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PubMed2000

Mechanism for antiplatelet effect of onion: AA release inhibition, thromboxane A(2)synthase inhibition and TXA(2)/PGH(2)receptor blockade.

Antiplatelet actions of aqueous extract of onion were investigated in rat and human platelet. IC(50)values of onion extract for collagen-, thrombin-, arachidonic acid (AA)-induced aggregations and collagen-induced thromboxane A(2)(TXA(2)) formation were 0.17 +/- 0. 01, 0.23 + 0.03, 0.34 +/- 0.02 and 0.12 +/- 0.01 g/ml, respectively. [(3)H]-AA release induced by collagen (10 microg/ml) in rat platelet was decreased by onion compared to control (22.1 +/- 2.13 and 5.2 +/- 0.82% of total [(3)H]-AA incorporated, respectively). In fura-2 loaded platelets, the elevation of intracellular Ca(2+)concentration stimulated by collagen was inhibited by onion. Onion had no cytotoxic effect in platelet. Onion significantly inhibited TXA(2)synthase activity without influence on COX activity. Platelet aggregation induced by U46619, a stable TXA(2)mimetic, was inhibited by onion, indicating its antagonism for TXA(2)/PGH(2)receptor. These results suggest that the mechanism for antiplatelet effect of onion may, at least partly, involve AA release diminution, TXA(2)synthase inhibition and TXA(2)/PGH(2)receptor blockade.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed2006

The production of reactive oxygen species and the mitochondrial membrane potential are modulated during onion oil-induced cell cycle arrest and apoptosis in A549 cells.

Protective effects of Allium vegetables against cancers have been shown extensively in experimental animals and epidemiologic studies. We investigated cell proliferation and the induction of apoptosis by onion oil extracted from Allium cepa, a widely consumed Allium vegetable, in human lung cancer A549 cells. GC/MS analysis suggested that propyl sulfides but not allyl sulfides are major sulfur-containing constituents of onion oil. Onion oil at 12.5 mg/L significantly induced apoptosis (13% increase of apoptotic cells) as indicated by sub-G1 DNA content. It also caused cell cycle arrest at the G2/M phase; 25 mg/L onion oil increased the percentage of G2/M cells almost 6-fold compared with the dimethyl sulfoxide control. The action of onion oil may occur via a reactive oxygen species-dependent pathway because cell cycle arrest and apoptosis were blocked by the antioxidants N-acetylcysteine and exogenous glutathione. Marked collapse of the mitochondrial membrane potential suggested that dysfunction of the mitochondria may be involved in the oxidative burst and apoptosis induced by onion oil. Expression of phospho-cdc2 and phospho-cyclin B1 were downregulated by onion oil, perhaps accounting for the G2/M arrest. Overall, these results suggest that onion oil may exert chemopreventive action by inducing cell cycle arrest and apoptosis in tumor cells.

Apoptosis↗

PubMed1997

Anti-bacterial action of onion (Allium cepa L.) extracts against oral pathogenic bacteria.

In this study, the focus was on the antibacterial activity of onions. This study researched the activities of onion extracts on Streptococcus mutans and Streptococcus sobrinus, the main causal bacteria for dental caries, and Porphyromonas gingivalis and Prevotella intermedia, considered to be the main causal bacteria of adult periodontitis. The results showed that the onion extracts possess an effect on all test bacterial strains (S.mutans JC-2, S. sobrinus OMZ176, P. gingivalis ATCC 33277 and P. intermedia ATCC 25611), and the effects were bactericidal against cultured and resting bacterial cells. The activity of the onion extracts was stable even after 48 hours in the culture medium. This result suggests that no decomposition or volatility of onion extracts occurred in the culture medium. The antibacterial activity of onion extracts was not markedly influenced by cysteine (10 mM) treatment. However, activity significantly decreased with alkali treatment. Grated onion left to stand at 37 degrees C for 48 hours did not show antibacterial activity. Also, activity of steam treated (100 degrees C, 10 min.) onion was not observed. Using avicel plate by thin layer chromatography with the solvent of n-butanol:acetic acid:water (3:3:1), the main component of the substance (the substance which develops color with ninhydrin) was observed at an Rf value of about 0.9.

