Consumption of strawberries on a daily basis increases the non-urate 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging activity of fasting plasma in healthy subjects

Abstract

Strawberries contain anthocyanins and ellagitanins which have antioxidant properties. We determined whether the consumption of strawberries increase the plasma antioxidant activity measured as the ability to decompose 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) in healthy subjects. The study involved 10 volunteers (age 41 ± 6 years, body weight 74.4 ± 12.7 kg) that consumed 500 g of strawberries daily for 9 days and 7 matched controls. Fasting plasma and spot morning urine samples were collected at baseline, during fruit consumption and after a 6 day wash-out period. DPPH decomposition was measured in both deproteinized native plasma specimens and pretreated with uricase (non-urate plasma). Twelve phenolics were determined with HPLC. Strawberries had no effect on the antioxidant activity of native plasma and circulating phenolics. Non-urate plasma DPPH decomposition increased from 5.7 ± 0.6% to 6.6 ± 0.6%, 6.5 ± 1.0% and 6.3 ± 1.4% after 3, 6 and 9 days of supplementation, respectively. The wash-out period reversed this activity back to 5.7 ± 0.8% (p<0.01). Control subjects did not reveal any changes of plasma antioxidant activity. Significant increase in urinary urolithin A and 4-hydroxyhippuric (by 8.7- and 5.9-times after 6 days of supplementation with fruits) was noted. Strawberry consumption can increase the non-urate plasma antioxidant activity which, in turn, may decrease the risk of systemic oxidants overactivity.

Addition of strawberries to the usual diet increases postprandial but not fasting non-urate plasma antioxidant activity in healthy subjects

“…This study was an extension of our previously published results of interventional trials in which consumption of strawberries (500 g daily) increased fasting non-urate plasma DPPH radical scavenging activity (10,11) while had no effect on FRAP. (11) It was executed just after interim analysis of these variables, therefore, the same strawberry pulp was used for dietary intervention.…”

“…There is a substantial body of evidence that regular strawberry consumption can have pro-healthy effect. (1–3) This may include cardiovascular protection, e.g., reduction of atherosclerotic markers in subjects with metabolic syndrome or decrease in low-density lipoprotein peroxidative damage; (4–7) anti-inflammatory activity (attenuation of the postprandial inflammatory response); (6,8,9) attenuation of the risk of oxidative stress by augmentation of plasma antioxidant defense (7,10–13) and suppression of baseline formation of reactive oxygen species by blood phagocytes. (11) These plausibly pro-healthy effects of strawberries can be attributed to the presence of numerous polyphenols such as anthocyanins (e.g., pelargonidin, cyanidin), ellagic acid and ellagitanins, phenolic acids (chlorogenic acid, hydroxycinnamic acid), catechin, quercetin and vitamins (ascorbic acid, folates).…”

“…(1–3) Apart from the direct antioxidant and anti-inflammatory properties polyphenols can modulate the expression of genes involved in cell metabolism and survival, enzymatic antioxidant defense and systems of DNA protection and repair. (1,2) Although, the enhancing effect of strawberry consumption on plasma antioxidant activity in humans seems extensively investigated (7,10–14) there are some controversies and unresolved issues regarding this effect: (A) – Consumption of 500 g strawberries daily for 16 days increased fasting plasma ferric reducing ability (FRAP) while had no effect on plasma ability to decolorize 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation (TEAC assay) in healthy subjects on low-polyphenols diet. (13) Conversely, in another study the same dose of strawberries consumed for 9 days did not alter fasting plasma FRAP or its ability to decompose 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical (DPPH-test) in healthy subjects also on low-polyphenols diet.…”

“…(13) Conversely, in another study the same dose of strawberries consumed for 9 days did not alter fasting plasma FRAP or its ability to decompose 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical (DPPH-test) in healthy subjects also on low-polyphenols diet. (10) On the other hand, under the same conditions a rise in DPPH-test was observed in fasting plasma deprived of uric acid (non-urate DPPH-test); (10) (B) – Withdrawal of strawberries from the diet resulted in the decrease of non-urate DPPH-test to baseline values within 6 days, (10) but in the other study increased fasting FRAP values persisted for 30 days after cessation of strawberry consumption; (13) (C) – 30 days consumption of 500 g strawberries daily did not alter fasting plasma FRAP and DPPH-test (but increased non-urate DPPH-test) in healthy subjects on their usual diet, (12) while plasma FRAP (but not TEAC assay) measured 3 and 4 h after single consumption of 1,000 g and 240 g of strawberries, respectively, increased substantially in healthy subjects. (12,14) These inconsistencies suggest that discovery of a positive effect of strawberries consumption on plasma antioxidant activity may depend on various factors including selection of the method used for plasma antioxidant activity measurement, time of blood sampling after strawberry intake and concomitant dietary restrictions.…”

Efek Produk Galohgor Terhadap Aktivitas Antioksidan dan Penurunan Stres Oksidatif Diabetes Melitus Tipe 2

“…32 Sementara itu, intervensi jus tomat dan minuman bekatul selama 4 minggu juga tidak signifikan meningkatkan aktivitas antioksidan plasma subjek. 33 Hasil berbeda ditunjukkan pada intervensi tahu kedelai hitam kaya serat selama 4 minggu mampu meningkatkan aktivitas antioksidan secara signifikan sebesar 4,77+9,49% pada penderita DM tipe 2. 23 Adapun prinsip dari pengujian aktivitas antioksidan plasma dengan metode DPPH adalah antioksidan yang terdapat dalam plasma akan mendonorkan atom hidrogennya ke DPPH yang bersifat radikal dan akan berpasangan dengan atom pada senyawa DPPH yang memiliki elektron tidak berpasangan (unpaired electron).…”