Anthocyanins are ubiquitous water-soluble pigments that have important roles in the propagation, protection, and physiology of higher plants. Evidence shows that these compounds can act by repelling herbivores and parasites,¹  attracting pollinators and seed dispersers,²  and protecting plants against biotic and abiotic stresses.³  In human health, anthocyanins have been associated with various benefits due to their antioxidant,⁴  anti-inflammatory,⁵  neuroprotective,⁶  and anti-diabetic properties.⁷  Chemically, anthocyanins are polyphenols and belong to a large class of secondary metabolites known as flavonoids, with a core structure in the form of 2-phenylbenzopyrylium or flavylium cation (Figure 1.1). They are polyhydroxy and polymethoxy derivatives of this flavylium cation and can have sugar groups or acylated moieties attached at different positions.⁸  Although more than 700 compounds have been described in the literature,⁹  they are mainly derived of six anthocyanidins (aglycone form): cyanidin, delphinidin, pelargonidin, peonidin, petunidin, and malvidin.¹⁰ 

An interesting feature of anthocyanins is that they can display a great diversity of colors depending on their chemical structure and the environment in which they are found, ranging from orange to blue.¹¹  Several factors likely contribute to the variations in anthocyanin content and profile in plants. Anthocyanin biosynthesis and structural skeleton diversity are controlled by a number of genes. As illustrated in a colored potato study, the red cultivars contained predominantly pelargonidin derivatives, while the purple/blue varieties had peonidin, petunidin, and malvidin as the main aglycones.¹²  A color change is usually seen in fruit over the growing and harvest seasons. For example, the intra-seasonal monitoring of total anthocyanins and specific components in blueberries showed that during the harvest season between June and August, the content had a generally increasing trend, but the percentages of delphinidin and malvidin glycosides were inversely mirrored.¹³  The environment also has an effect on anthocyanin production in plants. Although the specific role that these plant metabolites have in protecting against biotic and abiotic stresses is not well understood, studies have revealed interesting connections between anthocyanin profiles and various stress conditions. For example, Kovinich et al.¹⁴  reported a clear pattern of difference in model plant Arabidopsis thaliana under abiotic stresses, where low pH and phosphate deficiency induced anthocyanin accumulation, while osmotic stress with mannitol and high pH reduced the total anthocyanins level. Furthermore, some structural differences, mainly in the modification of glycoside chains, were observed under these stress conditions. In field crops, the anthocyanin content and profile are most likely affected by both genetic and environmental variations. A multi-year grape study by Ortega-Regules et al.¹⁵  showed that the total anthocyanins and fingerprint profiles varied considerably over 3 years with different weather conditions during the growing seasons for the same crop varieties, while the differences were relatively smaller for Monastrell variety grapes grown at two different locations.

Aside from their recognized health benefits, these colorful molecules from natural sources are very appealing to the food industry as colorants. The increasing interest in their use in food products has been driven by consumer and regulatory pressure to replace synthetic colorants. However, this substitution is not straightforward as anthocyanins can degrade under normal processing and storage conditions, such as during heat treatment, which would negatively impact the sensory properties of the product. Different strategies to improve the stability of these colorants have been investigated, some of which will be discussed in later chapters.

In this chapter, natural sources of anthocyanins, such as fruits, vegetables, and grains, are highlighted and discussed based largely on the literature of the past 20 years. Examples of anthocyanin-containing plants used in traditional Chinese and Indian medicine, as well as exotic plants found worldwide, are included. Mazza and Miniati⁸  have extensively reviewed the occurrence of anthocyanins in foods, and their work serves as the foundation for this updated account in the area.

Color is an important attribute of fresh or processed food products that is very appealing to consumers. As one of the largest groups of water-soluble pigments, anthocyanins are present in virtually all types of foods, contributing to the wide range of characteristic colors. The following sections list various types of foods available in North America (in alphabetical order by common name) and describe the main types of anthocyanins reported in the literature. Later sections include examples of anthocyanin sources used in traditional medicine and found in other parts of the world.

The red peel of certain cultivars of apples is very attractive and retains most of the pigment. Cyanidin-3-galactoside is the major anthocyanin in the red peel, while cyanidin-3-glucoside and cyanidin-3-arabinoside are minor ones.⁸  Apple flesh can also contain anthocyanins, as reported in red-fleshed apple varieties.^16,17  A recent study of 22 apple cultivars in Poland revealed that the average total anthocyanin content of the whole fruit was 30 mg/100 g dry tissue, ranging from 5 to 133 mg/100 g depending on the cultivar. From this content, 85–100% was found to be cyanidin-3-galactoside.¹⁸ 

Dried apricots were reported to have a total anthocyanin content of 3 mg cyanidin-3-glucoside equivalents/100 g.¹⁹  The major anthocyanin compound found in apricots is cyanidin-3-rutinoside.^20,21 

This small berry contains highly diverse anthocyanin compounds with various anthocyanidins and glycosylation patterns. The major anthocyanins are malvidin-3-glucoside (22%), delphinidin-3-galactoside (19%), cyanidin-3-galactoside (15%), petunidin-3-galactoside (14%), cyanidin-3-glucoside (9%), and delphinidin-3-glucoside (9%).⁸  Using high-performance liquid chromatography with electrospray ionization mass spectrometry (HPLC-ESI-MS), Dugo and co-workers²²  identified 14 anthocyanins from a black bilberry extract, including 3-arabinosides, 3-glucosides, and 3-galactosides of five anthocyanidins: cyanidin, delphinidin, peonidin, petunidin, and malvidin.

