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At least 181 records · Page 10Linked to original sources
PubMed2005

Flavonol glucoside profile of southern Italian red onion (Allium cepa L.).

High-performance liquid chromatography-diode array detector (HPLC-DAD) coupled with electron spray mass spectrometry (ESI-MS-MS) was used to determine the flavonol profile in southern Italian red onions (Allium cepa L.). This on-line technique allowed the identification of seven flavonols in southern Italian red onion, quercetin 4'-glucoside and quercetin 3,4'-diglucoside being the most abundant components. Five minor flavonols have been recognized, offering a characteristic profile of such compounds in red onions under study. Quercetin 3-glucoside, quercetin 7,4'-diglucoside, quercetin 3,7,4'-triglucoside, and isorhamnetin 4'-glucoside have been previously reported as minor flavonoid components in Allium cepa, while isorhamnetin 3,4'-diglucoside was previously found in Allium ascalonicum. Traces of isorhamnetin 3-glucoside and free quercetin were also detected.

Chromatography, High Pressure Liquid↗
PubMed2004

Application of inorganic element ratios to chemometrics for determination of the geographic origin of welsh onions.

The composition of concentration ratios of 19 inorganic elements to Mg (hereinafter referred to as 19-element/Mg composition) was applied to chemometric techniques to determine the geographic origin (Japan or China) of Welsh onions (Allium fistulosum L.). Using a composition of element ratios has the advantage of simplified sample preparation, and it was possible to determine the geographic origin of a Welsh onion within 2 days. The classical technique based on 20 element concentrations was also used along with the new simpler one based on 19 elements/Mg in order to validate the new technique. Twenty elements, Na, P, K, Ca, Mg, Mn, Fe, Cu, Zn, Sr, Ba, Co, Ni, Rb, Mo, Cd, Cs, La, Ce, and Tl, in 244 Welsh onion samples were analyzed by flame atomic absorption spectroscopy, inductively coupled plasma atomic emission spectrometry, and inductively coupled plasma mass spectrometry. Linear discriminant analysis (LDA) on 20-element concentrations and 19-element/Mg composition was applied to these analytical data, and soft independent modeling of class analogy (SIMCA) on 19-element/Mg composition was applied to these analytical data. The results showed that techniques based on 19-element/Mg composition were effective. LDA, based on 19-element/Mg composition for classification of samples from Japan and from Shandong, Shanghai, and Fujian in China, classified 101 samples used for modeling 97% correctly and predicted another 119 samples excluding 24 nonauthentic samples 93% correctly. In discriminations by 10 times of SIMCA based on 19-element/Mg composition modeled using 101 samples, 220 samples from known production areas including samples used for modeling and excluding 24 nonauthentic samples were predicted 92% correctly.

China↗
PubMed2006

Model studies on precursor system generating blue pigment in onion and garlic.

Reactions involved in blue-green discoloration in a mixture of onion (Allium cepa L.) and garlic (Allium sativum L.) were investigated. Vivid-blue color was successfully reproduced by using a defined model reaction system comprising only trans-(+)-S-(1-propenyl)-L-cysteine sulfoxide (1-PeCSO) from onion, S-allyl-L-cysteine sulfoxide (2-PeCSO) from garlic, purified alliinase (EC 4.4.1.4), and glycine (or some other amino acids). Four reaction steps identified and factors affecting the blue color formation were in good agreement with those suggested by earlier investigators. When crude onion alliinase was used in place of garlic alliinase, less pigment was formed. This result was explained by a difference in the amount of thiosulfinates, colorless intermediates termed color developers, yielded from 1-PeCSO by these enzymes.

Carbon-Sulfur Lyases↗
PubMed2000

Physicochemical characteristics of onion (Allium cepa L.) tissues.

