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.

Eight different solvent mixtures containing acetone or methanol pure or combined with an acid (acetic, formic, hydrochloric) were tested for their efficiency for extraction of phenolic compounds from strawberries belonging to five groups of polyphenols: anthocyanins, flavonols, flavan-3-ols, hydroxycinnamic acid derivatives and conjugated forms of ellagic acid. Twenty-eight compounds from these five groups have been detected and quantified using HPLC-DAD-ESI-MS(n). The yield of each phenolic compound and group was evaluated with regard to the extraction solvent composition. Acetone containing extraction mixtures were superior to the ones containing methanol for extraction yield of total phenolic compounds, which was especially pronounced for the groups of flavan-3-ols and conjugated forms of ellagic acid. The mixture acetone/acetic acid (99:1, v/v) gave the best results for the qualitative and quantitative assay of the polyphenols present in strawberries since all 28 compounds were detected only in these extracts in quantities higher or comparable to the other extraction solvents tested.