Anthocyanins. Plant Pigments and Beyond - Journal of Agricultural

Subscriber access provided by UNIV OF ARIZONA

Symposium Introduction

Anthocyanins. Plant pigments and beyond Celestino Santos-Buelga, Nuno Mateus, and Victor De Freitas J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/jf501950s • Publication Date (Web): 27 Jun 2014 Downloaded from http://pubs.acs.org on June 30, 2014

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Journal of Agricultural and Food Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 22

Journal of Agricultural and Food Chemistry

Anthocyanins. Plant pigments and beyond

C. Santos-Buelgaa,*, N. Mateusb, V. de Freitasb

a

Grupo de Investigacion en Polifenoles, Facultad de Farmacia, Universidad de Salamanca.

Campus Miguel de Unamuno. 37007 Salamanca (Spain). b

Chemistry Investigation Centre (CIQ), Department of Chemistry, Faculty of Sciences,

University of Porto, 4169-007 Porto, Portugal.

*Corresponding author (Tel: +34 923 294 537; Fax: +34 923 294 515; E-mail: [email protected])

1 ACS Paragon Plus Environment


Page 2 of 22

1

Abstract

2

Anthocyanins are plant pigments widespread in Nature. They play relevant roles in plant

3

propagation and ecophysiology, plant defense mechanisms and are responsible for the color of

4

fruits and vegetables. A large number of novel anthocyanin structures have been identified,

5

including new families like pyranoanthocyanins or anthocyanin oligomers, their biosynthesis

6

pathways have been elucidated and new plants with “a la carte” colors created by genetic

7

engineering. Furthermore, evidences about their benefits in human health have accumulated,

8

and processes of anthocyanin absorption and biotransformation in the human organism started

9

to be ascertained. These advances in anthocyanin research were revised in the 7th International

10

Workshop on Anthocyanins that took place in Porto (Portugal) in September 9-11, 2013.

11

Some selected communications are collected in this special issue, where aspects like

12

anthocyanin accumulation in plants, relationship with color expression and stability in plants

13

and food, bioavailability or biological activity are revised.

14

Keywords: anthocyanin, color, biosynthesis, analysis, bioavailability, health

15


Page 3 of 22


16

Introduction

17

Anthocyanins are one of the most widespread families of natural pigments in the Plant

18

Kingdom. They can be found in any plant tissue and display a great diversity of colors,

19

touching practically all visible spectra, from orange and red through to purple and blue hues.

20

Over the years, the scientific community has been focusing on these amazing molecules

21

trying to ascertain their chemistry and properties. It is known that anthocyanins play relevant

22

roles in plant propagation and ecophysiology. They assist in attracting pollinators and seed

23

dispersers and participate in plant defense mechanisms against biotic and environmental stress

24

factors.1 They are responsible for the color of many fruits and vegetables, and are also

25

regarded in the food industry as candidates for natural colorants alternative to synthetic food

26

coloring additives. Furthermore, they have been related with possible health benefits

27

protecting against a number of human diseases, as well as suggested for potential medicinal

28

uses.2

29

Following a broad search for the term “anthocyanin” in the ISI Wok of Science, it becomes

30

evident that research into anthocyanins gradually increased since the beginning of the 20th

31

century, where the first attempts to understand anthocyanin chemistry and their role in flower

32

coloration were made.3,4 Sir R. Robinson started the research on anthocyanins copigmentation

33

back in the 1920’s.5 Significant advances were made in the 1970’s-1980’s with the

34

elucidation of the equilibria among anthocyanin structures6-8 and the description of the

35

copigmentation mechanisms.9 An outstanding increase in anthocyanin research took place in

36

the 1990’s (Figure 1), favored by the advances in the analytical techniques. Since then the

37

number of published papers has steadily increased, risen by fifteen-fold between 1990 (110

38

papers) and 2013 (1557 papers) (Figure 1). Over the last twenty years, a large number of

39

novel structures have been identified and new anthocyanin families like pyranoanthocyanins

40

or anthocyanin oligomers described; biosynthesis pathways have been elucidated and new 3 ACS Paragon Plus Environment


Page 4 of 22

41

plants with “a la carte” colors created by genetic engineering; evidences for benefits in human

42

health have accumulated and processes of anthocyanin absorption and biotransformation in

43

the human organism started to be ascertained; also, new applications of anthocyanins as

44

colorants or putative bioactives to be exploited by food, pharmaceutical and cosmetic

45

industries have arisen.

