An overview of bioactivity of onion
Abstract and Figures
Onion (Allium cepa L.) is an important vegetable traditionally used as a food ingredient in the Mediterranean diet that has a high production, domestic, and foreign trade worldwide. It is consumed raw, cooked or processed into different onion products in the daily diet. Onion added into different foods makes these products rich in bioactive compounds with potential beneficial health effects. Among them, its effect on cardiovascular disease, including hypocholesterolemic, hypolipidemic, anti-hypertensive, antithrombotic, and hypoglycaemic activities, is one of the most extensively studied benefits. Onion consumption has also been reported to have antiproliferative effects in many cancer cell lines, to be involved in the bone metabolism and in the behaviour as a possible antidepressant agent, and to stimulate the growth of specific microorganisms in the colon (Bifidobacteria and Lactobacilli) with a general positive health effect. Moreover, traditionally, in the folk medicine, it has been described the use of onion as an antimicrobial, antioxidant, antiinflamatory and asthma-protective agent.
Evidence from several investigations suggests that these biological and medical functions are mainly due to the high organo-sulphur compounds content of onion. Along with organo-sulphur compounds, flavonols (quercetin and its glucosides) and dietary fibre (fructans and fructooligosaccharides (FOS)) have been also related to the onion biological properties. Moreover, recently, it has been demonstrated that additional onion constituents such as saponins and peptides have potentially beneficial health effects, including antifungal, antitumor, antispasmodic and cholesterol-lowering activities and capacity to inhibit the development and activity of osteoclasts in vitro.
As with every biologically active substance, with onion and its derivatives it is necessary to consider certain precautions to minimize the risk of adverse side effects. However, the usefulness of onion as therapeutic agent seems to be very safe, since all its possible adverse effects, such as gastrointestinal upsets and dermatological problems appear with an excessive and prolonged consumption.
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... Onion is a perfect blend of valuable bioactive compounds such as FOS, flavonoids, ascorbic acid, and OSCs, and these compounds have shown various health benefits to humans (Griffiths et al., 2002;Corzo-Martínez & Villamiel, 2012). Onion is a prime source of OSCs and flavonoids known for their antioxidant properties, whereas onion by-products possess a significantly higher amount of total phenols, flavonoids, and minerals compared to the edible bulb (Benítez, 2011). ...
... In their study, Bang and Kim (2010) fed rats with onion and results showed that preneo-plastic liver lesions were less and hepatocellular carcinogenesis was inhibited through suppression of ROS.Sulfur compounds were well admitted to have putative anticancer effects. Dipropyl disulfide, dipropyl sulfide, S-allyl cysteine (SAC), Smethylcysteine (SMC), and N-acetylcysteine were reported to retard the growth of early and late-stage carcinogenesis of the oesophagus, forestomach, lung, mammary gland, kidney, liver, and colon(Bora & Sharma, 2009;Fukushima et al., 2001;Guyonnet et al., 2001), whereas ajoene, methiin, SAMC, DATS, and DADS induced apoptosis and inhibited proliferation of human leukemic cells in vitro(Corzo-Martínez & Villamiel, 2012). Organoselenium compounds of onion were also reported to possess similar anticancer property and onion rich in selenium expresses higher anticancerous activity than other crops ( ...
Bioactive compounds possess different health benefits. Onion contains various bioactive compounds, such as organosulfur compounds, flavonols, ascorbic acids, and carbohydrate prebiotics, and its by‐products have more content of flavonoids than the bulb. Diallyl monosulfide, diallyl disulfide, diallyl trisulfide, and diallyl tetrasulfide are the major organosulfur compounds, whereas quercetin, kaempferol, anthocyanin, and luteolin are considered as main flavonoids. Ascorbic acid and fructooligosaccharides are also regarded as bioactive compounds. Onion bioactive compounds have the strong antioxidant potential for neutralizing oxidative stress of the cells. These bioactive components are beneficial as anticarcinogenic, antibiotic, anti‐inflammatory, antiplatelet, antidiabetic, and cardioprotective agents along with other nutritional benefits. However, various postharvest practices have an impact on these bioactive compounds, for example, curing mostly enhances the bioactive level and processing temperature generally decreases the concentration of many of them, whereas storage studies suggest an increase of others under optimized conditions. Additionally, conventional extraction techniques showed a negative impact on bioactive compounds of onion, whereas innovative methods yielded a higher amount of bioactive components. There is a need for innovative and integrated procedures in the postharvest sector to maintain or enhance the level of bioactive compounds without compromising the quality of onions. The present review comprehensively describes different bioactive compounds of onion, their chemistry, and their pharmacotherapeutic roles. Moreover, it also explores the effects of various postharvest factors, such as temperature, storage duration, and extraction conditions on the level of the bioactive components. It also suggests industrial applications of onion waste and its bioactive compounds in the food sector.
... Onion being a root crop gets infested by various soil-borne diseases during its growth. Symptoms of these diseases might not be visible in the crops when they are in the field (Corzo-Martínez M, Villamiel M. 2012) [3] , however, these pathogenic contaminants continue even after harvest and may result in complete spoilage of the bulbs during storage in a viable environment (Srinivasan R. and Shanmugam V. 2006) [13] . Onion is susceptible to numerous foliar, bulb and root pathogens that reduce yield and quality. ...
Onion is one of the most important underground vegetable bulb crops grown commercially in India. It belongs to family Liliaceae and is popularly known as Queen of Kitchen. Onion being a root crop gets infested by various soil-borne diseases during its growth. The incidence of Aspergillus niger (black mould) was found to be high on seed produced in Kota district of Rajasthan. The fungus was transmitted from contaminated seeds to the cotyledons. Aspergillus niger was found the main causal agent of seed-borne fungi of onion (Allium cepa L.) respectively. The pathogens were transmitted from infected seeds to seedlings, sets or bulbs. Based on symptomatology, cultural and morphological characteristics, microscopic observations and pathogenicity test, the test pathogen was identified as Aspergillus niger and its further identity was confirmed. Fungi was isolated on PDA media and was characterized in laboratory.
... Onion (Allium cepa L.) also known as bulb onion or common onion is an important root vegetable that is frequently consumed daily in the kitchen both in developing and developed nation of the world. It possesses several health benefits as it can lower the blood pressure, improves bone health, and also decrease the risk of cancer development (Corzo-Martinez and Villamiel, 2012) [3] . The onion is usually eaten as raw by many people in the form of food like salads and soups. ...
A mycological study was undertaken to know the natural occurrence of Aspergillus niger, a saprobic filamentous fungus, on the raw onions. A total of 47 onions collected from vegetable markets and street vendors were examined by swab technique. The sterile cotton swab dipped in glucose solution and chloramphenicol solution was rubbed on the bulb of each onion, and streaked on to the plates of Pal sunflower seed medium (Pal medium) and APRM agar. The inoculated plates were incubated at 30 0 C, and examined daily for the fungal growth. The fungal growth resembling Aspergillus was observed in 21 out of 47 onion samples. The cultural growth and detailed microscopic morphology in Narayan stain confirmed the identity of all the 15 fungal isolates as Aspergillus niger. Since A. niger has the potential to infect the humans, the housewives and others who work in kitchen should take great precautions to avoid the transmission of this medically important fungus. To the authors knowledge, this seems to be first study on the isolation of A. niger from onions on APRM agar and Pal medium.
... The high death rate caused by heart disease is reduced by limiting cholesterol through inhibiting cholesterol absorption, bile acid sequestrant, regulation of apoC-III genes, mobilization of fatty acids, and cholesteryl ester transfer protein (4). The secondary metabolites that have a major role in reducing cholesterol levels are flavonoids (such as quercetin) and organosulphur compounds (such as alliin, allyl propyl disulfide, diallyl disulfide, dimethyl disulfide, S-methyl-cysteine sulfoxide, and S-propyl-cysteine sulfoxide) (5). Those compounds reduce cholesterol by inhibiting the activity of HMG-CoA reductase, which plays a role in the synthesis of mevalonate, subsequently affecting the low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) levels (6). ...