The predominant anthocyanins identified in blackberries were cyanidin-3-glucoside and cyanidin-3-rutinoside.⁸  Additional anthocyanins, such as cyanidin-3-xyloside and cyanidin-3-malonylglucoside, were also found in a study examining 51 blackberry samples using liquid chromatography with ultraviolet detection coupled with mass spectrometry (LC-UV/MS).²³  In a Norwegian wild blackberry species, 3-O-β-(6″-(3-hydroxy-3-methylglutaroyl)-glucopyranoside) was also confirmed by high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR).²⁴ 

Major anthocyanins in highbush blueberries were 3-galactosides and 3-arabinosides of delphinidin, malvidin, and petunidin, in addition to 3-glucosides of these anthocyanidins, as well as cyanidin and peonidin at lower levels. In lowbush blueberry, the 3-galactosides of various anthocyanidins were more predominant.⁸  Acylated anthocyanins in the form of 3-acetylglucoside and 3-acetylgalactoside of malvidin were also found in lowbush blueberry, accounting for over 32% of its anthocyanin content.²⁵  In a Chinese lowbush blueberry species (V. uliginosum L.), the predominant anthocyanin was malvidin-3-glucoside (31.9% of total anthocyanins).²⁶ 

Cyanidin-3-glucoside and cyanidin-3-rutinoside were the main anthocyanins found in cherries.^27,28 

Glucosides of peonidin and cyanidin were found to be the main anthocyanins in small European cranberry species (V. oxycoccus L.), while the 3-galactosides and 3-arabinosides of these anthocyanidins were more abundant in American cranberries (V. macrocarpon Ait.).⁸  A study of 78 American cranberries revealed that the proportion of the two major anthocyanidins, peonidin and cyanidin, varied between 1 : 0.5 and 1 : 3.6. It also showed variation of glycosylation profiles, with galactosides ranging between 64 and 75%, arabinosides between 20 and 33%, and glucosides between 3 and 9%.²⁹ 

Cyanidin glycosides, such as 3-xylosylrutinoside, 3-glucosylrutinoside, 3-sambubioside, 3-rutinoside, and 3-glucoside, were the major anthocyanins found in redcurrants, while the 3-rutinoside and 3-glucoside of cyanidin and delphinidin were found in higher concentrations in blackcurrants.^8,30 

The distribution of anthocyanins in grapes is complex and, similar to other fruits, highly dependent on cultivar, climate, and plant maturity, among other factors. The anthocyanidins identified include cyanidin, delphinidin, petunidin, peonidin, and malvidin, mostly mono- and di-glucosylated, usually at C-3 and C-3,5 positions. Grapes are also known to have acylated anthocyanins, especially with p-coumaric acid substitutes attached to the glucose moiety.⁸  Anthocyanin dimers as minor components were also detected in grapes using HPLC with a diode array detector and tandem MS (HPLC-DAD-MS/MS).³¹ 

This fruit is native to Siberia and northeastern Asia, and fairly new in the North America market (Figure 1.2A). Commonly known as blue honeysuckle, these berries contain cyanidin-3-glucoside as the predominant anthocyanin.^32–34  Minor anthocyanins including cyaniding-3,5-di-glucoside, cyaniding-3-rutinoside, peonidin-3-glucoside, and pelargonidin-3-glucoside were also present.³⁵ 

This fruit mainly contains cyanidin-3-glucoside, cyanidin-3-rutinoside, cyanidin-3-galactoside, delphinidin-3-rutinoside, and cyanidin-3-(6″-rhaminosyl)glucoside.^36,37  A photograph of a mulberry plant is shown in Figure 1.2B.

Red oranges and blood oranges contain cyanidin-3-glucoside as the major anthocyanin, along with delphinidin glycosides.⁸  In orange juice from the Italian Moro cultivar, cyanidin-3-(6″-malonyl)glucoside was also found to be a predominant anthocyanin.³⁸ 

In a survey of 68 peach cultivars from China, Zhao et al.³⁹  reported that the most common anthocyanin present was cyanidin-3-glucoside, while its 3-rutinoside was only found in certain cultivars.

