Background: The supplementation of antioxidants, in particular those of plant origin, may help to prevent the development of diseases caused by oxidative stress. Therefore, it is important to study plants for their antioxidant contents. Up to now, only a few reports on the antioxidant activity of different varieties and parts of grapefruit have been published. Therefore, the aim of this study was to evaluate the antioxidant potential of different parts and varieties of grapefruit. Moreover, the impact of different extraction parameters on the activity of the obtained extracts was estimated.
Methods: Extracts of albedo, flavedo and flesh from three varieties of grapefruit – red, white and sweetie – were obtained using ultrasound-assisted extraction (time – 5, 10, 15 and 30 minutes; solvents – distilled water as well as 20, 40, 70 and 96% (v/v) ethanol). The samples were evaluated using the DPPH, ABTS, FRAP and Folin-Ciocalteu methods.
Results: The extracts of peel (in particular, those of albedo) showed higher antioxidant potential than the samples of flesh. In the majority of cases, the highest potential in the group of flesh and flavedo extracts was observed in the sweetie samples. The highest activity in the group of albedo samples was found in the white grapefruit extracts. Parameters such as the type of solvent and the extraction time had an impact on the antioxidant activity of the obtained extracts.
Conclusions: Grapefruit, in particular their peels, could be valuable sources of natural antioxidants. However, more detailed studies on the antioxidant properties of the studied plants are required.
Keywords: albedo; flavedo; red grapefruit; sweetie; ultrasound-assisted extraction; white grapefruit.