1-Butanol↗

PubMedDate not supplied

Anaphylactic reaction to the ingestion of raw onion. A case report.

A case of severe systemic reactions (intense itching, urticaria, confusion, blurred vision, transient loss of consciousness, sweating, tachycardia) after ingestion of raw or lightly-cooked onion is described. The patient, a 44-year-old woman, had no troubles with well-cooked onions. Differently from the cases of sensitivity to onion described in literature, this patient was monosensitized, being skin tests negative to pollens, inhalants and other foods. The patient had 3.7 kU/L of onion-specific segum IgE, as determined by REAST. The density of onion-specific IgE (calculated as percent ratio to total IgE) was 30.8%. The reactivity of patient's serum IgE towards thermolabile and thermostable components has been tested with unheated and heated (30' at 100 degrees C) onion extracts bound to polystyrene beads and tested in the RAST system. Unheated extract resulted positive in class 2, heated extract negative, demonstrating that this patients, differently from similar clinical cases described in literature, had IgE antibodies recognizing just thermolabile onion fraction. This is the first case described in literature of a monosensitization to the thermolabile component of onion, negative also to related foods (Liliacee) and characterized by severe systemic reactions. The importance of specific-IgE density (%) rather their absolute amount (kU/L) as parameter predictive for the clinical severity of allergic reactions is discussed.

Adult↗

PubMed1977

Effect of essential oil of onion and garlic on experimental atherosclerosis in rabbits.

The effects of the essential oils of onion (extracted from 2 g of raw onion per kg body weight) and garlic (extracted from 1 g of raw garlic per kg body weight) have been observed on experimental atherosclerosis produced by cholesterol feeding (0.5 g/kg) in rabbits. The rise in serum cholesterol and serum triglycerides was significantly reduced by both onion and garlic during the 4-month period of study. Cholesterol feeding significantly increased beta-(P less than 0.01) and pre-beta (P less than 0.001) lipoproteins while decreasing the alpha-fraction (P less than 0.001). Onion and garlic both prevented these changes. The beta/alpha ratio, which was initially 1.6 : 1, rose to 4.5 : 1 and 5.7 : 1 at the end of 2 months and 4 months of cholesterol feeding. However, this ratio did not increase significantly, both at the 2-month and 4-month period, when onion and garlic were added. Fibrinolytic activity significantly increased with onion (P less than 0.001) and garlic (P less than 0.001) while feeding only cholesterol actually decreased it (P less than 0.001). Onion and garlic reducec aortic atheroma by about half. It is suggested that the essential oils of onion and garlic protect against experimental atherosclerosis by preventing the fall in the alpha lipoprotein fraction and by enhancing fibrinolytic activity, as well as by lowering the serum cholesterol and triglyceride levels.

Animals↗

PubMed1996

An evaluation of garlic and onion as antithrombotic agents.

Garlic (Allium sativum) and onion (Allium cepa) have been evaluated as possible antithrombotic agents. Rats were given aqueous extracts of garlic and onion, orally or intraperitoneally, daily for a period of 4 weeks after which the rats were sacrificed. The blood was collected from the heart without anticoagulant and the serum was prepared. The level of thromboxane B2 (TXB2) in the serum was measured by radioimmunoassay. TXB2 levels in serum of rats treated with the low dose of aqueous extract of garlic (50 mg/kg) was significantly inhibited regardless of the mode of administration (orally or intraperitoneally). At the high dose of garlic and onion (500 mg/kg), a further decrease of TXB2 levels in the serum of the rats was observed. Boiled garlic and onion at high concentration (500 mg/ kg) had very little effect on TXB2 synthesis. This shows that garlic and onion should be consumed in a raw rather than cooked form in order to achieve a beneficial effect. Boiling of these plants may cause the decomposition of the potential antithrombotic ingredient present in these herbs. Garlic was found to be more potent than onion in lowering the TXB2 levels. A high dose of garlic and onion produces toxicity in the rats (unpublished observation). These results show that garlic and onion can be taken frequently in low doses without any side effects, and can still produce a significant antithrombotic effect.

Allium↗

PubMed1992

Hematologic effects and feeding performance in cattle fed cull domestic onions (Allium cepa).

