The Short- and Long-Term Acute Oral Toxicity of Onion Peel Aqueous Extract, In vivo Study

Onion (Allium cepa L.) was mentioned in the holy Quran and the Bible for its importance to ancient civilizations as a food flavor and healing herb. The onion Peels (OP) were traditionally used for various ailments with little data on their safety. The study was set up to determine the acute oral toxicity of the aqueous extract of onion peels in rats, in vivo using Protocol 425. The acute oral toxicity of the aqueous extract of OP was evaluated using the AOT 425 protocol, where the limit test was carried out, after an adaptation period of 7 days, using the 2000 mg/kg mode as a single dose, and a total of 5 rats were used to meet the stopping criteria, then the main test was carried out to estimate the LD₅₀ of the OP extract using the up-and-down procedure guided with software (AOT425ststpgm) and doses of (175, 550 and three 2000 mg/kg) as a single dose. Rats were observed for 14 days. On day fifteen, rats were anesthetized and blood samples were collected from all groups to evaluate the effects of hematological, biochemical, liver, and kidney functions, after euthanization of rats; all main organs were collected in formalin and sent for histopathological investigations. The results revealed that during the adaptation period, the limit group rats exhibited a significant increase in food consumption. The limit test showed normal results concerning general characteristics, hematologic, renal function, histopathological, and biochemical parameters, except reduction in glucose level. On the other hand, the total proteins of the liver increased, while albumin decreased. The main test showed normal results on the general characteristics, hematological, biochemical, renal function, and histopathological characteristics. Liver total protein and liver enzyme ALT increased, while albumin levels decreased. The OP extract has no signs of toxicity and mortality, and its estimated LD₅₀ is higher than 2000 mg/kg. We concluded that the dry onion peel aqueous extract has a wide margin of safety estimated as (LD₅₀), and it was also found to be free of any toxic effects on the histopathology, hematological, renal function, and biochemical parameters of the main organs.