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Allium vegetables and organosulfur compounds: do they help prevent cancer?

Allium vegetables have been shown to have beneficial effects against several diseases, including cancer. Garlic, onions, leeks, and chives have been reported to protect against stomach and colorectal cancers, although evidence for a protective effect against cancer at other sites, including the breast, is still insufficient. The protective effect appears to be related to the presence of organosulfur compounds and mainly allyl derivatives, which inhibit carcinogenesis in the forestomach, esophagus, colon, mammary gland, and lung of experimental animals. The exact mechanisms of the cancer-preventive effects are not clear, although several hypotheses have been proposed. Organosulfur compounds modulate the activity of several metabolizing enzymes that activate (cytochrome P450s) or detoxify (glutathione S-transferases) carcinogens and inhibit the formation of DNA adducts in several target tissues. Antiproliferative activity has been described in several tumor cell lines, which is possibly mediated by induction of apoptosis and alterations of the cell cycle. Allium vegetables and organosulfur compounds are thus possible cancer-preventive agents. Clinical trials will be required to define the effective dose that has no toxicity in humans.

Allium↗

[Deltosides from Allium nutans L].

Steroid glicoside which structure was elucidated by using mass-spectroscopic and NMR techniques, has been isolated using column chromatography on reverse-phase silicagel (C-18) from underground parts of Allium nutans. This compounds for the first time was isolated from the plants of genus Allium.

Allium↗

Different rRNA gene expression in primary and adventitious roots of Allium cepa L.

Sequentially used silver staining and in situ hybridization allowed to estimate the number of rDNA loci and their activity in meristematic cells of Allium cepa roots. In primary roots, obtained from germinated seeds, the rDNA probe hybridized with four chromosomes and showed four strong sites of hybridization. All of them displayed very clear positive silver staining. In cells of adventitious roots, from bulbs, only one pair of rRNA gene loci was active and after in situ hybridization showed strong signals while two other sites were very weak. The results indicate different transcriptional rRNA gene activity in meristematic cells of roots of different developmental origin. The reduction of the number of active rRNA loci can be the result of DNA methylation but the reduction mechanism of in situ hybridization sites in adventitious roots of Allium cepa remains an open question.

Allium↗

Garlic extract (allium sativum) reduces migration of neutrophils through endothelial cell monolayers.

Leukocytes play an important role during inflammation. They migrate from intravascular spaces into tissues and attack micro-organisms. In a recent study, the inhibitory effects of the non-steroidal anti-inflammatory drug, ibuprofen, on leukocyte transmigration were demonstrated using an in vitro assay. Little is know about the cellular effects of garlic extracts (allium sativum). The aim of the current study was to investigate the influence of garlic extract on leukocyte migration through endothelial cell monolayers and thereby evaluate a possible role in inflammatory processes. Human umbilical endothelial cells were cultured on microporous membranes to make an endothelial cell monolayer (ECM). Freshly isolated neutrophils were used in a recently described migration assay. The amount of untreated neutrophils migrating through the untreated ECM was used as control and set at 100%. Neutrophils and/or ECM were pre-treated with garlic extract using moderate, as well as higher and lower concentrations. Moderate plasma concentrations garlic extract inhibited neutrophil migration through ECM significantly (64 +/- 5.8% SD; P < 0.05), when both cell types were treated, (a situation that may have clinical relevance). Treating either neutrophils or ECM alone showed significant reductions in migratory rate (neutrophils treated alone: 81 +/- 7.7% SD, p < 0.05; ECM alone: 70 +/- 6.7%, p < 0.05). Thus, garlic extract is identified as a potent inhibitor of leukocyte migration through endothelial cell monolayers. Treatment of both cell types has an additive effect. Endothelial cells seem to be more affected than neutrophils. Further investigations are necessary to understand the potential clinical consequences. During inflammation, neutrophils play an important role. They migrate rapidly from the vascular space into tissues to destroy invading micro-organisms. During migration through endothelial cell monolayers (ECM), neutrophils undergo morphologic changes from rounded, relatively smooth cells to elongated, ruffled cells with pseudopodia. Recently, the influence of the non-steroidal anti-inflammatory drug, ibuprofen, on leukocyte function was investigated using an in vitro double chamber migration assay that includes ECM. Garlic extract (allium sativum) is a widely used "over the counter" herbal preparation. The effect of garlic on lipid metabolism is well documented. Previous studies have examined the influence of the extract on leukocyte function, e.g. respiratory burst. The effect of garlic on thrombocyte aggregation has also been recently described as has an anti-fungal effect. To our knowledge, nothing is known about the effect of garlic leukocyte transmigration. Therefore, we aimed to examine the effects of garlic extract on leukocyte transmigration through ECM in an in-vitro cell co-culture system.

