• Journal of the Korean Society of Food Culture
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• v.20 no.6
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• pp.721-730
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• 2005

Recently, epidemiological evidence has raised concerns that moderate elevation in body iron stores may increase oxidative stress and the risk of cardiovascular disease and cancer. Onion flesh or peel contains antioxidant such as flavonoids and alk(en)ylcysteine sulphoxides. This study was conducted to examine the effect of onion flesh or peel feeding on antioxidative capacity in aged rats supplemented with high dietary iron. Thirty-two Sprague-Dawley male 16-month-old rats weighing $618{\pm}6g$ were acclimated for 10 days with medium-iron diet (35ppm in diet), and blocked into 4 groups according to their body weights and raised for 3 months on either control diets (adequate iron-35ppm or high iron-350ppm) or experimental diets containing onion flesh/peel (5% w/w in diet) with high iron (350ppm). Rats fed high iron-onion peel diet had significantly high quercetin and isorhamnetin levels in plasma whereas rats fed high iron-onion flesh diet did not show. Plasma TBARS level was lowered by onion flesh or peel diet with high iron supplementation. However, there was no significant difference in cellular DNA damage in brain and kidney tissue among all experimental groups. We concluded that high iron diet (10 times higher than requirement) tend to increase oxidative stress and it is plausible that onion flesh or peel feeding enhances antioxidative capacity in the elderly even with iron supplementation.

• Journal of the Korean Dietetic Association
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• v.4 no.1
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• pp.14-19
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• 1998

This study was designed to investigate the role of onion as a natural antioxidant. Onion was distinguished as yellow onion peel and onion flesh. Onion samples were extracted with 5 different kinds of solvents such as water, 70% ethanol, 99.9%ethanol, 99.9% methanol, and 96% butanol in order to select optimal extraction solvents, In this part of study linoleic acid was used s an model system for the purpose of determining the antioxidant activities. The optimal extraction rate of various solvents containing onion samples was determined by measuring extraction yield, electron donating ability(EDA), thiobarbituric acid(TBA), and thiocyanate, which are common methods for measuring activity. As a result 70% ethanol was shown as the most effective solvent.

• Journal of Nutrition and Health
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• v.37 no.8
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• pp.623-632
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• 2004

This study was performed to investigate effect of dried powder or ethanol extracts of onion flesh and peel intakes on lipid metabolism, antioxidative and antithrombogenic capacities in l6-month -old rats. Total of 40 Sprague-Dawley male rats of l6-month-old and weighing 816$\pm$6g were blocked into 5 groups according to body weight and raised for three months with control and experimental diets containing 5% (w/w) of dried powders of onion flesh or peel or ethanol extracts from equal amount of each dried powder. Contents of total flavonoids and total dietary fibers in peel powder were highest among onion preparations. Body weight gain and epididymal pad fat weight were lower in peel powder group than other groups. Plasma total lipid, triglyceride and total cholesterol concentrations of onion-containing groups were lower than control group. Above all, peel ethanol extract intake decreased them most remarkably. Plasma HDL-cholesterol concentrations in onion-containing groups were higher than control group, especially that of flesh powder group was the highest among groups. Liver total lipid, triglyceride and total cholesterol concentrations were not significantly different among all experimental groups. However, liver total lipid and triglyceride concentrations were tended to be lower in onion-containing groups than control group. Thiobarbituric acid reactive substances (TBARS) concentrations in LDL + VLDL fraction was not significantly affected by onion intakes, However peel powder group showed the lowest concentration, Plasma TX $B_2$ concentrations in onion flesh powder, peel powder and peel ethanol extract groups were lower than control group, while plasma 6-keto-PG $F_{1a}$ concentrations in these same groups were higher than control group. Clotting time was tended to be increased in peel ethanol extract group. In conclusion onion diets seemed to improve lipid metabolism and antithrombogenic capacity while effect on antioxidative was not significant.t.

