Anti-Diabetic Effects of Ethanol Leaf Extract of Onions (Allium Cepa) On Alloxan- Induced Diabetic Wistar Albino Rats

Diabetes is a chronic disease characterised by high blood glucose level and abnormal metabolism of carbohydrates, protein and fat. The condition is characterised by persistent hyperglycaemia. Allium cepa leaf is a functional food used in traditional medicine for the treatment of diabetes mellitus. The use of plants especially vegetables as antidiabetic remedies have added interest of joining two basic diabetes mellitus control factors: food and medication. The ethanol extract of Allium cepa leaf was investigated for antidiabetic effects using alloxaninduced diabetic wistar albino rats. Wistar albino rats were randomly divided into six groups; Group A rats were non-diabetic control. Diabetes was induced in groups B, C, D, E and F by single intraperitoneal injection of alloxan (150mg/kg body weight). Group B were not treated and served as negative control group. Group C were treated with glibenclamide (5mg/kg body weight), thus served as postive control group. Groups D, E and F were treated with 200, 300 and 400mg/kg body weight of the extract respectively for a period of two weeks through intraperitoneal route. The effect of treatment with the doses of the extract and standard drug were studied on blood glucose level, total serum cholesterol and body weight. Allium Cepa extract produced a dosedependent significant reduction in the blood glucose level when compared with that of the control group. Significant total serum cholesterol reduction was observed at 300 and 400mg/kg. An observed decrease in body weight of the negative control group was recorded and significant increase for all other groups. The findings from this study indicate that the crude extract of Allium cepa leaf caused a significant hypoglycaemic and hypocholesterolemic activity in alloxan-induced diabetic rats thus, validates its use in ethno – medicine for the control of diabetes mellitus.


Introduction
Diabetes Mellitus (DM) is a group of metabolic disorders associated with disturbances in the metabolism of fuel molecules due to absolute deficiency of insulin, insufficient insulin secretion and / or its secretion [1]. It is a disorder that affects the body's ability to make or use insulin. Insulin is a hormone produced in the pancreas that helps transport glucose (blood sugar) from the bloodstream into the cells so they can break it down and use it for fuel. People cannot live without insulin [2].
It is also a widespread endocrine disorder that is associated with considerable morbidity and mortality and is found in all population throughout the world [3] Despite the presence of anti-diabetic drugs in the pharmaceutical market, the treatment of diabetes with medicinal plants is often successful. Herbal medicine and plant components with insignificant toxicity and less or no side effect are notable therapeutic options for the treatment of this disease around the world [4]. The most common herbal active ingredients used in treating diabetes are flavonoids, tannins, phenols and alkaloids [5]. The existence of these compounds implies the importance of the anti-diabetic properties of these plants [4].
Allium cepa is one of the recognised medicinal plants known to possess several medicinal properties including lowering of blood pressure, antiseptic, hypoglycaemic and hypocholesterolemic activity [6]. In the rural communities, many people depend solely on medicinal plants for the treatment of diabetes due to its easy accessibility, affordability and availability even when the efficacy of the herbal remedies has not been established [6].
Dietary therapy is unarguably the best treatment for diabetes. The diabetic diet should be carefully monitored to minimize the load placed on the blood glucose regulating mechanism. The use of plants, especially vegetables, by the population as antidiabetic remedies has added interest of joining two basic diabetes mellitus control factors: food and medication [7]. This research is thus geared towards finding a medicinal plant that will not only increase the energy content of diabetics but also lower glycaemic index properties for the management of diabetic pressures in our society.
The qualitative phytochemical screening of crude ethanol leaf extract of Allium cepa as showed in Table 1 revealed the presence of   cardiac glycosides, phenolic group,   saponins, tannins, flavonoids and alkaloids   while  anthracene  and  Cyanogenic glycosides were not detected in the sample.  As described by [10].       [25] reported that ethylene extracts of and help maintain the weight. [1].

Plant
The Allium cepa leaves used for the experiment was bought from Barkin Ladi

Phytochemical Screening of Secondary metabolites (Constituents)
The qualitative phytochemical screening of the ethanol leaf extract of Allium cepa was carried out using standard procedures as outlined by [8], [9].

Dose(LD50) test of ethanol leaf extract of Allium cepa.
The median Lethal Dose (LD50) was determined using Wistar albino mice as described by the modified method of [10].
Test animals were divided into six (6) groups. The first 3 groups which contain 3 animals each were given 10mg/kg, 100mg/kg and 1000mg/kg body weight of the ethanol extract of Allium Cepa leaves.
The Allium Cepa extract was administered orally and was monitored for 24 hours. The last 3 groups which contain one animal each per group were then given 1600mg/kg, 2900mg/kg and 5000mg/kg body weight of the ethanol extract of Allium Cepa leaves and were observed for 24 hours.

Induction of Diabetes.
Alloxan was prepared and induced by adopting the method of [11]. All rats,

Experimental Design
This study was carried out on alloxaninduced diabetic rats for two (2) weeks. A total of thirty-six (36) Wistar albino rats were used for the experiment. The albino rats were randomly divided into six (6) groups with six (6)

Biochemical Assay4
Blood glucose level determination Determination of the blood glucose level was done by the glucose-oxidase principle [12] using the one touch instrument and results were reported as mg/dl [13].