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PubMed1987

Effects of onion extract on the development of hamster buccal pouch carcinomas as expressed in tumor burden.

One-hundred male, young-adult Syrian hamsters (Mesocricetus auratus) were divided into five equal groups of 20 animals each. Groups 1, 2, and 3 were painted three times a week in the left buccal pouches with a 0.5% solution of 7,12-dimethylbenz[a]anthracene (DMBA) in mineral oil. Group 1 animals also received a 20% onion extract in their drinking water and were also painted in left buccal pouches three times a week with a 50% onion extract in mineral oil. Group 2 animals received the onion extract in their drinking water, but they received only mineral oil in buccal pouches as a control for the painting with onion extract in mineral oil. Group 3 animals received DMBA but no onion extract. Group 4 animals received onion extract but no DMBA, and Group 5 animals were left untreated. Onion extract was found to significantly delay tumor formation in Groups 1 and 2 compared with Group 3 DMBA controls.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1987

The C-S Lyases of Higher Plants : Direct Comparison of the Physical Properties of Homogeneous Alliin Lyase of Garlic (Allium sativum) and Onion (Allium cepa).

Garlic and onion alliin lyases, although from closely related species, have many differences. The two enzymes differ in their K(m) values, pH optima, and isoelectric points. There is a major difference in their molecular weight and subunit structure. The garlic holoenzyme has a molecular weight of 85,000 and consists of two subunits of molecular weight 42,000. The onion enzyme has a holoenzyme molecular weight of 200,000 composed of four subunits of molecular weight 50,000. The onion enzyme is much more difficult to dissociate into its subunits which suggests differences in subunit interaction between the two enzymes. The dimeric stucture of the garlic and the tetrameric structure of the onion enzyme is consistent with a coenzyme content (pyridoxal-5'-phosphate) equivalent to one mole per subunit. The two enzymes vary vastly in their spectra, the onion enzyme having a lower pyridoxal-5'-phosphate absorbance at 430 nanomoles and an inability to react with l-cysteine. Both enzymes are glycoproteins and bind to concanavalin A-Sepharose columns. The onion alliin lyase binds more tightly than the garlic enzyme. The amino acid content of both enzymes is similar as is the carbohydrate content. However, upon hydrolysis the onion lyase does yield more mannose units than the garlic enzyme which is consistent with the former's stronger affinity for concanavalin A.

Journal Article↗
PubMed2001

Effect of onion consumption by rats on hepatic drug-metabolizing enzymes.

Fruits and vegetables or their natural constituents which increase detoxication enzymes and/or reduce activating enzymes are considered as good candidates to prevent chemically-induced carcinogenesis. In this study, rats were fed a diet supplemented with 20% onion powder for 9 days. Several cytochrome P450 (CYP)s enzymes (CYP 1A, 2B, 2E1, 3A), which are involved in carcinogen activation, were determined by measuring their enzyme activities using specific substrates. In addition, phase II enzymes activities such as UDP-glucuronosyltransferase (UGT) and glutathione S-transferase (GST), involved in detoxication of carcinogens, were measured. Protein levels of CYPs and GST A1/A2, A3/A5, Ml, M2 and P1 were measured using antibodies in Western blots. Consumption of onion induced CYP 1A and CYP 2B activities while it decreased CYP 2E1 activity. This later modification was accompanied by a decrease of CYP 2E1 levels. The same dietary treatment caused a slight increase of the total GST activity. The relative proportions of GST subunits were modified. GST Al/A2 subunits were increased while GST A3/A5 and GST M2 subunits were decreased and GST M1 and P1 were not modified. Onion consumption also increased p-nitrophenol UGT activity. Taken together, these results suggest that the decrease of CYP 2E1 and the increase of phase II enzymes by onion can afford protection against some carcinogens, while the decrease of some GST subunits could increase the genotoxic effects of other chemicals. The modulating effect of onion could be ascribed to alk(en)yl polysulphides and/or glycosides of flavonols, which were identified in the onion powder.

