Comparative Assessment of Free Radical Scavenging and Reducing Power in Avocado (Percia americana) and Papaya (Carica papaya) Seed Oils

Abstract

Reactive oxygen species (ROS), a typical byproduct of aerobic respiration, comprises both the free radical species and non-radical species, and are essential for cell signalling. But when these ROS are present in excess, they can cause oxidative stress, which damages cells. However, antioxidants counteract the negative effects of ROS by preventing or delaying oxidation. Thus, the antioxidant properties of papaya and avocado seed oils were studied in this work using in vitro models. Fresh fruits of papaya and avocado were collected, the seeds harvested, and the oils extracted using conventional techniques. The capability of the oils to scavenge ROS was examined through standard methods. The ROS scavenging activities of seed oils was concentration dependent. At 80 mg/ml, papaya and avocado seed oils had the greatest radical scavenging capabilities in DPPH experiment, with 94.829±0.010% and 85.057±0.103% inhibition respectively. Similarly, papaya and avocado seed oils exhibited the highest ABTS scavenging activity at 300 mg/ml, with corresponding inhibitions of 71.670±0.423% and 59.091±0.317%. Again, superoxide scavenging activity results indicate that when increasing papaya seed oil from 10 to 20 mg/ml leads to increased activity from72.133 ± 0.344% inhibition to 74.699 ± 0.402% inhibition. However, when concentration is increased further from 40mg/ml to 80 mg/ml, the activity decreases. Finally, the findings revealed that the ferric reduction antioxidant capacity of the oils increases as concentration increases. The results in this study show that the seed oils demonstrated potent ferric reducing antioxidant capacity and free radical scavenging activities, thus, contributing to the inhibition or delay of the development and progression of several diseases associated with oxidative stress. Consequently, the findings in this study portrays the ability of the oils, especially papaya seed oil, to contribute to ameliorating diseases associated with oxidative stress, developing advanced biomaterials, and acting as essential preservatives in food and pharmaceuticals.