. DADS inhibits proliferation of both androgen dependent and independent prostate cancer cells in vitro. However there is no report available on the role of DADS on prostate cancer initiation in in vivo model. So the present chemoprevention study was conducted to evaluate the activity of diallyl disulfide as an anticancer agent in prostate carcinogenesis of male Sprague-Dawley rats. Testosterone and N-Methyl N-Nitroso Urea (MNU) were used to induce prostate carcinogenesis that involves a multi step process like, hyperplasia, dysplasia and prostatic intraepithelial neoplasia (PIN). The rats were induced prostate carcinogenesis by injection of testosterone and single dose of MNU and again the testosterone was continued throughout the experimental period. Forty percentage of animals carried PIN in dorsolateral prostate, while dysplasia and hyperplasia (55 to 65%) were common in ventral as well as dorsolateral prostates of the hormone and carcinogen treated rats. Rats treated with hormone and carcinogen along with DADS developed PIN at incidence of 10% in the ventral and dorsolateral prostates about 20 to 10%. Dysplasia and hyperplasia were less common in these rats. The results of this study provide evidence that DADS may have chemopreventive activity in rat prostate carcinogenesis.

Allyl Compounds↗
PubMed1985

Metabolic activation of 3-(2-chloroethoxy)-1,2-dichloropropene: a mutagen structurally related to diallate, triallate, and sulfallate.

3-(2-Chloroethoxy)-1,2-dichloropropene (CP), a Salmonella promutagen that was recently isolated from a sample of residue organics previously concentrated from drinking water, is structurally related to three other chlorinated promutagens, the S-chloroallyl thiocarbamate herbicides diallate, triallate, and sulfallate. These four chloroallyl ether compounds were found to be similar with respect to strain specificity, potency, and requirement for specific metabolic activation. The 9,000g supernatant (S9) fractions from polychlorinated biphenyl Aroclor 1254- or phenobarbital-induced rats metabolized the four chloroallyl ethers to mutagenic products, whereas S9 from 3-methylcholanthrene-induced or uninduced rats did not. The metabolic activation of CP, diallate, and triallate to mutagens was catalyzed by the 100,000g microsomal pellet of S9 alone, but the activation of sulfallate to mutagenic metabolites required both microsomal and cytosolic fractions of S9. Direct-acting (minus S9) mutagenic metabolites of diallate and triallate could be extracted into methylene chloride from S9 incubation mixtures. Incubations containing S9 and either sulfallate or CP did not yield methylene chloride-extractable metabolites with direct-acting mutagenic activity. On the basis of these results and those from previous studies on the metabolism of diallate, triallate, and sulfallate, a tentative model for the metabolic activation of CP is proposed in which this chloroallyl ether undergoes alpha-carbon hydroxylation to form multiple mutagenic products.

Allyl Compounds↗
PubMed2005

Spectral and catalytic properties of aryl-alcohol oxidase, a fungal flavoenzyme acting on polyunsaturated alcohols.

Spectral and catalytic properties of the flavoenzyme AAO (aryl-alcohol oxidase) from Pleurotus eryngii were investigated using recombinant enzyme. Unlike most flavoprotein oxidases, AAO does not thermodynamically stabilize a flavin semiquinone radical and forms no sulphite adduct. AAO catalyses the oxidative dehydrogenation of a wide range of unsaturated primary alcohols with hydrogen peroxide production. This differentiates the enzyme from VAO (vanillyl-alcohol oxidase), which is specific for phenolic compounds. Moreover, AAO is optimally active in the pH range of 5-6, whereas VAO has an optimum at pH 10. Kinetic studies showed that AAO is most active with p-anisyl alcohol and 2,4-hexadien-1-ol. AAO converts m- and p-chlorinated benzyl alcohols at a similar rate as it does benzyl alcohol, but introduction of a p-methoxy substituent in benzyl alcohol increases the reaction rate approx. 5-fold. AAO also exhibits low activity on aromatic aldehydes. 19F NMR analysis showed that fluorinated benzaldehydes are converted into the corresponding benzoic acids. Inhibition studies revealed that the AAO active site can bind a wide range of aromatic ligands, chavicol (4-allylphenol) and p-anisic (4-methoxybenzoic) acid being the best competitive inhibitors. Uncompetitive inhibition was observed with 4-methoxybenzylamine. The properties described above render AAO a unique oxidase. The possible mechanism of AAO binding and oxidation of substrates is discussed in the light of the results of the inhibition and kinetic studies.

