Table 1.
The health functions and potential mechanisms of onion.
| Product/compounds | Study type | Subjects/cell lines | Dose | Main effects and potential mechanisms | References |
|---|---|---|---|---|---|
| Antioxidant activity | |||||
| Onion methanol extract | In vitro | Rat dopaminergic cell line N27-A | 500 μg/mL | Upregulating antioxidant enzyme (HO-1, NQO1, and catalase) expressions | (6) |
| Onion powder | In vivo | Rats | 10% onion powder in diets | Enhancing the activity of CAT, SOD and GPx enzymes in erythrocytes and liver | (10) |
| Onion extract | In vivo | Ovalbumin-sensitized rats | 35, 70, and 140 mg/kg/d for 21 days | Enhancing the levels of SOD, CAT, and thiol | (53) |
| Onion | In vivo | Potassium bromate-induced oxidative damage in rats | 10, 20, and 30% in diets | Protecting against oxidative damage; reducing MDA levels; restoring the architecture of liver and kidney cells | (54) |
| Phenolic-rich onion extract | In vivo | Broiler chicks | 1, 2, and 3 g/kg diet | Increasing CAT, SOD activity, and GSH level | (55) |
| Pawpaw-onion powder | In vivo | African catfish | 2.5, 5, and 10 g/kg diet | Increasing antioxidant enzyme activity | (56) |
| Onion juice | Clinical trial | Healthy subjects | 100 mL for 8 weeks | Reducing total free radicals and superoxide anions levels; elevating the glutathione content and total antioxidant capacity | (57) |
| Antimicrobial activity | |||||
| Onion liquid and lyophilized extracts | In vitro | Staphylococcus aureus; Escherichia coli | Showing high antibacterial efficiency against Gram-positive bacteria, such as S. aureus | (58) | |
| Lemongrass and onion essential oils | In vitro | Escherichia coli; Salmonella Choleraesuis; Listeria monocytogenes; Staphylococcus aureus | Leafy vegetables treated with the essential oils combination showed higher antibacterial protection and odor acceptability | (59) | |
| Red onion polysaccharide fractions | In vitro | Staphylococcus aureus; Escherichia coli; Bacillus subtilis; Salmonella typhimurium | Showing stronger antibacterial effect against B. subtilis than other bacteria | (30) | |
| Graphene using extract of onion | In vitro | Escherichia Coli; Pseudomonas aeruginosa; Staphylococcus faecalis; Staphylococcus aureus | Showing great antibacterial activity | (60) | |
| Bulb extracts from onion and onion varieties | In vitro | Bacillus cereus; Staphylococcus aureus; Listeria innocua; Escherichia coli; Pseudomonas aeruginosa | Against three Gram-positive species (B. cereus, L. innocua, S. aureus) and P. aeruginosa | (5) | |
| Onion husks non-polar fraction; 7-Keto-(5-6-dihydro)-β-Sitosterol | In vitro | Pseudomonas aeruginosa; Chromobacterium violaceum | Inhibiting Quorum sensing effects; inhibiting swimming motilities | (61) | |
| Silver nanoparticles using extracts of neem, onion and tomato | In vitro | Staphylococcus aureus | Against Gram-positive bacteria Staphylococcus aureus in nutrient agar | (62) | |
| Red onion skin extract | In vitro | Staphylococcus epidermidis; Staphylococcus aureus; Listeria innocua; Enterococcus faecalis | Showing great antibacterial activity | (63) | |
| Onion essential oil | In vitro | Aspergillus, Fusarium, and Penicillium species | Showing fungicidal or inhibitory effects on the growth of fungal species from food | (64) | |
| Onion endophytic bacterium Bacillus endophyticus | In vitro | Magnaporthe oryzae | Showing effective antifungal effect against rice blast pathogen | (65) | |
| Red onion ethanol extract | In vitro | Trichophyton rubrum | Preventing tinea pedis caused by fungal infection | (66) | |
| Anti-inflammatory activity | |||||
| Onion methanol extract | In vitro | Lipopolysaccharide-induced BV-2 microglial cells | 50, 250, and 500 μg/mL | Preventing LPS-stimulated increases of proinflammatory cytokines, TNF-α, IL-6, and IL-1β; decreasing iNOS and COX-2 levels; reducing the release of NO | (6) |
| Red onion skin extract | In vitro | LPS-treated RAW 264.7 cells | Inhibiting IL-6 and IL-1; decreasing the release of NO | (63) | |
| Onion-derived nanoparticles | In vitro | LPS-treated RAW 264 cells | Inhibiting NO production | (67) | |
| Onion bulb extract | In vitro | Isolated bone-marrow derived neutrophils | 0.01, 0.1, 1, 10, and 100 μg/ml | Reversing and preventing colitis in mice via inhibition of proinflammatory signaling molecules and neutrophil activity | (14) |
| In vivo | Dextran sulfate sodium-induced colitis in mice | 100 and 200 mg/kg | |||
| Onion extract | In vivo | Rats | 0.175, 0.35, and 0.7 mg/mL in drinking water | Decreasing in total WBC and PLA2 level; decreasing neutrophil and eosinophil counts; increasing in lymphocytes count | (68) |
| Onion bulb extract | In vivo | Dextran sulfate sodium-induced colitis in mice | 30, 60, 100, and 200 mg/kg | Modulating the expression and the activity of important pro-inflammatory molecules and signaling pathways involved in the inflammatory response | (69) |
| Onion bulb extract | In vivo | Mice | 10, 30, 60, and 100 mg/kg | Alleviating house dust mite-induced perivascular and peribronchial inflammation through EGFR, ERK1/2, and AKT pathway | (13) |
| Onion aqueous extract | In vivo | Carrageenan-induced paw edema in rats | 0.1, 0.5, and 1.5 mg/kg I.P injection | Reducing rat paw edema dose dependently | (70) |
| Anti-obesity activity | |||||
| Onion peel extracts; quercetin and isoquercetin | In vitro | 3T3-L1 cells | Extract 50, 100, and 150 μg/ml; quercetin and isoquercetin 25, 50, and 100 μM | Remodeling white adipocytes to brown-like adipocytes | (27) |
| In vivo | HFD-fed mice | 0.5% in diets for 8 weeks | |||
| Onion peel extract | In vitro | 3T3-L1 cells | 25, 50, 100, 150, 200, 300, 400, and 500 μg/mL | Inhibiting lipid accumulation | (71) |
| In vivo | HFD-fed mice | 36, 90, and 144 mg/kg for 8 weeks | Reducing body weight; lowering fat coefficient and improving serum lipid levels | ||
| Quercetin; red onion extract | In vivo | HFD-fed mice | Diets with 17 mg/kg of quercetin equivalents for 9 weeks | Preventing hypermethylation in the Pgc-1α promoter | (72) |
| Onion oil | In vivo | HFD-fed rats | 46.3 and 92.6 mg/kg/d for 60 days | Reducing body weight gain and tending to decrease adipose tissue weight | (73) |
| Quercetin-rich onion peel extract | Clinical trial | 72 subjects with BMI > 23 kg/m2 | 170 mg capsule contains 50 mg quercetin, 2 capsules/d for 12 weeks | Reducing weight and percentage of body fat; decreasing blood glucose and leptin levels | (7) |
| Quercetin-rich onion powder | Clinical trial | 70 healthy Japanese subjects | 9 g/d for 12 weeks | Lowering alanine aminotransferase; reducing visceral fat area in lower high-density lipoprotein cholesterol subjects | (74) |
| Steamed onion | Clinical trial | 70 overweight subjects | 300 mg capsule contains 37.5% steamed onion; 3 capsules/d for 12 weeks | Reducing percentage of body fat and fat mass with no significant effects on lean body mass | (75) |