46 47

Advances in anthocyanin analysis

48

For a long time the analysis of anthocyanins mostly relied on planar chromatography

49

techniques and UV-vis spectrophotometry, together with nuclear magnetic resonance for

50

complete structural characterization after tedious compound isolation. Since its introduction

51

for anthocyanin analysis10 HPLC has become the technique of choice for their qualitative and

52

quantitative analysis. Further development in the mid eighties of improved reversed-phase

53

columns and coupling to photodiode-array detectors represented a great advance, as in a

54

single analysis it allowed obtaining separation and information for structural identification

55

based on chromatographic retention and UV-vis spectra, which notably provides more clues

56

for compound identification. Mass spectrometry atmospheric pressure ionization (API)

57

interfaces, and especially electrospray ionization (ESI) and atmospheric pressure chemical

58

ionization (APCI) interfaces, led in the nineties to hyphenation of HPLC and MS. This

59

facilitated the identification of a plethora of compounds, including new anthocyanin families,

60

such as pyranoanthocyanins, flavone/flavanol-linked anthocyanins or dimeric anthocyanins,

61

as well as other related anthocyanins-like pigments like oaklins resulting from the

62

condensation of catechins and hydroxycinnamic acids.11 Many of these new pigments were

63

firstly identified in red wines to be further reported in plant tissues. According to Andersen

64

and Jordheim12, by 2013 the number of anthocyanins identified in nature was 702, with about

65

more 200 additional structures proposed as tentative. 4 ACS Paragon Plus Environment

Page 5 of 22


66

Nowadays the introduction of a new generation of HPLC as favored by the development of

67

new column supports and smaller particle sizes has allowed further decreasing the analysis

68

time and increasing peak capacity and sensitivity. Also, high-resolution mass spectrometers

69

(HR-MS), like time-of-flight (TOF), Fourier transform ion cyclotron resonance (FTICR-MS)

70

and Orbitrap equipments, able to provide accurate masses have been developed making

71

possible distinction between compounds differing in mass by around 20 mDa. The enhanced

72

selectivity of these equipments reduces interfering background ions increasing sensitivity

73

compared with triple quadrupole and ion trap systems. Another advantage of these

74

equipments is that compounds signals may be used directly for compound tentative

75

identification. Indeed the combination of these high resolution spectrometers coupled to the

76

new high capacity separation techniques and enhanced software platforms opens improved

77

prospective for qualitative (non-targeted compound identification) and quantitative analyses

78

using single runs. Also, developments in mass spectrometry imaging (MSI) should be

79

expected to help visualizing the spatial distribution of compounds by their molecular masses,

80

which should have an impact in determining tissue distributions and establishing biological

81

targets of metabolites.

82

An interesting feature of LC-MS is that it provides another separation dimension to HPLC,

83

through the use of selective detection modes, like monitoring single ions, extracting particular

84

ions or recording characteristic transitions in the fragmentation of compounds. Selective

85

detection increases sensitivity and possibilities of detecting and quantifying metabolites in

86

biological samples, allowing important progress in understanding the processes of

87

anthocyanin absorption and biotransformation in the human organism.

88

Hyphenation of liquid chromatography to NMR spectroscopy is another promising tool for

89

the separation and structural elucidation of unknown compounds in mixtures. Even though it

90

emerged in the mid-1990’s this technique has not yet become popular, among others due to 5 ACS Paragon Plus Environment


Page 6 of 22

91

the existence of technical drawbacks that hamper its application. The technique is mostly

92

restricted to H-NMR, as low abundance of

93

peaks of high concentration. In the particular case of anthocyanins, problems may also arise

94

from their existence as different forms in equilibrium. Recent advances have been made

95

concerning the improvement in NMR flow probe technology, introduction of new techniques

96

for solvent suppression, or coupling to an on-line solid-phase extraction unit for concentrating

97

the eluted peaks prior to spectra recording so as to increase the sensitivity (LC-SPE-NMR).

