Black raspberry: the king of antioxidants!

  • Contrary to popular belief, blueberry is not the king of antioxidants, the largely unknown, black raspberry is.
  • In a study published today, which compared the antioxidant activities of extracts of seven high antioxidant fruits (blueberry, jackfruit, blackberry, black raspberry, red raspberry, strawberry, grapes), black raspberry has been found to have the highest polyphenol content and the highest activity on the DPPH free radical.
  • Red raspberry on the other hand was best in reducing the FRAP free radical, and jackfruit in reducing O2- and ABTS free radicals.
  • All fruit extracts had increased antioxidant activity with increased concentration, which goes to show that higher concentrations of extracts in supplements and anti-ageing / anti-cellulite creams have a stronger potential at preventing oxidation damage.
  • Black raspberry, boasting the highest overall number of polyphenols, in addition to it's strong antioxidant activity, is clearly the most healthful fruit examined in this study, and clearly more powerful than blueberries, red raspberries and blackberries.
  • Polyphenols have multiple health benefits, in addition to their antioxidant capacity, as they have been found to exert anti-inflammatory, anti-obesity and anti-cancer actions in multiple studies in the past. So high polyphenol content is more beneficial than high antioxidant content, per se.
  • It is important to note here that the black raspberry (rubus occidentalis) is a closely related - but distinct - plant to the common red raspberry (rubus idaeus).
  • The jackfruit, the largest tree fruit in the world, is also an important antioxidant fruit, yet still largely unknown in the West.
  • Source: In vitro Antioxidant Activities and Polyphenol Contents of Seven Commercially Available Fruits.
  • Abstract: 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 μg/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 μg/ml) exhibited the highest DPPH activity (A517 =89.03 ± 0.0471). Jackfruit extract (100 μg/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. SUMMARY: All fruit extracts exhibited increasing radical scavenging activities with increased concentrations. Black raspberry extract is enriched in total phenols, flavonoids, and proanthocyanidins and showed the highest 2,2-diphenyl-1-picrylhydrazyl scavenging activity and red raspberry extract showed the highest ferric reducing power and ferric reducing antioxidant potential activityJackfruit extract exhibited the highest 2,2'azino-bis (3-ethylbenzothiazoline-6-sulfonicacid) diammonium salt, nitric oxide, O2- scavenging activities. Positive correlations were observed between IC50 values for different radical scavenging activities and different polyphenolics. Abbreviations Used: Abs: Absorbance, ABTS: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, BHT: Butylated hydroxytoluene, DPPH: 2,2-diphenyl-1-picrylhydrazyl, DW: Dry weight, FRAP: Ferric reducing antioxidant potential, FW: Fresh weight, GAE: Gallic acid equivalents, NADH: β-nicotinamide adenine dinucleotide hydrate, NFL: The National Food Laboratories, NO: Nitric oxide, ONPG: ortho-nitrophenyl-β-galactoside, PBS: Phosphate buffered saline, PMS: Phenazine methosulfate, QE: Quercetin equivalents, ROS: Reactive oxygen species, SD: Standard deviation, SOD: Superoxide dismutase, TCA: Trichloroacetic acid, TPTZ: 2,4,6-tris(2-pyridyl)-s-triazine, Trolox: (±)-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid.