Polyphenolic content and comparative antioxidant capacity of flavoured black teas

2012 ◽  
Vol 63 (6) ◽  
pp. 742-748 ◽  
Author(s):  
Anna Pękal ◽  
Paulina Dróżdż ◽  
Magdalena Biesaga ◽  
Krystyna Pyrzynska
2009 ◽  
Vol 112 (1) ◽  
pp. 84-88 ◽  
Author(s):  
Cristina Martínez-Villaluenga ◽  
Henryk Zieliński ◽  
Juana Frias ◽  
Mariusz K. Piskuła ◽  
Halina Kozłowska ◽  
...  

2013 ◽  
Vol 36 (4) ◽  
pp. 229-237 ◽  
Author(s):  
Nemanja Miletić ◽  
Olga Mitrović ◽  
Branko Popović ◽  
Viktor Nedović ◽  
Branislav Zlatković ◽  
...  

2010 ◽  
Vol 5 (3) ◽  
pp. 1934578X1000500 ◽  
Author(s):  
Rasyidah Razab ◽  
Azlina Abdul Aziz

Plants that contain high amounts of polyphenolic compounds are potential candidates for natural antioxidant sources. Studies are on going in the search for new sources of antioxidants. Not much data are available on the antioxidant capacity of tropical herbs. With this in mind, 19 commonly consumed Malaysian herbs were analyzed for their polyphenolic content and antioxidant activities. A majority of these plants have never been studied before with regards to their polyphenolic content and antioxidant activities. The shoots of Anacardium occidentale, the shoots and fruits of Barringtonia racemosa, Pithecellobium jiringa and Parkia speciosa had high polyphenolic contents (> 150 μg gallic acid equivalents/mg dried plant) and antioxidant activities when measured using the ferric reducing antioxidant power (FRAP) (>1.2 mM) and Trolox equivalent antioxidant capacity (TEAC) assays (>2.4 mM). A strong correlation was observed between the two antioxidant assays (FRAP vs TEAC) implying that the plants could both scavenge free radicals and reduce oxidants. There was also a strong correlation between the antioxidant activities and polyphenolic content suggesting the observed antioxidant activities were contributed mainly by the polyphenolics in the plants.


Author(s):  
Márcia Carvalho ◽  
Irene Gouvinhas ◽  
Isaura Castro ◽  
Manuela Matos ◽  
Eduardo Rosa ◽  
...  

2009 ◽  
Vol 27 (No. 5) ◽  
pp. 330-337 ◽  
Author(s):  
I. Radojčić Redovniković ◽  
K. Delonga ◽  
S. Mazor ◽  
V. Dragović-Uzelac ◽  
M. Carić ◽  
...  

Cocoa liquor used in the confectionery industry comes from a wide range of geographical areas and may have different chemical compositions, sensory properties, and nutritional values. We found it interesting to study the polyphenolic content and composition of cocoa liquors for their potential use in industrial production. Six defatted samples originating from different countries were extracted with aqueous methanol (70%, v/v), and the polyphenolic profiles were determined using RP-HPLC method. According to our results, all samples of cocoa liquors have similar polyphenolic profiles, however, quantitatively varied. In the samples, about 13 compounds were identified by comparison of their retention times and UV spectra, and the quantified peaks were (+)-catechin, (–)-epicatechin, (–)-gallocatechin, (–)-epigallocatechin, caffeic acid derivative, caffeine, and theobromine. Also, several peaks were identified as oligomeric procyanidins. The free-radical scavenging activity was determined by the DPPH• (1,1'-dipheny-2-picrylhydrazyl) and Oxygen Radical Antioxidant Capacity (ORAC) assays. The order of antioxidant activity of the cocoa liquors studied was the same with both methods (Madagascar > Mexico > Ecuador > Venezuela > Sao Tome > Ghana samples). In addition, correlation between the antioxidant capacity and polyphenolic content was also determined, a high correlation coefficient having been obtained by both methods (<i>R<sup>2<Isup> = 0.9868 for DPPH, and 0.9375 for ORAC).


2015 ◽  
Vol 77 ◽  
pp. 658-665 ◽  
Author(s):  
Jan Oszmiański ◽  
Joanna Kolniak-Ostek ◽  
Sabina Lachowicz ◽  
Józef Gorzelany ◽  
Natalia Matłok

2006 ◽  
Vol 57 (5-6) ◽  
pp. 292-304 ◽  
Author(s):  
Reşat Apak ◽  
Kubilay Güçlü ◽  
Mustafa Özyürek ◽  
Saliha Esin Karademir ◽  
Erol Erçağ

2012 ◽  
Vol 32 (1) ◽  
pp. 126-133 ◽  
Author(s):  
Vanessa Graciela Hartwig ◽  
Luis Alberto Brumovsky ◽  
Raquel María Fretes ◽  
Lucila Sánchez Boado

Yerba maté extracts have in vitro antioxidant capacity attributed to the presence of polyphenolic compounds, mainly chlorogenic acids and dicaffeoylquinic acid derivatives. DPPH is one of the most used assays to measure the antioxidant capacity of pure compounds and plant extracts. It is difficult to compare the results between studies because this assay is applied in too many different conditions by the different research groups. Thus, in order to assess the antioxidant capacity of yerba maté extracts, the following procedure is proposed: 100 µL of an aqueous dilution of the extracts is mixed in duplicate with 3.0 mL of a DPPH 'work solution in absolute methanol (100 µM.L-1), with an incubation time of 120 minutes in darkness at 37 ± 1 °C, and then absorbance is read at 517 nm against absolute methanol. The results should be expressed as ascorbic acid equivalents or Trolox equivalents in mass percentage (g% dm, dry matter) in order to facilitate comparisons. The AOC of the ethanolic extracts ranged between 12.8 and 23.1 g TE % dm and from 9.1 to 16.4 g AAE % dm. The AOC determined by the DPPH assay proposed in the present study can be related to the total polyphenolic content determined by the Folin-Ciocalteu assay.


2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Reza Afrisham ◽  
Mohammad Aberomand ◽  
Mohammad Ali Ghaffari ◽  
Amir Siahpoosh ◽  
Mostafa Jamalan

Postprandial hyperglycemia plays an important role in the development of type 2 diabetes. Inhibition of alpha-amylase was led to a delay in breaks down of starch and glycogen and prevented a rapid rise in blood sugar. Alpha-amylase was isolated by gel filtration chromatography Sephadex G-75 from bovine pancreas. Then, total methanolic extracts of plants were prepared and IC50 values of extracts on alpha-amylase were obtained and compared with acarbose IC50. The polyphenolic content of extracts and antioxidant capacity were determined by Folin-Ciocalteu test and DPPH test, respectively. The specific activity of alpha-amylase was 48.2 U/mg. For inhibition of alpha-amylase, IC50 values of H. persicum, Z. jujuba, and acarbose were 307, 827, and 113 μg/ml, respectively. For inhibition of DPPH radical, IC50 values of extracts were 235 and 701 μg/ml. Total phenolic contents of methanol extracts were 73.8±3.2 and 44.2±1.8 μg tannic acid equivalent/mg extract. Acarbose causes gastrointestinal symptoms and liver toxicity, but H. persicum and Z. jujuba decrease these side effects and prevent gastrointestinal disorders. Due to the high polyphenolic content and antioxidant capacity of these plants and significant inhibitory effect of the plants on alpha-amylase, these plants can be proposed for treatment of diabetic patients.


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