In Vitro Antioxidant Activities of Ethanolic Extract of White and Red Onion Bulb (allium Cepa L.)

Onion (Allium cepa L.) has been valued as a food and a medicinal plant since ancient times, it is widely cultivated, second only to tomato, and is a vegetable bulb crop known to most cultures and consumed worldwide (FAO, 2012) Antioxidant are substance that protect the cells against free radicals, which play a role in heart disease, cancer, and other disease. The sample was prepared using cold maceration method. The DPPH free radical scavenging activity was expressed as percentage inhibition. The percentage of DPPH activity of the ethanol extract of onion bulb of red onion ranges from 55.9 – 10.5% in a decreasing manner while that of white onion also ranges from 22.9-38.4% in a increasing manner (fig. 4.1). While the dose of DPPH activity ranges from 50 – 250 μg/ml.The absorbance of ethanolic extract of onion bulb increases with increased concentration from 300 - 700μg/ml for both the red and white onion. The absorbance of ethanolic extract of red onion bulb at 300μg/ml is 0.053nm, the ethanolic extract at 400μg/ml was 0.097nm, at 500μg/ml was 0.124nm, at 600μg/ml was 0.182nm and the ethanolic extract at 700μg/ml was 0.201nm Total Antioxidant Activity The results shows that the ethanolic extract red onion has an antioxidant activity value of 0.32±0.00 and the white onion has an antioxidant activity value of 0.25±0.00 which indicates an appreciable amount of antioxidant is found to be in both red and white onion. The study revealed that Allum cepa has shown the potential and certain level of antioxidant. Therefore it has a better chance of donating electrons that react with free radicals to form a stable substances and prevent oxidative stress.