Anthocyanins were only found in red skinned pear cultivars among 19 European and Tunisian varieties studied, at levels of 134 mg kg⁻¹ for cyanidin-3-O-hexoside and 38 mg kg⁻¹ for peonidin-3-O-hexoside (on a fresh weight basis).⁴⁰  Similar findings were also reported for 37 pear cultivars grown in China, where cyanidin-3-galactoside was revealed as the major anthocyanin in red skinned cultivars.⁴¹ 

Studies from a large number of plum cultivars revealed that cyanidin-3-rutinoside was the predominant anthocyanin, along with its 3-glucoside.^42,43  In addition, the glycoside of peonidin was also reported for some European plum varieties.⁴⁴  In South African plum cultivars, cyanidin-3-glucoside was detected as the predominant anthocyanin.⁴⁵ 

Cyanidin-3,5-diglucoside, cyanidin-3-glucoside, delphinidin-3,5-diglucoside, delphinidin-3-glucoside, and pelargonidin-3-glucoside were identified as the major anthocyanins in pomegranate juice.^46,47 

Cyanidin-3-rutinoside and 3-diglucoside are anthocyanins that have been identified in rosehip, shown in Figure 1.2C.⁸ 

This plant is native to Canada and the northern US. An example is shown in Figure 1.2D. The major anthocyanins that were found in saskatoon berries were 3-galactoside, 3-glucoside, 3-arabinoside of cyanidin, with its xyloside also present as a minor constituent.^8,48,49  However, delphinidin-3-glucoside was reported as the dominant anthocyanin in another study.⁵⁰ 

Pelargonidin-3-glucoside and cyanidin-3-glucoside have been identified as the major anthocyanins in cultivated strawberries.⁸  Using LC-MS, the presence of the 3-rutinoside and 3-acetylglucoside of pelargonidin and cyanidin-3-rutinoside was confirmed from the variety Carmarosa. This variety was also shown to contain 5-carboxypyranopelargonidin-3-glucoside.^51,52  In 14 oriental strawberry cultivars, pelargonidin-3-glucoside, cyanidin-3-glucoside, and pelargonidin-3-rutinoside were the major anthocyanins.⁵³ 

Cyanidin-3-(3″-glucosyl-6″-rhamnosyl)-glucoside and cyanidin-3-rutinoside were the major anthocyanins found in purple asparagus (A. officinalis cv. Purple Passion).^54,55 

In black beans (P. vulgaris L.), delphinidin-3-glucoside, petunidin-3-glucoside, and malvidin-3-glucoside were isolated and identified to be the major anthocyanins, and the total content was determined to be around 213 mg/100 g.^56,57  Other anthocyanins found in black and kidney beans included delphinidin-3,5-diglucoside, petunidin-3,5-diglucoside, delphinidin-3-galactoside, malvidin-3,5-diglucoside, petunidin-3-galactoside, pelargonidin-3-glucoside, and malvidin-3-galactoside.^57–60  In addition, some C–C linked flavanol anthocyanin derivatives, such as gallocatechin–delphinidin, catechin–cyanidin-3-glucoside, catechin–cyanidin, catechin–petunidin, catechin–peonidin, and afzelechin–poinidin, were identified in Guatemala kidney beans and scarlet red runner beans (P. coccineus L.).⁶¹ 

Red cabbage contains a large number of acylated cyanidin glycosides, with cyanidin-3-diglucoside-5-glucoside, cyanidin-3-(p-coumaroyl)diglucoside-5-glucoside, and cyanidin-3-(sinapoyl)diglucoside-5-glucoside as the predominant compounds.^58,62,63  In the Chinese purple cabbage (B. rapa L. ssp. pekinensis), the major anthocyanins were found to be cyanidin-3-(p-coumaroylsophoroside)-5-maolonylglucoside, cyanidin-3-ferulylsophoroside-5-malonylglucoside, cyanidin-3-(sinapyl-p-coumaroyl)sophoroside-5-malonylglucoside, and cyanidin-3-(sinapyl-ferulyl)sophoroside-5-malonylglucoside.⁶⁴  It is reported that the level of anthocyanins in red cabbage can reach up to 1780 mg/100 g (dry weight basis).⁶⁵ 

Several cyanidin glycosides have been reported in purple carrot varieties, including 3-(xylosyl)-glucosyl-galactoside, 3-(xylosyl)(sinapoyl)-glucosyl-galactoside, 3-(xylosyl)(feruloyl)-glycosyl-galactoside, and 3-(xylosyl)(coumaroyl)-glucosyl-galactoside.⁵⁵  In addition to these cyanidin glycosides, pelargonidin-3-xylosyl(feruloylglucosyl)galactoside, peonidin-3-xylosylgalactoside, and peonidin-3-xylosyl(feryloylglucosyl)galactoside were found as minor constituents in a black carrot cultivar (D. carota ssp. Sativus var. atrorubens Alef).⁶⁶ 

The major anthocyanins in purple cauliflower (Figure 1.3A) are cyanidin glycosides, including 3-(6-p-coumaryl)-sophoroside-5-glucoside, 3-(6-feruloyl)-sophoroside-5-glucoside, 3-sophoroside-5-glucoside, 3-(6-p-coumaryl)-sophoroside-5-(6-sinapyl)-glucoside, and 3-(6-feryloyl)-sophoroside-5-(6-sinapyl)-glucoside.^55,67 

