The phenolic profile of four blueberry varieties (Vaccinium corymbosum L., cv. Toro, Legacy, Duke and Bluecrop) and two varieties (Rosenthal and Rovada) of red currants (Ribes rubrum L.) and black currants (Ribes nigrum L.) cultivated in Macedonia have been analyzed using HPLC coupled to diode-array detection and tandem mass spectrometry with electrospray ionization. A complex profile of anthocyanins, flavonols, flavan-3-ols and hydroxycinnamic acid derivatives has been assayed in acetone-acetic acid (99:1, v/v) extracts. Anthocyanins comprised the highest content of total phenolic compounds in currants (>85%) and lower and variety dependent in blueberries (35-74%). Hydroxycinnamic acid derivatives comprised 23-56% of total phenolics in blueberries and 1-6% in currants. Chlorogenic acid was the major hydroxycinnamic acid in blueberries, only in the Legacy variety, two malonyl-caffeoylquinic acid isomers were major components. Flavonols, mainly quercetin and myricetin glycosides, were a minor group, but glucosides of laricitrin and syringetin were also detected in the blueberry varieties counting for 10-34% of total flavonols. From flavan-3-ols, catechin was detected in most samples; the dimer B2 was specific for blueberries whereas epigallocatechin was detected in currants.

Strawberry fruits contain phenolic compounds that exhibit antioxidant, anticancer, antiatherosclerotic, antinflammatory and anti-neurodegenerative properties. High-performance liquid chromatography (HPLC) coupled to electrospray ionization mass spectrometric (ESI-MS) detection in the positive and negative ion mode has been used to identify the phenolic compounds in extracts from sixteen different strawberry cultivar fruits from Republic of Macedonia. Photodiode-array detection (DAD) has been used for screening of the different classes of phenolic compounds, whereas MS and MSn fragmentation data were employed for their structural characterization. The phenolic compounds identified were grouped as: ellagic acid and ellagic acid conjugates with sugars, ellagitannins, anthocyanins, flavonols, flavanols, and acylated sugars (feruloyl, caffeoyl and coumaroyl hexoses). Quercetin and kaempferol were the major flavonols found as quercetin 3-O-glucoside, quercetin 3-O-glucuronide, kaempferol 3-O-glucoside, kaempferol 3-O-glucoronide, kaempferol 3-O-malonylglucoside, kaempferol 3-O-acetylglucoside and kaempferol 3-O-coumaroylglucoside. Pelargonidin-3-O-glucoside was the most abundant anthocyanin in all strawberry extracts. Proanthocyanidins were also identified by MSn fragmentation as dimers, trimers and tetramers of (epi)catechin and (epi)afzelechin. This is the first assay of the phenolic profile of the strawberry cultivars in Macedonia, which can be further developed for characterization and evaluation of their quality with regards to their phenolic composition.

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Apples (Malus domestica Borkh.) contain a large array of phenolic compounds belonging to flavonoids and non-flavonoids. This study systematically evaluates the polyphenolic content of 21 apple cultivars from the Republic of Macedonia, both commercial and autochthonous, applying spectrophotometric methods for the determination of total polyphenolic compounds, total flavonoids, total anthocyanins and total flavan-3-ols. The reliability of these methods was checked by confirming the method linearity and accuracy with standards and spiked samples. The efficiency of acetone, water, methanol and a mixture of methanol/water (90 : 10, V/V) as extraction solvents was compared. Evident differences between extracts obtained from freeze-dried apple peel and pulp, extracted with different solvents, and analyzed with the four spectrophotometric tests, were observed and discussed. The most satisfactory extraction efficiency was achieved using methanol/water (90 : 10, V/V) mixture. The results obtained from the methanol/water extracts illustrate evident differences between polyphenol contents and reveal the diversity in polyphenols, total flavonoid and flavanol composition between the assayed commercial and autochthonous cultivars. The maximum abundance of polyphenols was noticed in the peel of Tetovka and Livadarka cultivars (15.63 mg/g GAE and 14.85 mg/g GAE, respectively) and in the pulp of Pasalma, Tetovka and Livadarka cultivars (12.55 mg/g GAE, 11.45 mg/g GAE and 11.22 mg/g GAE, respectively).Keywords: apples; polyphenols; flavonoids; anthocyanins; flavan-3-ols; spectrophotometry; extraction СПОРЕДБА НА РАЗЛИЧНИ РАСТВОРУВАЧИ ЗА ОПРЕДЕЛУВАЊЕ НА СОДРЖИНАТА НА ПОЛИФЕНОЛИ ВО ЛУШПАТА И ПУЛПАТА НА ЈАБОЛКО ОД РАЗЛИЧНИ СОРТИ ОД МАКЕДОНИЈАПлодовите од јаболкo (Malus domestica Borkh.) содржат различни фенолни соединенија кои се од групите на флавоноиди и не-флавоноиди. Ова истражување систематски ја оценува содржината на полифеноли во 21 сорта јаболко од Македонија, комерцијални и автохтони, со употреба на спектрофотометриски методи за определување на вкупни полифеноли, вкупни флавоноиди, вкупни антоцијани и вкупни флаван-3-оли. Веродостојноста на методите е проверена и потврдена е линеарноста и точноста со употреба на стандарди и стандардни додатоци. Споредена е ефикасноста на растворувачите ацетон, вода, метанол и смеса метанол/вода (90 : 10, V/V). Воочени и дискутирани се разлики помеѓу екстрактите добиени од лиофилизирани лушпи и пулпа од јаболко со различни растворувачи и анализирани со четирите спектрофотометриски методи. Највисока ефикасност на екстракцијата е добиена со употреба на смеса метанол/вода A. Petkovska, V. Gjamovski, M. Stefova Maced. J. Chem. Chem. Eng. 35 (1), 29-38 (2016) 30(90:10, V/V). Добиените резултати за екстрактите во метанол/вода покажуваат разлики во содржи-ната на полифенолите и укажуваат на различност на полифенолниот, флавоноидниот и флаванол-ниот состав на испитуваните комерцијални и автохтони сорти. Најголема застапеност на полифеноли е утврдена во лушпата од сортите тетовка и ливадарка (1...

Qualitative and quantitative analyses of polyphenols extracted from 21 Malus domestica cultivars using ultra high performance liquid chromatography with diode array detection coupled to heated electrospray ionization mass spectrometric detection wаs performed for separation of 27 phenolic compounds on a reversed phase UHPLC column with an optimized gradient consisting of 1% formic acid in water and 1% formic acid in methanol within 20 minutes. According to retention times, UV maxima and mass spectra of the peaks in the chromatograms obtained from extracts of apple peel, flesh and leaves, the polyphenolic compounds were identified and quantified. Based on fragmentation patterns, 6 phenolic acids, 5 flavan-3-ols, 5 dihydrochalcones, 8 flavonols and 3 flavone derivatives were characterized in the studied samples. The method was then employed for analysis of the polyphenolic pattern of 21 apple cultivars, both commercial and autochthonous for the Macedonian region, as well as for monitoring the influence of long term storage on the polyphenolic content and composition of apple fruits and for comparison of polyphenolic profiles of apple cultivars during two years of harvesting. The obtained results revealed minor differences in the quality and major variation in the content of phenolic compounds in the flesh, peel and leaves in the studied apple cultivars that is attributed mainly to cultivar differences and meteorological factors.