98

This has contributed to improve the sensitivity, so that an increase in its applications should

99

be expected in coming years, also favored by the introduction of cheaper equipments making

100

13

C isotopes limits obtaining C-NMR spectra to

the technique available to more laboratories.13

101 102

Uncovering flower color

103

It is well known that anthocyanins are structurally depending on the conditions and

104

composition of the media where they are dissolved and suffer interactions among them and

105

with other compounds that influence their chemical equilibria and modify their color. Kinetic

106

and thermodynamic equilibria between colored and colorless anthocyanin forms as a function

107

of the pH and temperature are well established since the works performed by Brouillard and

108

coworkers in the 1970’s.7,8 Anthocyanins are usually represented as their red flavylium cation,

109

but in aqueous media this form undergoes rapid proton transfer reactions, leading to blue

110

quinoidal bases, and hydration, generating colorless hemiketals in equilibrium with chalcone

111

structures. The highly colored flavylium forms predominate only in very acidic solutions,

112

whereas in weakly acidic aqueous media, even if they are kept in conditions (temperature, pH,

113

light, oxygen) similar to those found in plant vacuoles, anthocyanins mostly occur as colorless

114

species and tend further to degrade by irreversible cleavage of their molecules. Nevertheless,

115

in their natural media, anthocyanins are able to express intense red, blue or violet colors even 6 ACS Paragon Plus Environment

Page 7 of 22


116

at weakly acidic pH’s, and, what is more, the same anthocyanin can be found in different

117

flowers providing them distinct colorations.14 This apparent paradox is explained by the

118

existence of stabilizing mechanisms, among which the processes of copigmentation and metal

119

complexation are prominent.9,15 Nevertheless, although basic mechanisms involved in flower

120

pigmentation have been clarified to a considerable extent, many unresolved questions still

121

remain. Further research has still to be undertaken to extend our understanding about the

122

molecular and biological basis that control color expression and stability. Physicochemical

123

studies are required to identify the most promising chromophores and to establish the

124

influence of structural differences on the formation of metalloanthocyanins and the atomic

125

structure of intra- and intermolecular stacking. Also, a better understanding is needed about

126

charge transfer effects implicated in spectral shifts, mechanisms of metal and pigment

127

transport into vacuoles or the identification of transcriptional factors and the regulatory

128

network controlling anthocyanin biosynthesis.15 Expected advances in these fields in the

129

coming years should offer plant breeders new options to produce flowers with the desired

130

coloration.

131 132

Enhancing anthocyanin production

133

Anthocyanins

134

shikimate/phenylpropanoid pathway) and their synthesis constitutes the most studied

135

secondary metabolic pathway in plants. Actually most of the knowledge about transcriptional

136

regulation in plants has initially come from studies of the regulation of anthocyanin

137

biosynthesis in the monocot maize, further extended to dicots, with Arabidopsis as a

138

paradigm.1

139

The identification of transcription factors and a better understanding of the regulatory network

140

controlling anthocyanin biosynthesis in plants is a crucial prerequisite for the development of

are

produced

by

a

branch

of

the

flavonoid

pathway

(i.e.,



Page 8 of 22

141

plants with enhanced or improved anthocyanin composition. By 1990, all the enzymes

142

involved in the early specific part of anthocyanin biosynthesis (from chalcone to

143

anthocyanidin) had been solved, and cloning of the anthocyanin synthetic genes was nearly

144

completed. Since that time, several genes coding for glycosyltransferases and acyltransferases

145

in flower petals have been cloned and several transcriptional factors regulating anthocyanin

146

biosynthesis have been described.15 Available findings indicate that transcription factors

147

regulating anthocyanins share a great conservation of functional domains and that functional

148

diversification in a species and among closely related species generally resides more in

149

regulatory sequences than in coding regions. This high conservation may help in selecting the

150

proper heterologous regulators to obtain anthocyanin-rich varieties through metabolic

151

engineering.

152

The transcription factors controlling anthocyanin biosynthesis have been characterized for

153

many species and an ‘MBW’ regulatory complex consisting of a ternary complex of

154

R2R3MYB, bHLH and WD-Repeat proteins.16 Thus, manipulating the anthocyanin pathway

155

has often involved the overexpression of heterologous MYB and bHLH genes.1 Various

156

transgenic approaches have been taken to increase flavonoid levels in tomato fruit by

157

overexpressing either the structural or regulatory genes involved in the biosynthetic pathway.