For 119 days, 36 cattle, allotted to 6 treatment groups, were fed a balanced growth diet containing 0, 5, 10, 15, 20, or 25% cull onions on a dry-matter basis. Cattle performance was comparable to that associated with barley-base non-onion diet; statistical differences were not observed among treatments. During the first 28 days of the study, reduction in numbers of RBC, hemoglobin concentration, and PCV was observed in all cattle fed onions, but clinical anemia was not seen in any individual animal. After onion feeding was discontinued at 119 days, RBC numbers, hemoglobin concentration, and PCV returned to baseline values within 30 days. Heinz bodies were detected in erythrocytes of all cattle fed onions, and the percentage was proportional to the amount of onions consumed. Addictive onion consumption was prevented by mixing chopped or crushed onions in a total balanced ration.

Allium↗

PubMed1990

The effect of raw onions on acid reflux and reflux symptoms.

Patients with gastroesophageal reflux often describe heartburn after "spicy meals." One ingredient common to most such meals is onion. We investigated the effects of onion on acid reflux and reflux symptoms in 16 normal subjects and 16 heartburn subjects. Subjects were studied with an esophageal pH probe for 2 h after the ingestion of a plain hamburger and a glass of ice water. The identical meal, with the addition of a slice of onion, was ingested on a counterbalanced day. Variables measured were number of reflux episodes, percentage of the time pH was less than four, heartburn episodes, and belches. Ingestion of onions did not increase any of the reflux variables measured in normals. However, onions significantly increased all measures in heartburn subjects, compared with the no-onion condition, and compared with normals under the onion condition. Onions can be a potent and long-lasting refluxogenic agent in heartburn patients.

Adult↗

PubMed2005

The L locus, one of complementary genes required for anthocyanin production in onions (Allium cepa), encodes anthocyanidin synthase.

Bulb color in onions (Allium cepa) is an important trait, but its complex, unclear mechanism of inheritance has been a limiting factor in onion cultivar improvement. The identity of the L locus, which is involved in the color difference between Brazilian yellow and red onions, is revealed in this study. A cross was made between a US-type yellow breeding line and a Brazilian yellow cultivar. The segregation ratio of nine red to seven yellow onions in the F(2) population supports the involvement of two complementary genes in anthocyanin production in the F(1) hybrids. The high-performance liquid chromatography (HPLC) and reverse-transcriptase (RT)-PCR analysis of the Brazilian yellow onions indicated that the genes are involved late in the anthocyanin synthesis pathway. The genomic sequence of the anthocyanidin synthase (ANS) gene in Brazilian yellow onions showed a point mutation, which results in an amino acid change of a glycine to an arginine at residue 229. Because this residue is located adjacent to a highly conserved iron-binding active site, this mutation is likely responsible for the inactivation of the ANS gene in Brazilian yellow onions. Following the isolation of the promoter sequence of the mutant allele, a PCR-based marker for allelic selection of the ANS gene was designed. This assay is based on an insertion (larger than 3 kb) mutation. The marker perfectly co-segregated with the color phenotypes in the F(2) populations, thereby indicating that the L locus encodes ANS.

Amino Acid Sequence↗

PubMed2006

Chemoprevention of aberrant crypt foci in the colon of rats by dietary onion.

Onion intake might reduce the risk of colorectal cancer, according to epidemiology. However, Femia showed in 2003 that diets with a 20% onion intake increase carcinogenesis in rats. We speculated this dose was too high. Prevention of initiation was thus tested in 60 rats given a 5% dried onion diet or AIN76 diet, and initiated 12 days later with azoxymethane (AOM, 1x20 mg/kg i.p.), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ, 2x200 mg/kg p.o.), or N-nitroso-N-methylurea (2x50 mg/kg p.o.). Prevention of promotion was tested in 38 rats given AOM, then randomised to: AIN76 diet; 5% onion diet; phytochemicals diet (supplemented with propyl-disulfide, quercetine-glycosides and oligofructose); 1% pluronic F68 diet (a potent chemopreventive PEG-like block-polymer, used as a positive control). Aberrant crypt foci (ACF) were scored 30 days (initiation) or 100 days (promotion) after carcinogen injection. The onion diet given during initiation reduced the number of AOM-induced ACF (60 versus 86, p=0.03), and the size of IQ-induced ACF (1.33 versus 1.97, p=0.02). Given post-initiation, the onion diet reduced the number of ACF (34 versus 59, p=0.008) and of large ACF (6 versus 15, p=0.02). Phytochemicals diet and pluronic diet reduced ACF growth similarly. Data show that a 5% onion diet reduced carcinogenesis during initiation and promotion stages, and suggest this chemoprevention is due to known phytochemicals.

