The enhancing effects of 12 kinds of flavonoids on the mutagenicity of 2-acetylaminofluorene (AAF) in Salmonella typhimurium TA98 were investigated. In the mixed applications of AAF (22.4 nmoles/plate) with flavonoids (31.4-45.0 nmoles/plate) in the presence of a mammalian metabolic activation system (S9 mix), morin, galangin, flavonol, kaempferol, quercetin and myricetin enhanced the mutagenicity of AAF by 3.3-10.2-fold. The potency of the mutagenicity enhancing effects increased in the described order. For the mutagenicity-enhancing effects of the flavonoids on AAF, the flavonol structure, including the free 3-hydroxyl group and the 2,3-double bond, were essential. In the quercetin analogues, the 5-hydroxyl group was also essential. Further, the numbers of the hydroxyl groups substituted at the 3', 4' and 5'-positions in the B-ring contributed to an increase of the enhancing effect, whereas the substitution of a hydroxyl group at the 2'-position depressed the potency of the effect.
Friday, May 9, 2008
Influence of ethyl acetate extract and quercetin-3-methyl ether from Polygonum amphibium on activation lymphocytes from peripheral blood of healthy do
The influence of an ethyl acetate extract from Polygonum amphibium L. and quercetin-3-methyl ether isolated from them were examined on the human immune system. The investigations were made on peripheral blood mononuclear cells from healthy donors. The cells were stimulated by plant extract and quercetin-3-methyl ether in 24 h culture and analysed in flow cytometry. The following mice monoclonal antibody anti human activate markers were used: anti HLA-DR PE, anti CD25 FITC, anti CD69 FITC and anti CD71 FITC. The level of Interleukine-2 in blood serum and in culture supernatants was measured by ELISA method. Ethyl acetate extract from Polygonum amphibium caused the rise in the number of CD25 and HLA-DR positive lymphocytes and increased the expression of CD25 and CD71 antigens. The level of IL-2 was increasing for the duration of the culture, independently from the presence of stimulators. Besides quercetin-3-methyl ether, from herb of Polygonum amphibium L., trans-taxifolin, quercetin and kaempferol were isolated The structure of the isolated compounds was determined by spectroscopic (UV, 1H NMR, 13C NMR and CI-MS) methods.
Anti-inflamatory, Antimutagenecity & Antitumor-promoting Activities of Mahogany Seeds (Swietenia macrophylla)
The crude ethanol extract of mahogany (Swietenia macrophylla King) seeds was tested for anti-inflammatory, antimutagenic, and antitumor-promoting activities. Solvent fractions of the ethanol extract, namely hexane, CCl4 and methanol fractions were also tested for their anti-inflammatory and antitumor-promoting activities.
At a dosage of 1 mg per gram body weight of the test mice, the ethanol extract reduced carrageenan- induced inflammation by 79%. Less activities were observed for the solvent fractions, with the highest inhibition given only at 60% for the methanol fraction and a low of 23% inhibition for the hexane fraction. These observations indicate anti-inflammatory activity.
Mutagenicity/antimutagenicity of the ethanol extract was studied using the Micronucleus test. The result indicate antimutagenicity of the extract. At a dosage of 0.02 mg per gram body weight, the extract reduced the number of micronucleated polychromatic erythrocytes induced by mitomycin C, a known mutagen, by almost 50%.
The antitumor promoting activity of the crude extract and the solvent fractions were studied using the Epstein-Barr early-antigen (EBV-EA) activation, with 12-0 tetradecanoylphorbol-13-acetate (TPA) as the tumor promoter. The results indicate significant inhibitory effects on EBV-EA activation indicating the antitumor-promoting activity.
Saturday, May 3, 2008
Onion and garlic use and human cancer
Background: Interest in the potential benefits of allium vegetables, in particular, onion (Allium cepa) and garlic (Allium sativum), has its origin in antiquity, but the details of these benefits are still open to discussion.
Objective: We investigated the role of allium vegetables in the etiology of various neoplasms. Previous data are scanty and are based mainly on Chinese studies.
Design: Using data from an integrated network of Italian and Swiss case-control studies, we analyzed the relation between frequency of onion and garlic use and cancer at several sites. We calculated odds ratios (ORs) by using multivariate logistic regression models that were adjusted for energy intake and other major covariates.
Results: Consumption of onions varied between 0–14 and 0–22 portions/wk among cases and controls, respectively. The multivariate ORs for the highest category of onion and garlic intake were, respectively, 0.16 and 0.61 for cancer of the oral cavity and pharynx, 0.12 and 0.43 for esophageal cancer, 0.44 and 0.74 for colorectal cancer, 0.17 and 0.56 for laryngeal cancer, 0.75 and 0.90 for breast cancer, 0.27 and 0.78 for ovarian cancer, 0.29 and 0.81 for prostate cancer, and 0.62 and 0.69 for renal cell cancer.
