Abstract
The kinetic behavior of the antioxidant activity of aqueous/organic polyphenol extracts from navel orange peel was evaluated using DPPH and FRAP assays to assess their capacity to scavenge DPPH and ferric reducing antioxidant power. The stability of polyphenol extracts, including the influencing factors of temperature, pH, light, and the correlation of total phenolic content and antioxidant activity were also investigated. The kinetic reaction results showed that the antioxidant activity i.e. DPPH radical scavenging capacity and ferric reducing antioxidant power depended on concentration and reaction time. Its stability in aqueous phase and organic phase was influenced by temperature, pH and light in varying degrees. 50 °C was a key temperature point above which the total polyphenol content and antioxidant ability decreased remarkably. The phenolic compounds were not stable at pH 7, but showed a strongest DPPH radical scavenging capacity in both aqueous and organic phases. Acidic conditions seemed to be better for maintaining antioxidant ability of extracts from navel orange peel than alkaline conditions in aqueous and organic phases. Avoiding light kept the extracted phenolic compounds stable. There is a significant correlation between total phenolic content and antioxidant activity. These results provide some basic understanding of extracts from navel orange peel and promote the application of the extracted polyphenol from navel orange peel as antioxidants.
Highlights
There are more recent evidences that free radicals induce oxidative damage, which has been implicated in ageing and in several human pathologies and other diseases (Gliszczyńska-Świgł, 2006)
It is consistent with our results that the DPPH radical scavenging capacity of aqueous /organic phase polyphenol extract depends on concentration and reaction time, while our results showed a higher scavenging capacity at a similar concentration
The results indicated that there was no uniform regularity in the influence of pH on the change of DPPH radical scavenging capacity, ferric reducing antioxidant power and polyphenol content, which can cause the different effects on specific polyphenol stability
Summary
There are more recent evidences that free radicals induce oxidative damage, which has been implicated in ageing and in several human pathologies and other diseases (Gliszczyńska-Świgł, 2006). Numerous studies have shown that plant polyphenol have good effects on anti-mutagenesis, antiaging, anti-cancer, anti-inflammatory, anti-diabetes, weight loss and neuroprotection (Braicu et al, 2013; Hano, 2020; Williams & Spencer, 2012; Zaveri, 2006), and have certain therapeutic or preventive effects on some diseases that seriously harm human health, such as hypertension, heart disease, cancer and so on (Hertog et al.,1993; DuPont et al, 2002) These protective effects have been given credit for the antioxidant substances, such as polyphenolic compounds, carotenoids, vitamins C and E. This has led to increasing development of natural antioxidants, especially from fruits and vegetables
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