Allium↗

Interspecific chromosomal rearrangements in monosomic addition lines of Allium.

Monosomic alien addition lines (MAALs) are useful for assigning linkage groups to chromosomes. We examined whether the chromosomal rearrangements following the introduction of a single onion (Allium cepa) chromosome into the Allium fistulosum genome were produced by homeologous crossing over or by a nonreciprocal conversion event. Among the monosomic lines available, 17 were studied by fluorescent genomic in situ hybridisation, using total A. cepa genomic DNA as the probe and total A. fistulosum genomic DNA as the competitor. In this way, rearrangements such as chromosomal translocations between A. cepa and A. fistulosum were identified as terminal regions consisting of tandem DNA repeats. Homeologous crossing over between the two closely related genomes occurred in 4 of the 17 lines, suggesting that such events are not rare. On the basis of a detailed molecular cytogenetic characterisation, we identified true monosomic alien addition lines for A. cepa chromosomes 3, 4, 5, 7, and 8 that can reliably be used in genetic studies.

Allium↗

Antioxidative activity of Allium victorialis L. extracts.

Allium victorialis L. (Liliaceae, "Hon-Gyoujya Nin-Niku" in Japanese) was successively extracted with hexane, acetone, methanol and 70% methanol and the extracts were further separated into a total of twenty-five fractions by silica gel and ODS column chromatographies. The biological activities of these four extracts and 25 column fractions were compared. The cytotoxic activity of all extracts and fractions against two oral tumor cell lines was significantly higher than that against normal human gingival fibroblasts, suggesting their tumor-specific action. Three methanol column fractions [M2, M3, M6] and a 70% methanol column fraction [70M6] most effectively reversed the multidrug resistance (MDR) against L5178 mouse T cell lymphoma. The electron spin resonance (ESR) spectroscopy showed that methanol column fractions and 70% methanol extracts produced the highest amount of radical(s) and most efficiently scavenging O2*-, generated by the hypoxanthine-xanthine reaction system, suggesting that the same substances in these fractions display both prooxidant and antioxidant properties. They showed no anti-human immunodeficiency virus (HIV) or anti-Helicobacterpylori activity. These data suggest the medicinal efficacy of Allium victorialis extract.

Allium↗

[Organization of the 378 bp satellite repeat in terminal heterochromatin of Allium fistulosum].

Telomeres, DNA-protein structures, are important elements of the eukaryotic chromosome. Telomeric regions of the majority of higher plants contain heptanucleotides TTTAGGG arranged into a tandem repeat. However, some taxa have no such repeats. These are some species of lilies (Lilium) and onions (Allium). For example, terminal regions of chromosomes of Spanish onion (Allium fistulosum) contain satellite DNA whose unit repeats are 380 bp in length, and the short arm of its chromosome 8 contains rDNA repeats. This study deals with the terminal heterochromatin and organization of the satellite repeat in A. fistulosum. Fluorescent in situ hybridization (FISH) was used to locate the satellite DNA on chromosomes and on extended DNA of A. fistulosum. Nonsatellite DNA was found in the structure of telomeric repeat. Polymerase chain reaction (PCR) and Southern hybridization were used for analysis of terminal heterochromatin. Various rearrangements were found in the satellite repeat. The roles of retrotransposones and microsatellites in the formation of terminal heterochromatin are discussed.

Allium↗

[Study of anti-tumor action and influence on immune function of Allium stativum].