• Journal of Life Science
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• v.19 no.11
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• pp.1598-1604
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• 2009

In order to determine chemical components of onion flesh and peel, general nutrients, vitamin C, and total flavonoids were measured. Onion peel showed less moisture (14.3%) and no vitamin C compared to onion flesh. Onion peel contained more amounts of total flavonoids compared to onion flesh. In addition, the inhibitory effects of solvent extracts from onion flesh and peel on $H_2O_$-induced oxidative stress and growth of cancer cell lines (AGS human gastric adenocarcinoma and HT-29 human colon cancer cells) were investigated. Acetone with methylene chloride (A+M) and methanol (MeOH) extracts from onion flesh and peel appeared to significantly reduce the levels of intracellular reactive oxygen species (ROS) (p<0.05) and a greater antioxidant effect was observed in onion peel. Among fractions, 85% aq. methanol showed a higher protective activity against oxidative stress in both flesh and peel and there was no effect in the water and hexane fractions. The growth of cancer cells exposed to medium containing extracts and fractions from onion flesh and peel was inhibited dose-dependently. The growth of AGS was inhibited more in both flesh and peel compared to HT-29, and onion peel was more effective than onion flesh. Among fractions, 85% aq. methanol showed the greatest effect on growth inhibition in both flesh and peel. $IC_{50}$ values of 85% aq. methanol fraction from onion flesh and peel on AGS were 0.04 and 0.03 mg/ml, respectively, while those on HT-29 were 0.23 and 0.04 mg/ml. From our results, 85% aq. methanol fraction had an inhibitory effect against oxidative stress and growth of cancer cells, suggesting that it may contain biological active compounds.

• Food Science and Biotechnology
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• v.18 no.1
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• pp.108-112
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• 2009

Antioxidant and anticancer effects of methanolic extracts from the flesh (WFME) and peel (WPME) of white onion, the flesh (YFME) and peel (YPME) of yellow onion, the flesh (RFME) and peel (RPME) of red onion were studied. The content of total phenolics in WFME, WPME, YPME, YFME, RPME, and RFME were $0.260{\pm}0.01$, $4.480{\pm}0.23$, $0.319{\pm}0.02$, $719.12{\pm}37.36$, $0.248{\pm}0.01$, and $806.21{\pm}26.38\;mg/g$, respectively. The quercetin content of WFME, WPME, YFME, YPME, RFME, and RPME were $12.56{\pm}0.19$, $3.57{\pm}0.14$, $15.24{\pm}0.65$, $755.29{\pm}22.24$, $5.70{\pm}0.23$, and $774.03{\pm}29.48\;mg$/100 g, respectively. Like total phenolics, the highest 2,2'-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities were found in RPME. However, inhibitory effects on lipid oxidation of RPME were similar to those of WPME and YPME. In addition, inhibitory effect of WPME, YPME, and RPME for human breast cancer cell (MCF-7) growth were 78.43, 81.90, and 96.52% while those on human prostate cancer cell (LNcap) were 71.58, 77.93, and 98.47% at $100{\mu}g/mL$, respectively. Total phenolics, quercetin content, antioxidant, and anticancer activities exhibited significant variation among the 3 onion varieties in this experiment. Therefore, it is assumed that antioxidant and anticancer activities were affected by the total phenolics and quercetin level of onion.

• Journal of the Korean Society of Food Culture
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• v.30 no.1
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• pp.86-96
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• 2015

Onions contain antioxidant flavonoids and bioactive sulfur compounds. These substances are more abundant in the peel than in onion flesh. For this reason, whole onions including peels were added to soy milk to produce soy milk with whole onions (SWO), whereas peeled onions were added to soy milk to produce soy milk with peeled onions (SPO). The functional and antioxidant properties of these two kinds of soy milk were then analyzed and compared. Compared to control soy milk (CS) without onion powder, treated samples (to which freeze dried onion powder was added at 1.4, 1.6, 1.8, and 2.0%, respectively) showed significantly increased amounts of quercetin, isoflavone, and total phenol (p=0.05). The magnitude of the increase rose as the amount of added onion powder increased and when onion powder contained onion peels. With regards to antioxidant activity (DPPH and ABTS), SWO showed a greater value than SPO. The sensory evaluation scores of SWO and SPO were lower than CS for roughness and swallowing, as adding onion powder increased solid contents and viscosities. However, higher overall acceptability were obtained 1.8SPO and 1.8SWO.

