Intact Anthocyanins Research Articles

Effect of encapsulation on stability of anthocyanins and chlorogenic acid isomers in aronia during in vitro digestion and their transformation in a model system

Aronia extract was encapsulated with maltodextrin (MD) or MD plus carboxymethyl cellulose, gum Arabic, or xanthan gum and digested under simulated conditions. The retention of anthocyanins was higher (75 %) in encapsulated aronia as compared to non-encapsulated one (58 %). Cryptochlorogenic acid significantly increased after in vitro digestion, whereas neochlorogenic acid and chlorogenic acid decreased. The increase of cryptochlorogenic acid was about two-fold higher in non-encapsulated aronia than encapsulated aronia. In a model system, cyanidin 3-galactoside and chlorogenic acid were separately digested under simulated conditions. Cyanidin 3-galactoside-C7H12O6 adduct (m/z 640) was firstly observed in the digested cyanidin 3-galactoside solution, suggesting that degradation products of anthocyanins bind to intact anthocyanins. In a separate study, cryptochlorogenic acid increased as much as chlorogenic acid decreased, indicating that chlorogenic acid can be transformed into cryptochlorogenic acid during digestion. The results show that encapsulation lowered molecular transformations of anthocyanins and chlorogenic acid during in vitro digestion.

Nanotechnology as a Tool to Mitigate the Effects of Intestinal Microbiota on Metabolization of Anthocyanins

Anthocyanins are an important group of phenolic compounds responsible for pigmentation in several plants. For humans, a regular intake is associated with a reduced risk of several diseases. However, molecular instability reduces the absorption and bioavailability of these compounds. Anthocyanins are degraded by external factors such as the presence of light, oxygen, temperature, and changes in pH ranges. In addition, the digestion process contributes to chemical degradation, mainly through the action of intestinal microbiota. The intestinal microbiota has a fundamental role in the biotransformation and metabolization of several dietary compounds, thus modifying the chemical structure, including anthocyanins. This biotransformation leads to low absorption of intact anthocyanins, and consequently, low bioavailability of these antioxidant compounds. Several studies have been conducted to seek alternatives to improve stability and protect against intestinal microbiota degradation. This comprehensive review aims to discuss the existing knowledge about the structure of anthocyanins while discussing human absorption, distribution, metabolism, and bioavailability after the oral consumption of anthocyanins. This review will highlight the use of nanotechnology systems to overcome anthocyanin biotransformation by the intestinal microbiota, pointing out the safety and effectiveness of nanostructures to maintain molecular stability.

Gastrointestinal metabolism and bioaccessibility of selected anthocyanins isolated from commonly consumed fruits

There is uncertainty about the identity of digestive metabolites of anthocyanins because many are naturally present in foods and/or are formed from other phenolic compounds during the digestive process. Studies using pure anthocyanins are needed to clarify this uncertainty. In this study, selected anthocyanins were purified from common fruits and individually subjected to gastric and small intestinal digestion in vitro to determine their stability, metabolites generated and bioaccessibility. Anthocyanins were highly stable during the gastric phase of simulated digestion (p > 0.05). The recovery of anthocyanins decreased during the small intestinal phase of digestion (p < 0.05). Stability was dependent on anthocyanidin structure and type of glycation (p < 0.05). Gastric and gastrointestinal phases mainly contained anthocyanins as bioaccessible flavylium cations and chalcones. Expected anthocyanin metabolites (i.e., phenolic acids and phoroglucinaldehyde) were not detected in chyme. Deglycation of anthocyanins during simulated digestion was quite limited and the bioaccessibility of intact anthocyanins was very low (0.07–2.21%).