| Onion peel extract | Clinical trial | 61 overweight and obese subjects | Capsule contains 50 mg quercetin, 119.2 mg total polyphenol, and 65.0 mg total flavonoid; 2 capsules/d for 12 weeks | Regulating erythrocyte n-6/n-3 ratio and preventing fat accumulation in various body regions | (76) |
| Anti-diabetic activity | |||||
| Onion seed extract | In vivo | Streptozotocin-induced male rats | 200 and 400 mg/kg/d for 28 days | Protecting against adverse effects of diabetes on reproductive system | (77) |
| Fenugreek seeds and onion | In vivo | Streptozotocin-induced diabetes in rats | 10% fenugreek seeds or 3% onion or their combination in diet for 6 weeks | Ameliorating hyperglycemia and its associated metabolic disorders | (78) |
| Fenugreek seeds and onion | In vivo | Streptozotocin-induced diabetes in rats | 10% fenugreek seeds or 3% onion or their combination in diet for 6 weeks | Reducing oxidative stress | (79) |
| Fenugreek seeds and onion | In vivo | Streptozotocin-induced diabetes in rats | 10% fenugreek seeds or 3% onion or their combination in diet for 6 weeks | Alleviating cardiac damage | (80) |
| Fenugreek seeds and onion | In vivo | Streptozotocin-induced diabetes in rats | 10% fenugreek seeds or 3% onion or their combination in diet for 6 weeks | Attenuating diabetic nephropathy | (81) |
| Fenugreek seeds and onion | In vivo | Streptozotocin-induced diabetes in rats | 10% fenugreek seeds or 3% onion or their combination in diet for 6 weeks | Ameliorating eye lens abnormalities | (82) |
| Fenugreek seeds and onion | In vivo | Streptozotocin-induced diabetes in rats | 10% fenugreek seeds or 3% onion or their combination in diet for 6 weeks | Countering the deformity and fragility of erythrocytes | (83) |
| Red onion scales extract | In vivo | Streptozotocin-induced diabetes in rats | 150 and 300 mg/kg/d for 4 weeks | Improving fasting blood glucose and advanced glycation end products levels; elevating serum insulin level; down-regulating inflammatory mRNA expression | (84) |
| Heat-processed onion extract | In vivo | Male rats | 500 mg/kg | Showing anti-diabetic effect by suppressing carbohydrate absorption via inhibition of intestinal sucrase, thereby reducing the post-prandial increase of blood glucose | (85) |
| Fenugreek seeds and onion | In vivo | Streptozotocin-induced diabetes in rats | 10% fenugreek seeds or 3% onion or their combination in diet for 6 weeks | Attenuating diabetic nephropathy via suppression of glucose transporters and renin-angiotensin system | (86) |
| Onion peel extract/onion powder | In vivo | Alloxan-induced diabetes in rats | 1 and 3% onion peel extract, 5 and 7% onion powder in bread | Reducing blood glucose and MDA levels; improving antioxidant enzyme activities | (87) |
| Raw red onion | clinical trial | 53 overweight or obese non-diabetic patients with polycystic ovary syndrome | 2 × 40–50 g/d for overweight and 2 × 50–60 g/d for obese patients or 2 × 10–15 g/d for 8 weeks | Improving insulin resistance markers; increasing the chance of menses occurrence | (88) |
| Anticancer activity | |||||
| Onion methanolic extract | In vitro | MDA-MB-231 cells; A1235 cells | 100 μg/mL in a complete medium | Inhibiting tumor cells proliferation | (89) |
| Onion varieties extract | In vitro | Caco-2 cells | 1:10 dilution (10 μL of extract with 90 μL of growth media) | Inhibiting tumor cells proliferation | (90) |
| Onion bulb extract | In vitro | HeLa cells; HCT116 cells; U2OS cells | IC50: 24.79 μg/mL for HeLa; 24.73 μg/mL for HCT116; 36.6 μg/mL for U2OS | Inducing apoptosis in cancer cells | (91) |
