Antioxidant Capacity and Polyphenolic Content of Blueberry (Vaccinium corymbosumL.) Leaf Infusions

Abstract

Antioxidant capacity and polyphenolic content of leaf infusions prepared from six highbush blueberry cultivars (Vaccinium corymbosum L.), one wild lowbush blueberry cultivar (Vaccinium myrtillus L.), and one commercially available mix of genotypes were determined. In order to simulate household tea preparation conditions, infusions were prepared in water heated to 95 degrees C. The dynamics of extraction of polyphenolic antioxidants were monitored over the course of 30 minutes. Extraction efficiency, quantified in terms of the total phenol (TP) content, and antioxidant capacity of infusions, evaluated by the ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging assays, were compared with cultivar type and extraction time. The 30-minute infusions exhibited the highest TP content and antioxidant capacity according to all three assays. Wild blueberry infusion had the highest TP content (1,879 mg/L gallic acid equivalents [GAE]) and FRAP values (20,050 microM). The range of TP values for 30-minute infusions was 394-1,879 mg/L GAE with a mean of 986 mg/L GAE across cultivars; FRAP values fell between 3,015 and 20,050 microM with a mean of 11,234 microM across cultivars. All 30-minute infusions exhibited significant scavenging capacity for DPPH(*) and ABTS(*+) radicals, comparable to different concentrations of catechin, gallic acid, and 6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid. Overall, tested infusions showed significant reducing capacity as well as radical scavenging potential, which places blueberry leaf tea high on the list of dietary sources of antioxidants.

Effect ofVaccinium ashei readeLeaf Extracts on Lipid Metabolism in Obese OLETF Rats

“…[21][22][23] Infusions of BBL have been used as a folk medicine treatment for lifestyle-related diseases, 8,9) and recent reports have revealed that the polyphenolic content and anthocyanidin from BBL had several physiological functions. 24,25) Taken together, these findings led us to explore the effects of hot water extraction and the polyphenolic extracts from BBL on the lipid metabolism in OLETF rats.…”

Effect of thermal treatment and storage on bioactive compounds, organic acids and antioxidant activity of baobab fruit (Adansonia digitata) pulp from Malawi

“…An increase in TPC may be attributed to transformation of proanthocyanidins (oligomeric and polymeric flavan-3-ols) to dimers or monomeric phenolic compounds or formation of other phenolic compounds during juice storage (Piljac-Zegarac et al, 2009). The trend of evolution of TPC during storage is also dependent on fruit species besides processing and preservation conditions employed.…”

Rhamnus intermedia Steud. et Hochst. – a New Source of Bioactive Phytochemicals

“…According to all four assays, bark extract has shown a significantly lower antioxidant capacity in comparison to the leaf extract (2.6- 33 and explained by the fact that ABTS •+ radical reacts with a wider range of compounds, including both hydrophilic and lipophilic antioxidants. 34 Furthermore, the ORAC value of R. intermedia methanol extracts (leaf: 738.27 ± 58.58 µmol TE g -1 DW , bark: 117.65 ± 14.43 µmol TE g -1 DW) was greater than the antioxidant capacity measured either by ABTS or DPPH assay (3.4, and 3.7-fold, respectively, for leaf and 1.6 and 2.04-fold, respectively, for bark extracts).…”