Structure−Antioxidant Efficiency Relationships of Phenolic Compounds and Their Contribution to the Antioxidant Activity of Sea Buckthorn Juice

Abstract

The phenolic composition of juice derived from fruits of sea buckthorn (Hippophae rhamnoides) was investigated by high-performance liquid chromatography (HPLC) with diode array and electrochemical detection. Flavonols were found to be the predominating polyphenols while phenolic acids and catechins represent minor components. Of the seven flavonols identified, isorhamnetin 3-O-glycosides were the most important representatives quantitatively. However, because of their structural properties, they were poor radical scavengers as shown by electron spin resonance spectroscopy. Phenolic compounds such as quercetin 3-O-glycosides, catechins, and hydroxybenzoic acids with a catechol structure exhibited good antioxidant capacities, but their concentration in sea buckthorn juice was small. These phenolic compounds, determined by HPLC, accounted for less than 5% of the total antioxidant activity of the filtered juice. Ascorbic acid was shown to be the major antioxidant in sea buckthorn juice. Because of its high concentration of 1.22 g/L, it contributes approximately 75% to total antioxidant activity. The remaining difference can be attributed to higher molecular weight flavan-3-ols (proanthocyanidins), which were determined photometrically after acid depolymerization to colored anthocyanidins.

Comparison of in vitro anti-lipase and antioxidant activities, and composition of commercial chokeberry juices

“…The results were expressed as g of cyanidin 3-glucoside equivalents (CGE) per 1 l of juice using a molar extinction of cyanidin 3-glucoside of 26,900 l/mol cm and molar weight of 449.2 g/mol. The content of total proanthocyanidins in juices was determined after acid depolymerization to the corresponding anthocyanidins as described by Rösch et al [17]. In fact, 0.1 ml of diluted (2-20 times) juice was mixed with 9.9 ml of a solution of concentrated hydrochloric acid in n-butanol (1:9, v/v) and heated for 90 min in a boiling water bath.…”

Evaluation of Spent Coffee Obtained from the Most Common Coffeemakers as a Source of Hydrophilic Bioactive Compounds

“…The ESR spectroscopy measurements were performed with Fremy´s salt and TEMPO as stabilized radicals with the same procedure as described by Roesch et al 27 …”

Proteic and phenolics compounds contents in Bacupari callus cultured with glutamine and nitrogen sources

“…Solvent was evaporated and the precipitate was suspended again in 5 mL of ethanol. Total phenolic compounds were determined by using the Folin-Ciocalteau method (Ainsworth and Gillespie, 2007), total flavonoids were determined by using the aluminum chelating method (Ebrahimzadeh et al, 2008), and the proanthocyanidins content was obtained after acid depolymerization for the corresponding anthocyanidins (Rosch et al, 2003).…”