The structure and mechanical properties of onions are important factors affecting their textural quality. The onion bulb consists of several layers of pigmented, papery scales surrounding fleshy storage scales that comprise an upper epidermis, an intermediate parenchyma tissue, and a lower epidermis. The purpose of this study was to examine the chemical composition of cell walls from the papery scales and outer fleshy scales of onion (Allium cepa L. cv. Sturon) in relation to their mechanical properties. Cell-wall material (CWM) was prepared from the component tissues and analyzed for its carbohydrate and phenolic composition. The CWMs were rich in uronic acid and glucose, with smaller quantities of arabinose, galactose, and xylose. In the fleshy scales, the lower epidermis contained relatively more galactose-rich pectic polysaccharides, whereas the upper epidermis and the papery scales contained virtually no galactose. Analysis of mechanical properties showed that the order of strength of the tissues was papery scales > fleshy scales, which were in the order lower epidermis > upper epidermis > intermediate parenchyma. The upper epidermis of fleshy scales was stronger in the vertical than the horizontal direction, and both orientations showed negligible notch sensitivity. Cyclohexane-trans-1,2-diaminetetraacetate-induced vortex-induced cell separation of the intermediate layer of fleshy scales indicated that calcium cross-linking may play an important role in cell-cell adhesion. A small but significant amount of ferulic acid was found in the walls, predominantly in the thick cuticle of the lower epidermis of fleshy scales. Alkali-labile wall-bound flavonoids were also detected.

Carboxylic Acids↗
PubMed2006

Dynamics of fresh and freeze-dried strawberry and red onion by quasielastic neutron scattering.

The microscopic behavior of fresh and freeze-dried strawberry and red onion at different water contents (45 and 20 wt % water) has been investigated by quasielastic neutron scattering (QENS). To distinguish between the dynamics of the water and the biological material isotopic (H/D) substitution was used. The results show that all samples exhibit an onset of anharmonic motions on the experimental time scale (3-100 ps) at about 230-240 K. Above 250 K the dynamics is mainly of translational character and strongly dependent on the hydration level. The diffusion constant increases rapidly with increasing water content and at 280 K it is approximately 20% higher for the hydration water in freeze-dried strawberry than in freeze-dried red onion and around 2 orders of magnitude faster for the hydration water than for the biological material. Moreover, the diffusion constant of the biological part is about 50% faster in freeze-dried strawberry than in freeze-dried red onion. It was also found that the average relaxation time is slightly faster in fresh strawberry than in freeze-dried strawberry. From the results we can conclude that the water dynamics is not only promoting motions in the biological material, it is also affected by the structure (and possibly also the dynamics) of the biological material. Thus, the microscopic properties of the biological materials are interrelated with the properties of their hydration water.

Fragaria↗
PubMed2000

Garlic and onions: their effect on eicosanoid metabolism and its clinical relevance.

Garlic (Allium sativum) and onion (Allium cepa) are among the oldest of all cultivated plants. Additionally, both plants have been used as medicinal agents for thousands of years. Both garlic and onion have been shown to have applications as antimicrobial, antithrombotic, antitumor, hypolipidaemic, antiarthritic and hypoglycemic agents. In recent years, extensive research has focussed on the beneficial and medicinal properties of garlic and onions. In particular, the use of these agents in the treatment and prevention of cardiovascular disease and cancer is an area of considerable investigation and interest.

Animals↗
PubMed2000

Influence of the onion as an essential ingredient of the Mediterranean diet on arterial blood pressure and blood fluidity.

Mediterranean diet has got a favourable effect on life expectancy. One of the crucial components of the diet are onions. In an open and a randomized, placebo-controlled, double-blind, cross-over phase-I study a spontaneous pharmacological effect 5 h after administration of an onion-olive-oil maceration capsule formulation on arterial blood pressure could be demonstrated in apparently healthy subjects. In addition to a decrease in arterial blood pressure, a significant reduction in plasma viscosity and haematocrit were observed. These results are indicating a vasodilative effect of the onion-olive-oil-maceration product. The stickiness of the platelets was reduced. The effects were stronger in subjects with reduced blood fluidity compared to those subjects with normal rheological parameters.

Adolescent↗
PubMed2001

An outbreak of hepatitis A associated with green onions.

Forty-three cases of serologically confirmed hepatitis A occurred among individuals who ate at restaurant A in Ohio in 1998. Serum samples from all restaurant A employees who worked during the exposure period were negative for IgM antibodies to hepatitis A virus (HAV). A matched case-control study determined that foods containing green onions, which were eaten by 38 (95%) of 40 case patients compared with 30 (50%) of 60 control subjects, were associated with illness (matched odds ratio, 12.7; 95% confidence interval, 2.6-60.8). Genetic sequences of viral isolates from 14 case patients were identical to each other and to those of viral isolates from 3 patients with cases of hepatitis A acquired in Mexico. Although the implicated green onions, which could have come from one of 2 Mexican farms or from a Californian farm, were widely distributed, no additional green onion-associated cases were detected. More sensitive methods are needed to detect foodborne hepatitis A. A better understanding of how HAV might contaminate raw produce would aid in developing prevention strategies.

