Investigation of Antioxidant Activity of Pomegranate Juices by Means of Electron Paramagnetic Resonance and UV-Vis Spectroscopy.
Pomegranate fruit (Punica granatum L.) is a source of numerous phenolic compounds, and it contains flavonoids such as anthocyanins, anthocyanidins, cyanidins, catechins and other complexes of flavonoids, ellagitannins, and hydrolyzed tannins. Pomegranate juice shows antioxidant, antiproliferative, and anti-atherosclerotic properties. The antioxidant capacity (TEAC) of the pomegranate juices was measured using electron paramagnetic resonance (EPR) spectroscopy and 1,1-diphenyl-2-picrylhydrazyl (DPPH•) as a source of free radicals, and the total phenolic (TP) content was measured using UV-Vis spectroscopy. All the examined pomegranate juices exhibited relatively high antioxidant properties. The TEAC values determined by means of EPR spectroscopy using Trolox (TE) as a free radical scavenger were in the range of 463.12 to 1911.91 μmol TE/100 mL juice. The TP content measured by the Folin-Ciocalteu method, using gallic acid (GA) as a free radical scavenger, widely varied in the investigated pomegranate juice samples and ranged from 1673.62 to 5263.87 mg GA/1 L juice. The strongest antioxidant properties were observed with the fresh pomegranate juices obtained from the fruits originating from Israel, Lebanon, and Azerbaijan. Correlation analysis of numerical data obtained by means of EPR spectroscopy (TEAC) and UV-Vis spectroscopy (TP) gave correlation coefficient (r)=0.90 and determination coefficient (r2)=0.81 (P<0.05).
University of Silesia, Institute of Chemistry, Department of Synthesis Chemistry, 9 Szkolna St, Katowice, Poland.
Violetta
V
Kozik
Krystyna
K
Jarzembek
Agnieszka
A
Jędrzejowska
Andrzej
A
Bąk
Justyna
J
Polak
Mariola
M
Bartoszek
Katarzyna
K
Pytlakowska
D000975:Antioxidants / Q000494:pharmacology*; D001628:Beverages / Q000032:analysis; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D029561:Lythraceae / Q000737:chemistry; D059808:Polyphenols / Q000032:analysis; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
D000975:Antioxidants; D059808:Polyphenols