Dipropyl Disulfide Research Articles

Volatile compounds thermally generated from S-propylcysteine and S-propylcysteine sulfoxide-aroma precursors of Allium vegetables.

Two nonvolatile flavor precursors occurring in Allium vegetables, S-propyl-L-cysteine and its sulfoxide, were heated in closed model systems at different temperatures (from 80 to 200 degrees C) in the presence of variable amounts of water (0-98%) for 1-60 min. It seems to be indisputable that thermally generated breakdown products of both S-propyl-L-cysteine and particularly S-propyl-L-cysteine sulfoxide can significantly participate in the aroma formation of culinary processed Alliumvegetables. Dipropyl disulfide, dipropyl trisulfide, propylthiol, and dipropyl thiosulfonate were identified as the predominant volatile compounds generated by thermal degradation of S-propylcysteine sulfoxide. Dipropyl disulfide and 2-(propylthio)ethylamine were the major breakdown products formed from S-propylcysteine. Substantial amounts of various alkyl- and alkylthio-substituted pyridines were also generated from both S-propylcysteine and its sulfoxide.

Modulation of Phase II Enzymes by Organosulfur Compounds from Allium Vegetables in Rat Tissues

The naturally occurring organosulfur compounds (OSCs) diallyl sulfide (DAS), diallyl disulfide (DADS), dipropyl sulfide (DPS), and dipropyl disulfide (DPDS) were studied with respect to their effects on hepatic, intestinal, renal, and pulmonary phase II drug metabolizing enzymes, i.e., glutathioneS-transferase (GST), microsomal epoxide hydrolase (mEH), quinone reductase (QR), and UDP-glucuronosyltransferase (UGT). OSCs were administered po to male SPF Wistar rats. In addition to assays of total enzyme activity, the ability of OSCs to modify the levels of mEH and rGSTA1/A2, A3/A5, M1, M2, and P1 was assessed by Western blotting. Remarkably, DADS significantly increased all Phase II enzyme activities, except the pulmonary mEH. It was noteworthy that only DADS induced QR activity. DAS, DPS, and DPDS induced mEH, GST, and UGT activities in the liver. Interestingly, DAS, DPS, and DPDS significantly decreased renal GST activity. In the same manner, DAS, DPS, and DPDS decreased rGSTA1/A2 and A3/A5 levels in the kidney. Conversely, all OSCs were able to induce GST of alpha and mu classes in the liver. In the intestine, DADS and DAS increased rGSTA1/A2, M2, and P1, while rGSTA3/A5 and M2 were only increased by DADS. In addition, DADS induced rGSTP1 dramatically in the four tissues analyzed. DADS also increased the mEH levels in the liver, intestine, and kidney, while DAS and DPS moderately induced mEH level in the liver. This study brings additional insights into the effects of OSCs on Phase II enzymes and suggests that DADS could be a promising chemopreventive agent considering its pleiotropic capacity of induction.

Distribution of Volatile Sulfur Compounds in an Interspecific Hybrid between Onion (Allium cepa L.) and Leek (Allium porrum L.)

Volatile sulfur compounds of an interspecific hybrid between Allium cepa and Allium porrum were analyzed by gas chromatography (GC) and GC/mass spectrometry prior to isolation of the individual oils by a simultaneous distillation/extraxtion (SDE) method. Furthermore, the aroma profiles of various onion and leek cultivars were investigated. Major volatile components detected in onion were 2-methyl-2-pentenal, (E)-methyl 1-propenyl disulfide, methyl propyl trisulfide, and propanethiol, whereas dipropyl trisulfide, dipropyl disulfide, and (E)-propenyl propyl disulfide predominated in leek oils. According to the higher amount of leek chromosomes in the cell nucleus, the percentages of the measured sulfur volatiles in the hybrid material correspond more to the leek than to the onion flavor profile. Discrimination analysis was successfully applied to classify the three predefined Allium groups. It has been found that at minimum five of the most important aroma volatiles were necessary to receive sufficient diff...