| Flavonol glucosides from red onion waste | In vitro | HeLa cells | 5, 10, 20, 50, and 100 μM | QG, QDG, isoquercetin, and spiraeoside showed potent anticancer effect | (92) |
| Spiraeoside from red onion skin | In vitro | HeLa cells | 0.1, 1, 10, 50, and 100 ug/mL | Inhibiting cell growth; promoting apoptosis by activating caspase-3 and caspase-9; inhibiting the expression of cyclin-dependent kinase 2-cyclin-E | (93) |
| Onion extract | In vitro | AsPC-1, MCF-7, HCT116, HEP2, and HepG2 | Encapsulated on nano chitosan | Decreasing IC50 in cancer cell lines; inducing apoptosis by down-regulating BCL-2 level and up-regulating the activity of caspase-3 and caspase-9 | (94) |
| Onionin A from onions | In vitro | LM8 cells | 4 and 20 mg/kg | Inhibiting tumor proliferation by suppressing Stat3 activation; inhibiting subcutaneous tumor development and lung metastasis | (95) |
| In vivo | LM8 murine tumor-implanted model | 20 mg/kg | |||
| Fresh yellow onion | Clinical trial | Breast cancer patients during doxorubicin-based chemotherapy | 30–40 g/d and 100–160 g/d for 8 weeks | Ameliorating hyperglycemia and insulin resistance during doxorubicin-based chemotherapy | (96) |
| Cardiovascular protection | |||||
| Onion methanol fractions and flavonols | In vitro | Collagen-induced platelet aggregation in rat platelet-rich plasma | 0.5, 1, 3, and 5 mg/mL onion methanol fractions; 0.5, 1, and 2 mg/mL quercetin glycosides | Inhibiting platelet aggregation | (97) |
| Onion peel extract | In vivo | High-cholesterol diet-induced male mice | 100 and 200 mg/kg/d for 12 weeks | Lowering liver weight, total cholesterol, LDL cholesterol, triacylglycerol, atherogenic index, and cardiac risk factor; increasing fecal cholesterol levels | (98) |
| Onion bulb powder | In vivo | High-cholesterol diet-induced male rats | 10% onion powder in high-cholesterol diets for 7 weeks | Altering fecal bile acid composition by modulating microbiome | (99) |
| Onion bulb powder | In vivo | High-cholesterol diet-induced male rats | 10% onion powder in high-cholesterol diets for 7 weeks | Modulating hepatic prostaglandins; enhancing ω-3 oxylipins in the liver; modifying sphingolipids in liver and spleen tissue | (100) |
| Onion bulb powder | In vivo | High-cholesterol diet-induced male rats | 10% onion powder in high-cholesterol diets for 7 weeks | Increasing SOD, CAT, and GPx activities; anti-inflammatory response, and cardiovascular risk biomarkers | (10) |
| Onion extract | In vivo | High-cholesterol diet-induced male rats | 0.5, 1.5, and 4.5 g/kg/d for 4 weeks | Alleviating hyperlipidemia with downregulation of HMGCR and upregulation of LDL receptor | (101) |
| Red wine extract of onion | Clinical trial | Healthy hypercholesterolemic volunteers | 250 mL/d (contains 10.5% of alcohol, 1.4 g/L polyphenols, and 170 mg/L total flavonoids) for 10 weeks | Altering cholesterol; improving antioxidation; inhibiting inflammatory marker levels; attenuating cardiovascular disease incidence | (102) |
| Quercetin from onion skin extract powder | Clinical trial | Overweight to obese adults with hypertension | Capsule contains 132 mg onion skin extract powder, eq. 54 mg quercetin | Acute intake of quercetin does not influence post-prandial blood pressure and endothelial function | (103) |
| Quercetin from onion skin extract powder | Clinical trial | Overweight to obese patients with (pre-) hypertension | 3 capsules/d (eq. 162 mg quercetin) for 6 weeks | Quercetin did not affect glucose, insulin, blood biomarkers of liver and renal function, hematology, and serum electrolytes | (104) |