Animals↗

PubMed2004

Varietal differences in phenolic content and antioxidant and antiproliferative activities of onions.

Epidemiological studies have indicated that the consumption of fruits and vegetables is associated with a reduced risk for the development of chronic diseases, such as cardiovascular disease and cancer. Phytochemicals, including phenolics and flavonoids, are suggested to be the major bioactive compounds contributing to the health benefits of fruits and vegetables. Onions are a major source of dietary flavonoids; however, there may exist varietal differences in composition, concentration, and beneficial activities. To characterize these differences, shallots and 10 onion (Allium cepa L.) varieties commonly available in the United States (Western Yellow, Northern Red, New York Bold, Western White, Peruvian Sweet, Empire Sweet, Mexico, Texas 1015, Imperial Valley Sweet, and Vidalia) were evaluated for total phenolic and flavonoid contents and antioxidant and antiproliferative activities. Shallots contained the highest total phenolic content (114.7 +/- 10.0 mg/100 g of sample) among the varieties tested, with a 6-fold difference observed when compared to the variety with the lowest phenolic content (Vidalia, p < 0.05). Western Yellow onion variety exhibited the highest total flavonoid content (69.2 +/- 3.7 mg/100 g of onion) of the varieties tested, with an 11-fold difference when compared to the variety with the lowest flavonoid content (Western White, p < 0.05). Shallots exhibited the highest total antioxidant activity (45.5 +/- 2.1 micromol of vitamin C equiv/g of onion), followed by Western Yellow, New York Bold, Northern Red, Mexico, Empire Sweet, Western White, Peruvian Sweet, Texas 1015, Imperial Valley Sweet, and Vidalia. For all varieties, both total phenolic and flavonoid contents were strongly correlated with total antioxidant activity (R (2) = 0.9668, p < 0.05; and R (2) = 0.7033, p < 0.05, respectively). The proliferation of HepG(2) and Caco-2 cells was significantly inhibited in a dose-dependent fashion after exposure to the Western Yellow, shallots, New York Bold, and Northern Red extracts, with Western Yellow, shallots, and New York Bold exhibiting the highest antiproliferative activity against HepG(2) cells and New York Bold and Western Yellow exhibiting the highest antiproliferative activity against Caco-2 cells. However, the varieties of Western White, Peruvian Sweet, Empire Sweet, Mexico, Texas 1015, Imperial Valley Sweet, and Vidalia demonstrated weak antiproliferative activity against both HepG(2) and Caco-2 cells. These results may influence consumers toward purchasing onion varieties exhibiting greater potential health benefits and may significantly affect future breeding efforts to enhance onion nutritional qualities.

Antioxidants↗

PubMed2005

Assessment of initial stages of Maillard reaction in dehydrated onion and garlic samples.

The initial steps of the Maillard reaction in freshly laboratory-freeze-dried and commercial dehydrated onion and garlic samples have been assessed by quantitative determination of 2-furoylmethylamino acids, obtained after acid hydrolysis of the corresponding Amadori compound. In freshly prepared samples, hardly any presence of 2-furoylmethylamino acids was detected, whereas in commercial samples, onion contained much more important levels of 2-furoylmethylamino acids as compared to garlic species. 2-Furoylmethyl-gamma-aminobutyric acid (1), 2-furoylmethyl-lysine (furosine; 2), and 2-furoylmethylarginine (3) were identified in all commercial dehydrated onion samples, with compound 3 being the most abundant. All garlic samples presented slightly higher levels of 2 than 3 with no presence of 1. The observed differences between onion and garlic commercial samples may be due to their very different content of reducing sugars. Moreover, some variations found in 2-furoylmethyl derivatives within both onion and garlic species could be also attributed to different processing and storage conditions during the manufacture of these products. The findings of this study show the first evidence of important levels of Amadori compounds in dehydrated garlic and onion samples, as well as the usefulness of 2-furoylmethyl derivatives as quality indicators for the early detection of the Maillard reaction in onion and garlic products.