Animals↗
PubMedDate not supplied

Fungi genus and concentration in the air of onion fields and their opportunistic action related to mycotic keratitis.

The authors determined fungi concentrations and genera from onion fields located in monsoon and nonmonsoon areas of Taiwan, as well as concentrations from a county housing location, which served as the comparison site. The authors explored the relationship(s) among onion harvesting, monsoon characteristics, airborne fungal levels, and mycotic eye infection. Airborne fungal levels in the onion field in the nonmonsoon area were the highest, followed by decreasing levels in the monsoon area and control sites, regardless of the sampling periods. The geometric mean of airborne fungal concentrations was the highest during onion harvesting. Cladosporium was the most dominant fungus during pre- and postharvest seasons, whereas Aspergillus, Fusraium, Acremonium, Alternaria, Penicillium, Monilia, Mycelia, and Rhizopus were increased significantly during harvesting. Although fungal concentrations in monsoon onion fields were lower than concentrations measured in the nonmonsoon area, the invasion of dangerous fungal pathogens following eye trauma by airborne sharp exotics (e.g., onion flakes) dispersed in high wind may account for the increase in corneal ulcer cases that occur in the monsoon area.

Adult↗
PubMed2003

Honey bee (Hymenoptera: Apidae) foraging in response to preconditioning with onion flower scent compounds.

Onion (Allium cepa L.) seed production has long been plagued with yield problems because of lack of pollination by the honey bee, Apis mellifera L. To attempt to attract more pollinators to the onion seed production field, honey bees were conditioned to associate onion floral odor components with a reward. Isolated nucleus hives of honey bees were fed 30% sucrose solutions scented with a 0.2% solution of onion floral odor compounds. After feeding on these solutions for 6 wk, bees were not found to prefer onion flowers to two competing food sources, carrot and alfalfa flowers, at the 5% significance level. However, there was an overall trend indicating a change in honey bee behavior, with fewer "trained" bees visiting alfalfa and carrot and more visiting onion. Thus, it may be possible to alter honey bee behavior with preconditioning but probably not to a degree that would be economically significant.

Animals↗
PubMed2002

Acid and heat stability of the anticoagulative activity of an onion extract.

An onion extract possessed anticoagulative activity apparently by inhibiting thrombin, and it was dependent upon the concentration of onion extract added. Boiling the onion extract at 100 degrees C for 30 min made no difference to its anticoagulative activity compared to that of fresh onion. The anticoagulative activity of the onion extract was also retained after an acid treatment by incubating at pH 2.0 for 4 hrs. However, dialyis of the extract substantially eliminated the anticoagulative activity. Therefore, the anticoagulant in the onion extract seems to have been a heat- and acid-stable substance of low molecular weight.

Anticoagulants↗
PubMed2003

Biological control of Fusarium oxysporum, the causal agent of onion wilt by antagonistic bacteria.

Fusarium wilt caused by Fusarium oxysporum Sch. is one of the most important diseases of onion in Iran. Application of chemicals especially as soil drench, increased cost of onion production and may be dangerous for environment. One of the effective techniques to suppress soil-born diseases in biological control with antagonistic rhizobacteria. Experiment were carried out with 120 bacterial isolates that were collected from onion rhizosphere. Six highly effective isolates were selected from these antagonists for subsequent studies. These strains were used to investigate their biocontrol traits in vitro and their ability to suppress the onion wilt in vivo (soil and seed treatments). According to the biochemical, physiological and morphological test, the isolates 22, 38, 46 and 52 were identified as Bacillus spp. The isolates 16 and 48 were identified as Pseudomonas fluorescens. The isolates of Bacillus spp. produced volatile metabolites that inhibited mycelia growth of Fusarium oxysporum. In soil treatment, the isolates 22 and 52 with 56% and 51% had the highest effect in reducing the Fusarium wilt of onion. The mixture of two isolates reduced 60% the disease. In seed treatment the isolate 22 with 41% had the greatest effect on reducing the onion Fusarium wilt.