Effects of oil-soluble organosulfur compounds from garlic on doxorubicin-induced lipid peroxidation.

Clinical efficacy of doxorubicin is compromised due to free radical generation leading to cardiac toxicity. Oil-soluble organosulfur compounds, diallyl sulfide (DAS), diallyl disulfide (DADS), dipropyl sulfide (DPS) and dipropyl disulfide (DPDS), present in garlic were examined for their antiperoxidant effects. DADS inhibited liver microsomal lipid peroxidation induced by NADPH, ascorbate and doxorubicin. DAS, DPS and DPDS were ineffective inhibitors of liver microsomal lipid peroxidation. DADS could be used in combination with doxorubicin to protect oxidative injuries to improve the clinical efficacy of doxorubicin.

Induction of glutathione S-transferase pi as a bioassay for the evaluation of potency of inhibitors of benzo(a)pyrene-induced cancer in a murine model.

There is a growing need for short-term and cost-effective bioassay to assess the efficacy of potential chemo-preventive agents. We report that the induction of glutathione (GSH) S-transferase pi (mGSTP1-1) by a chemo-preventive agent can be used as a reliable marker to assess its efficacy in retarding chemical carcinogenesis induced by benzo(a)pyrene (BP), which is a widespread environmental pollutant and believed to be a risk factor in human chemical carcinogenesis. This conclusion is based on 1) the relative contribution of mGSTP1-1 of the liver and forestomach of female A/J mice in the detoxification of the ultimate carcinogenic metabolite of BP, (+)-anti-7,8-dihydroxy-9, 10-oxy-7,8,9, 10-tetrahydrobenzo(a)pyrene [(+)-anti-BPDE]; and 2) a positive correlation between the induction of hepatic and forestomach mGSTP1-1 by 5 naturally occurring organosulfides (OSCs) from garlic (diallyl sulfide, diallyl disulfide, diallyl trisulfide, dipropyl sulfide and dipropyl disulfide) and their effectiveness in preventing BP-induced forestomach neoplasia in mice. In the liver, the combined contribution of other GSTs in the detoxification of (+)-anti-BPDE was far less than the contribution of mGSTP1-1 alone. Likewise, in the forestomach, the contribution of mGSTP1-1 far exceeded the combined contribution of other GSTs. Studies on the effects of OSCs against BP-induced forestomach neoplasia revealed a good correlation between their chemo-preventive efficacy and their ability to induce mGSTP1-1 expression in the liver (r = -0.89; p < 0.05) as well as in the forestomach (r = -0.97; p < 0.05). Our results suggest that the induction of mGSTP1-1 may be a reliable marker for evaluating the efficacy of potential inhibitors of BP-induced cancer in a murine model.

Modification of hepatic drug-metabolizing enzymes in rats treated with alkyl sulfides

Natural compounds which elevate detoxification enzymes and/or reduce activating enzymes could be considered as good candidates to protect against cancer. In this work, we studied the modulation of hepatic drug-metabolizing enzymes in rats treated with dimethyl sulfide (DMS), dimethyl disulfide (DMDS), methylpropyl disulfide (MPDS), dipropyl sulfide (DPS), dipropyl disulfide (DPDS) and diallyl disulfide (DADS) issued from Allium species. Compounds containing methyl groups had little or no effect. Compounds with two propyl groups or two allyl groups provoked a pleiotropic response on drug-metabolizing enzymes. DPS, DPDS and DADS induced ethoxyresorufin O-deethylase, methoxyresorufin O-demethylase and mostly pentoxyresorufin O-depentylase and decreased nitrosodimethylamine N-demethylase and erythromycin N-demethylase. These modifications of enzyme activities were accompanied by an increase of CYP 2B1,2 and a decrease of CYP 2E1, evidenced by immunoblotting. The same treatments stimulated some phase II enzyme activities such as glutathione transferase and UDP-glucuronyl transferases. This pattern of induction and/or inhibition of drug metabolizing enzymes was qualitatively similar to that elicited by the enzyme inducer, phenobarbital. The magnitude of the effects produced by DPDS was smaller than those produced by DADS and DPS. Our results suggest a possible protective effect of alkyl sulfides as well as diallyl disulfide, on the first step of carcinogenesis via the modulation of enzymes involved in carcinogen metabolism.