Introduction: Allium cepa extract has been reported to have anti-hypercholesterolemic activity in rats. This study was conducted to investigate the effects of standardized fermented A. cepa L. var aggregatum extract on cholesterol levels and HMG-CoA reductase enzyme. Methods: The fermented A. cepa extract was standardized by the presence of quercetin using a validated high performance liquid chromatography (HPLC) method. The activity of the extract on HMG-CoA reductase was determined using HMG-CoA Assay kits, then measured by Nano spectrophotometry. In vivo study was conducted in hypercholesterolemic rats. The extract was administered orally at doses of 100, 200, and 300 mg/kg body weight (bw) to rats for 21 days and the cholesterol levels were measured every week. Results: All doses of fermented A. cepa extract and its marker compound, quercetin, ameliorated the levels of high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) as compared to those of negative control (P<0.05). Of all the doses, fermented A. cepa extract at the dose of 200 mg/kg bw displayed the highest reduction in LDL-C levels. In addition, the extract at the dose of 200 mg/kg bw showed the strongest enhancement in HDL-C levels. The fermented A. cepa extract and quercetin also inhibited the HMG-CoA reductase enzyme with inhibitory activity of 61.78%. Conclusion: The ethanol extract of fermented A. cepa shows anti-hypercholesterolemic activity. The strong anti-hypercholesterolemic activity of the extract might be due to the high amounts of quercetin, although other constituents may also contribute.
Apart from the culinary usage, Alliums are known for their therapeutic potential since antiquity. Alliums contain diverse bioactive compounds such as, sulfur-containing compounds (allicin, diallyl sulfides), flavonoids, and saponins. These compounds have demonstrated a wide range of pharmacological actions, including antioxidant, anticancer, anti-inflammatory, antimicrobial, neuroprotective, cardioprotective activities and treatment of metabolic disorders such as diabetes and hyperlipidemia. Despite encouraging preclinical results, translating these findings into clinical practice remains difficult, necessitating more rigorous human trials and molecular research. One of the major constrain in enhancing the therapeutic efficacy of these bioactive compound is to develop large-scale extraction techniques besides improving their stability, solubility, and bioavailability. The current scenario urges to focus research on optimizing the bioavailability of these compounds, evaluate their synergistic effects with existing therapies, as well as their long-term safety. This perspective article provides a comprehensive overview of the therapeutic potential of Allium spp. and suggests the key avenues for future research aiming at realising their full clinical potential.
In the present study, a total of 270 chicks were divided into 6 main groups and 3 subgroups within 15 chicks in each subgroup. Except for the control group, 0,5% garlic, 0,5% onion, 1% onion, 1% garlic, and a mixture of 1% onion + 1% garlic powder were added to the diet of the study groups. According to the results of the study, there were no significant differences between the control and experimental groups in the body weight gain and feed consumption (P>0,05). In biochemical analyses, there were no significant differences between the groups in low density lipoprotein and cholesterol levels but significant differences were found in high density lipoprotein and malondialde-hyde levels, especially in 1% onion powder (P<0,05). According to histological analysis, significant differences were found in villus length, crypt depth, and goblet cell count and the highest villus length was recorded in the 1% onion powder group (P<0,05). A significant statistical difference was found between all experimental groups and the control group in the viability and the highest rate was recorded in the 1% onion powder group (P<0,01). As a result, onion garlic powders increased the viability of chukar partridge chicks, which are quite difficult to breed. When all the data were examined, it was determined that the most beneficial supplementation was 1% onion powder.
We are frequently exposed to potentially harmful microbes of various types on a daily basis. Our immune system is an amazing collection of unique organs and cells that defends us from hazardous germs as well as certain diseases. It plays a crucial role in protecting the body against external invaders, including bacteria, viruses, and parasites. Maintaining a healthy immune system requires consuming a balanced diet that provides a variety of macro‐ and micronutrients. By consuming sufficient amounts of water, minerals such as zinc and magnesium, micronutrients, herbs, and foods rich in vitamins C, D, and E, and adopting a healthy lifestyle, one can enhance their health and immunity, and prevent infections. This article provides a comprehensive review of the scientific literature on common foods known for their potential to boost human immunity. The review begins by discussing the various components of the immune system and their functions. It then delves into the current understanding of how nutrition can influence immune response, highlighting the importance of a well‐balanced diet in supporting optimal immune function. The article presents an extensive analysis of a range of common foods that have been studied for their immune‐boosting properties. These foods include fruits, vegetables, whole grains, and animal‐based foods. Each food category is explored in terms of its specific nutrients and bioactive compounds that contribute to immune support. Foods such as milk, eggs, fruits, leafy greens, and spices like onion, garlic, and turmeric contain beneficial compounds that can enhance the immune system's function, activate and inhibit immune cells, and interfere with multiple pathways that eventually lead to improved immune responses and defense. The available literature on the issue was accessed via online resources and evaluated thoroughly as a methodology for preparing this manuscript.