158

Most of these attempts have exploited heterologous genes, and in only one case was an

159

endogenous tomato regulatory gene (ANT1) overexpressed in tomato plants. Although a

160

significant increase in the final content of some flavonoids (flavonols in particular) was

161

obtained, in tomato, the overexpression by activation tagging of the MYB ANT1 gene

162

realized only a partial enhancement of anthocyanins1, which were expressed either only in the

163

vegetative tissues of the plant or induced only a partial, spotted pigmentation, mostly limited

164

to the peel of the fruit, which could be explained by the low availability of flavonoid

165

biosynthetic precursors or the absence of other limiting regulatory factors (e.g., bHLH).17 8 ACS Paragon Plus Environment

Page 9 of 22


166

These constraints were overcome by Butelli et al.18, who produced a tomato highly enriched

167

with anthocyanins throughout the fruit tissues, averaged ~3 mg/g fresh weight, by the ectopic

168

expression of two selected transcription factors (Del, a bHLH-type TF, and Ros1, an R2R3

169

MYB-type TF) from the ornamental flower snapdragon (Antirrhinum majus L.). Interestingly,

170

the high production of anthocyanins in these ‘purple’ tomatoes was not obtained at the

171

expense of other major classes of tomato fruit pigments, and the antioxidant activity

172

attributable to the carotenoid fraction remained unchanged.17

173

Similar developments could be anticipated for the development of other anthocyanin-rich crop

174

or ornamental plants. Furthermore, given that the biological properties of different

175

anthocyanin compounds and of the other classes of flavonoids are often molecule-specific, a

176

major objective of metabolic engineering approaches might be not only increasing but also

177

optimizing their levels and composition in crops so that they could eventually be promoted as

178

functional foods. Additionally, researchers could exploit natural genetic resources, either as

179

an alternative to genetic engineering approaches or to strengthen them.17

180 181

Anthocyanins in food

182

For years the main focus on anthocyanins in food has been put on their influence in color. In

183

intact plant tissues (i.e., unprocessed fruits and vegetables), anthocyanins remain relatively

184

stable. Nonetheless, tissue disruption during food processing affects anthocyanin

185

extractability and stability. It has been suggested that anthocyanin extraction from berries into

186

juice could be limited by their interaction with macromolecules from disrupted cell walls such

187

as polysaccharides, tannins and proteins. However, the factors that govern those interactions

188

are still not well defined and remain a promising research area. On the other hand, storage

189

may also affect anthocyanin stability leading to color changes. In food systems, in addition to

190

be subjected to the equilibria among structural forms, anthocyanins can be involved in 9 ACS Paragon Plus Environment


Page 10 of 22

191

chemical and enzymatic reactions that may degrade them to colorless products or transform

192

them into new structures. Indeed, the search for improved processing and storage methods to

193

better control anthocyanin losses and/or to address anthocyanin reactions in the “right”

194

direction to obtain more stable and desired colors constitutes a major challenge for the food

195

industry.

196

Anthocyanin stability and reactions have been particularly studied in red wine, in which a

197

variety of anthocyanin-derived products have been identified over the last two decades, such

198

as pyranoanthocyanins, anthocyanin-flavanol condensed pigments, either directly linked or

199

involving aldehydes, anthocyanin dimers, or xanthylium pigments.11 Similar products have

200

further been found in fruits and vegetables19-22 and other plant-derived food.23,24 Some of

201

these compounds possess interesting chromatic properties, displaying a variety of colors from

202

orange to blue and being more resistant to color bleaching by water or sulfur dioxide attack,

203

so that they show more color capacity at weakly acidic and neutral pH values than original

204

anthocyanins.11 Anthocyanins are authorized as food additives both in the European Union

205

(E-163) and the United States, where the Food and Drug Administration (FDA) includes them

206

as natural ‘Colorants Exempt from Certification’.12 However, the applications of anthocyanins

207

as food colorants are seriously limited due to their problems of stability. In these

208

circumstances, the improved color properties that exhibit some anthocyanin-derived pigments

209

make them potential candidates for their use as natural food colorants, which is particularly

210

relevant taking into account the current concerns and restrictions for the use of synthetic dyes.