Mechanism of differential efficacy of garlic organosulfides in preventing benzo( a)pyrene-induced cancer in mice

The mechanism of differential efficacies of diallyl sulfide (DAS), diallyl disulfide (DADS), diallyl trisulfide (DATS), dipropyl sulfide (DPS) and dipropyl disulfide (DPDS) in preventing benzo( a)pyrene (BP)-induced cancer in mice has been investigated by determining their effects on the enzymes of BP activation/inactivation pathways. With the exception of DATS, treatment of mice with other organosulfides (OSCs) caused a small but significant increase (37–44%) in hepatic ethoxyresorufin O-deethylase (EROD) activity. However, the forestomach EROD activity did not differ significantly between control and treated groups. Only DAS treatment caused a modest but statistically significant reduction (about 25%) in pulmonary EROD activity. These results suggest that while reduction of EROD activity may, at least in part, contribute to the DAS-mediated inhibition of BP-induced lung cancer, anticarcinogenic effects of OSCs against BP-induced forestomach carcinogenesis seems to be independent of this mechanism. Treatment of mice with DAS, DADS and DATS resulted in a significant increase, as compared with control, in both hepatic (3.0-, 3.2- and 4.4-fold, respectively) and forestomach (1.5-, 2.7- and 2.7-fold, respectively) glutathione transferase (GST) activity toward anti-7β,8α-dihydroxy-9α,10α-oxy-7,8,9,10-tetrahydrobenzo ( a)pyrene ( anti-BPDE), which is the ultimate carcinogen of BP. The pulmonary GST activity was not increased by any of the OSCs. Even though epoxide hydrolase (EH) activity was differentially altered by these OSCs, a correlation between chemopreventive efficacy of OSCs and their effects on EH activity was not apparent. The results of the present study suggest that differences in the ability of OSCs to modulate GST activity toward anti-BPDE may, at least in part, account for their differential chemopreventive efficacy against BP-induced cancer in mice.

Aroma Volatiles of `GoldRush' and `Golden Delicious' Apples

The aroma volatiles of ripe fresh `GoldRush' and `Golden Delicious' apples (Malus ×domestica Borkh) were examined using dynamic headspace to capture the volatiles and gas chromatography (GC)–GC–mass spectroscopy (MS) analysis for compound identification. A total of 21 aroma volatiles were identified, with 16 being common to both cultivars: toluene, butyl acetate, hexyl formate, 2-methylbutyl acetate, xylene, butyl propionate, pentyl acetate, s-butyl butanoate, hexyl acetate, iso-butyl 2-methylbutanoate, hexyl propionate, hexyl butanoate, hexyl 2-methylbutanoate, hexyl hexanoate, a-farnesene, and ethyl phthalate. Three volatiles [dipropyl disulfide, pentyl 2-methylpropionate, and 2,6-bis(1,1-dimethylethyl)-2,5-cyclohexadiene-1,4-dione] were unique to `Golden Delicious'; two compounds (nonanal and nerolidol) were unique to `GoldRush'. Most identified compounds were esters. Hexyl acetate (18.39%) was the major volatile in `Golden Delicious', while butyl acetate (13.40%) was the highest in `GoldRush'.

Diallyl disulfide induces apoptosis of human colon tumor cells.