California↗
PubMed2001

Consumption of flavonoids in onions and black tea: lack of effect on F2-isoprostanes and autoantibodies to oxidized LDL in healthy humans.

BACKGROUND: Oxidative damage to lipids in vivo may be involved in the development of atherosclerosis and cancer. Onions and black tea are foods rich in flavonoids, predominantly the flavonoid quercetin, which is a potent in vitro inhibitor of membrane lipid peroxidation and LDL oxidation. OBJECTIVE: Our objective was to investigate the effects of consuming a high-flavonoid (HF) diet enriched with onions and black tea on indexes of oxidative damage in vivo compared with a low-flavonoid (LF) diet. DESIGN: Thirty-two healthy humans were studied in a randomized crossover design. Indexes of oxidative damage used were plasma F2-isoprostanes (a biomarker of lipid peroxidation in vivo) and the titer of antibodies to malondialdehyde (MDA)-modified LDL. RESULTS: There were no significant differences in the intake of macronutrients or assessed micronutrients, plasma F2-isoprostane concentrations, and MDA-LDL autoantibody titer between the HF and LF dietary treatments. In the men, however, plasma concentrations of the F2-isoprostane 8-epi-prostaglandin F2alpha were slightly higher after the HF treatment phase than after the LF treatment [0.31 +/- 0.029 nmol/L (111 +/- 10.4 ng/L) compared with 0.26 +/- 0.022 nmol/L (92 +/- 7.8 ng/L); P = 0.041]. In all subjects, plasma quercetin concentrations were significantly higher after the HF treatment phase than after the LF treatment: 221.6 +/- 37.4 nmol/L compared with less than the limit of detection of 66.2 nmol/L. CONCLUSION: Flavonoid consumption in onions and tea had no significant effect on plasma F2-isoprostane concentrations and MDA-LDL autoantibody titer in this study and thus does not seem to inhibit lipid peroxidation in humans.

Adult↗
PubMed2000

Effects on the growth of carrots (Daucus carota L.), cabbage (Brassica oleracea var. capitata L.) and onion (Allium cepa L.) of restricting the ability of the plants to intercept resources.

The objective of this paper is to assess the size and penetration of edge effects in carrot, cabbage and onion field crops and the extent to which these edge effects are modified by the presence of aerial or soil competition between the crop rows. In all three crops, large weight differences developed between the plants in the edge rows and those in the central rows. There was no indication of plant weight fluctuating between large and small values with each successive row in from the edge, as suggested by others. In carrot and onion, edge effects were greatly reduced by the presence of either white reflective aerial partitions or soil partitions, indicating that these species competed for both light and soil resources in UK field conditions. In cabbage, the mere presence of clear aerial partitions between rows reduced edge effects and there was little effect of soil partitions. This indicates the predominance of shoot over root competition in this species. The differences between species are possibly related to the architectural flexibility of their shoots. These results suggest that, within crops, carrot and onion plants compete for light over a distance of about 20 cm in each direction and for below-ground resources over a distance of about 50 cm in each direction. For cabbage, interactions between plants appeared to be dominated by the requirement for sufficient space to deploy the shoots for efficient light interception.

Brassica↗
PubMed2000

Deglucosidation of quercetin glucosides to the aglycone and formation of antifungal agents by peroxidase-dependent oxidation of quercetin on browning of onion scales.

