**2. Traditional use of black chokeberries**

Although wild-growing black chokeberries (*Aronia melanocarpa*) were known to the North American settlers, the taste of the fruits was dissuading for a use as foodstuff. They employed fruits and bark as an astringent. The Forest Potawatomi Native Americans used the fruits of this plant in cold treatment and the preparation of traditional pemmican [17].

In Russia and Lithuania, the cultivated black chokeberry fruits were used as adjuvant treatment for high blood pressure and as anti-atherosclerotic agent [22]. Other uses include treatment of hemorrhoids, achlorhydria, avitaminosis and convalescence [17].

Because of their astringent taste, black chokeberry fruits are not usually consumed as such, but they are used for the production of juices, wines, teas, jellies or syrups, especially in fruit blends [23, 24]. Chokeberry powders are used as a natural dye in the food industry [25].

The high content of phenolic compounds, mainly anthocyanins, which are responsible for the black color of the fruits, determined an increased interest in the medicinal properties of this plant. *Aronia* ssp. fruits have a higher antioxidant activity than other berries. Various studies emphasized antioxidant, anticancer, anti-diabetic, anti-inflammatory and hepatoprotective properties for the juice or fruit extract, which made cultivated black-fruited Aronia an important health food and dietary supplement [26].

#### **3. Phytochemistry**

Several analyses have been performed in order to evaluate the organic as well as inorganic constituents of black chokeberries. They include the research of the differences in the chemical composition of wild vs. cultivated chokeberry [21, 27], the influence of the cultivar type [28–30], the degree of fruit maturity [31], fertilization [32], the application of biosynthesis regulators [33] and geographic location [34].

Wild *Aronia* genotypes contain less water and more phenolics and have a higher antioxidant activity than cultivated black chokeberries [21]. Typical values for the dry weight of cultivated black chokeberry fruits are 17.9–26%; fresh chokeberries afford 11.1–17.4% juice and 44.6–50% pomace [35]. The majority (72%) of the dry weight is constituted by dietary fiber, higher than other fruits like bilberries and currants. The study of dietary fiber with solid-state NMR could show that its components are water-insoluble fibers (cellulose, hemicellulose, lignin, cutin and pectins), soluble fibers and other constituents, which are valuable antioxidants, anthocyanins and procyanidins [36].

The sour taste of *Aronia* ssp. berries is due to the presence of organic acids, mainly malic and citric acids. Their total content is however lower than in other berries [37]. Cultivated black chokeberries contain between 5.71 and 19.36% reducing sugars [23] and are characterized by a relatively high sorbitol amount (median content of 70 g/kg) [34] when compared to other berries. The high sorbitol content, shared as well by rowan berries (*Sorbus aucuparia*), may be related to the possible hybrid nature of cultivated chokeberry. Large-fruited Aronia cultivars have been hypothesized to contain the genomes of *Aronia melanocarpa* and *Sorbus aucuparia* in a ratio of 3:1 [19, 21]. The high sorbitol content has been proposed to serve as an analytical tool in the control of juice blends [38]. Another feature of the sugar profile in cultivated black chokeberry is the absence of sucrose; its presence in black Aronia-based products suggests the addition of sugar or other fruits [34].

The lipid content of black cultivated chokeberries is reduced (below 0.2%) [23] and is mainly owed to hydrophobic constituents of the skin and seeds. The content in proteins is also low, with values of 10.7% in the pomace. The main amino acid was glutamic acid (19.8%), followed by aspartic acid (8.9%) and arginine (7.9%) [39].

Regarding the content in minerals, chokeberries may be valuable to complement dietary potassium and zinc intake. Among vitamins, Aronia fruits contain vitamins B1, B2, B6 and C, pantothenic acid and niacin; the detailed content has been extensively reviewed [23, 38].

The analysis of the volatile constituents in Aronia berry juice afforded the detection of 74 constituents, of which the most abundant were 3-penten-2-one, 3,9-epoxy-p-menth-1-ene and benzaldehyde. Among the aroma-active compounds, ethyl-2-methyl butanoate, ethyl-3-methyl butanoate and ethyl decanoate could account for the "fruity" aroma notes, while nonanal is responsible for the "green" notes [40]. The bitter-almond scent of the fruits is due to the presence of amygdalin [34]. This compound is a cyanogenic glycoside present in many representatives of the Rosaceae family [35]. Interestingly, a recent research aimed at identifying compounds, which inhibit adipocyte differentiation, was able to isolate from the butanol fraction of a chokeberry extract amygdalin and prunasin as active compounds [41]. These two cyanogenic glycosides suppress the expressions of peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding protein α (C/ EBPα), sterol regulatory element-binding protein 1c, fatty acid synthase (FAS), and adipocyte fatty-acid–binding protein (aP2) [42].