Applying mice test on cancer model of S180 and Lewis cancer by using method clystered stomach(oral), observs the Anti-tumor function. Experiments showed that Allium sativum can inhibit tumor growth and Lengthen lift duration of mice, the rate of inhibiting tumor was 74.35% and life lengthening rate were 42.4%, with control grou comparison. There was profund difference between them. Besides, we discoved Allium sativum can raise immune function of mice.

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[Genotoxic effects of pesticide-treated vegetable extracts using the Allium cepa chromosome aberration and micronucleus tests].

The presence of chemical residues in vegetables and fruit is a source of human exposure to toxic and genotoxic chemicals. The mutagenic and carcinogenic action of herbicides, insecticides and fungicides on experimental animals is already known. Several studies have shown that chronic exposure to low levels of pesticides can cause adverse health effects and that many pesticides are mutagenic/carcinogenic. In the present research we monitored concurrently the presence of pesticides and genotoxic compounds extracted from 21 treated vegetables and 8 types of grapes sampled from the markets of a region in Southern Italy. The extracts were analysed for pesticides by gas-chromatography and HPLC, and for genotoxicity with two plant tests in Allium cepa roots: the micronucleus test and the chromosomal aberration test. We found 33 pesticides, some of which are outlawed. Genotoxicity was found in some of the vegetables and grapes tested. Allium cepa tests were sensitive for monitoring genotoxicity in food extracts. The micronucleus test in interphase cells gave much higher mutagenicity than the chromosomal aberration test in anaphase-telophase cells.

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A prospective cohort study on Allium vegetable consumption, garlic supplement use, and the risk of lung carcinoma in The Netherlands.

The association between the consumption of onions and leeks (vegetables belonging to the Allium genus), garlic supplements, and the risk of lung carcinoma was investigated in a large-scale prospective cohort study on diet and cancer in the Netherlands. The Netherlands Cohort Study was started in 1986 among 120,852 men and women, ages 55-69 years, by collecting information on usual diet and important life-style characteristics. After 3.3 years of follow-up, 550 incident lung carcinoma cases were observed. Information on Allium vegetable consumption was available for 484 lung carcinoma cases and 3123 members of a randomly sampled subcohort. In stratified analysis, a lower lung carcinoma risk was observed in the highest onion intake category [rate ratio (RR) = 0.65; 95% confidence interval, 0.45-0.95] compared to the lowest consumption category. After including other, dietary and nondietary, determinants of lung carcinoma in the multivariable models and using pack years for past and current smoking, instead of using smoking status categorized as never, ex-, and current smoking, the rate ratio in the highest intake category increased to 0.80 and was no longer significantly different from unity (95% confidence interval, 0.52-1.24). Leek consumption was not associated with risk for lung carcinoma (RR = 1.08; 95% confidence interval 0.80-1.45 in the highest intake category, compared to the lowest). No statistically significant trends in the rate ratios associated with increasing consumption of these vegetables were detected for lung carcinoma or the four histological subtypes. A higher lung carcinoma risk was observed for those subjects who used exclusively garlic supplements (RR = 1.78; 95% confidence interval, 1.08-2.92), compared to those not taking dietary supplements. A lower lung carcinoma risk was seen for those using garlic supplements together with any other supplement (RR = 0.93; 95% confidence interval 0.46-1.86) compared to those using any other supplement. In conclusion, we found no evidence of a relation between the consumption of onions or leeks and the risk of lung carcinoma or any of the histological subtypes. Garlic supplement use seems not associated with a lower risk of lung carcinoma.

Aged↗

Clastogenicity of atrazine assessed with the Allium cepa test.

Atrazine is classified as a restricted use pesticide and it is currently included in an international revision program for re-evaluating the human and ecological (non-human populations) health risks associated with its release into the environment. The present study was undertaken to add new data on the genotoxic potential of atrazine using the Allium cepa chromosome aberration test. The test concentrations were based on the Maximum Contaminant Levels in water intended for human consumption set by European and US regulations. Atrazine produced a concentration-related increase in the number of total somatic chromosome aberrations, although this increase was statistically significant (p<0.05) only at the highest test concentration (5 microg/L). Analysis of the categories of structural chromosome damage indicated that breaks were the predominant lesion induced; the percent of cells per bulb with breaks also increased in a concentration-related manner, and the increase was statistically significant at the two highest test concentrations (1 and 5 microg/L) (p<0.05). The Allium cepa plant assay detected the clastogenicity of atrazine at concentrations that are likely to be encountered in water, a common site of atrazine contamination.