Cyanidin 3-glucoside improves diet-induced metabolic syndrome in rats

Increased consumption of dark-coloured fruits and vegetables may mitigate metabolic syndrome. This study has determined the changes in metabolic parameters, and in cardiovascular and liver structure and function, following chronic administration of either cyanidin 3-glucoside (CG) or Queen Garnet plum juice (QG) containing cyanidin glycosides to rats fed either a corn starch (C) or a high-carbohydrate, high-fat (H) diet. Eight to nine-week-old male Wistar rats were randomly divided into six groups for 16-week feeding with C, C with CG or QG, H or H with CG or QG. C or H were supplemented with CG or QG at a dose of ∼8mg/kg/day cyanidin glycosides from week 8 to 16. H rats developed signs of metabolic syndrome including visceral adiposity, impaired glucose tolerance, hypertension, cardiovascular remodelling, increased collagen deposition in left ventricle, non-alcoholic fatty liver disease, increased plasma liver enzymes and increased inflammatory cell infiltration in the heart and liver. Both CG and QG reversed these cardiovascular, liver and metabolic signs. However, no intact anthocyanins or common methylated/conjugated metabolites could be detected in the plasma samples and plasma hippuric acid concentrations were unchanged. Our results suggest CG is the most likely mediator of the responses to QG but that further investigation of the pharmacokinetics of oral CG in rats is required.

Effect of consuming hi-oleic peanuts on adiposity and cardiometabolic health

Effect of consuming hi-oleic peanuts on adiposity and cardiometabolic health

Anthocyanins and human health: How gastric absorption may influence acute human physiology

This review aims to highlight some aspects regarding anthocyanins bioavailability. Although there is a considerable variability in the values for the biokinetic parameters, anthocyanins appear to be rapidly absorbed and eliminated, reaching low maximal concentrations in plasma and urine. Nevertheless, some works have reported a high content of intact anthocyanins in plasma, possibly resulting from gastric absorption. So far, no anthocyanin metabolites have been detected in the stomach and the possible mechanism of anthocyanin gastric absorption is still unknown. Some progress in this field is expected to be obtained through studies involving a new human cell culture model of the gastric surface suitable for bioavailability screening of nutraceuticals like anthocyanins and anthocyanin-derived pigments. The positive health effects associated with anthocyanin consumption could derive from the contribution afforded by the stomach to intact anthocyanin absorption. Nonetheless, these latter may be further metabolized to other bioactive forms.

Matrix Effects on the Stability and Antioxidant Activity of Red Cabbage Anthocyanins under Simulated Gastrointestinal Digestion

Red cabbage is, among different vegetables, one of the major sources of anthocyanins. In the present study an in vitro digestion method has been used to assay the influence of the physiological conditions in the stomach and small intestine, as well as faecal microflora on anthocyanins stability in red cabbage and anthocyanin-rich extract. The recovery of anthocyanins during in vitro gastrointestinal digestion was strongly influenced by food matrix. The results showed that other constituents present in cabbage enhanced the stability of anthocyanins during the digestion. The amount of anthocyanins (HPLC method) and antioxidant capacity (ABTS and FRAP assays) strongly decreased after pancreatic-bile digestion in both matrices but total phenolics content (Folin-Ciocalteu assay) in these digestions was higher than in initial samples. Incubation with human faecal microflora caused further decline in anthocyanins content. The results obtained suggest that intact anthocyanins in gastric and products of their decomposition in small and large intestine may be mainly responsible for the antioxidant activity and other physiological effects after consumption of red cabbage.

Bioconversion of Pinot noir anthocyanins into bioactive phenolic compounds by lactic acid bacteria

There has been increasing interest in red wine anthocyanins in relation to changes brought about by lactic acid bacteria in the human digestive system. Anthocyanins are modified multiple times prior to being absorbed, so that intact anthocyanins are unlikely to survive the process, although the parent compounds may still act as local antioxidants within the digestive system. Metabolites such as phenolic acids are easier to absorb, and are thus more bioavailable. This study has investigated the biotransformation of the representative Pinot noir anthocyanin, malvidin-3-glucoside, into metabolites by Lactobacillus plantarum at pH 3.4, 4.2, 5.9 and 7.0 incubated anaerobically at 37 ◦ C for up to 24 hours. The metabolites were identified by HPLC-MS. Anthocyanin glycosides were found to be completely hydrolyzed by all selected strains at pH 5.9 after 24 h of incubation. The anthocyanins were quite stable under acidic conditions (pH 3.4) but were highly unstable at neutral pH due to both chemical and microbial degradation. The main metabolites were phenolic acids such as gallic acid and protocatechuic acid. They showed greater antioxidant activity than the parent anthocyanins, as indicated by radical scavenging assays and through an assessment of reducing strength using cyclic voltammetry.