Antibiosis↗
PubMed2001

Mutation of the zebrafish glass onion locus causes early cell-nonautonomous loss of neuroepithelial integrity followed by severe neuronal patterning defects in the retina.

Mutation of the glass onion locus causes drastic neuronal patterning defects in the zebrafish retina and brain. The precise stratified appearance of the wild-type retina is absent in the mutants. The glass onion phenotype is first visible shortly after the formation of optic primordia and is characterized by the rounding of cells and disruption of the ventricular surface in the eye and brain neuroepithelia. With exception of the dorsal- and ventral-most regions of the brain, neuroepithelial cells lose their integrity and begin to distribute ectopically. At later stages, the laminar patterning of retinal neurons is severely disrupted. Despite the lack of lamination, individual retinal cell classes differentiate in the glass onion retina. Mosaic analysis reveals that the glass onion mutation acts cell nonautonomously within the retina and brain, as neuroepithelial cell morphology and polarity in these tissues are normal when mutant cells develop in wild-type hosts. We conclude that the glass onion mutation affects cell-cell signaling event(s) involved in the maintenance of the neuroepithelial cell layer shortly after its formation. The disruption of neuroepithelial integrity may be the cause of the neuronal patterning defects following neurogenesis. In addition, the expression of the glass onion phenotype in a subset of neuroepithelial cells as well as its onset following the initial formation of the neuroepithelial sheets indicate the presence of genetically distinct temporal and spatial subdivisions in the development of this histologically uniform tissue.

Animals↗
PubMed1986

Onion exerts antiaggregatory effects by altering arachidonic acid metabolism in platelets.

In vitro effects of an oily extract of onion were examined on the metabolism of arachidonic acid (AA) in human platelets. Onion was found to reduce the formation of thromboxane and lipoxygenase products from exogenous arachidonic acid in platelets; it did not inhibit the incorporation of AA into platelet phospholipids. While not affecting the platelet phospholipase activity it did reduce the formation of thromboxane B2 and lipoxygenase products in platelets that were prelabelled with arachidonic acid and then activated by A23187. This suggests that onion inhibits the formation of AA metabolites by exerting its effect at steps later than the liberation of AA. With concentrations of onion extract producing abolition of AA-induced aggregation, only partial inhibition of aggregation was observed with ADP- and epinephrine-induced aggregation. Onion did not inhibit A23187 induced aggregation. The results suggest that inhibition of platelet aggregation by onion is mediated largely by its effect on platelet thromboxane production.

Adenosine Diphosphate↗
PubMed2000

Antioxidant effect of onion oil (Allium cepa. Linn) on the damages induced by nicotine in rats as compared to alpha-tocopherol.

The beneficial effects of onion oil as an antioxidant has been assessed in nicotine administered rats by studying whether the peroxidative damage caused by nicotine can be effectively combated with the onion oil and the effects compared to vitamin E, a highly efficient antioxidant. Lipid peroxidation products and antioxidant defence system have been studied in liver, lungs, and heart. The rats were injected with nicotine (0.6 mg/kg body wt.) and simultaneously given onion oil (100 mg/kg body wt.) or vitamin E (100 mg/kg body wt.) for 21 days. Concentration of free fatty acids, TBA reactive substances (TBARS), conjugated dienes and hydroperoxides were significantly increased in the tissues of nicotine treated rats as compared to normal rats. Onion oil supplemented to nicotine treated rats showed increased resistance to lipid peroxidation and the effect was near to that of vitamin E fed rats. The activity of catalase and superoxide dismutase decreased in nicotine treated rats. Antioxidants-glutathione content, vitamin C and retinol showed no significant difference but liver vitamin E content significantly decreased in nicotine treated rats. On onion oil or vitamin E supplementation, the concentration of antioxidants were significantly raised in all the tissues studied, however, a significantly increased concentration of glutathione, vitamin E and retinol was noticed in vitamin E+nicotine treated rats. Thus, these results indicate that onion oil is an effective antioxidant against the oxidative damage caused by nicotine as compared to vitamin E.

Animals↗
PubMed2000

Effective onion vinegar production by a two-step fermentation system.