Outer scales of yellow onion bulbs turn brown during maturing. The brown outer scales contain an antifungal component, 3,4-dihydroxybenzoic acid. An aim of the present study is to elucidate the mechanism of formation of the benzoic acid. In a browning scale, the scale was divided into three areas; fleshy, drying and dried brown areas. Levels of quercetin glucosides in dried brown areas were less than 10% of the glucosides in fleshy and drying areas, whereas levels of quercetin were high in dried brown areas. This result suggests that quercetin was formed by deglucosidation of quercetin glucosides on the border between drying and dried brown areas. Peroxidase (POX) activity of dried brown areas was about 10% of those of fleshy and drying areas. Quercetin was oxidized by autooxidation, and cell-free extracts of drying areas and POX isolated from onion scales enhanced the oxidation even in the absence of externally added hydrogen peroxide. The enhancement of quercetin oxidation was suppressed by catalase. No tyrosinase-like activity was detected in the cell-free extracts and the POX preparation. These results suggest that, during the enhanced oxidation of quercetin, hydrogen peroxide is formed. 3,4-Dihydroxybenzoic acid and 2,4,6-trihydroxyphenylglyoxylic acid, which were the oxidation products of quercetin, were found in dried brown area. These results suggest that an antifungal agent 3,4-dihydroxybenzoic acid is formed by POX-dependent oxidation of quercetin on browning of onion scales.

Antifungal Agents↗
PubMed2001

Relative activities of organosulfur compounds derived from onions and garlic in increasing tissue activities of quinone reductase and glutathione transferase in rat tissues.

There is evidence that onions and garlic protect against cancer in humans. It has been suggested that this effect is due to the organosulfur compounds in these vegetables and that these substances act through induction of phase II detoxification enzymes. In the present studies, we have compared the ability of diallyl sulfide, dially disulfide, and diallyl trisulfide, compounds that are derived from garlic, to increase the activity of the phase II enzymes quinone reductase and glutathione transferase in a variety of rat tissues. We have also examined the onion-derived substances, dipropyl sulfide, dipropyl disulfide, dipropenyl sulfide, and dipropenyl disulfide, under identical conditions. Diallyl trisulfide and diallyl disulfide were potent inducers of the phase II enzymes. Dipropenyl disulfide was much less active, while little effect on enzyme activity was seen in animals dosed with dipropyl disulfide. Diallyl sulfide and dipropyl sulfide were weak inducers of quinone reductase and glutathione transferase, but dipropenyl sulfide was very active, with an effect similar to that of diallyl disulfide. It is possible that diallyl disulfide and diallyl trisulfide are important in the anticancer action of garlic, while dipropenyl sulfide could be involved in the beneficial action of onions.

Allyl Compounds↗
PubMed1999

Dose estimations of fast neutrons from a nuclear reactor by micronuclear yields in onion seedlings.

Irradiations of onion seedlings with fission neutrons from bare, Pb-moderated, and Fe-moderated 252Cf sources induced micronuclei in the root-tip cells at similar rates. The rate per cGy averaged for the three sources, , was 19 times higher than rate induced by 60Co gamma-rays. When neutron doses, Dn, were estimated from frequencies of micronuclei induced in onion seedlings after exposure to neutron-gamma mixed radiation from a 1 W nuclear reactor, using the reciprocal of as conversion factor, resulting Dn values agreed within 10% with doses measured with paired ionizing chambers. This excellent agreement was achieved by the high sensitivity of the onion system to fast neutrons relative to gamma-rays and the high contribution of fast neutrons to the total dose of mixed radiation in the reactor's field.

Fast Neutrons↗
PubMed2002

Relative biological effectiveness of fission neutrons for producing micronuclei in the root-tip cells of onion seedlings after irradiation as dry seeds.

The relative biological effectiveness (RBE) of mixed neutron and gamma-ray radiation emitted at a 252Cf source at the Research Institute for Radiation Biology and Medicine, Hiroshima University, compared with 60Co gamma-ray radiation was determined. The tissue-absorbed dose contribution of the accompanying gamma radiation was about 35.7% to the total tissue-absorbed dose from the 252Cf mixed radiation. The 252Cf mixed radiation and 60Co gamma rays produced approximate linear changes in the frequency of micronuclei induced in root-tip cells of Allium cepa L. onion seedlings after irradiation as dry dormant seeds with varying absorbed doses in onion seeds. Therefore, the RBE for radiation-induced micronuclei was calculated as the ratio of the slopes for the 252Cf mixed radiation and the 60Co gamma rays. The deduced RBE value of 252Cf mixed radiation to 60Co gamma rays to induce micronuclei in dry dormant onion seed cells was about 90.5 +/- 3.6 (+/- 1sigma); the RBE of neutrons from the 252Cf mixed radiation was about 150 +/- 6 (+/- 1sigma). Furthermore, the sensitivity ratio of the induction rate of micronuclei in dry dormant seeds to that in seedlings by neutrons from 252Cf mixed radiation was significantly different from that by 60Co gamma rays. From these results, we concluded that the repair efficiency of DNA damage induced by neutrons may be different from that by gamma rays.