Biotransformation of blueberry anthocyanins to bioavailable phenolic compounds by Lactobacillus

Blueberries are one of the most anthocyanin-rich fruits, containing more than 25 forms of anthocyanins. This high anthocyanin content may contribute to the health benefits of blueberries against cardiovascular diseases, diabetes and cancers. However, the bioavailability of anthocyanins is relatively low, meaning that intact anthocyanins are unlikely to act as local antioxidants. Anthocyanin metabolites, such as phenolic acids, are easier to absorb, and are thus more bioavailable. This study has investigated the biotransformation of blueberry anthocyanins and a standard anthocyanin, malvidin-3-glucosides, into metabolites in the presence of Lactobacillus plantarum and Lactobacillus sakei at pH 3.4, 4.2, 5.9 & 7.0 and incubated anaerobically at 37oC for up to 24h. Samples were centrifuged and the supernatants were analysed using semi-preparative liquid chromatography. The metabolites were identified using high performance liquid chromatography-mass spectrometry (LC-MS). Malvidin glycosides were found to completely hydrolyse at pH 4.2 and 5.9 after 24h of incubation. The anthocyanins were quite stable under acidic conditions (pH 3.4) but were highly unstable at neutral pH and disappeared after 8h at pH 7.0 by both chemical and microbial degradation. Similar results were obtained when testing the same strains with blueberry samples, although most of the anthocyanins were not fully transformed due to their high initial concentrations. The primary metabolites were phenolic acids and aldehydes such as syringic acid, gallic acid and protocatechuic acid (Figure 1). These metabolites showed a greater antioxidant capacity than the anthocyanins themselves as the antiradical power was found to increase in the order, malvidin-3-glucoside < syringic acid < protocatechuic acid < gallic acid. Thus, the metabolites of blueberry anthocyanins may be mainly responsible for the antioxidant activity of blueberries against chronic diseases, which then contribute to a healthy heart.

Bioavailability of anthocyanins and derivatives

Anthocyanins are naturally occurring compounds widespread in plant-derived foodstuffs and therefore abundant in human diet. There are evidences regarding the positive association of their intake with healthy biological effects displayed in vivo. This review aims to highlight some aspects regarding anthocyanins bioavailability; these include a short introductory part of anthocyanin chemistry, stability, occurrence and intake.This first part is followed by a more detailed one concerning the main topic of the review that includes the bioavailability and metabolism of anthocyanins. Special attention is given to the contribution of the gastric mucosa to anthocyanin absorption as the result of the high content of intact anthocyanins (20–25%) detected is plasma few minutes after intake. The contribution of intestinal tissue and the microbiota impact in anthocyanin absorption and bioactivity is also highlighted. Despite the biological activities that have been associated with these compounds, anthocyanins appear to be rapidly absorbed and eliminated, reaching only low maximal concentrations in plasma and urine. Some possible critical factors that may contribute to this paradox were also explored including the ability of a compound to cross membranes, the effect of pH, digestive enzymes, biliary acids and microbiota, the lack of sensitivity of the analytical method, the possible ingestion of pigments (anthocyanin derivatives, especially in the case of red wine) and the influence of the food matrix.Generally, the bioavailability of anthocyanins is presumed but whether the effect is due to the native compounds or other forms, which mechanism are involved or which factors have crucial impact on bioavailability still remain underexplored.

Gut Microbiota Metabolism of Anthocyanin Promotes Reverse Cholesterol Transport in Mice Via Repressing miRNA-10b