The skin of 14 cultivars of eggplants from Japan and Bangladesh contained delphinidin-3-p-coumarylrutinoside-5-glucoside and delphinidin-3-glucosylrhamnoside as the major anthocyanins.^68,69  Other compounds found in eggplants included delphinidin-3-rutinoside,^55,70–72  delphinidin-3-glucoside,⁵⁵  and petunidin-3-(p-coumaroylrutinoside)-5-glucoside.⁷³ 

Two anthocyanins, cyanidin-3-glucoside and peonidin-3-rutinoside, were isolated from Japanese ginger rhizomes.⁷⁴ 

In a study involving 11 lentil cultivars grown in northern US, Pardina and French Green lentils were shown to have considerably high levels of anthocyanins (approximately 16 and 67 mg/100 g, respectively), although the exact composition was not determined.⁷⁵  Delphinidin-3-glucosylarabinoside was isolated and identified from Beluga black lentils,⁷⁶  while delphinidin-3,5-diglucoside and a small amount of cyanidin-3-glucoside were recently reported in Italian black lentils.⁷⁷ 

Data on the anthocyanin content and profile in peas are scarce. Only one study reported the isolation and identification of delphinidin-3-xylosylgalactoside-5-acetylglucoside and delphinidin-3-xylosylgalactoside-5-glucoside from purple pods.⁷⁸ 

The purple-black peanut coat has cyanidin-3-xylosylglucoside as the predominant anthocyanin,^79,80  while cyanidin-3-sophoroside was reported as another major anthocyanin.⁸¹ 

The major anthocyanin in violet peppers was reported to be delphinidin-3-trans-coumaroylrutinoside-5-glucoside,⁷⁰  while both the trans and cis isomers were found in chili peppers of the Arbol and Uvilla types.⁸²  Total anthocyanins in chili peppers were reported to range between 0.79 and 4.70 mg kg⁻¹ (fresh weight) and 62.9 and 70.3 mg kg⁻¹ (dry weight).⁸³ 

Pigmented or colored potatoes contain relatively high levels of anthocyanins. Based on our study of 20 colored clones, the total anthocyanin content in the peels and tubers was up to 25.79 and 14.42 mg g⁻¹ (dry weight basis), respectively.⁸⁴  The red-fleshed potatoes contained mainly pelargonidin glycosides (3-p-coumaroylrutinoside-5-glucoside and 3-feruloylrutinoside-5-glucoside), while the blue and purple varieties had glycosides of petunidin (3-p-coumaroylrutinoside-5-glucoside), peonidin (3-p-coumaroylrutinoside-5-glucoside), and malvidin (3-p-coumaroylrutinoside-5-glucoside).¹²  Furthermore, a few cis isomers of acylated anthocyanins, such as petunidin 3-cis-caffeoylruntinoside-5-glucoside and petunidin 3-cis-feruloylrutinoside-5-glucoside, were recently characterized in Korean colored potatoes.⁸⁵ 

Red onions contain mainly cyanidin glycosides, including 3-glucoside, 3-laminaribioside, 3-malonylglucoside, and 3-malonyllaminaribioside. Two minor anthocyanins, peonidin-3-glucoside and peonidin-3-malnolyglucoside, were also detected.^55,86  Anthocyanins with a unique aglycone, 5-carboxyyranocyanidin, were also isolated from red onions and characterized as 3-glucoside and 3-malonylglucoside.⁸⁷  Additionally, comparative analysis of red and yellow onions showed the presence of delphinidin glycoside.⁸⁸ 

The major anthocyanins in red radishes are acylated pelargonidin glycosides, such as 3-p-coumaroylsophoroside-5-glucoside, 3-trans-feruloylsophoroside-5-glucoside, 3-trans-feruloylsophoroside-5-malonylglucoside, 3-trans-p-coumaroylsophoroside-5-malonylglucoside,⁸⁹  and other di-acylated compounds.^90–92  The total anthocyanin level in red radish from Finland was reported to be 32 mg/100 g (fresh weight basis).⁹³ 

Cyanidin-3-rutinoside and cyanidin-3-glucoside were detected in the R. rhaponticum cultivar Crimson Crown.⁹⁴  In another study, delphinidin-3-rutinoside was also found in rhubarb juice.⁹⁵ 

The main anthocyanins found in black soybean seed coats were delphinidin-3-glucoside, cyanidin-3-glucoside, petunidin-3-glucoside, and pelargonidin-3-glucoside.^96–99  Other minor anthocyanins including catechin–cyanidin-3-glucoside, delphinidin-3-galactoside, cyanidin-3-galactoside, and peonidin-3-glucoside were also detected.¹⁰⁰  In 60 Chinese black soybean varieties, cyanidin-3-glucoside was revealed to be the most abundant anthocyanin, and malvidin-3-glucoside was also present. The total anthocyanins measured in these varieties ranged between 98.8 and 2132.5 mg/100 g.¹⁰¹ 