211

Owing to the current interest in the potential associations between anthocyanin consumption

212

and health promotion, the estimation of the dietary intake of anthocyanins has also become a

213

point of interest, so that adequate relationships with the incidence of chronic diseases can be

214

established. It is, however, difficult to properly calculate anthocyanin consumption.12

215

Accurate data on the qualitative and quantitative anthocyanin composition in foods and 10 ACS Paragon Plus Environment

Page 11 of 22


216

beverages are neither always available nor easy to obtain due to the structural diversity of

217

anthocyanins and their stability problems. Anthocyanin contents can vary tremendously

218

within a certain type of foods depending on varietal, agronomic and environmental conditions

219

and, furthermore, both degradation and formation of derived products have great influence in

220

the anthocyanin contents and profiles in processed foods and beverages. Indeed, stability is a

221

very important (and challenging) element when considering the impact of dietary

222

anthocyanins on the human organism. The common anthocyanins show instability toward a

223

variety of chemical and physical parameters, including oxygen, high temperatures, light, pH

224

values, enzymes and reactions with compounds in the food or body systems, which may vary

225

anthocyanin properties.12

226

Estimations made by different researchers varied within a wide range, oscillating from 3 to

227

150 mg/day, depending on the country and nutrition habits. In a rough calculation, average

228

adult intake of anthocyanins in Europe and the United States has been estimated that could be

229

in the scale of 10 mg/day.12 Further studies are, nevertheless, required to increase our

230

knowledge on anthocyanin composition in most consumed foods over different countries,

231

taking into account that not only total intake is important but also qualitative profiles should

232

have an influence on their putative health promoting effects. Moreover, attention will also

233

have to be paid to the increasing popularity of food supplements and the developing market

234

for functional foods, as they may contribute substantially to a rise in the dietary intake levels.

235 236

Bioavailability and health issues

237

Dietary anthocyanins have been related with health promotion, namely relief of oxidative

238

stress and protection against coronary heart disease, but also antimicrobial anti-inflammatory

239

and anticarcinogenic activities, control of obesity and diabetes or improvement of eye vision.2

240

The biological effects of anthocyanins have been classically associated to their antioxidant 11 ACS Paragon Plus Environment


Page 12 of 22

241

capacity, although the actual mechanisms involved at the physiological level are yet to be

242

established, and a recent emerging view is that modulatory effects affecting signaling

243

pathways in cells should also be important.17

244

For understanding of the exact impact of dietary anthocyanins on health and their underlying

245

mechanisms, further knowledge is required about their bioavailability. Aspects like absorption

246

and biotransformation, the exact nature and amount of circulating metabolites and their

247

activity, tissue distribution and accumulation, or the forms able to reach particular cellular or

248

molecular targets are still largely unknown. In these circumstances, the ability to detect,

249

identify and determine the metabolites at physiological concentrations is crucial. Furthermore,

250

pure metabolites are required to be used activity and mechanistic studies, but are not always

251

available as commercial standards. On this matter, chemical or enzymatic synthesis constitute

252

different promising strategies to obtain some in vivo occurring anthocyanin metabolites.25

253

A fraction of anthocyanins could be absorbed both in the stomach and small intestine. The pH

254

changes considerable in the human body from the stomach (1.5), intestine surface (5.3), urine

255

(5.75), liver (7.0) to the blood (7.40), and, therefore, anthocyanins will thus most probably

256

under physiological conditions occur on different structural forms similar to those described

257

in model systems.12 Anthocyanin structure (e.g., type of aglycone, number and type of

258

glycosyl and acyl moieties) would influence forms distribution and stability, thus affecting

259

their bioavailability, metabolism or degradation mechanisms. Furthermore, a part of the

260

anthocyanins in processed foods, but also in intact plants, may occur in the form of more

261

complex structures (e.g., derived pigments), whose equilibrium schemes, stability and

262

reactivity characteristics are not well elucidated and should differ from those of the simple

263

anthocyanins.12 Finally, the relevance of the food matrix and the interactions between

264

anthocyanins and other food components, both macronutrients and bioactives, must also be

265

considered. At present most of this of knowledge is to a large extent lacking. 12 ACS Paragon Plus Environment

Page 13 of 22


266

Existing data indicate that the proportion of absorbed anthocyanins including their

267

metabolized derivatives is very low. Actually, anthocyanins have been reported to have one of

268

the lowest bioavailabilities of all of the dietary flavonoid subclasses26, with typical urinary

269

excretion of the total amount of anthocyanins and their derivatives well below 1% of the

270

ingested amount. Nevertheless, recent studies using

271

humans by Czank et al.27 have concluded that these compounds could be more bioavailable

272

than previously reported. Thus, on the basis of the recovered

273

glucoside (Cy3G) was established to have a relative bioavailability in humans of

274

12.38±1.38% on average, from which 0.18±0.11% of the 13C dose was recovered from blood,

275

5.37±0.67% from urine, and 6.91±1.59% from breath, whereas 32.13±6.13% of the

276

found in feces. The fate of the remaining ingested 13C remains unknown, although there was

277

considerable inter-individual variability in the recovery of the

278

15.1% to 99.3%, probably as a result of a high variation in gastric and intestinal transit times,

279

composition, and catabolic activity of colonic flora and the ability to take up and excrete

280

catabolites and metabolites.