Biological Assay↗
PubMed2003

Enhancing effect of lipids and emulsifiers on the accumulation of quercetin metabolites in blood plasma after the short-term ingestion of onion by rats.

The effects of co-ingested lipids and emulsifiers on the accumulation of quercetin metabolites in blood plasma after the short-term ingestion of onion by rats were investigated. Plasma extracts of rats that had been fed onion-containing diets for one and two weeks were analyzed by HPLC with electrochemical detection after a treatment with sulfatase/beta-glucuronidase. Almost all of the quercetin metabolites in the plasma were sulfate/glucuronide conjugates of quercetin and isorhamnetin. More than 4.6% (w/w) of soybean oil in the diets significantly enhanced the accumulation of quercetin metabolites in the plasma. Fish oil and beef tallow increased this to an extent similar to that with soybean oil, and lecithin was more effective than the other three lipids. Two emulsifiers, sodium caseinate and sucrose fatty acid ester, also showed an enhancing effect on the accumulation of quercetin metabolites. These results indicate that co-ingested lipids and emulsifiers could enhance the bioavailability of quercetin glucosides in onion.

Animals↗
PubMed2005

The effects of fungicide benomyl (benlate) on growth and mitosis in onion (Allium cepa L.) root apical meristem.

In this study, the effects of benomyl, a systemic fungicide were investigated in the mitotic cell division in onion (Allium cepa) root tip cells during germination. For this aim, different concentrations (1, 2, 5, 10 and 20 mM) of benomyl solutions were used. All the concentrations used caused several abnormalities in mitotic cell divisions and the mitotic frequency in the onion root tip cells decreased as the concentration of benomyl solution increased. Based on our findings, it is reported that benomyl has some negative effects on mitotic divisions in onion root tip cells.

Benomyl↗
PubMed2000

Response of omnivorous leafroller (Lepidoptera: Tortricidae) and onion thrips (Thysanoptera: Thripidae) to low-temperature storage.

Eggs and first-fifth instars of omnivorous leafroller, Platynota stultana Walshingham, had a mean percentage survival to the adult stage of 60.7-95.2% for nonexposed immatures and 14.5-54.3% for immatures exposed to 1 wk at 0-1 degree C. Exposures of 2-5 wk resulted in 0-6.7% survival, and a 6-wk exposure resulted in < 1% survival of all stages tested. A significant reduction in survival of all larval stages occurred between exposures of 0 and 1 wk and between 1 wk and 2-6 wk. Survival of eggs after exposures of 0 and 1 wk was significantly different than survival after exposures of 2-6 wk. The second instar was the stage least susceptible to low-temperature storage. Adults that were exposed to low temperature for 1 wk in the third through fifth instars laid a mean of 120-289 eggs per female, and the mean percentage viability of the eggs ranged from 56.2 to 71.4%. Mean percentage survival of adults and nymphs of onion thrips, Thrips tabaci Lindeman, was inversely related to the duration of exposure from 1 through 3-6 wk at 0-1 and 5 degrees C and was lower at 0-1 (0.2-52.5%) than at 5 degrees C (17.6-66.6%). Exposure to 0-1 degree C for 4 wk attained 91.2% control, which increased to 99.8% after 6 wk. Low-temperature storage has potential to control omnivorous leafroller in table grapes, Vitis vinifera L., and onion thrips in onions, Allium cepa L.

Animals↗
PubMed2000

Effect of nectar composition and nectar concentration on honey bee (Hymenoptera: Apidae) visitations to hybrid onion flowers.

Floral nectar characteristics of nine inbred lines of onion (Allium cepa L.) were examined to determine their influence on the attractiveness of the onion flowers to honey bees (Apis mellifera L.). Potassium concentrations and sugar concentrations of the nectar did not significantly correlate with the number of bee visits received by an umbel. The average amount of nectar produced by both the umbels and the individual florets was significantly positively correlated with the number of bee visits. Our results suggest that selection for flowers with high nectar production may lead to a higher rate of pollination of the onion seed crop.

Animals↗