Atrazine↗

Quercetin reduces chromosome aberrations induced by atrazine in the Allium cepa test.

Quercetin is a widely distributed plant flavonoid possessing a variety of chemical and biological activities, including chelation, free-radical scavenging, and antioxidant activity. Atrazine is a selective triazine herbicide that has been the subject of an international revision program for human and ecological health risks because of its persistence in the environment. In a previous study, we demonstrated that atrazine was clastogenic in the Allium cepa test. In this present study, we investigated whether quercetin affords protection from the chromosome breaks induced by atrazine. In a preliminary assay, 0.1-20 microg/ml quercetin produced no toxicity or clastogenic activity in the Allium cepa test. Subsequently, we evaluated the effects of 0.5 and 5 microg/ml quercetin on the clastogenicity of 2.5, 5.0, and 7.5 microg/l atrazine. Quercetin (0.5 microg/ml) significantly reduced the frequency of total aberrations induced by 7.5 microg/l atrazine, while both concentrations of quercetin significantly decreased the frequency of fragments induced by 7.5 microg/l atrazine. The results of this study indicate that plant flavonoids such as quercetin may protect against the genotoxic effects of atrazine. Efforts to understand the extent to which plant flavonoids influence the biological activities of genotoxicants and the mechanisms involved in the interactions could help to better discern the advantages and disadvantages of their use and to clarify their possible protective role against pollutants.

Atrazine↗

In vitro anti-Helicobacter pylori potential of methanol extract of Allium ascalonicum Linn. (Liliaceae) leaf: susceptibility and effect on urease activity.

The crude methanol extract of the leaf of Allium ascalonicum was screened in vitro against fi ve strains of Helicobacter pylori (Hp) (ATCC 24376, UCH 97001, UCH 97009, UCH 98026 and UCH 99039) for antibacterial activity by the agar diffusion method in Mueller-Hinton agar supplemented with de fi brinated horse blood. All the strains were inhibited by the extract to varying degrees. The minimum inhibitory concentrations (MICs) of the extract against all the tested strains ranged from 6.25 to 12.5 mg/mL. The effects of increasing concentrations of the extract on the urease activity of three of the Helicobacter pylori strains were investigated further. The results showed that increasing the concentration of the extract decreased the urease activity of all the strains tested. Phytochemical screening of the plant showed that it contains alkaloids, cardiac glycosides and saponins. The anti-Hp activity observed is discussed in relation to the chemical constituents reportedly isolated from these plants and their traditional uses. The result of this work suggests that Allium ascalonicum has some therapeutic potential against Helicobacter pylori infection, which could be explored for patients with gastroduodenal disorders.

Anti-Bacterial Agents↗

A PCR-based marker system monitoring CMS-(S), CMS-(T) and (N)-cytoplasm in the onion ( Allium cepa L.).

The chimerical mitochondrial CMS(1)-specific sequence in chives ( Allium schoenoprasum) was used to develop a PCR-marker that distinguishes both male-sterility inducing cytoplasms, CMS-(S) and CMS-(T), from the normal cytoplasm in onion ( Allium cepa). In combination with a previously described marker for CMS-(S), which anchors in the upstream region of the mitochondrial gene cob, all of the three known cytoplasms in the onion are distinguishable. The PCR-marker system was tested in 361 onion plants, which were selected from F(1)-hybrids and different open-pollinated varieties. The latter are mainly landraces from Turkey, in which all three cytoplasm types were detected.

Breeding↗

Increased sulfur precursors and volatiles production by the leek Allium porrum in response to specialist insect attack.