The present studies compared the effects of various oil-soluble compounds containing allyl and disulfide groups on the proliferation of cultured human colon tumor cells (HCT-15). Diallyl disulfide (DADS) was more effective in inhibiting the growth of HCT-15 cells than isomolar concentrations of S-allyl cysteine, dipropyl disulfide (DPDS), allyl chloride, allyl glycidyl ether and allyl alcohol. These studies clearly demonstrate the importance of both the diallyl and the disulfide groups in DADS. Treatment of HCT-15 cells with 100 microM DADS increased the intracellular calcium levels by 40%, while DPDS caused only a 12% increase in intracellular calcium. Exposure to 100 microM DADS or more, but not DPDS, caused the cells to undergo apoptosis as determined by morphological changes and DNA fragmentation. A positive correlation (r=0.944) was found between DADS-induced DNA fragmentation and its ability to increase intracellular free calcium levels. The widespread effectiveness of DADS was evident by its ability to inhibit the growth of human colon (HCT-15), skin (SK MEL-2) and lung (A549) tumor cell lines.

Naturally occurring diallyl disulfide inhibits the formation of carcinogenic heterocyclic aromatic amines in boiled pork juice.

Three heterocyclic aromatic amines, 2-amino-3-methyl-imidazo[4, 5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoxaline and 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, have been found in boiled pork juice. We have investigated the effect of naturally occurring organosulfur compounds, which are present in garlic and onion, on mutagen formation in boiled pork juice. Six organosulfur compounds - diallyl disulfide (DAD), dipropyl disulfide (DPD), diallyl sulfide (DAS), allyl methyl sulfide (AMS), allyl mercaptan (AM) and cysteine - were added separately to the pork juice before reflux boiling and then the mutagenicity of each sample was examined with the Salmonella typhimurium strain TA98 in the presence of S9 mix. All six compounds were found to inhibit the mutagenicity of boiled pork juice. The greatest inhibitory effect was observed with DAD and DPD, and this was 111-fold higher than that of the lowest, cysteine. To elucidate the inhibitory effect of DAD on mutagen formation in boiled pork juice, the major mutagenic fractions were monitored after HPLC separation by their mutagenicity with S. typhimurium TA98. By comparing the retention times of authentic IQ compounds from boiled pork juice with those following the addition of DAD, we showed that the mutagenicity of three major fractions was significantly inhibited compared with those same fractions in boiled pork juice alone. In addition, the Maillard reaction products (MRPs) in the boiled pork juice with and without the addition of DAD were quantified and identified by capillary gas chromatography and gas chromatography-mass spectrometry. The results show that the reduction in the total amount of MRPs (pyridines, pyrazines, thiophenes and thiazoles) in boiled pork juice after boiling for 12 h is correlated with their mutagenicity. Among the MRPs, tetrahydrothiophene-3-one exhibited the strongest correlation. These data suggest that the inhibition of IQ mutagen formation by DAD is mediated through the reduction of MRPs production.

Diallyl disulfide inhibits the proliferation of human tumor cells in culture

Diallyl disulfide (DADS), an oil-soluble organosulfur compound in processed garlic, was more effective in inhibiting the in vitro growth of human tumor cell lines: HCT-15 (colon), A549 (lung), and SK MEL-2 (skin) than isomolar quantities of the water-soluble compound S-allyl cysteine (SAC). Addition of DADS (100 μM) was cytostatic to all three cell lines. The importance of the allyl and the disulfide groups were revealed by the lack of a comparable depression in the growth of HCT-15 cells exposed to its saturated analogue, dipropyl disulfide (DPDS). Treatment with DADS also resulted in a dose-dependent increase in intracellular free calcium in cells. A dose-dependent decrease in the activity of calcium-dependent ATPase enzyme occurred in HCT-15 cells exposed to increasing quantities of DADS. A correlation ( r = −0.975) was found between the intracellular free calcium levels and the Ca-ATPase activity in DADS-treated cells. These studies document that DADS, a constituent of garlic oil, is an effective inhibitor of the growth of human neoplastic cells. Alterations in calcium homeostasis are likely involved in the growth inhibition/cytotoxicity caused by DADS.