Aminobutyrates↗

PubMed1999

Effect of raw versus boiled aqueous extract of garlic and onion on platelet aggregation.

The effects of aqueous extracts of raw and boiled garlic and onions were studied in vitro on the collagen-induced platelet aggregation using rabbit and human platelet-rich plasma. A dose dependant inhibition of rabbit platelet aggregation was observed with garlic. Onion also showed dose-dependent inhibitory effects on the collagen-induced platelet aggregation but this inhibition was of a lesser magnitude compared to garlic when related to dose. The concentration required for 50% inhibition of the platelet aggregation for garlic was calculated to be approximately 6.6 mg ml(-1) plasma, whereas the concentration for onion was 90 mg ml(-1) plasma. Boiled garlic and onion extracts showed a reduced inhibitory effect on platelet aggregation. Garlic but not onion significantly inhibits human platelet aggregation in a dose-dependent fashion. The potency of garlic in inhibiting the collagen-induced platelet aggregation is approximately similar to that of rabbit platelets (8.8 mg ml(-1) produced 50% inhibition of platelet aggregation). The results of this study show that garlic is about 13 times more potent than onion in inhibiting platelet aggregation and suggest that garlic and onion could be more potent inhibitors of blood platelet aggregation if consumed in raw than in cooked or boiled form.

Animals↗

PubMed2002

Antithrombotic effect of onion in streptozotocin-induced diabetic rat.

In the present study, we investigated whether onion has antithrombotic effect in streptozotocin (STZ)-induced diabetic rats. In diabetic rats, serum thromboxane B(2) (TXB(2)) level was elevated compared to that in normal, and this elevation in diabetes was significantly inhibited by treatment with onion (0.5 g/ml/kg/day, i.p.) for 4 weeks. In normal rats, the serum TXB(2) level remained unaltered after the treatment with onion. To investigate in vitro effect of onion, we examined its effect on TXB(2) formation, platelet aggregation and arachidonic acid (AA)-release in platelets from diabetic and normal rats. Onion showed a significant inhibitory effect on collagen- or AA-induced TXB(2) formation with greater potency in diabetic platelets than in normal. Similarly, more potent inhibitory effects of onion in diabetes were observed in collagen- or AA-induced platelet aggregation and collagen-induced AA release response. In conclusion, these results suggest that onion can produce more beneficial antithrombotic effect in diabetes.

Animals↗

PubMed2001

Administration of raw onion inhibits platelet-mediated thrombosis in dogs.

A number of studies suggest that dietary intake of onions is of benefit to cardiovascular health. Onion juice inhibits in vitro human platelet aggregation. To study the in vivo effect of onion on platelet aggregation, 11 dogs were prepared with mechanically damaged and stenosed coronary arteries. Periodic platelet-mediated thrombus formation followed by embolization produced cyclic flow reductions (CFR). In five dogs, 0.09 +/- 0.01 mL/kg onion juice administered intravenously abolished CFR within 20 min. This was followed by a 60 +/- 14% (P = 0.002) reduction in collagen-induced ex vivo whole-blood platelet aggregation. Six dogs were given 2.0 g/kg raw onion homogenate intragastrically. CFR were eliminated within 2.5-3 h in five of the dogs. This was accompanied by a 44 +/- 24% (P = 0.04) reduction in ex vivo aggregation. These findings suggest that the consumption of raw onion may help prevent platelet-mediated cardiovascular disorders. However, in vitro incubations of onion juice demonstrated that the platelet inhibitory response was significantly greater in dog blood than in human blood.

Analysis of Variance↗

PubMed2000

Adaptation of pregnant ewes to an exclusive onion diet.