Onions offer layers of protection against cancer and other illnesses
Better Nutrition, Jan, 1997 by Patricia Andersen-Parrado
Considered an almost essential ingredient in an array of dishes, especially soups and stews, onions are probably best known for their culinary contributions -- and their ability to make us weep. However, given the wonderful flavor that they provide and the many health benefits which they bestow, the tears they cause are but a small price to pay.
A member of the lily family, and thou t to be of Central Asian origin, the (Allium cepa) is one of the oldest known vegetables. A cousin to garlic, it comes to us in more than 10 different varieties with some of the most well-known kinds being Spanish, Pearl, and Vidalia.
The reported health benefits of this vegetable are many, including the ability to fight infections, lower blood pressure and cholesterol, alleviate asthma, and reduce the risk of developing heart disease.
Onion's anti-cancer effects
Among onion's most powerful health-promoting properties are its anti-cancer capabilities. When discussing this particular health benefit in her book, Meals that Heal: A Nutraceutical Approach to Diet and Health, Lisa Turner cites "organosulfur compounds," and "nitrosamin-blocking abilities" as the likely factors. She says, "Organosulfur compounds occur in plants from the allium family, including onions, garlic, leeks, scallions, and shallots. Of the organosulfur compounds, diallyl disulfide, or DADS, may be the most potent agent in blocking or suppressing tumor growth. Garlic and onions may also block the formation of nitrosamines, carcinogenic compounds created in the digestive tract. Epidemiological studies have shown that people who eat lots of garlic and onions have a lower risk of stomach cancer, probably by virtue of garlic's action in blocking nitrosamine formation."
The results of one recent study that support this theory were published in the January 1996 issue o the journal, Gastroenterology. In this case-control trial, a reduced risk for stomach cancer was linked to onion consumption.
These results were obtained from the Netherlands Cohort Study on diet and cancer which looked at 120,852 men and women between the ages of 55 and 69. The findings demonstrated that the people who consumed more than one-half an onion per day were 50 percent less likely to develop stomach cancer than those who ate no onions daily. These results also held true for those with a history of stomach disorders.
Turner also cites the flavonoid, quercetin, a potent plant antioxidant, as a reason for onion's cancer-fighting capabilities. She says, "...studies by the National Cancer Institute have shown that onions may inhibit the growth of cancer cells, especially cells of the gastrointestinal tract and leukemia cells, possibly by virtue of their quantities of flavonoids, including quercetin [which is not destroyed by cooking or freezing], and their content of coumarin and ellagic acid." (Note, white onions do not contain quercetin.)
Choosing the perfect onion
Thankfully, onions can be enjoyed year-round. In her book, subtitled A Guide for Adventurous Cooks, Curious Shoppers, and Lovers of Natural Foods, Dianne Onstad offers the following "onion buying tips," saying, "Onions should be firm and well-shaped, with dry, paperlike skins. Avoid those that are sprouting or have a wet, soggy feeling at the neck. Size has nothing to do with quality."
And, while it's hard to imagine actually peeling an onion without weeping, Onstad offers a peeling method which she says will enable us to enjoy the flavor and health benefits of onions without bringing tears to our eyes. She suggests holding an onion under cold water while peeling it, explaining that this "prevents the oil fumes from rising and causing tears. The fumes contain ammonia, an irritant to the eyes and nose."
Considered an almost essential ingredient in an array of dishes, especially soups and stews, onions are probably best known for their culinary contributions -- and their ability to make us weep. However, given the wonderful flavor that they provide and the many health benefits which they bestow, the tears they cause are but a small price to pay.
A member of the lily family, and thou t to be of Central Asian origin, the (Allium cepa) is one of the oldest known vegetables. A cousin to garlic, it comes to us in more than 10 different varieties with some of the most well-known kinds being Spanish, Pearl, and Vidalia.
The reported health benefits of this vegetable are many, including the ability to fight infections, lower blood pressure and cholesterol, alleviate asthma, and reduce the risk of developing heart disease.
Onion's anti-cancer effects
Among onion's most powerful health-promoting properties are its anti-cancer capabilities. When discussing this particular health benefit in her book, Meals that Heal: A Nutraceutical Approach to Diet and Health, Lisa Turner cites "organosulfur compounds," and "nitrosamin-blocking abilities" as the likely factors. She says, "Organosulfur compounds occur in plants from the allium family, including onions, garlic, leeks, scallions, and shallots. Of the organosulfur compounds, diallyl disulfide, or DADS, may be the most potent agent in blocking or suppressing tumor growth. Garlic and onions may also block the formation of nitrosamines, carcinogenic compounds created in the digestive tract. Epidemiological studies have shown that people who eat lots of garlic and onions have a lower risk of stomach cancer, probably by virtue of garlic's action in blocking nitrosamine formation."
