Effects of onion peel water extracts on swimming endurance in rat

다국어 초록 (Multilingual Abstract)

Onion (Allium cepa L.) contains high levels of dietary fibers and antioxidants, including vitamin C, D, and folates. Onion is also known as a quercetin-rich vegetable with high flavonoid content. Onion peel contains over 20 times more quercetin than onion flesh. The aim of this study was to examine the question of whether onion peel extract supplementation has an effect on maximal exercise performance in rat. Onion peel extracts were extracted with hot water. Thirty male Sprague Dawley rats were maintained on a pellet diet for one week, and then randomly divided into five groups: Normal control, Positive control (quercetin 20 mg/kg), Onion peel 4 mg/kg, Onion peel 20 mg/kg, and Onion peel 100 mg/kg. Oral administration was performed daily. The experimental period was four weeks. Thereafter, animals were then forced to swim in water and the maximal exercise performance period from the swimming start time to the exhausted time, in which they failed to rise to the surface of the water to breathe within a 7 second period, was measured. After necropsy, weights of gastrocnemius muscles were measured. Lactate dehydrogenase concentration in serum was measured using an enzymatic method, using a commercial kit. The maximal exercise performance period was significantly longer in the onion peel extracts fed groups, compared with the control group. The lactate dehydrogenase concentration of the onion peel extracts fed groups was significantly lower, compared with the control group. Based on these results, we suggest that onion peel water extract supplementation can enhance exercise capacity caused by the mechanism of decreasing lactate dehydrogenase concentration.