Background: Humanity is faced with various kinds of infections (viral, bacterial and fungal). The recent spread of coronavirus disease 2019 (COVID-19) has led the World Health Organization to declare the coronavirus disease outbreak as a global pandemic. Medical experts suggested that people with high immunity tend to survive the infection more than those with low immunity. Hence, people must boost their immunity by consuming more fruit and vegetable or medications with immune-boosting potential to survive any form of unforeseen infections.
Aim: This study aimed to review horticultural fruit, vegetables and medicinal plants with immune-boosting potentials that may be useful in drug formulations to combat infectious diseases.
Methods: A literature search was conducted on electronic databases such as Google Scholar, Scopus and Web of Science. Several terms and free text words were combined in an appropriate manner to perform the search. Identified articles were reviewed independently for eligibility and extract of information.
Results: The study highlighted medicinal and horticultural crops with the potential to combat the symptoms of Covid-19 such as cold, cough, chest pain and high fever. Details about how despite effective vaccines, respiratory infections such as asthma, tuberculosis, pneumonia and measles are causing significant death worldwide.
Conclusion: This review highlights the fact that pharmaceutical companies should be encouraged to maximise the use of medicinal plants suggested for drug formulation strategies and humans should consume more fruit and vegetables to boost their immune systems.
Contribution: The use of natural products is now receiving global attention against synthetic ones to combat infections and the recent COVID-19 outbreak has called for innovative methods of treating the disease and its symptoms. This review provided information about medicinal plants with immune-boosting potential that when consumed or used in drug formulations can boost immune systems against various forms of infections. Insights on how the burden of diseases can be reduced and healthy lifestyles enhanced naturally are provided for social and economic developments.
Background: Research on the association between fruit and vegetable intake and risk of colorectal adenoma is inconclusive.
Objective: We studied whether intake of fruit, vegetables, or their subgroups is associated with a lower risk of prevalent colorectal adenoma.
Design: In men and women (aged 55–74 y) who were screened for colorectal cancer in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) (1993–2001), we compared 3057 cases with at least one prevalent histologically verified adenoma of the distal large bowel with 29 413 control subjects. Using a food-frequency questionnaire, we quantified intake of fruit and vegetables in the 12 mo before screening as energy-adjusted pyramid servings/d (ps/d). Adjusted odds ratios (ORs) and 95% CIs were estimated by logistic regression.
Results: Risk of distal adenoma was significantly lower among subjects in high (≈5.7 ps/d) versus low (≈1.2 ps/d) quintiles of total fruit intake (OR: 0.75; 95% CI: 0.66, 0.86, P for trend <0.001), which was not completely explained by dietary folate or fiber intake. Inverse associations between adenoma and total fruit intake were observed regardless of adenoma histopathology and multiplicity. However, the protective effect was seen only for colon and not rectal adenoma. Total vegetable intake was not significantly associated with reduced risk of adenoma. ORs for colorectal adenoma among persons with high versus low intakes of deep-yellow vegetables, dark-green vegetables, and onions and garlic were significantly related to lower risk of adenoma, although the P for trend for dark-green vegetables was not significant.
Conclusion: Diets rich in fruit and deep-yellow vegetables, dark-green vegetables, and onions and garlic are modestly associated with reduced risk of colorectal adenoma, a precursor of colorectal cancer.
