Allium cepa: A Treasure of Bioactive Phytochemicals with Prospective Health Benefits

Table 2

Clinical studies of Allium cepa based on its pharmacological effects.

Field of Study	Subject	Dosage	Outcome	Mechanism of Action	References
Cardioprotective effect	24 healthy pilot	100 mL onion juice/day	Total cholesterol, waist circumference, and LDL-C reduced substantially	Onion juice contains quercetin which markedly attenuated LDL-c, serum total cholesterol, and HDL-c levels in healthy mild hypercholesterolemic subjects	[68]
Wound healing	39 patients	Onion extract (Allium cepa) 10%	Hypertrophic scars and keloids were attenuated properly	Onion extracts inhibit vascular endothelial growth factor (VEGF) production which is the prime cause of HTS and keloids	[82]
Antihypertensive effects	70 people	162 mg/day	Systolic BP was reduced by −3.6 mmHg	Mechanisms remain unclear	[133]
Anti-inflammatory effects	In human epidermal keratinocytes	15 mg/mL extract	Stimulatory effect on Th1 and inhibitory effect on Th2 activity	Reduced amounts of IL-6, IL-10, and TNF-α	[4]
Anticancer effects	Human	10 g/day	Reduced risk of prostate cancer	Activation of detoxifying enzymes by organosulfur compounds	[1]
	Human	Taking a combination of 200 mg synthetic DATS and 100 μg selenium per month/year for 3 years	Gastric cancer risk is reduced	DATS triggers cancer cell cycle arrest at the G2/M phase	[96]
Antihypercholesterolemic effect	24 hypercholesterolemic patients	100 mL onion juice for 8 weeks	Reduction in serum TC, LDL-c, LDL-c/HDL-c levels	Increase LDL receptor mRNA expression and increase bile acid synthesis	[68]
Antiobesity effects	72 overweight and obese humans	50 mg	Reduction in body weight, BMI, waist circumference	As an anti-oxidant, quercetin scavenges free radicals and restores the respiration process in the adipocytes	[127,128]

BW = body weight; n.m. = not mentioned; DATS = diallyl trisulfide; TC = total cholesterol; LDL-c = low density lipoprotein cholesterol; HDL-c = high density lipoprotein cholesterol; HTS = hypertrophic scars; BP = blood pressure; OPE = onion peel extract; ZnO-NPs = zinc oxide nanoparticles.