In vitro Antioxidant Activities and Polyphenol Contents of Seven Commercially Available Fruits

Background

Fruits are considered one of the richest sources of natural antioxidants. Their consumption has been linked to the prevention of oxidative stress-induced diseases.

Objective

In this study, in vitro antioxidant activities of blueberry, jackfruit, blackberry, black raspberry, red raspberry, strawberry, and California table grape extracts were evaluated.

Materials and Methods

Antioxidant activities were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant potential (FRAP), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), nitric oxide (NO), superoxide anion (O₂⁻) scavenging assays, and ferric reducing power.

Results

Black raspberry extract had the highest phenolic (965.6 ± 2.9 mg gallic acid equivalents [GAE]/g), flavonoid (186.4 ± 1.7 mg quercetin equivalents/g), and proanthocyanidin (2677 ± 71.1 mg GAE/g) contents. All fruit extracts exhibited increasing radical scavenging activities with increased concentrations. At 100 mg/ml, red raspberry extract showed the highest ferric reducing power (A₇₀₀ = 0.3 ± 0.0052) and FRAP activity (A₅₉₃ = 11.43 mM Fe2+/g). Black raspberry extract (100 mg/ml) exhibited the highest DPPH activity (A₅₁₇ = 89.03 ± 0.0471). Jackfruit extract (100 mg/ml) had the highest ABTS (A₇₃₄ = 35.6 ± 0.613), NO (A₅₄₀ = 81.7 ± 0.2), and O₂⁻ radical scavenging (A₂₃₀ = 55.5 ± 0.2) activities. Positive correlations were observed between IC₅₀ values for different radical scavenging activities and different polyphenolics. Red raspberry extract had the highest Pearson’s coefficient values (0.952–1) between total phenolics, flavonoids, and proanthocyanidins and DPPH and superoxide radical scavenging activities.

Conclusions

The antioxidant rich fruits in this study are good source of functional food and nutraceuticals that have the potential to improve human health.