Alcohol Oxidoreductases↗
PubMed2002

Induction of apoptosis by diallyl sulfide in DMBA-induced mouse skin tumors.

Diallyl sulfide (DAS), an organosulfur compound in garlic, has received increasing attention as a potential cancer-chemopreventive agent. DAS has been shown to possess antitumorigenic potential in various rodent tumor models. The present study demonstrates induction of apoptosis as the possible mechanism of the antiproliferative effect of DAS in solid tumors, as evident by the appearance of a sub- G1 fraction in flow cytometry. Biochemical analysis of skin tumors revealed other characteristic features of apoptosis, including formation of DNA ladders on agarose gel, compaction of nuclear DNA, and formation of apoptotic bodies. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay of skin tumors of DAS-supplemented animals showed a significant increase in the number of apoptotic cells compared with animals exposed to 7,12- dimethylbenz[a]anthracene alone. The increase in apoptotic index in nonmalignant and malignant tumors was 78% and 94%, respectively, in DAS-pretreated animals and 68% and 82%, respectively, in animals given DAS 1 h after carcinogen administration. These observations suggest that induction of apoptosis may be the major contributing factor for antitumorigenic properties of DAS.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2006

Experimental study on the action of allitridin against human cytomegalovirus in vitro: Inhibitory effects on immediate-early genes.

Garlic (Allium sativum) extraction has been reported having anti-HCMV efficacy. This study was aimed to investigate the effect of allitridin (diallyl trisulfide, a compound from A. sativum extraction) on the replication of HCMV and the expression of viral immediate-early genes. In HCMV plaque-reduction assay, allitridin appeared a dose-dependent inhibitory ability with EC(50) value of 4.2 microg/ml (selective index, SI=16.7). Time-of-addition and time-of-removal studies showed that allitridin inhibited HCMV replication in earlier period of viral cycle before viral DNA synthesis. Both immediate early gene (ie1) transcription and IEA (IE(1)72 and IE(2)86) expression was suppressed by allitridin, but not by GCV in a single HCMV cycle format. In addition, allitridin appeared stronger inhibition on IE(2)86 than on IE(1)72. Decrease of viral DNA load in infected cells was also detected under allitridin treatment, probably due to an indirect consequence of the reduction in ie gene transcription. In summary, this study indicated that allitridin has anti-HCMV activity and the mechanism is associated with suppression of ie gene transcription.

Allyl Compounds↗
PubMed1992

Enhancing effects of diallyl sulfide on hepatocarcinogenesis and inhibitory actions of the related diallyl disulfide on colon and renal carcinogenesis in rats.

It has been reported that diallyl sulfide (DS) and diallyl disulfide (DDS), major volatile compounds in garlic (Allium sativum), exert anticarcinogenic activity in several organs in rodents. The modifying effects of these two chemicals were therefore assessed using two-step liver and multi-organ carcinogenesis models. In experiment 1, male F344 rats were given a single i.p. injection of N-diethylnitrosamine (200 mg/kg body wt) and then received DS or DDS by intragastric intubation at doses of 200 and 50 mg/kg body wt, respectively, three times a week for 6 weeks. All rats were subjected to two-thirds partial hepatectomy at experimental week 3. In experiment 2, male F344 rats were sequentially treated with five carcinogens with different organ target sites for 4 weeks, and then administered DS or DDS as in experiment 1 for 24 weeks. DS demonstrated clear enhancing effects on the development of glutathione S-transferase placental form positive foci in both experiments. On the other hand, an inhibitory potential in colon and renal carcinogenesis was observed in rats treated with DDS. Therefore, while DDS may act as a chemopreventive agent, DS may promote hepatocarcinogenesis.

Allyl Compounds↗
PubMed1999

Developmental vasculotoxicity associated with inhibition of semicarbazide-sensitive amine oxidase.

