Antioxidant effect of ethanolic onion (Allium cepa) husk extract in ageing rats

Abstract

The role of natural antioxidants in preventing of age-relating diseases is evident. The vegetable industry generates a large amount of waste, which is a good source of antioxidants. The aim of the study was the investigation of the antioxidant effect of long-term consumption of ethanolic yellow onion husk extract in ageing laboratory rodents. Twenty male Wistar albino rats were divided randomly into two groups (n = 10): a control group and an experimental group that received ethanolic yellow onion husk extract (2 mL/rat diluted with distilled water; activity of 4.44 µmol-equiv. quercetin) for 188 days. Oxygen radical absorbance capacity and ferric reducing antioxidant power assays were used to determine the total antioxidant capacity of the extract, which amounted to 941.4 ± 32.7 µmol equiv. Trolox/g raw material and 167.4 ± 16.4 µmol-equiv. quercetin/g raw material, respectively. Oral intake of the onion husk extract affected the indicators of the antioxidant system of the liver and the brain but not of the blood and plasma, mainly due to elevations in the activity of catalase and superoxide dismutase in the liver by 44.4% and 79.1%, respectively, and in the brain by three-fold and 79.1%, respectively. The availability, cheapness and high antioxidant potential of onion waste qualifies it a good source of functional ingredients and bioactive substances applicable in the food and pharmaceutical industries.

Keywords: AOS, antioxidant system; Ageing; Antioxidant system; CAT, catalase; FR, free radical; FRAP, fFerric reducing antioxidant power; GC–MS, gas chromatography–mass spectrometry; GSH, reduced glutathione; HAT, hydrogen atom transfer; HPLC-MS, high performance liquid chromatography–mass spectrometry; IICI, integral indicators of chronic intoxication; MDA, malondialdehyde; OHE, onion husk ethanolic extract; ORAC, oxygen radical absorbance capacity; Onion husk; Oxidative stress; Plant antioxidants; ROS, reactive oxygen species; SET, single electron transfer; SOD, superoxide dismutase; TAC, total antioxidant capacity; TBARS, thiobarbituric acid reactive substances; Vegetable waste.