The results of one recent study that support this theory were published in the January 1996 issue o the journal, Gastroenterology. In this case-control trial, a reduced risk for stomach cancer was linked to onion consumption.
These results were obtained from the Netherlands Cohort Study on diet and cancer which looked at 120,852 men and women between the ages of 55 and 69. The findings demonstrated that the people who consumed more than one-half an onion per day were 50 percent less likely to develop stomach cancer than those who ate no onions daily. These results also held true for those with a history of stomach disorders.
Turner also cites the flavonoid, quercetin, a potent plant antioxidant, as a reason for onion's cancer-fighting capabilities. She says, "...studies by the National Cancer Institute have shown that onions may inhibit the growth of cancer cells, especially cells of the gastrointestinal tract and leukemia cells, possibly by virtue of their quantities of flavonoids, including quercetin [which is not destroyed by cooking or freezing], and their content of coumarin and ellagic acid." (Note, white onions do not contain quercetin.)
Choosing the perfect onion
Thankfully, onions can be enjoyed year-round. In her book, subtitled A Guide for Adventurous Cooks, Curious Shoppers, and Lovers of Natural Foods, Dianne Onstad offers the following "onion buying tips," saying, "Onions should be firm and well-shaped, with dry, paperlike skins. Avoid those that are sprouting or have a wet, soggy feeling at the neck. Size has nothing to do with quality."
And, while it's hard to imagine actually peeling an onion without weeping, Onstad offers a peeling method which she says will enable us to enjoy the flavor and health benefits of onions without bringing tears to our eyes. She suggests holding an onion under cold water while peeling it, explaining that this "prevents the oil fumes from rising and causing tears. The fumes contain ammonia, an irritant to the eyes and nose."
Thursday, May 1, 2008
FLAVONOIDS AS ANTIOXIDANT AGENTS: IMPORTANCE OF THEIR INTERACTION WITH BIOMEMBRANES
INTRODUCTION
Flavonoids, a group of naturally occurring benzo-g-pyrone derivatives, have been shown to possess several biological properties (including hepatoprotective, anti-thrambotic, antiinflammatory, and antiviral activities), many of which may be related, partially at least, to their antioxidant and free-radical-scavenging ability.9,10 The antiradical property of flavonoids is directed mostly toward HO; and 02 - as well as peroxyl and alkoxyl radicals.11-14 Furthermore, as these compounds present a strong affinity for iron ions (which are known to catalyze many processes leading to the appearance of free radicals), their antiperoxidative activity could also be ascribed to a concomitant capability of chelating iron.15,16
Flavonoids, a group of naturally occurring benzo-g-pyrone derivatives, have been shown to possess several biological properties (including hepatoprotective, anti-thrambotic, antiinflammatory, and antiviral activities), many of which may be related, partially at least, to their antioxidant and free-radical-scavenging ability.9,10 The antiradical property of flavonoids is directed mostly toward HO; and 02 - as well as peroxyl and alkoxyl radicals.11-14 Furthermore, as these compounds present a strong affinity for iron ions (which are known to catalyze many processes leading to the appearance of free radicals), their antiperoxidative activity could also be ascribed to a concomitant capability of chelating iron.15,16
DISCUSSION
In agreement with our results, quercetin is reported to exhibit the highest antiradical property toward hydroxyl and peroxyl radicals and superoxide anions, and this predominance has been well attributed to its structural characteristics.9,11,12,14 Furthermore , we have confirmed the favorable antioxidant: activity of flavonoids carrying methoxy-phenolic structures, such as hesperetin,39 compared to poly-OH-substituted flavonoids, which were demonstrated to generate potentially toxic oxygen species at biologically relevant pH.40 In our experiments, rutin has shown an antioxidant effect comparable to that of quercetin; this also occurs if the sugar moiety known to mask the antioxidant activity of a flavonoid, probably preventing its access to the lipid membranes.38 Rutin has been demonstrated to be an effective inhibitor of iron-dependent lipid peroxidation due to the formation of inert complexes with iron.15,16,41
In conclusion, the antioxidant activity of flavonoids appears to be dictated not only by their structural features but also by their location in the membrane. This result must be taken into consideration in further developments of these protective flavonoids, which could have important applications in human diseases accompanied by free radical injury.
Fig. 2. Inhibition of autooxidation of rat cerebral membranes by increasing concentrations of quercetin, rutin, hesperitin or naringenin.
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