The purple fleshed sweet potato has been widely studied for its anthocyanin profile, with the main compounds reported as peonidin-3-O-(6-O-trans-caffeyl)-2-O-(6-O-trans-caffeylglucosyl)glucosyl-5-O-glucoside, peonidin-3-O-(6-O-trans-caffeyl)-2-O-(6-O-trans-feruloylglucosyl)glucosyl-5-O-glucoside, peonidin-3-O-(6-O-trans-caffeyl)-2-O-(6-O-p-hydroxylglucosyl)-5-O-glucoside,¹⁰²  cyanidin-3-caffeoylsophoroside-5-glucoside, cyanidin-3-caffeoyl-p-hydroxybenzoylsophoroside-5-glucoside, cyanidin-3-(6″,6″′-dicaffeoylsophoroside)-5-glucoside, cyanidin-3-(6″-caffeoyl-6″′-feruloylsophoroside)-5-glucoside,^103,104  pelargonidin-3-caffeoyl-feruloylsophoroside-5-glucoside, pelargonidin-3-caffeoyl-p-coumaryl sophoroside-5-glucoside,¹⁰⁵  cyanidin-3-cafeoyl-vanilloyl sophoroside-5-glucoside, and peonidin-3-cafeoyl-vanilloyl sophoroside-5-glucoside.¹⁰⁶  The total anthocyanin content was reported to be as high as 1190 mg/100 g in purple sweet potatoes (dry weight basis).¹⁰⁵  The red variety (I. batatas L. cv. okiyumemurasaki) contained cyanidin-3-sophoroside-5-glucoside and peonidin-3-(6-caffeoyl-sophoroside)-5-glucoside.¹⁰⁷ 

Red turnips were found to contain cyanidin glycosides, including 3-diglucoside-5-glucoside, 3,5-diglucoside, 3-glucoside, 3-p-coumaryl-diglucoside-5-malonylglucoside, and 3-ferulyl-diglucoside-5-malonylglucoside.^8,108  In Chinese purple turnip varieties (B. rapa L. ssp. rapifera Metzg. and B. rapa L. ssp. chinensis (L.) Makino), the main anthocyanin was found to be acylated pelargonidin-3-diglucoside-5-glucoside.¹⁰⁹  A photograph of turnips is presented in Figure 1.3B.

Colored barley varieties were reported to contain up to 35 mg/100 g of total anthocyanins, with cyanidin-3-glucoside as the major compound in purple barley and delphinidin-3-glucoside in blue and black varieties.¹¹⁰  Delphinidin-3-rutinoside and petunidin-3-glucoside were also found in Canadian yellow and purple barley varieties.¹¹¹  The Japanese purple waxy hull-less barley cultivar Faishimochi was revealed to have malonylated cyanidin glycosides, 3-(3,6-dimaloyl)glucoside, 3-(6-malonyl)glucoside, and 3-(3-malonyl)glucoside as the major pigments.¹¹²  Cyanidin-3-malonylglucoside and delphinidin-3-malonylglucoside were also shown to be predominant in purple winter barley cultivars.¹¹³ 

Four dark red native maize varieties from Mexico were shown to have anthocyanin contents ranging from 54 to 115 mg/100 g. Cyanidin-3-glucoside, pelargonidin-3-glucoside, peonidin-3-glucoside, cyanidin-3-malonylglucoside, and cyanidin-3-dimalonylglucoside were the main anthocyanins.¹¹⁴  Similar profiles were also observed in Andean purple corn and Chinese purple corn.^115,116  Pelargonidin-3-glucoside was identified to be the major compound in Korean black waxy corn.¹¹⁷  In blue corn from southwestern US, cyanidin-3-disuccinylglucoside was also identified.¹¹⁸  In a study examining 398 genetically diverse pigmented accessions of maize, cyanidin-3-malonylglucoside was found to be the most dominant anthocyanin.¹¹⁹ 

Black rice was found to contain mainly cyanidin-3-glucoside and peonidin-3-glucoside,^120,121  and smaller amounts of cyanidin-3,5-diglucoside and cyanidin-3-rutinoside.^122,123  The cyanidin and peonidin glucosides were also revealed to be the predominant anthocyanins in Japanese black-purple rice and black rice from France.^124,125  Other anthocyanins recently identified in black rice include cyanidin-3-gentiobioside, cyanidin-3-sambubioside, cyanidin-3-galactoside, delphindin-3-galactoside, and delphinidin-3-arabinoside.^126,127  Analysis of eight colored rice cultivars (black, red, and green) revealed the presence of malvidin- and petunidin-3-glucoside. In the four red cultivars studied, only malvidin was found. Total anthocyanins varied between 79.5 and 473.7 mg/100 g in black and 7.9 and 34.4 mg/100 g in red rice cultivars.¹²⁸ 