| Neuroprotection | |||||
| Onion methanol extract | In vitro | Rat dopaminergic cell line N27-A | 500 μg/mL | Upregulating antiapoptotic gene (Bcl-2); protecting against MPP+-induced death | (6) |
| Red onion ethanolic extract | In vivo | Streptozotocin-induced rats | 125 and 250 mg/kg/d for 4 weeks | Improving learning and memory impairments in diabetic rats | (105) |
| Onion leave extract | In vivo | Rats with neuropathic pain | 25, 50, and 100 mg/kg | Ameliorating diabetes-induced and chronic constriction injury-induced neuropathic pain | (106) |
| Onion ethanolic extract | In vivo | 6-hydroxydopamine-induced rats | 50, 100, and 200 mg/kg/d | Reducing malondialdehyde levels; ameliorating cognitive dysfunction | (11) |
| Onion water extract | In vivo | Pterygopalatine artery ligated mice | 300 mg/kg | Ameliorating retinal damage by regulating the expression of neurotrophic factors | (107) |
| Onion outer scale extract | In vivo | Mice with cerebral ischemia-reperfusion injury | Ethyl acetate fraction: 85 and 170 mg/kg; aqueous fraction: 115 and 230 mg/kg | Improving the memory and sensorimotor functions in cerebral injury | (108) |
| Hepatorenal protection | |||||
| Onion juice | In vivo | Doxorubicin-induced rats | 1 mL for 14 days | Preventing doxorubicin -induced hepatotoxicity | (109) |
| Red onion peel extract | In vivo | CCl4-induced rat hepatorenal toxicity | 50 and 100 mg/kg | Ameliorating hepatonephro-linked serum and tissue markers dose dependently | (12) |
| Onion bulb powder | In vivo | High-cholesterol diet-induced rats | 10% in diets for 7 weeks | Increasing liver SOD and GPx activity; decreasing liver protein carbonyls | (10) |
| Red onion scales extract | In vivo | Streptozotocin-induced rats | 150 and 300 mg/kg/d for 4 weeks | Ameliorating kidney histopathological alterations | (84) |
| Onion powder | In vivo | High-fat, high sugar diet rats | 7% in diets for 7 weeks | Lowering hepatic steatosis and hepatic TNF-α gene expression | (110) |
| Quercetin-rich onion powder | Clinical trial | Healthy Japanese subjects | 9 g/d for 12 weeks | Improving liver function; lowering alanine aminotransferase level | (74) |
| Respiratory system protection | |||||
| Onion extract | In vitro | Isolated rat tracheal smooth muscle | 2, 4, 8, 16, 32, and 64 mg/ml add to organ bath every 5 min | Relaxing tracheal smooth muscle via calcium channel blockade or β2-adrenergic stimulatory | (111) |
| Onion aqueous-alcoholic extract | In vivo | Asthmatic rats sensitized with ovalbumin | 0.175, 0.35, and 0.7 mg/mL in drinking water | Decreasing tracheal responsiveness, neutrophil and eosinophil counts; increasing lymphocytes count; reducing monocyte count | (68) |
| Onion extract | In vivo | Nicotine-induced lung damage in rats | 50 mg/kg/d | Attenuating the pathological effect of nicotine in the lung | (112) |
| Onion bulb extract | In vivo | House dust mite-challenged male mice | 10, 30, 60, and 100 mg/kg | Mediating anti-inflammatory effects through the inhibition of the EGFR/ERK1/2/AKT-dependent pathway | (13) |
| Digestive system protection | |||||
| Red onion suspension | In vivo | Rats | 200 and 500 mg/kg | Mitigating various experimental triggers of gastric mucosal injury | (113) |
| Onion powder | In vivo | Broiler chicks | 1.5, 2, and 2.5 g/kg in diet | Improving the population of gut microflora and intestinal histomorphology | (114) |