281

The accumulation of multiple phenolic metabolites might ultimately be responsible for the

282

reported bioactivity of anthocyanins, with the gut microflora apparently playing an important

283

role in the biotransformation process. Although phase II conjugates of Cy3G and cyanidin

284

(cyanidin-glucuronide, methyl cyanidin-glucuronide, and methyl Cy3G-glucuronide) were

285

detected, the most important metabolites corresponded to products from the anthocyanin

286

degradation (i.e., benzoic, phenylacetic and phenylpropenoic acids, phenolic aldehydes and

287

hippuric acid) and their phase II conjugates, which were found at 60- and 45-fold higher

288

concentrations than their parent compounds in urine and plasma, respectively.27 An interesting

289

observation was the rapid appearance of Cy3G degradation products and their phase II

290

conjugates within the serum, which suggested that some degradation likely occurred in the

13

C-labelled anthocyanins carried out in

13

13

C dose, cyanidin-3-O-

13

C was

C tracer that ranged from



Page 14 of 22

291

small intestine (either pre- or post-absorption) and, therefore, anthocyanin C-ring cleavage

292

may not require the action of colonic microflora. Estimates made by Czank et al.27 of the half-

293

lives of elimination for

294

51.62±22.55h, which suggested a relatively slow urinary clearance of some metabolites. Long

295

elimination half-lives may be the result of a combination of hepatic recycling, enterohepatic

296

circulation, and prolonged colonic production and absorption. All in all, these data suggested

297

that anthocyanins would be as bioavailable as other flavonoid subclasses, such as flavan-3-ols

298

and flavones, which have relative bioavailabilities between 2.5% and 18.5% (26).

299

Further intervention studies using different anthocyanins and food matrices are, nevertheless,

300

required to confirm these preliminary conclusions on anthocyanin absorption and

301

bioavailability, as well as to establish their putative effects on human health. It is expected

302

that the advances in analytical methodologies enabling the identification and quantification of

303

metabolites, both in food and body fluids and tissues, together with bioinformatic strategies

304

should allow the characterization of changes produced in the human metabolome as a

305

consequence of anthocyanin intake, so that possible biomarkers of consumption and effects

306

can be identified and adequate relationships with the incidence of diseases established.

13

C-labeled metabolites were between 12.44±4.22 h and

307 308

The 7th International Workshop on Anthocyanins (IWA 2013)

309

Advances in anthocyanin research are revised every two years in the International Workshop

310

on Anthocyanins (IWA), whose last edition took place in the beautiful city of Porto

311

(Portugal). The IWA is the only world congress that focuses exclusively on anthocyanins and

312

acts an essential meeting point for all people working in these amazing molecules. Since the

313

first IWA took place in Melbourne (Australia) back in 2000, five more IWA meetings have

314

been held in Australia (Adelaide 2002 and Sydney 2004), New Zealand (Rotorua 2006), Japan

315

(Nagoya 2009), and the United States (Charlotte NC 2011). In September 2013, the IWA 14 ACS Paragon Plus Environment

Page 15 of 22


316

came for the first time to Europe, with the goal of bringing together scientists from

317

Universities, Institutes and Industries, from different research areas but with the common

318

ground of working on anthocyanins, and attracting European researchers who did not have the

319

opportunity to join the previous workshops. The meeting was divided into 6 topics: (1)

320

Biosynthesis, Trafficking and Functionality, (2) Genetic & Metabolic engineering, (3)

321

Horticultural and Ornamental Plants, (4) Phytochemistry & Analysis, (5) Anthocyanin in

322

Health & Nutrition, and (6) Anthocyanins in Foods & Industry. Around 130 participants from

323

21 different countries attended the IWA2013, presenting 16 invited lectures (6 plenary

324

lectures and 10 invited keynotes), 21 regular oral communications and 80 posters. In relation

325

to previous IWAs, which were more focused on plant anthocyanins (physiological roles,

326

biosynthesis, metabolic engineering, etc.), the Porto’s meeting was enlarged upon food

327

anthocyanins, as related to sensory properties and health.