A two-step fermentation system combining a repeated batch process using a flocculating yeast with a charcoal pellet bioreactor was developed for onion vinegar production. Juice from the red onion R-3, which contained 67.3 g/l total sugar, was smoothly converted to onion alcohol containing 30.6 g/l ethanol by repeated batch operation using the flocculating yeast Saccharomyces cerevisiae strain IR-2. Stable operation was possible and the maximum productivity was about 8.0 g/l/h. A packed bed bioreactor containing charcoal pellets produced from waste mushroom medium was then applied to continuous onion vinegar production from the onion alcohol. Onion vinegar was successfully produced, with a maximum productivity and acetic acid concentration of about 3.3 g/l/h and 37.9 g/l, respectively. The total acetic acid yield calculated from the amount of sugar consumed was 0.86. The two-step system was operated for 50 d and proved to be competitive with other systems in terms of its high productivity, high acetic acid yield, operational stability and low production costs.

Journal Article↗
PubMed2004

Quantitation of the intense aroma compound 3-mercapto-2-methylpentan-1-ol in raw and processed onions (Allium cepa) of different origins and in other Allium varieties using a stable isotope dilution assay.

A stable isotope dilution assay was developed for the quantitation of the potent onion odorant 3-mercapto-2-methylpentan-1-ol (1) using mass chromatography and synthesized [(2)H(2)]-3-mercapto-2-methylpentan-1-ol as the internal standard. Application of the newly developed method on onions from different origins revealed amounts between 8 and 32 microg/kg in raw onions, whereas 34-246 microg was found in sliced, stored (50 min), and then cooked onions. In extracts prepared by simultaneous steam distillation-extraction the highest concentrations of 1 were formed, amounting to >1200 microg/kg. The much higher content of 3-mercapto-2-methylpentan-1-ol in cooked onions suggested its formation from specific, yet unkown, precursors enzymatically formed during cutting of raw onions. 1 was for the first time identified and also quantified in other Allium species such as chives, scallions, and leek, whereas surprisingly garlic and bear's garlic did not contain the aroma compound.

Allium↗
PubMed1990

Inhibition of DMBA-induced mouse skin tumorigenesis by garlic oil and inhibition of two tumor-promotion stages by garlic and onion oils.

A single 2-mg dose of garlic oil applied 30 minutes before a single carcinogenic dose of 7,12-dimethylbenz[a]-anthracene (DMBA) inhibited papilloma production in Sencar mice. The three groups were controls (Group 1), garlic oil applied 30 minutes before DMBA (Group 2), and garlic oil applied 30 minutes after DMBA (Group 3). The percents of mice with papillomas at 20 weeks were 94, 72, and 79, respectively. The decreases in Groups 2 and 3 were significant. The number of papillomas per mouse was 4.2 +/- 0.5 (Group 1), 2.3 +/- 0.8 (Group 2), and 3.4 +/- 0.6 (Group 3). The decrease in Group 2 was significant. A single 5-mg dose of garlic oil maximally inhibited DMBA-induced epidermal DNA synthesis by 86% when applied two hours before the carcinogen. Two-stage promotion in DMBA-initiated Sencar mice was achieved by twice-weekly applications of 8.5 nmol of 12-O-tetradecanoylphorbol-13-acetate (TPA) for 2 weeks followed by twice-weekly applications of 8.5 nmol of mezerein for 18 weeks. The oils were applied 30 minutes after each promotion by TPA or mezerein. Single doses of 1 mg onion or garlic oil inhibited the first and second stages of promotion. The groups used were control (Group 1), garlic oil applied after stage 1 (Group 2), onion oil applied after stage 1 (Group 3), propenyl sulfide applied after stage 1 (Group 4), garlic oil applied after stage 2 (Group 5), onion oil applied after stage 2 (Group 6), and propenyl sulfide applied after stage 2 (Group 7). The percent of mice with papillomas was significantly decreased by all agents in Groups 2-7. The data are 81, 83, 91, 68, 96, and 86, respectively. The number of papillomas per mouse was significantly reduced by onion and garlic oils but not by propenyl sulfide. The data are 9.4 +/- 0.8, 6.3 +/- 0.7, 7.4 +/- 0.5, 9.2 +/- 1.2, 3.7 +/- 0.9, 6.2 +/- 0.6, and 9.1 +/- 1.4 for Groups 1-7, respectively. Onion and garlic oils inhibited the TPA-stimulated DNA synthesis when given as single doses of 5 mg one hour before TPA. The inhibition by garlic oil was most effective when given one hour before TPA but was evident when given from two hours before to two hours after TPA. These results, and those of others (AS Sadhana, Cancer Lett, 40, 193-197, 1988), who obtained inhibition of initiation, indicate that onion and garlic oils inhibit all stages of mouse skin tumorigenesis.(ABSTRACT TRUNCATED AT 400 WORDS)