| Onion quercetin monoglycosides | In vivo | High-fat diet fed rats | 0.15% (quercetin:quercetin monoglycosides, 98:2 and 69:31) in diet for 4 weeks | Increasing the enzymatic activity of the intestinal microbiota | (115) |
| Onion quercetin monoglycosides | In vivo | Dextran sulfate sodium-induced colitis in mice | 0.15% (quercetin:quercetin monoglycosides, 98:2 and 69:31) in diet | Reducing dextran sulfate sodium-induced colitis | (116) |
| Onion bulb extract | In vivo | Dextran sulfate sodium-induced colitis in mice | 30, 60, 100, and 200 mg/kg | Reducing colitis severity; regulating expression and activity of pro-inflammatory molecules and signaling pathways | (69) |
| Onion bulb extract | In vitro | Isolated bone-marrow derived neutrophils | 0.01, 0.1, 1, 10, and 100 μg/ml | Reducing the percentage of viable bone-marrow derived neutrophils; increasing spontaneous apoptosis | (14) |
| In vivo | Dextran sulfate sodium-induced colitis in mice | 100 and 200 mg/kg | Reducing colitis severity; regulating colonic expression/activity profile of pro-inflammatory molecules | ||
| Phenolic-rich onion extract | In vivo | Broiler chicken | 1, 2, and 3 g/kg in diet | Improving growth rate by improving amino acid ileal digestibility and intestinal histology | (55) |
| Reproductive system protection | |||||
| Cysteine sulfoxides | In vitro | Testis-derived I-10 cells | 0.3, 1, and 3 mg/mL | Enhancing progesterone production via activation of the protein kinase A pathway | (117) |
| Onion juice | In vivo | Rats | 3 mL/d | Increasing testosterone level | (118) |
| Onion juice | In vivo | Rats | 3 mL/d | Against permethrin-induced testis damages | (119) |
| Onion juice | In vivo | Rats | 3 mL/d | Maintaining reproductive ability and improving sexual activities | (120) |
| Onion juice | In vivo | Rats | 3 mL/d | Restoring permethrin-induced reductions in hormonal of FSH and LH levels, and gene expression of LHCGR and SF1 | (121) |
| Onion juice | In vivo | Rats | 40 mg/kg/d | Improving the sperm quality and fertility after testicular torsion/detorsion | (15) |
| Onion extract | In vivo | Rats | 100 and 1,000 mg/kg | Improving sperm count, motility, and morphology; ameliorating sera testosterone and SOD levels | (122) |
| Onion extract | In vivo | Rats | 500 mg/kg | Protecting against dexamethasone-induced testicular damage in rats | (123) |
| Onion juice | In vivo | Rats | 5 mL/kg for 21 days | Protecting against maternal dexamethasone-induced reproductive toxicity in rat female offspring | (124) |
| Onion juice | In vivo | Rats | Intracavernosal injection of 200 uL | Improving dutasteride-induced erectile dysfunction in rats | (125) |
| Onion extract | In vivo | Brown laying hens | 0.0032% in diet | Improving egg quality and productive performance | (126) |
| Immune modulation | |||||
| Onion bulb extract | In vitro | NK CD16+ immune cells | Inducing the growth of CD16+ natural killer cells | (127) | |
| Onionin A | In vitro | CD4+ and CD8+ cells | 10, 30, 50, and 100 μM | Improving the activity of lymphocytes | (95) |
| In vivo | Tumor-bearing mice | 20 mg/kg/d for 2 weeks | Preventing the immunosuppressive activities of macrophages | ||
| Onion extract | In vivo | Immune-suppressed rats | 500 mg/kg/d for 4 weeks | Increasing the levels of cytokines (TNF and IL-6) and immunoglobulins (IgG and IgM) | (16) |
| Onion extract | In vivo | Ovalbumin-sensitized rats | 35, 70, and 140 mg/kg/d for 21 days | Decreasing the levels of IL-4 and IgE | (53) |