We and others have demonstrated that anthocyanins have antiatherogenic capability. Because intact anthocyanins are absorbed very poorly, the low level of circulating parent anthocyanins may not fully account for their beneficial effect. We found recently that protocatechuic acid (PCA), a metabolite of cyanidin-3 to 0-β-glucoside (Cy-3-G), has a remarkable antiatherogenic effect. To investigate whether mouse gut microbiota metabolizes Cy-3-G into PCA and to determine whether and how PCA contributes to the antiatherogenic potency of its precursor, Cy-3-G. PCA was determined as a gut microbiota metabolite of Cy-3-G in ApoE(-/-) mice, verified by the utilization of antibiotics to eliminate gut microbiota and further microbiota acquisition. PCA but not Cy-3-G at physiologically reachable concentrations promoted cholesterol efflux from macrophages and macrophage ABCA1 and ABCG1 expression. By conducting a miRNA microarray screening, we revealed that expression of miRNA-10b in macrophages can be reduced by PCA. Functional analyses demonstrated that miRNA-10b directly represses ABCA1 and ABCG1 and negatively regulates cholesterol efflux from murine- and human-derived macrophages. Further in vitro and ex vivo analyses verified that PCA accelerates macrophage cholesterol efflux, correlating with the regulation of miRNA-10b-ABCA1/ABCG1 cascade, whereas Cy-3-G consumption promoted macrophage RCT and regressed atherosclerotic lesion in a gut microbiotaendependent manner. PCA, as the gut microbiota metabolite of Cy-3-G, exerts the antiatherogenic effect partially through this newly defined miRNA-10b-ABCA1/ABCG1-cholesterol efflux signaling cascade. Thus, gut microbiota is a potential novel target for atherosclerosis prevention and treatment.

Identification of Anthocyanins in the Liver, Eye, and Brain of Blueberry-Fed Pigs

Dietary intervention with anthocyanins may confer benefits in brain function, including vision. Research to date indicates that animals have only a limited capacity to absorb anthocyanins, compared to other types of flavonoids. Pigs, which are a suitable model for human digestive absorption, were used to examine the deposition of anthocyanins in tissues including the liver, eye, and brain tissue. Pigs were fed diets supplemented with 0, 1, 2, or 4% w/w blueberries ( Vaccinium corymbosum L. 'Jersey') for 4 weeks. Prior to euthanasia, pigs were fasted for 18-21 h. Although no anthocyanins were detected in the plasma or urine of the fasted animals, intact anthocyanins were detected in all tissues where they were sought. LC-MS/MS results are presented for the relative concentration of 11 intact anthocyanins in the liver, eye, cortex, and cerebellum. The results suggest that anthocyanins can accumulate in tissues, including tissues beyond the blood-brain barrier.

Effect of Dose Size on Bioavailability of Acylated and Nonacylated Anthocyanins from Red Cabbage (Brassica oleracea L. Var. capitata)

Recent studies indicate that anthocyanin intake conveys a variety of health benefits, which depend on absorption and metabolic mechanisms that deliver anthocyanins and their bioactive metabolites to responsive tissues. The anthocyanin bioavailability of red cabbage (Brassica oleracea L. var. capitata) was evaluated as reflected by urinary excretion of anthocyanins and anthocyanin metabolites. Twelve volunteers consumed 100, 200, and 300 g of steamed red cabbage (containing 1.38 micromol of anthocyanins/g of cabbage) in a crossover design. Anthocyanin concentration in cabbage extract and urine was measured by HPLC-MS/MS. Six nonacylated and 30 acylated anthocyanins were detected in red cabbage, and 3 nonacylated anthocyanins, 8 acylated anthocyanins, and 4 metabolites were present in urine. Mean 24 h excretion of intact anthocyanins increased linearly from 45 (100 g dose) to 65 nmol (300 g dose) for acylated anthocyanins and from 52 (100 g dose) to 79 nmol (300 g dose) for nonacylated anthocyanins. Urinary recovery of intact anthocyanins (percent of anthocyanin intake) decreased linearly from 0.041% (100 g dose) to 0.020% (300 g dose) for acylated anthocyanins and from 0.18% (100 g dose) to 0.09% (300 g dose) for nonacylated anthocyanins. Anthocyanin metabolites consisted of glucuronidated and methylated anthocyanins. The results show that red cabbage anthocyanins were excreted in both intact and metabolized forms and that recovery of nonacylated anthocyanins in urine was >4-fold that of acylated anthocyanins.

Intact Anthocyanins and Metabolites in Rat Urine and PlasmaAfter 3 Months of Anthocyanin Supplementation

: Anthocyanins are polyphenols responsible for most red to purple colors in plants. Human consumption of these pigments is increasing because of their potential health benefits and use as natural colorants. With more than 600 different anthocyanins found in nature, the impact of chemical structure on their absorption and metabolism needs to be investigated. Urine and plasma samples were collected from 32 rats receiving control diet or chokeberry-, bilberry-, and grape-enriched (3.85 g cyanidin 3-galatoside equivalent/kg) diet for 14 wk. Below 2 μmol/l of anthocyanins and relatively higher levels of presumable metabolites were detected by high-performance liquid chromatography-photodiode array in the plasma. In the urine the total concentration of intact anthocyanins and methylated derivatives ranged from 17.4 (bilberry) to 52.6 (chokeberry) nmol/l. The type and number of anthocyanin glycosylations affected the absorption remarkably. Detection of an acylated anthocyanin in plasma and urine suggests bioavailability of these anthocyanin derivatives that are commonly found in commercially available colorants.