The most intensively studied compounds in cultivated black chokeberries are phenolic compounds, mainly anthocyanins, procyanidins and phenolic acids. The total phenolic content ranges from 3440 mg/100 g dry weight to 7849 mg/100 g dry weight, depending on cultivar, ripening stage at harvest, cultivation conditions or analytical methods used for the quantification [38]. Analysis of several chokeberry cultivars identified a higher polyphenolic content for the fruits of 'Hugin' cultivar compared to 'Viking,' 'Galicjanka' and 'Nero' cultivars [29]. There are differences in the polyphenols content in chokeberry products; for example, the pomace has a five-fold higher content compared to juice [16].

*Cardioprotective Effects of Cultivated Black Chokeberries (*Aronia *spp.): Traditional Uses… DOI: http://dx.doi.org/10.5772/intechopen.92238*

Polymeric proanthocyanidins represent 66% of chokeberry polyphenols, while anthocyanins represent about 25%. The fruits contain up to 5181.60 mg/100 g dried weight polymeric procyanidins [43]. The constitutive unit is mainly (−)-epicatechin and the units are connected by C4▬C6 and C4▬C8 bonds (B-type bonds). The degree of polymerization ranges from 2 to 23 units. The main proanthocyanidins found in the fruits and bark of chokeberry are dimeric procyanidin B2 and procyanidin B5 and trimeric procyanidin C1 (**Figure 1**) [44].

Anthocyanins are a class of flavonoids that give blue, dark red or purple color of the fruits and they are important compounds for the biological activity of chokeberries [38]. Black chokeberries have a higher content of anthocyanins than other berries, such as blackberries, strawberries or red raspberries [45]. Anthocyanins are found mainly in fruit skin [46]. They are represented by cyanidin glycosides such as

#### **Figure 1.**

*Chemical structures of polyphenolic compounds from cultivated black-fruited chokeberries. (1) Procyanidin B2; (2) procyanidin B5; (3) procyanidin C1; (4) chlorogenic acid; (5) anthocyanins.*

cyanidin-3-glucoside, cyanidin-3-galactoside, cyanidin-3-xyloside and cyanidin-3-arabinoside [43]. The study of the fruits of black chokeberry, 'Viking', 'Nero' and 'Galicjanka' cultivars revealed that 'Nero' and 'Viking' cultivars had higher anthocyanin content. Cyanidin-3-galactoside and cyanidin-3-arabinoside are the major anthocyanins in chokeberries, while cyanidin-3-xyloside and cyanidin-3-glucoside are found in lower amounts [47]. The fruits also contain pelargonidin-3-arabinoside and pelargonidin-3-galactoside in trace amounts [17, 38]. Other anthocyanins such as cyanidin-3-pentoside-(epi)catechin, cyanidin-3,5-hexoside-(epi)catechin, and cyanidin-3-hexoside-(epi)cat-(epi)cat were identified in black chokeberry juice and powder [46].

The main phenolic acids in black chokeberries are chlorogenic and neochlorogenic acids. They represent about 7.5% of fruit polyphenols [43]. In addition to chlorogenic and neochlorogenic acids, other phenolic acids such as cryptochlorogenic acid, 3-*O*-p-coumaroylquinic acid and di-caffeic quinic acid have been reported in chokeberries [46]. Chokeberry juice contains a greater amount of these compounds than pomace [43]. Fruits of 'Viking' cultivar and wild chokeberry have a higher content of phenolic acids compared to fruits of 'Nero' and 'Galicjanka' cultivars [47].

Chokeberry also contains flavonol glycosides such as quercetin 3-*O*-galactoside, quercetin 3-*O*-rutinoside, quercetin 3-*O*-glucoside, quercetin 3-*O*-arabinoside, isorhamnetin 3-*O*-rutinoside or kaempferol 3-*O*-glucoside [48]. Other phenolic compounds identified in chokeberry fruits and flowers are the flavanone eriodictyol-7-*O*-β-glucuronide and the flavonols quercetin-3-robinobioside and quercetin-3-vicianoside [49]. Even though the fruits were the most investigated for the polyphenols in their composition, black chokeberry leaves also contain these compounds, with a higher content in the young leaves compared to the old ones (**Figure 1**) [50].