To defend themselves against herbivory, plants use a variety of direct and indirect strategies involving induced increases in secondary substances. Species of the Allium genus (Alliaceae), such as the leek Allium porrum (L.), produce nonprotein sulfur amino acids derived from cysteine, i.e., alk(en)yl-cysteine sulfoxides that are precursors of volatile thiosulfinates and disulfides. These defend most species including the specialist leek moth, Acrolepiopsis assectella. We determined by measuring the increase in the sulfur precursor propyl-cysteine sulfoxide (PCSO) if production of this precursor is induced in response to moth attack and mechanical wounding. The concentration of PCSO was determined by HPLC in 2- or 6-mo-old leeks after attacks of various intensity either by the specialist leek moth or by a generalist moth, Agrotis ipsilon. Injury-induced release of sulfur volatiles was measured by GC/MS after the attacks. Results showed an increase in the production of sulfur compounds in both the precursor and volatile form, occurring only in association with intensive attacks by leek moths. The increase in sulfur precursors also led to an increase in the release of sulfur volatiles. This induced response may provide an effective defense strategy against the plant's main natural enemy, both directly and indirectly by attracting entomophagous insects.

Animals↗

Chlorinated phenoxyacetic acids and chlorophenols in the modified Allium test.

The chlorinated phenoxyacetic acids 2-methyl-4-chlorophenoxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4,5-T butoxyethyl ester and the chlorophenols 2,4-dichlorophenol and 2,4,5-trichlorophenol were tested for genotoxicity in the modified Allium test, which is based on exposure to the test chemicals of growing onions. The mean length of growing roots were measured and chromosome damage was recorded. Of the substances tested, MCPA was the most toxic and the chlorophenoxyacetic acids were more toxic than the chlorophenols. The lower threshold values for growth retardation were below 0.1 ppm for the acids, approx. at 0.1 ppm for the ester and less than 5 ppm for the phenols. Though a monocotyledon, Allium cepa was sensitive enough to respond to even low concentrations of these dicotyledon-selecting pesticides.

2,4,5-Trichlorophenoxyacetic Acid↗

Loss of DNA and euchromatin in senescing leaf cells of Allium.

The leaves of the chive, Allium schoenoprasum, have an average life-span of 53 days, then they fade from top to bottom, in the same sequence as cells originated. Starting during the adult phase, the amount of DNA per nucleus decreases significantly. Nuclei of senescent cells exhibit about 15% less DNA than nuclei of juvenile cells. Electron-microscopic investigations have shown that the diffuse chromatin is lost from the nuclei, followed by shrinkage of the space left. Quantitation was achieved by measurement of the percentage of condensed chromatin per nucleus. Senescence starts in different tissues, and in individual cells of a tissue, asynchronously. Chloroplasts undergo structural changes after initiation of aging in the nuclei. The short life-span, in spite of a relatively high DNA content (11.8 pg), is suggestive of a programmed senescence in Allium leaves.

Cell Nucleus↗

Allium micronucleus (MNC) assay to assess bioavailability, bioconcentration and genotoxicity of mercury from solid waste deposits of a chloralkali plant, and antagonism of L-cysteine.

Samples of solid waste from a chloralkali plant were bioassayed employing the Allium micronucleus (MNC) assay. The endpoints measured were root length, root mercury and frequency of root meristematic cells with MNC. Chemical extraction methods such as 10% HNO3, ammonium acetate-EDTA and 0.05 or 0.1 M CaCl2 were used to assess the bioavailability of mercury from soil contaminated with solid waste. Analysis of mercury was by cold vapour atomic absorption spectrophotometry. The frequency of MNC induced by contaminated soil, which followed a concentration-response curve, was statistically correlated with soil mercury, extractable mercury and root mercury. The antagonism of L-cysteine against the suppression of root growth and induction of MNC by solid waste suggested the involvement of mercury as well as thiol groups in the process. The threshold assessment values, such as the median effective concentration (EC50) for root growth, gross toxicity concentration tested (GTCT) as indicated by complete inhibition of sprouting of roots, lowest effective concentration tested (LECT) and highest ineffective concentration tested (HICT) for induction of MNC, were determined. These assessment values may be useful for environmental management and regulatory purposes. Furthermore, the detection limit of the Allium MNC assay for solid waste mercury as indicated by LECT was 9.6 mg kg-1 which corresponded to 0.13 mg kg-1 of 0.05 M CaCl2 extractable or 8.3 mg kg-1 dry weight bioconcentrated mercury.

Mercury↗