Delphinidin-3-rutinoside was reported to be the predominant anthocyanin in rye, along with delphinidin-3-glucoside, cyanidin-3-rutinoside, and petunidin-3-rutinoside as the minor ones. Rye bran contained 29.3 mg kg⁻¹ (dry weight) and whole grain flour had 3.6 mg kg⁻¹ (dry weight) of total anthocyanins.¹²⁹ 

Black and red sorghum cultivars contain only 3-deoxyanthocyanins, including epigeninidin, apigeninidin-5-glucoside, 7-O-methyl apigeninidin, luteolinidin, luteolinidin-5-glucoside, and 5-methoxyluteolinidin.^130–132  Red/purple sorghums had 3-deoxyanthocyanin levels of between 32 and 680 µg g⁻¹.¹³³ 

Colored wheat cultivars contain anthocyanins in the range of 6.7–211.9 µg g⁻¹, with the highest levels identified in blue and purple varieties, and considerably lower contents detected in red wheat. In blue wheat, the major anthocyanins were identified as delphinidin-3-glucoside, delphinidin-3-rutinoside, cyanidin-3-glucoside, and cyanidin-3-rutinoside. In purple wheat, cyanidin-3-glucoside and petunidin-3-glucoside were found in relatively high concentrations in comparison to other anthocyanins.^134,135  Acylated anthocyanins, mainly malonylated and succinylated delphinidin glycosides, were also found in blue spring wheat.¹³⁶  In addition, the presence of cyanidin-3-glucoside as the main anthocyanin in purple wheat was reported in a separate study.¹³⁷  In a dark blue cultivar (T. aestivum L. cv. Hedong Wumei), cyanidin-3-glucoside was identified as the predominant anthocyanin, along with cyanidin-3-galactoside, pelargonidin-3-glucoside, and peonidin-3-glucoside.¹³⁸ 

Around the world, many plants have been used for thousands of years in traditional medicines for the prevention and treatment of diseases or to maintain good health. Traditional Chinese medicine and Indian Ayurvedic medicine are two ancient medical practices that continue to serve the health needs of billions of people. In this section, some of the herbs listed in the China Pharmacopoeia and the Ayurvedic Pharmacopoeia of India are briefly discussed regarding the presence of anthocyanins.

The Chinese date or jujube (Figure 1.4A) is one of the most common fruits used both in traditional Chinese medicine and food. The mature and dry fruit has bright red skin, which has been shown to contain anthocyanins up to 42.53 mg/100 g (dry weight basis). The pulp of Chinese dates also contains anthocyanins, although at a lower level (1.38–10.59 mg/100 g, dry weight basis), based on a study of three cultivars.¹³⁹  A recent study on an Iranian jujube cultivar revealed the presence of the following anthocyanins: cyanidin-3,5-diglucoside, cyanidin-3-glucoside, delphinidin-3-glucoside, delphinidin-3,5-diglucoside, peonidin-3-glucoside, pelargonidin-3-glucoside and pelargonidin-3,5-diglucoside.¹⁴⁰ 

The aerial parts of colored chicory varieties (Figure 1.4B) contain cyanidin-3-glucoside, cyanidin-3-malonylglucoside, and delphinidin-3-malonylglucoside.¹⁴¹  Cyanidin-3-malonylglucosdie was also found in red chicory as the predominant anthocyanin.^142,143  In the leaves of Chinese C. intybus var. foliosum Hegi, total anthocyanins were determined to be 37.3 mg/100 g (fresh weight basis). The major anthocyanin was found to be cyanidin-3-malonylglucoside (82% of total anthocyanin content), while three minor ones (cyanidin-3-glucoside, cyanidin-3-malonylgalactoside, and cyanidin-3-succinylglucoside) were also present.¹⁴⁴  In Italian cultivars, delphinidin-3-malonylglucoside-5-glucoside, cyanidin-3,5-dimalonylglucoside, petunidin-3-malonylglucoside, cyanidin-3-galactoside, cyanidin-3-acetylglucoside, malvidin-3-glucoside, pelargonidin-3-monoglucuronide, and apigenin-7-glucoside were also detected.¹⁴⁵ 

Sea buckthorn berries (Figure 1.4C) contain mainly cyanidin-3-galactoside, malvidin-3-glucoside, and cyanidin-3-rutinoside along with other minor anthocyanins (delphinidin-3-glucoside, delphinidin-3-rutinoside, cyanidin-3-glucoside, peonidin-3-galactoside, peonidin-3-arabinoside, and malvidin-3-galactoside).⁵⁰ 

Cyanidin-3-galactoside was found to be the major anthocyanin in Chinese hawthorn fruits (Figure 1.4D), along with cyanidin-3-glucoside, cyanidin-3-arabinoside, and peonidin-3-glucoside.^146–148 

Two anthocyanins were isolated from the fresh fruit of C. officinalis (Figure 1.5A) and identified as cyanidin-3-galactoside and pelargonidin-3-galactoside, with the latter as the predominant anthocyanin.¹⁴⁹ 