328

This highlights issue presents a selection of papers from IWA2013 communications dealing

329

with anthocyanins accumulation in plants, relationship with color expression and stability in

330

plants and food, copigmentation effects, stability during food processing an storage, chemical

331

applications, bioavailability and effects in model systems, properties of anthocyanin-related

332

pigments, microbial degradation, or influence on allergenic properties of food components.

333

Now the countdown to the 8th International Workshop on Anthocyanins, that will take place in

334

Montpellier (France) in 2015 organized by Dr. Véronique Cheynier, is on.

335

We wish to thank the Editor-in-Chief, Prof. Jim Seiber, and the JAFC editorial office for the

336

opportunity offered to publish this special issue, as well as to all submitting authors and

337

reviewers for their invaluable contribution.

338 339



Page 16 of 22

340

REFERENCES

341

1. Petroni, K., Tonelli, C. Recent advances on the regulation of anthocyanin synthesis in

342

reproductive organs. Plant Sci. 2011, 181, 219-229.

343

2. He, J.A., Giusti, M. Anthocyanins: natural colorants with health-promoting properties. Ann.

344

Rev. Food Sci. Technol. 2010, 1, 163-187.

345

3. Willstatter, B., Everest, A.E. Ueber den Farbstoff der Kornblume. Liebigs Ann. Chem.

346

1913, 401, 189-209.

347

4. Wheldale, M. Our present knowledge of the chemistry of the mendelian factors for flower-

348

colour. J. Genet. 1914, 4, 109-129.

349

5. Robinson, G.M., Robinson, R. A survey on anthocyanins I. Biochem. J. 1931, 25, 1687-

350

1705.

351

6. Asen, S., Stewart, R.N., Norris, K.H. Co-pigmentation of anthocyanins in plant tissues and

352

its effect on colour. Phytochemistry 1972, 11, 1139-1144.

353

7. Brouillard, R., Delaporte, B., Dubois, J.E. Chemistry of anthocyanins pigments 2. Kinetic

354

and thermodinamic study of proton transfer, hydration, and tautomeric reactions of malvidin-

355

3-glucoside. J. Am. Chem. Soc. 1977, 99, 8461-8468.

356

8. Brouillard, R., Dubois, J.E. Mechanism of the structural transformations of anthocyanins in

357

acidic media. J. Am. Chem. Soc. 1977, 99, 1359-1364.

358

9. Goto, T., Kondo, T. Structure and molecular stacking of anthocyanins-flower color

359

variation. Ang. Chem. Int. Eng. Ed. 1991, 30, 17-33.

360

10. Wulf, L.W., Nagel C.W. Analysis of phenolic acids and flavonoids by high-pressure

361

liquid chromatography. J. Chromatogr. 1976, 116, 271-279.


Page 17 of 22


362

11. de Freitas, V.A.P., Mateus, M. (2010). Updating wine pigments. In, Recent Advances in

363

Polyphenol Research. Volume 2. (C. Santos-Buelga, M.T. Escribano-Bailon, V. Lattanzio,

364

eds.). Wiley-Blackwell, Chichester, West Sussex, UK; pp 59-80.

365

12. Andersen, Ø.M., Jordheim, M. (2013). Basic anthocyanin chemistry and dietary sources.

366

In, Anthocyanins in Health and Disease. (T.C. Wallace, M. Giusti, eds.). CRC Press, Boca

367

Raton, FL, USA; pp 13-90.

368

13. Timmers M, Urban S. On-line (HPLC-NMR) and off-line phytochemical profiling of the

369

Australian plant, Lasiopetalum macrophyllum. Nat. Prod. Comm. 2012, 7, 551-560.

370

14. Brouillard, R., Chassaign, S., Isorez, G., Kueny-Stotz, M., Figueiredo, P. (2010). The

371

visible anthocyanins: from research to applications. In, Recent Advances in Polyphenol

372

Research. Volume 2. (C. Santos-Buelga, M.T. Escribano-Bailon, V. Lattanzio, eds.). Wiley-

373

Blackwell, Chichester, West Sussex, UK; pp 1-22.