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

A prospective cohort study on the relationship between onion and leek consumption, garlic supplement use and the risk of colorectal carcinoma in The Netherlands.

The association between onion and leek consumption, garlic supplement use and colon and rectum carcinoma among men and women was evaluated in the Netherlands Cohort Study, a large-scale prospective cohort study on diet and cancer. Onions, leeks, and garlic belong to the Allium genus and contain large amounts of potentially chemopreventive compounds. The Netherlands Cohort Study was started in 1986 among 120 852 men and women, aged 55-69 years. Dietary intake was measured with a 150-item food frequency questionnaire. After 3.3 years of follow-up, 150 and 143 incident male and female cases of colon carcinoma, and 93 and 57 cases of rectum carcinoma, respectively, with complete dietary data were available for analysis. Dietary data were available for 1525 men and 1598 women of a randomly selected subcohort, that was followed up to estimate person-time in the entire cohort. In men, the adjusted rate ratios (RRs) in multivariable analysis for colon and rectum carcinoma in the highest compared to the lowest onion consumption categories were 0.87 (95% confidence interval [CI] = 0.48-1.65), and 0.66 (95% CI = 0.28-1.52), respectively. The RRs for proximal colon carcinoma were lower than for distal colon carcinoma. Leek consumption was not associated with colon and rectum carcinoma incidence in men. None of the RRs were significantly different from unity and no trends in the RRs were detected. A lower risk was found for rectum carcinoma in women consuming less than 0.25 onions per day (RR=0.36, 95% CI = 0.13-0.99), but the trend in the RRs was not statistically significant (P = 0.25). All other RRs for colon and rectum carcinoma associated with onion consumption were slightly higher than one. Leek consumption was not associated with colon and rectum carcinoma incidence. The use of garlic supplements was not associated with colon and rectum carcinoma in men and women combined. This study does not support an inverse association between the consumption of onions and leeks, or the use of garlic supplements and the incidence of male and female colon and rectum carcinoma.

Age Distribution↗
PubMed1999

Welsh onion (Allium fistulosum L.) extracts alter vascular responses in rat aortae.

Welsh onion, a member of the genus Allium, has been consumed for prevention of cardiovascular disorders. However, its underlying mechanisms are still unclear. We investigated whether Welsh onion extracts (green or white portion, raw or boiled) can alter vascular responses in vitro in the thoracic aortae of Sprague-Dawley rats. The possible roles of endothelium-derived factors in the Welsh onion extract-induced vascular responses were examined by applying various inhibitors, such as Nomega-nitro-L-arginine (10(-4) M), tetraethylammonium (10(-3) M), and SQ29548 (10(-5) M). Our results showed that Welsh onion extracts caused vasodilation on precontracted vessel rings. These effects were most pronounced in vessel rings treated with raw green-leaf extract (RG). Low doses of RG induced vasorelaxation, which was mediated by endothelium-derived nitric oxide. High doses of RG induced endothelium-independent vasorelaxation. On the other hand, the boiled Welsh onion extract also stimulated the release of an endothelium-derived contracting factor, which might be thromboxane A2. We conclude that Welsh onion extract can modulate vascular tone in both endothelium-dependent and endothelium-independent manners.