The endogenous substrate(s) and physiological function(s) of semicarbazide-sensitive amine oxidase (SSAO), a group of enzymes exhibiting highest activity in vascular smooth muscle cells of the mammalian aortic wall, remain undetermined. This study examines the pathophysiological effects in the thoracic aortic wall resulting from specific in vivo SSAO inhibition. Weanling Sprague-Dawley rats were treated acutely or chronically with either semicarbazide hydrochloride or the allylamine derivatives MDL-72274 or MDL-72145 (Marion Merrell Dow Research Institute, Cincinnati, OH). Treatment with these compounds produced acute (6 and 24 h) and chronic (21 day) lowering of SSAO activity in aorta and lung with little effect on the activity of the vital matrix-forming enzyme, lysyl oxidase, in aortas of chronically treated animals. Chronic SSAO inhibition produced lesions consisting of striking disorganization of elastin architecture within the aortic media accompanied by degenerative medial changes and metaplastic changes in vascular smooth muscle cells. No significant difference in the total weight of dry, lipid-extracted aortic elastin and collagen components were observed between chronically SSAO inhibited and control animals. However, the amount of mature elastin was lowered and mature collagen was raised in the aortas of animals treated chronically with semicarbazide. Descending thoracic aortic rings isolated from chronically SSAO-inhibited animals had larger cross-sectional diameters (i.e., exhibited dilation) when compared to corresponding rings from control animals. This study demonstrates that developmental toxicity, characterized by striking vascular lesions and dilated thoracic aortas, can result from specific in vivo SSAO inhibition, suggesting a role for SSAO in connective tissue matrix development and maintenance, and specifically in the development of normal elastin.

Allyl Compounds↗
PubMedDate not supplied

Inhibition of cytochrome P-450 2E1 by diallyl sulfide and its metabolites.

Diallyl sulfide, a major flavor ingredient from garlic, was previously shown to inhibit chemically induced carcinogenesis and cytotoxicity in animal model systems. It modulated cytochrome P-450 compositions by inactivating P-450 2E1 and inducing P-450 2B1. The present studies examined the inhibition of P-450 2E1 mediated p-nitrophenol hydroxylase activity by diallyl sulfide and its putative metabolites diallyl sulfoxide and diallyl sulfone (DASO2). Each compound displayed competitive inhibition of p-nitrophenol hydroxylase activity in incubations using liver microsomes from acetone-pretreated male Sprague-Dawley rats. Preincubation of the microsomes with DASO2 inactivated p-nitrophenol hydroxylase activity in a process that was time- and NADPH-dependent and saturable, exhibited pseudo-first-order kinetics, was protected by alternate substrate, was accompanied by a loss of microsomal P-450-CO binding spectrum, and was unaffected by exogenous nucleophile. The Ki value for DASO2 was 188 microM and the maximal rate of inactivation was 0.32 min-1. DASO2 was ineffective in the inactivation of ethoxyresorufin dealkylase, pentoxyresorufin dealkylase, or benzphetamine demethylase activity. Purified P-450 2E1 in a reconstituted system was inactivated in a time- and NADPH-dependent manner by DASO2. The metabolic conversion of diallyl sulfide to the sulfoxide and sulfone was observed in vivo and in vitro. The results suggest that diallyl sulfide inhibits the metabolism of P-450 2E1 substrates by competitive inhibition mechanisms and by inactivating P-450 2E1 via a suicide-inhibitory action of DASO2.

Allyl Compounds↗
PubMed2004

Enhancement of diallyl disulfide-induced apoptosis by inhibitors of MAPKs in human HepG2 hepatoma cells.

We examined the effects of diallyl disulfide (DADS), an oil-soluble organosulfur compound found in garlic, on human HepG2 hepatoma cells to better understand its effect on apoptosis and apoptosis-related genes. Our study has demonstrated that DADS affects cell proliferation activity and viability and elicits typical apoptotic morphologic changes (chromatic condensation and nuclear fragmentation) in human HepG2 hepatoma cells. Also, treatment with DADS induces a temporary increase in phosphorylated p38 MAPK (phospho-p38) and phosphorylated p42/44 MAPK (phospho-p42/p44) in a time- and concentration-dependent manner. Inhibition of activated/phosphorylated mitogen-activated protein kinase (MAPK) with phospho-p38 or phospho-p42/44 specific inhibitors, SB203580 or U0126, induces apoptosis without DADS treatment, indicating that at least the endogenous activated forms of p38 MAPK and p42/p44 MAPK markedly exert cytoprotective roles from cell apoptosis in the HepG2 hepatoma cells. Combined treatment with these inhibitors followed by DADS further enhances the DADS-induced apoptosis. Taken together, these results show that both DADS and the specific inhibitors of MAPKs could induce apoptosis in HepG2 hepatoma cells and that the MAPKs inhibitors further enhance the apoptotic effect in DADS-treated HepG2 hepatoma cells.

Allyl Compounds↗