374

15. Yoshida, K., Mori, M., Kondo, T. Blue flower color development by anthocyanins: from

375

chemical structure to cell physiology. Nat. Prod. Rep. 2009, 26, 884-915.

376

16. Davies, K.M., Albert, N.W., Schwinn, K.E. From landing lights to mimicry: the molecular

377

regulation of flower colouration and mechanisms for pigmentation patterning. Funct. Plant

378

Biol. 2012, 39, 619-638.

379

17. Gonzali, S., Mazzucato, A., Perata, P. Purple as a tomato: towards high anthocyanin

380

tomatoes. Trends Plant Sci. 2009, 14, 237-24.

381

18. Butelli, E., Titta, L., Giorgio, M., Mock, H.P., Matros, A., Peterek, S., Schijlen,

382

E.G.W.M., Hall, R.D. Bovy, A.G., Luo, J., Martin, C. Enrichment of tomato fruit with health-

383

promoting anthocyanins by expression of select transcription factors. Nat. Biotechnol. 2008,

384

26, 1301-1308.

385

19. Fossen, T., Rayyan, S., Andersen, Ø.M. Dimeric anthocyanins from strawberry (Fragaria 17 ACS Paragon Plus Environment


Page 18 of 22

386

ananassa) consisting of pelargonidin 3-glucoside covalently linked to four flavan-3-ols.

387

Phytochemistry 2004, 65, 1421-1428.

388

20. Gonzalez-Paramas, A.M., Lopes, F., Martin, P., Macz, G., Gonzalez-Manzano, S.,

389

Alcalde, C., Perez, J., Escribano-Bailon, M.T., Rivas-Gonzalo, J.C., Santos-Buelga, C.

390

Flavanol-anthocyanin condensed pigments in plant extracts. Food Chem. 2006, 94, 428-436.

391

21. Fossen, T., Andersen, Ø.M. Anthocyanins from red onion, Allium cepa, with novel

392

aglycone. Phytochemistry 2003, 62, 1217-1220.

393

22. Vidal, S., Meudec, E., Cheynier, V., Skouroumounis, G., Hayasaka, Y. Mass

394

spectrometric evidence for the existence of oligomeric anthocyanins in grape skin. J. Agr.

395

Food Chem. 2004, 52, 7144-7151.

396

23. Tarascou, I., Mazauric, J.-P., Meudec, E., Souquet, J.-M., Cunningham, D., Nojeim, S.,

397

Cheynier,

398

proanthocyanidins by LC-ESI-MS. Food Chem. 2011, 128, 802-810.

399

24. McDougall, G.J., Gordon, S., Brennan, R., Stewart, D. Anthocyanin-flavanol

400

condensation products from black currant (Ribes nigrum L.). J. Agric. Food Chem. 2005, 53,

401

7878-7885.

402

25. Fernandes, I., Azevedo, J., Faria, A., Calhau, C., de Freitas, V., Mateus, N. Enzymatic

403

hemisynthesis of metabolites and conjugates of anthocyanins. J. Agric. Food Chem. 2009, 57,

404

735-745.

405

26. Manach, C., Williamson, G., Morand, C., Scalbert, A., Remesy, C. Bioavailability and

406

bioefficacy of polyphenols in humans. I. Review of 97 bioavailability studies. Am. J. Clin.

407

Nutr. 2005, 81, 230S-242S.

408

27. Czank, C.; Cassidy, A., Zhang, Q., Morrison, J. Preston, T., Kroon, P.A., Botting, N.P.,

409

Kay, C.D. Human metabolism and elimination of the anthocyanin, cyanidin-3-glucoside: a

V.,

Fulcrand,

H.

Characterisation

of

genuine

and

derived

cranberry


Page 19 of 22

410


13

C-tracer study. Am. J. Clin. Nutr. 2013, 97, 995-1003.

411 412



413

Page 20 of 22

Figure captions

414 415

Figure 1. Number of publications obtained from the ISI Web of Knowledge database looking

416

for the word “anthocyanin” in title and abstract for the periods 1900-2009 (upper graph), and

417

1990-2013 (lower graph).


Page 21 of 22


Figure 1



Page 22 of 22

TOC Graphic


Anthocyanins. Plant Pigments and Beyond - Journal of Agricultural

Recommend Documents