Allium↗
PubMed2004

Effect of feeding green onions (Allium ascalonicum) to White Chinese geese (Threskiornis spinicollis).

Sudden increase in mortality was observed in 2 different flocks of mature breeder geese fed green onions. At necropsy, birds had pale epicardium with random petechiation, sanguinous fluid accumulation in the pericardial sac, and mild swelling of the liver and spleen. Histologically, there was accumulation of hemosiderin in hepatocytes, Kupffer cells of the liver, macrophages, and renal tubules. There was also moderate to severe hepatic necrosis, vacuolation of hepatocytes, splenitis, and renal tubular nephrosis. To assess the effects of green onion ingestion, 2 feeding trials were carried out in 3 mature White Chinese geese. In the first trial, onions were thoroughly mixed with pellet maintenance ration. In the second trial, onions were offered in a separate trough from the pelleted diet. During the 21 days of experiments, the red blood cell count and hematocrit decreased, whereas the polychromasia and reticulocyte estimate increased. The blood changes were more marked in birds from the second feeding trial. Gross and histologic changes were similar in both trials. Mild swelling and severe darkening of the liver were the only significant findings at necropsy. Histologically, the liver looked similar to that seen from the field outbreak. The liver contained moderate amounts of hemosiderin in the hepatocytes and Kupffer cells, and had centrolobular necrosis and vacuolation of hepatocytes. This experimental study demonstrated that anemia and liver pathology could be caused by ingestion of onions. Furthermore, Heinz bodies are not a consistent finding in the blood of geese fed onions.

Anemia↗
PubMed2005

Genetic mapping of expressed sequences in onion and in silico comparisons with rice show scant colinearity.

The Poales (which include the grasses) and Asparagales [which include onion (Allium cepa L.) and other Allium species] are the two most economically important monocot orders. Enormous genomic resources have been developed for the grasses; however, their applicability to other major monocot groups, such as the Asparagales, is unclear. Expressed sequence tags (ESTs) from onion that showed significant similarities (80% similarity over at least 70% of the sequence) to single positions in the rice genome were selected. One hundred new genetic markers developed from these ESTs were added to the intraspecific map derived from the BYG15-23xAC43 segregating family, producing 14 linkage groups encompassing 1,907 cM at LOD 4. Onion linkage groups were assigned to chromosomes using alien addition lines of Allium fistulosum L. carrying single onion chromosomes. Visual comparisons of genetic linkage in onion with physical linkage in rice revealed scant colinearity; however, short regions of colinearity could be identified. Our results demonstrate that the grasses may not be appropriate genomic models for other major monocot groups such as the Asparagales; this will make it necessary to develop genomic resources for these important plants.

Base Sequence↗
PubMed2001

Genetic analyses of correlated solids, flavor, and health-enhancing traits in onion (Allium cepa L.).

Onion possesses organosulfur compounds and carbohydrates that provide unique flavor and health-enhancing characteristics. Significant phenotypic correlations have been reported among soluble solids content (SSC), total dry matter, pungency, and onion-induced in vitro antiplatelet activity. A genetic map and segregating F3M families derived from a cross between two inbred populations were used to identify and estimate the effects of quantitative trait loci (QTLs) controlling these traits at 30 and 90 days postharvest. In vitro antiplatelet activities among different onion populations were consistent across six human blood donors. Most of the populations showed in vitro antiplatelet activities; however, for some donors, one of the parental lines and two F3M families had pro-aggregatory effects under our experimental conditions. SSC, dry matter, pungency, and in vitro antiplatelet activity showed significant positive phenotypic and genetic correlations. A chromosome region on linkage group E accounted for a significant amount of the phenotypic variation for all of these traits. The correlations among these traits may be due to linkage or pleiotropy of genes controlling solids content. Our results indicate that it will be difficult to develop onion populations with lower pungency and high in vitro antiplatelet activity; however, the strong genetic and phenotypic correlations between high in vitro antiplatelet activity and high SSC are beneficial for the health functionality of onion.

Adult↗