The stalk of Allium schoenoprasum L (fistular onion stalk) has been used in traditional Chinese medicine. In this study, we investigated the effects of fistular onion stalk extracts on nitric oxide (NO) production and endothelial NO synthase (eNOS) expression in cultured human umbilical vein endothelium cells (HUVECs). We found that the extracts of fistular onion stalk significantly increased the level of NO and the activity of eNOS. Our findings demonstrated that fistular onion stalk extracts could be a good candidate for new drugs to treat cardiovascular diseases by enhancing endothelial production of NO.
We evaluated the effects of heat treatment on various properties of onion extracts (Allium cepa). Onion was heated at various temperatures (110-150°C) for various times (1-5 hr), and the total polyphenol, flavonoid, and free sugar contents, and antioxidant activity were investigated. With increased heating temperatures and exposure times, the total contents of polyphenols and flavonoids, as well as antioxidant activity increased. The highest total polyphenol content (189.80 mg/100 g) occurred after heating for 2 hr at 140°C. The highest total flavonoid content (252.51 mg/100 g) occurred after heating for 3 hr at 150°C. The antioxidant activity assessed using the DPPH method was highest, at 2.19 mg/mL (IC50 value), after heating for 2 hr at 150°C. Correlations between antioxidant activity and the total polyphenol, total flavonoid, and fructose contents were highly significant (all p<0.01). The optimal heating time and temperature were 2 hr and 130°C.
Hypoglycemic effect of onion skin extract in vitro and in vivo was investigated. A methanol extract of onion skin inhibited yeast α-glucosidase with an IC50 of 0.159 mg/mL. A single oral administration of the onion skin extract (500 mg/kg) significantly lowered the postprandial area under the glucose response curve to starch (1 g/kg, p<0.05). Three-week-old db/db mice were fed an AIN-93G diet or a diet supplemented with a 0.5% onion skin extract for 7 weeks after a 1-week adaptation period. Consumption of onion skin extract significantly reduced the levels of plasma glucose, insulin, and blood glycated hemoglobin as compared with the control group (p<0.05). These findings suggest that onion skin is effective in controlling hyperglycemia in animal models of type 2 diabetes mellitus, at least in part by inhibiting α-glucosidase activity.
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 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.
In the present scenario, herbal medicines have gained global importance with both medicinal and economic implications. Widespread use of herbs throughout the world has raised serious concerns over their quality, safety and efficacy. Thus, accurate scientific assessment has become a prerequisite for acceptance of health claims. Onion (Allium cepa Linn.), a member of the genus Allium, is the second most important horticulture crop all over the world. It is used as an important source of phytoconstituents and food flavour. Onions are one of the richest sources of flavonoids and organosulphur compounds. They possess a high level of antioxidant activity attributable to flavonoids quercetin, kaempferol, myricetin; pigments such as anthocyanins, and organonosulphur compounds. The most important among the sulphur compounds are the cysteine derivatives non-volatile Samino acids, S-alk(en)yl-substituted cysteine sulphoxides and their decomposition products such as thiosulfinates and polysulfides. These sulphure compounds and flavonoids possess antioxidant, antidiabetic, anti-inflammatory, anticancer, antimicrobial, antihyperlipidaemic, anticholesterolaemic, fibrinolytic, antiatherosclerotic, anticataractogenetic, antiplatelet aggregation, immunomodulatory, neuroprotective in ischemia and reperfusion-induced cerebral injury, and various other biological activities. Wide spectrum of biological activities makes A. cepa as potential therapeutic agent.
The effect of fructans in human nutrition became more and more important during the last years and in the same way the knowledge about the fructan metabolism in plants and the production of fructans from plants. About 15 % of higher plants and also numerous crops store fructans. The use of fructans is either indirectly as food ingredients or directly by the use of vegetables. Fructans are mostly gained from chicory, but the use of Jerusalem artichoke, transgenic potato and sugar beet lines are also discussed. Vegetable crops like onion, leek, asparagus, and sprouts from cereals contain rather high amounts of fructans and may become more important in the near future, e.g. as 'functional food'. Many foods can be enriched with fructans as dietary fibers without any negative impact on the taste of the product. With an additional uptake of 10-15 g of fructans per day, the recommended daily uptake of dietary fibers (30 g) could be reached. Fructans are stimulating the growth of specific microorganisms in the colon (e.g. Bifidobacteria) with a general positive health effect.