• Korean Journal of Food Science and Technology
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• v.52 no.3
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• pp.263-273
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• 2020

In this study, in order to confirm the ameliorative effects of onion (Allium cepa L.) flesh and peel on amyloidbeta (Aβ)-induced cognitive dysfunction, we evaluated their in vitro neuroprotection and in vivo cognitive functions. As the result of in vitro neuroprotection, the protective effect of the ethyl acetate fraction of onion flesh (EOF) on Aβ-induced cytotoxicity was similar to that of the ethyl acetate fraction of onion peel (EOP). In the behavioral tests, the EOF and EOP effectively improved the Aβ-induced learning and memory impairments. For this reason, it could be concluded that the EOF and EOP improved the antioxidant activities (superoxide dismutase, oxidized glutathione/total glutathione, and malondialdehyde) in brain tissue. In addition, the EOF and EOP effectively activated mitochondrial functions by protecting the mitochondrial membrane potential, ATP, mitochondria-mediated protein (BAX and cytochrome c), and caspase 3/7 activities. The EOF and EOP also improved the cholinergic system (acetylcholinesterase and acetylcholine). Therefore, we suggest that onion could be used for management of Aβ-induced cognitive dysfunction.

• Korean Journal of Medicinal Crop Science
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• v.22 no.3
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• pp.203-209
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• 2014

Onion (Allium cepa L.) is one of the richest sources of flavonoids in human diet. Onion peel contains over 20 times more quercetin than onion flesh. In this study, we studied the effects of onion peel water extract (OPE) on the blood lipid profiles in mice. The onion peel extracts was extracted with hot water. The experimental groups were divided with 3 groups (n = 6) of ICR male mice: normal diet + distilled water (NC), high-fat diet + distilled water (HF), high-fat diet + onion peel water extract 20 mg/kg (OPE-20). The oral administration was conducted daily. The experimental period was 7 weeks. Onion peel water extract showed higher concentration of polyphenol gallic acid and anti-oxidant trolox equivalent than the ethanol extract. The body weight gain and food efficiency ratio was significantly lower in the OPE-20 group as compared with HF group (p < 0.05). The epididymal fat and retroperitoneal fat showed significantly lower weights and sizes in the OPE-20 group as compared with HF group (p < 0.05). The serum levels of total cholesterol, LDL cholesterol and triglyceride were significantly lower in the OPE-20 group as compared with HF group (p < 0.05). The OPE-20 group showed higher HDL cholesterol concentration than HF group (p < 0.05). Atherogenic index was ignificantly lower in as compared with HF group (p < 0.05). The serum levels of glucose, GOT and GPT were significantly lower in the OPE-20 group as compared with HF group (p < 0.05). In these results, we suggests that onion peel water extracts supplementation can reduces the serum lipid components and improves the lipid metabolism in hyperlipidemic mice induced with a high-fat diet.

• Journal of the Korean Society of Food Culture
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• v.14 no.1
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• pp.57-65
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• 1999

This study was examined the current situation of utilization of meat broth materials for the development of various broth products. The 500 housewives living in Seoul were asked. The results obtained as follows; Beef(93%) was used most frequently for making broth. In order to reduce rancid smell of broth, garlic(72%), ginger(68%), green onion(60%), onion(58%), black pepper(44%), radish(25%) were used. Most housewives used beef three or four times a month and hardly used chicken or pork for making broth. Commercial broth materials were used two or three times a month. For making broth the bricket of beef, a whole or half chicken and bones of pig were consumed most frequently. Before making broth, from flesh only blood was removed. Also housewives slightly boiled bone blood-removed in water. The older age is, the longer marriage duration is, the higher monthly income and education level is, the more beef was consumed. The higher the education level is, the more vegetables like garlic, ginger, green onion, onion, radish were used. It is suggested that in order to develop various broth products made of natural materials, the characteristics of preferred broth materials should be defined and it is necesarry to accomplish the preference test of preferred broth products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.1
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• pp.119-123
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• 2003

From the 80% ethanol extraction of onion flesh, fraction I,II and III were separated by Sephadex LH-20 column chromatography. Fraction II and III had a high inhibitory effect on ACE and xanthine oxidase. The ACE was about 80% at 50 ppm of fraction IIand III. The xanthine oxidase was about 82.5% at 100 ppm of fraction In. This research was studied to investigate the effects of the fraction In isolated from onion on the reduction of fat accumulation in rats fed high fat diet for 2 months. The metabolism was examined by analyzing the fat in serum and liver. It was shown that cholesterol in serum was remarkably reduced in onion fraction In as compared with those of control.