Pyruvate and flavor development in macerated onions ( Allium cepa L.) by γ-glutamyl transpeptidase and exogenous C-S lyase

Effect of γ-glutamyl transpeptidase in conjunction with exogenous C-S lyase on pyruvate content in macerated onion and flavor profile was studied. Pyruvate production of 2.5-fold greater than that of the control was obtained in γ-glutamyl transpeptidase and exogenous C-S lyase treated onions held for 20 h at 37 °C. Relative abundance of flavor compounds in Spartan Banner, a pungent onion, varied from a yellow sweet salad-type onion. The effect of γ-glutamyl transpeptidase and exogenous C-S lyase on onion flavor profile was shown by a shift of major components from methyl propyl disulfide, methyl propenyl trisulfide, dimethyl tetrasulfide and propyl 1-propenyl trisulfide, into new major components, methyl 1-propenyl disulfide, dipropyl disulfide, propyl 1-propenyl disulfide, methyl 1-propenyl trisulfide, and propyl 1-propenyl trisulfide. This increase in 1-propenyl containing flavor compounds may effect overall flavor of γ-glutamyl transpeptidase and exogenous C-S lyase treated onion extracts.

Volatile Components in Protoplasts Isolated from the Marine Brown Alga Dictyopteris prolifera (Dictyotales).

The volatile compounds released from protoplasts of Dictyopteris prolifera were extracted by a closed looping head space (CLHS) procedure. The volatile compounds in the extract were identified by GC and GC-MS. The major characteristic volatile compounds in both the protoplast and the intact plant, were dictyopterenes. Dipropyl disulfide was detected only in the protoplast, whereas cubenol was detected only in the intact plant. These volatile compounds were shown to be produced by the algal enzyme and not by attached bacteria or other epiphytes and then released into Provasoli's enriched seawater modification (PESI) medium. This suggests that a protoplast preparation is a useful tool for research of volatile compounds and their biogeneses in marine algae.

Flavor production in tissue cultures of chive ( A. schoenoprasum L.): callus structure and flavor production

Allium species are an important source of natural flavourings for food and pharmaceutical preparations and have often been investigated in secondary metabolite studies. Tissue cultures of chive were initiated and subcultured for more than three years. Tissues producing organs and non-organogenetic tissues were examined for their structure and aroma compounds. The organ-generating ones developed root-like structures. Flavor production was investigated as sulfur volatile constituents and as amounts of enzymatically-produced pyruvic acid when tissues were crushed. Calli produced sulfur-containing flavor components, but less than fresh leaves. The main aroma component of fresh leaves was dipropyl disulfide, although asymmetric methyl and 1-propenyl disulfides were also present. The relative proportions of disulfides were modified in tissue cultures, with 1-propenyl disulfide being the main compound.

Effect of freezing, freeze-drying, and air-drying on odor of chive characterized by headspace gas chromatography and sensory analyses

Aroma compounds of fresh and processed chives were analyzed using headspace gas chromatography-mass spectrometry to determine the effect of freezing, freeze-drying, and air-drying on chive. The main aroma component of fresh chive was dipropyl disulfide. The relative proportions of disulfides were smaller in the frozen, freeze-dried, and air-dried chives than in the fresh. The most abundant carbonyl compounds were 2-hexenal in frozen chive and 2-methylpentenal in freeze-dried and air-dried chives. Differences between chive samples were also studied by sensory analyses to determine whether processing affects the odor characteristics of chives

Ovipositional Stimulus Deprivation and its Effect on Lifetime Fecundity of Delia antiqua (Meigen) (Diptera: Anthomyiidae)