The major anthocyanins in this red berry (Figure 1.5B) were identified as cyanidin-3-xylosylrutinoside,^150,151  cyanidin-3-glucosylrutinoside, cyanidin-3-xylosylglucoside, and cyanidin-3-rutinoside.¹⁵² 

The flower of V. yedoensis (Figure 1.5C) contains the following anthocyanins: malvidin-3-trans-p-coumaroylrutinoside-5-glucoside, petunidin-3-trans-p-coumaroylrutinoside-5-glucoside, delphinidin-3-trans-p-coumaroylrutinoside-5-glucoside, cyanidin-3-p-coumaroylrutinoside-5-glucoside, petunidin-3-cis-p-coumaroylrutinoside-5-glucoside, malvidin-3-cis-p-coumaroylrutinoside-5-glucoside, peonidin-3-p-coumaroylrutinoside-5-glucoside, delphinidin-3-cis-p-coumaroylrutinoside-5-glucoside, and delphinidin-3-acetlyrutinoside-5-glucoside.¹⁵³ 

The predominant anthocyanin in the aerial parts of this plant (Figure 1.5D) is cyanidin-3-coumaroylglucoside-5-glucoside, along with other minor ones identified in the purple leaves, such as cyanidin-3,5-diglucoside, cyanidin-3-glucoside, cyanidin-3-caffeoylglucoside-5-glucoside, and cyanidin-3-coumaroylglucoside.¹⁵⁴ 

Cyanidin-3-glucoside was reported as the major anthocyanin in the seeds of this plant (Figure 1.6A).¹⁵⁵ 

Red lotus petals (Figure 1.6B) were reported to have malvidin-3-glucoside as the major anthocyanin, and malvidin-3-galactoside, delphinidin-3-galactoside, cyanidin-3-glucoside, and cyanidin-3-arabinoside as the minor ones.¹⁵⁶  Malvidin-3-glucoside and delphinidin-3-glucoside were also determined to be the major anthocyanins in red and pink lotus from another study analyzing 108 lotus cultivars.^157,158 

Fresh date fruits (Figure 1.6C) were found to have 0.24 to 1.52 mg/100 g anthocyanins.¹⁵⁹ 

In addition to the foods that are readily available to consumers in North America, there are many other natural sources of anthocyanins in the form of plants that are native to specific regions in the world, such as South America. In this section, some examples of these exotic plants are presented with respect to their anthocyanin content.

This fruit, also known as palm berry (Figure 1.7A), is native to South America and a rich source of polyphenols, with an anthocyanin content ranging from 3.2¹⁶⁰  to 100 mg g⁻¹ (dry weight).¹⁶¹  Predominant anthocyanins were found to be cyanidin-3-rutinoside and cyanidin-3-glucoside,¹⁶²  and other compounds identified were cyanidin-3-sambubioside, peonidin-3-glucoside, and peonidin3-rutinoside.¹⁶⁰ 

Also known as the Andean raspberry (Figure 1.7B), this perennial shrub is a species of blackberry native to the Andes. Garzón et al.¹⁶³  estimated the total anthocyanin content to be 45 mg/100 g (fresh weight basis), with cyanidin-3-sambubioside as the main anthocyanin,¹⁶⁴  along with 3-glucoside, 3-xylorutinoside, and 3-rutinoside derivatives of cyanidin, pelargonidin-3-glucoside, and pelargonidin-3-rutinoside.

The bayberry tree is native to China (Figure 1.7C), where it is praised as a “precious southern Yangtze fruit of early summer.”¹⁶⁵  The dominant anthocyanin is cyanidin-3-glucoside,^166,167  with content ranging between ∼310 and 620 mg/100 g pomace (dry weight basis).¹⁶⁸ 

Camu-camu (Figure 1.7D) is a small fruit native to the Amazonian rainforest. Zanatta et al.¹⁶⁹  identified cyanidin-3-glucoside as the main component, accounting for almost 90% of the total anthocyanin content (30–54 mg/100 g of fresh peel). In another study, Fracassetti et al. identified cyanidin-3-glucoside only in the powder prepared from the pulp.¹⁷⁰ 

This exotic berry is native to India and Sri Lanka and is cultivated in the southwestern region of Brazil. It contains approximately 320 mg of anthocyanins/100 g pulp (dry weight basis).¹⁷¹  In another study, Bochi et al.¹⁷²  reported that the anthocyanin content was higher in the fruit skins (284–351 mg/100 g, fresh weight basis) than the pulp (49–69 mg/100 g). Five main anthocyanins were identified in the peel, namely delphinidin-3-rutinoside (∼48%), cyanidin-3-rutinoside (∼24%), delphinidin-3-glucoside (9%), petunidin-3-rutinoside (9%), and cyanidin-3-glucoside (5.8%), along with four minor anthocyanins (peonidin-3-rutinoside, maldivin-3-rutinoside, delphinidin-3-(6″-acetyl)-glucoside, and pelargonidin-3-rutinoside).¹⁷³ 