A diet consisting entirely of cull onions fed to pregnant ewes produced Heinz body hemolytic anemia in all sheep after 21 d. After 28 d of daily consumption of 20 kg of onions/ewe, the anemia stabilized, and for the remaining 74 d the packed cell volume increased in the majority of sheep, although it did not return to normal. Compared to control ewes fed an alfalfa and grain diet, the onion-fed ewes had comparable body condition scores and fleece weights. There was no significant difference (alpha = 0.05) in pregnancy or lambing rate, number of lambs born/ewe exposed, or number of lambs born/ewe lambing. Greater numbers of sulfate-reducing bacteria (Desulfovibrio spp) and more ruminal hydrogen sulfide were present in onion-fed sheep compared to controls. Although an average 27% reduction in packed cell volume and Heinz body anemia developed in the onion-fed ewes, on the basis of this study it appears that pregnant ewes may be fed a pure onion diet with minimal detrimental effects. This adaptation to a pure onion diet is in part likely due to the apparent ability of the sheep's rumen to quickly develop a population of sulfate-reducing bacteria that decrease the toxicity of onion disulfides.

Adaptation, Physiological↗

PubMed2006

A salt-free zero-charged aqueous onion-phase enhances the solubility of fullerene C60 in water.

An onion-phase (multilamellar vesicular phase or Lalpha-phase) was prepared from salt-free zero-charged cationic and anionic (catanionic) surfactant mixtures of tetradecyltrimethylammonium hydroxide (TTAOH)/lauric acid (LA)/H2O. The H+ and OH- counterions form water (TTAOH + LA --> TTAL + H2O), leaving the solution salt free. The onion-phase solution has novel properties including low conductivity, low osmotic pressure and unscreened electrostatic repulsions between cationic and anionic surfactants because of the absence of salt. The spherical multilamellar vesicles have an average 250 nm radius as measured by freeze-fracture transmission electron microscopy (FF-TEM) and the maximum interlayer distance, i.e., the thickness of the hydrophobic bilayer and the water layer, was calculated to be around 52 nm by small-angle X-ray scattering (SAXS). Extremely hydrophobic C60 fullerene can be solubilized in this salt-free zero-charged aqueous onion-phase. As a typical result, 0.588 mg.mL(-1) (approximately 0.82 mmol.L(-1)) C60 has been successfully solubilized into a 50 mmol.L(-1) catanionic surfactant onion-phase aqueous solution. The weight ratio of fullerene to TTAL is calculated to be around 1:40. Solubilization of C60 in the salt-free catanionic onion-phase solution was investigated by using different sample preparation routes, and a variety of techniques were used to characterize these vesicular systems with or without encapsulated C60. The onion-phase solution changed color from slightly bluish to yellow or brown after C60 was solubilized. 1H and 13C NMR measurements indicated that the C60 molecules are located in the hydrophobic layers, i.e., in the central positions [omega-CH3 and delta-(CH2)x] of the hydrophobic layers of the TTAL onion-phase. Salt-free zero-charged catanionic vesicular aqueous solutions are good candidates for enhancing the solubility of C60 in aqueous solutions and may broaden the functionality of fullerenes to new potential applications in biology, medicine, and materials. Hopefully, our method can also be extended to solubilize functionalized carbon nanotubes in aqueous solutions.

Fullerenes↗

PubMed2003

Factors accounting for the variability in the behavioral response of the onion fly (Delia antiqua) to n-dipropyl disulfide.

The onion fly Delia antiqua is a specialist herbivore attacking only onions and closely related Allium species. n-Dipropyl disulfide (Pr2S2) has long been known to be attractive to onion flies in the laboratory and in the field. However, the insect's response is highly variable. Using behavioral bioassays we found that Pr2S2 was highly attractive to gravid, mated female onion flies,but did not stimulate oviposition. The response of female onion flies was concentration dependent. The physiological state of the flies (i.e., age, mating status, egg load/oviposition experience) also affected their responsiveness. The response of both sexes of onion flies varied with age, but females were always more strongly attracted than males. Responsiveness of females increased during the first 10 days after emergence. It stayed at a high level until 21 days after which the experiment was terminated. The responsiveness of males reached a maximum at 6-7 days after which it declined. Mated, gravid females responded more strongly to Pr2S2 than unmated, gravid females. Females deprived of the opportunity to oviposit were more attracted compared to females that had oviposited on cut onions prior to the experiment. Electroantennograms (EAG) of females revealed a higher response to stimulation compared to males. The EAG-response of females was not affected by mating status.

Allium↗