# _Vaccinium_ Species (Ericaceae): From Chemical Composition to Bio-Functional Activities
## 3 Phytochemicals of _Vaccinimum_ Fruits
Delphinidin-3-O-xyloside, delphinidin-3-O-glucose, malvidin-3-O-galactoside, malvidin-3-O-glucose petunidin-3-O-galactoside, petunidin-2-O-glucose, malvidin-3-O-xyloside, and petunidin-3-O-xyloside were isolated from _V. arctostaphylos_[45; 46]. Except anthocyanins, to date, more than 50 other flavonoids (mainly flavanols and proanthocyanidins) have been isolated and identified from the genus _Vaccinium_ (Figure 2) [25; 28; 29; 30; 40; 41; 42; 43; 44]. Glycosides are usually \(O\)-glycosides, with the sugar moiety bound to the hydroxyl group at the C-3 or C-7 position. The most common sugar moieties include D-glucose, L-rhamnose, D-xylose, D-galactose, and L-arabinose [25]. Figure 2: The main flavonoids identified in _Vaccinium_ species [25; 28; 29; 30; 41]. Quercetin is the most common flavonoid isolated from _Vaccinium_ species [25]. It was found in high quantities in _V. uliginosum_ and _V. myrtillus_[29]; however, the richest source of quercetin is _V. axycoccos_ with 20-40 mg/100 g fresh weight [38]. Several glycosides of myricetin and quercetin were identified in _V. myrtillus_. Different studies reported the presence of myricetin 3-glucose, myricetin 3-arabinoside, myricetin 3-O-rhammoside, quercetin 3-O-arabinoside, quercetin 3-O-rhammoside, quercetin 3-O-galactoside, quercetin 3-O-glucose, and quercetin 3-O-rutinoside [28; 29; 30; 31]. Apigenin, chrysoeriol, myricetin, myricetin-3-xyloside, quercetin 3-O-glucuron, quercetin 3-O-xyloside, isorhannentin 3-O-glucose [41], luteolin are other flavonoids described in _V. myrtillus_[47]. Kaempferol, isorhannentin, laricitrin, syringetin, isorhannetin 3-O-galactoside, myricetin 3-O-glucuron, laricitrin 3-O-glucose, syringeetin 3-O-glucose [48; 41; 35], kaempferol 3-O-glucose, myricetin 3-O-galactoside, and isorhannetin 3-O-xyloside are also described [48]. The flavonoids identified in _V. axycoccos_ are mainly glycosides of quercetin and myricetin, and to a lesser extent, of kaempferol [49]. Quercetin 3-O-galactoside is the dominant compound, but at least 11 other glycosides are present in lower concentrations [38]. Epicatechin is the dominant constitutive unit of _V. axycoccos_, whereas catechin and (epi)gallocatechins are present only in trace amounts [24; 40]. The major flavonoids described in _V. vitis idea_ are kaempferol [41], quercetin [41; 50], myricetin, myricetin 3-O-glucose [44], quercetin derivatives (bond to glucose, galactose, glucuronide, rhamnose, arabinose, and xylose), kaempferol 3-O-rhammoside, isorhannetin 3-O-galactoside [40; 51], isorhannentin 3-O-glucose, syringeetin-3-O-glucose, kaempferol 3-O-glucose, and rutin [51]. The fruits of _V. uliginosum_ are characterized by the presence of kaempferol, laricitrin [50], quercetin [50; 52; 53; 54], myricetin [54], syringetin, quercetin 3-O-glucose, quercetin 3-O-galactoside, quercetin 3-O-glucose, quercetin 3-O-glucuron, isorhannetin 3-O-glucose, syringeetin 3-O-glucose, myricetin 3-O-galactoside, rutin [50; 52], and myricetin 3-O-glucuron [48]. [PERSON] et al. [55] described, in _V. corymbosum_, the presence of catechin, myricetin, quercetin and kaempferol, but not the presence of epicatechin. Seventeen phenolic acids were identified in some varieties of _V. myrtillus_ (Figure 3) [56]. [PERSON] et al. [55] found gallic, \(p\)-couamaric, ferulic, ellagic and caffe acids as phenolic acids in _V. corymbosum_ produced in the state of Georgia (US). These results were confirmed by [PERSON] et al. [30] who analysed the phenolic acids composition of _V. corymbosum_ and _V. axycoccos_. The two species have different compositions. In fact, _V. corymbosum_ was characterised by the presence of chlorogenic acid as a major phenolic acid, followed by caffeic, ferulic, \(p\)-couamaric and traces of \(p\)-hydroxybenzoic acids, while \(p\)-couamaric acid was the principal phenolic acid of _V. axycoccos_, followed by ferulic, chlorogenic, caffeic and \(p\)-hydroxybenzoic acids. Other studies have reported \(p\)-couamaric, sinapic, caffeic, and ferulic acids as the main hydroxycinnamic acids identified in _V.