This wild palm (Figure 1.7E) is found in warm regions of the Central and South Americas. Its purple-black fruits contain cyanidin-3-rutinoside (accounting for ∼72% of the total anthocyanin content) and cyanidin-3-glucoside (∼16%) as the main anthocyanins. Other compounds identified in minor fractions were peonidin-3-rutinoside, peonidin-3-glucoside, cyanidin-3-(6-O-malonyl)glucoside, and cyanidin-3-sambubioside.^174,175 

Jaboticaba (Figure 1.7F) is native to Southern Brazil and yields purple fruits with the color retained mainly in the peel, which is not often consumed with the fresh pulp. The skin has been reported to contain an anthocyanin content of 1.6 to 2.1 g/100 g (dry weight). Two main compounds were identified in the skin, cyanidin-3-glucoside and delphinidin-3-glucoside,¹⁷⁶  and the former was also found in small concentrations in the pulp.¹⁷⁷  In an early study, Trevisan¹⁷⁸  identified peonidin and peonidin-3-glucoside by paper chromatography.

Jambolan tree is commonly found in northeast Brazil and produces fruits that resemble purple olives (Figure 1.8A), with a sour taste. Brito et al.¹⁷⁹  identified five main anthocyanins in these fruits, namely delphinidin-3,5-diglucoside (256 mg/100 g, dry weight basis), petunidin-3,5-diglucoside (245 mg/100 g), malvidin-3,5-diglucoside (166 mg/100 g), peonidin-3,5-diglucoside (75 mg/100 g), and cyanidin-3,5-diglucoside (29 mg/100 g). In another study, it was reported that the extraction yield was highest (145 mg total anthocyanins/100 g, fresh weight basis) with 95% ethanol acidified with HCl (99 : 1, v/v).¹⁸⁰ 

Juçara is a palm tree found in the Atlantic Forest in Brazil (Figure 1.8B). Its fruits, commonly known as juçara, have a purple pulp that is commonly used for preparation of juice. Two cyanidin derivatives were identified in these fruits, namely 3-glucoside (∼1360 mg/100 g, dry weight basis) and 3-rutinoside (∼1570 mg/100 g), along with minor anthocyanins, cyanidin-3-sambubioside, pelargornidin-3-glucoside, cyanidin-3-rhamnoside, and pelargonidin-3-rutinoside.¹⁷⁹  Similar results were obtained in another study, in which a wide range of total anthocyanin content (14.8 to 409.9 mg/100 g, fresh weight basis) was reported depending on growing conditions/region.¹⁸¹ 

These fruits (Figure 1.8C) have high concentrations of bioactive compounds and contain on average ∼138 mg total anthocyanins/100 g (fresh weight basis).¹⁸²  Fredes et al.¹⁸³  reported a higher total anthocyanin content, ranging from 660 to 1500 mg/100 g (fresh weight basis) depending on the geographical location in Chile in which the fruits were grown. Eight anthocyanins have been identified in these berries, namely 3-glucosides, 3,5-diglucosides, 3-sambubiosides, and 3-sambubioside-5-glucosides of delphinidin and cyanidin.^182–185  Delphinidin 3-sambubioside-5-glucoside is the main compound, accounting for ∼34% of the total anthocyanin content.¹⁸⁴ 

This tree is native to Malaysia and is widespread throughout tropical areas. Its red fruits (Figure 1.8D) contain approximately 13¹⁸⁶  to 300 mg anthocyanins/100 g (fresh weight basis),¹⁸⁷  mostly concentrated in the peel, and three main compounds were reported, namely cyanidin-3-glucoside, cyanidin-3,5-diglucoside, and peonidin-3-glucoside.¹⁸⁶ 

Roselle flowers (Figure 1.8E) have attracted considerable attention over the years owing to their health-promoting benefits, such as treatment of hypertension and liver damage. Its calyx contains delphinidin- and cyanidin-3-sambubioside as major anthocyanins,^188–190  and delphinidin- and cyanidin-3-glucoside as minor constituents.¹⁹¹  Wong et al.¹⁸⁹  estimated the anthocyanin content to be ∼2.5 g/100 g calyx.

Being one of the largest groups of water-soluble pigments found in plants and particularly fruits, vegetables, and grains, anthocyanins play important roles in human nutrition, health, and wellness. This chapter highlights common and exotic natural sources of anthocyanins based on studies from the past two decades, including herbs. The structural diversity, as demonstrated in some recent studies, will continue to expand by using advanced analytical methodologies, such as LC-MSⁿ, to characterize the minor, although unique, aglycones and complex substituted or acylated sugar moieties. Furthermore, increasing research activities on the health benefits of anthocyanins will also lead to commercial development of some naturally abundant ones in functional foods, nutraceutical, cosmetic, and pharmaceutical applications. This will also stimulate research activities in screening and profiling of natural anthocyanins from other plant species that have not been well studied and continue to extend our understanding of anthocyanins and their natural presence in the years to come.