Fast Access of Some Grape Pigments to the Brain

Anthocyanins represent the main flavonoid pigments in red grape and wine, in red berries, and in many other fruits and vegetables and are widespread in the human diet. After ingestion, these complex, hydrophilic compounds quickly appear as intact molecules in the plasma. This study investigated their presence in the brain of anesthetized rats that received 8 mg/kg of body weight of a pure anthocyanin mixture extracted from Vitis vinifera grapes. The mixture was maintained in the stomach for 10 min. After this time, intact anthocyanins were detected by HPLC-DAD-MS not only in the plasma (176.4 +/- 50.5 ng/mL, mean +/- SEM) but also in the brain (192.2 +/- 57.5 ng/g). These results demonstrate for the first time that grape pigments can reach the mammalian brain within minutes from their introduction into the stomach.

Pharmacokinetics of Anthocyanidin‐3‐Glycosides Following Consumption of Hibiscus sabdariffa L. Extract

Pharmacokinetic parameters of several dietary anthocyanins following consumption of Hibiscus sabdariffa L. extract were determined in 6 healthy volunteers. Subjects were given a single oral dose of 150 mL of Hibiscus sabdariffa L. extract yielding 62.6 mg of cyanidin-3-sambubioside, 81.6 mg of delphindin-3-sambubioside, and 147.4 mg of total anthocyanins (calculated as cyanidin equivalents). Within 7 hours, the urinary excretion of cyanidin-3-sambubioside, delphinidin-3-sambubioside, and total anthocyanins (ie, the sum of all quantifiable anthocyanidin glycosides) was 0.016%, 0.021%, and 0.018% of the administered doses, respectively. Maximum excretion rates were determined at 1.5 to 2.0 hours after intake. The dose-normalized plasma area under the curve estimates were 0.076, 0.032, and 0.050 ng x h/mL/mg for cyanidin-3-sambubioside, delphinidin-3-sambubioside, and total anthocyanins, respectively. The dose-normalized C(max) estimates were 0.036, 0.015, and 0.023 ng/mL/mg in the same sequence. They were reached each at 1.5 hours (median) after intake. The geometric means of t1/2 were 2.18, 3.34, and 2.63 hours for cyanidin-3-sambubioside, delphinidin-3-sambubioside, and total anthocyanins, respectively. The urinary excretion of intact anthocyanins was fast and appeared to be monoexponential. To evaluate the contribution of anthocyanins to the health-protecting effects of Hibiscus sabdariffa L. extract, it will be necessary to perform further studies on both the intact glycosides and their in vivo metabolites or conjugates in human plasma and urine.

Anthocyanin Determination in Black Raspberry (Rubus occidentalis) and Biological Specimens Using Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry

ABSTRACT: The capabilities of mass spectrometry for microscale determination of anthocyanins were investigated using high-performance liquid chromatography electrospray ionization mass spectrometry (LC-ESI/ MS) and tandem mass spectrometry (MS-MS). Four anthocyanins [cyanidin 3-glucoside, cyanidin 3-sambubioside, cyanidin 3–(2G−xylosylrutinoside) and cyanidin 3-rutinoside] were characterized in black raspberry samples by LC-ESI/MS-MS using both positive and negative ion analyses. Quantification of anthocyanins was conducted using ESI/MS-MS with selected reaction monitoring (SRM). Linear responses of several anthocyanins were determined during MS-MS analyses. Detection limits as low as 1 femtomol for most anthocyanins were obtained during ESI/MS-MS. Compared with other quantitative procedures such as high-performance liquid chromatography (HPLC) and ultraviolet/visible spectrophotometry, the current method provides an improved sensitive, specific technique for direct determination of intact anthocyanins. The developed methodology was successfully applied to analysis of trace levels of anthocyanins in human plasma and epithelial cells.