Lifetime oviposition was measured for female Delia antiqua (Meigen) caged individually with cups of moist sand or surrogate onions possessing combinations of host-plant color and chemical stimuli. Females laid more eggs on surrogates than on sand and laid more eggs on surrogates coated with synthetic onion volatiles ( n -dipropyl disulfide, Pr2S2)than on untreated surrogates. Surrogate color had no effect on fecundity. Flies deprived of exposure to Pr2S2 took longer to initiate oviposition and took longer to complete ovipositional cycles. The presence of untreated surrogates increased the percentage of eggs laid in ovipositional cups from 14 to 74%, whereas the presence of Pr2S2 or host-plant color resulted in nearly all eggs being laid in cups. The number of eggs retained at death did not differ among treatments. The results suggest that differential oviposition may have resulted from reduced rates of egg maturation as a consequence of accumulation of unlaid eggs. Host specialization by the onion fly is probably due to ecological factors as well as an ovipositional preference for onion.

Comparative study by gas chromatography-mass spectrometry of methods for the extraction of sulfur compounds in Allium cepa L.

The influence of two extraction processes on the composition and yield of organic sulfur compounds present in the bulb of Allium cepa L. was evaluated using gas chromatography-mass spectrometry. The direct extraction method with diethyl ether, using chopped and macerated plant tissue, yielded methyl propyl disulfide as the major component, with a mean concentration of 34.37 μg per 100 g of fresh tissue. Prior steam distillation followed by extraction of the distillate identified the same components with the exception of methyl propyl disulfide, as in direct extraction method. The major component of the steam distillate was dipropyl disulfide, with a mean concentration of 110.2 μg per 100 g of fresh tissue.

A METHOD TO MEASURE SULFUR-CONTAINING VOLATILES IN ONIONS USING A GAS CHROMATOGRAPH.

A 50 g sample taken as a horizontal section from the mid-height of an onion bulb was blended with 100 g water for 1 min in a closed plastic mason jar. A 0.5 ml of a headspace sample was drawn and injected into a Perkin Elmer 8500 GC equipped with FPD for detection of sulfur compounds. The major volatiles tentatively identified in onion were thiopropanal S-oxide, methyl propyl disulfide, dipropyl disulfide, and propyl allyl disulfide. We observed significant variation of peak pattern and height depending on position in a bulb, among bulbs within variety, and between varieties. These results seemed to comply well with taste test. There were no significant correlations between total peak height and bulb weight, soluble solids, or pyruvate concentration in juice extract. Our investigation suggested that this procedure provided better understanding and measurement of onion pungency than pyruvate analysis.

Comparison of onion varieties by headspace gas chromatography-mass spectrometry

Volatile aroma compounds of crushed onions (Allium cepa L.) were analyzed over a 6-month storage period after harvesting. Compositions of the headspace of five varieties, Jumbo, Robusta, Sturon, Hygro, and Lafort, were analyzed by a static sampling procedure using gas chromatography (GC) and GC-mass spectrometry. Most prominent among the 27 identified aroma compounds were dipropyl disulfide, methyl propyl disulfide, 1-propenyl propyl disulfides, methyl 1-propenyl disulfides. The distribution pattern of the major comounds varied little during storage

Production of onion fly attractants and ovipositional stimulants by bacterial isolates cultured on onion

Decomposing onions at certain microbial successional stages produce potent volatile attractants and ovipositional stimulants of the onion fly,Delia antiqua (Diptera: Anthomyiidae). A reproducible source of these compounds was obtained by culturingErwinia carotovora var.carotovora (EC) on sterile onion tissue. In laboratory choice tests, EC-inoculated onion was more attractive thanKlebsiella pneumoniae (KP) cultured on onion, EC cultured on potato (a nonhost of onion fly), or the chemical synthetic baits dipropyl disulfide and an aqueous solution of 2-phenylethanol and pentanoic acid. Onion flies were mildly attracted to potato after inoculation with EC, but females did not accept EC-inoculated potato for oviposition. This work emphasizes that sources of semiochemicals may need to be defined microbiologically as well as physically and chemically.