Strawberry Anthocyanins Research Articles

Effects of pelargonidin-3-O-glucoside and its metabolites on lipopolysaccharide-stimulated cytokine production by THP-1 monocytes and macrophages

Epidemiological evidence suggests cardioprotective effects of anthocyanin consumption. This study examined the predominant strawberry anthocyanin, pelargonidin-3-O-glucoside (Pg-3-glc), and three of its plasma metabolites (protocatechuic acid [PCA], 4-hydroxybenzoic acid, and phloroglucinaldehyde [PGA]) for effects on the production of selected cytokines by lipopolysaccharide-stimulated THP-1 monocytes and macrophages. Concentrations of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, IL-8 and IL-10 were determined using a cytometric bead array kit. PCA at 0.31, 1.25 and 20 μM and PGA at 5 and 20 μM decreased the concentration of IL-6 in the monocyte cultures, but there were no effects on TNF-α, IL-1β, IL-8 and IL-10 and there were no effects of the other compounds. In the macrophage cultures, PGA at 20 μM decreased the concentrations of IL-6 and IL-10, but there was no effect on TNF-α, IL-1β and IL-8 and there were no effects of the other compounds. In conclusion, while the effects of PGA were only observed at the higher, supraphysiological concentration and are thus considered of limited physiological relevance overall, the anti-inflammatory properties of PCA were observed at both the lower, physiologically relevant, and the higher concentrations; however, effects were modest and limited to IL-6 and monocytes. These preliminary data suggest potential for physiologically attainable PCA concentrations to modulate IL-6 production by monocytes.

Isolation of strawberry anthocyanins using high-speed counter-current chromatography and the copigmentation with catechin or epicatechin by high pressure processing

Three anthocyanins were isolated from strawberry extract by high-speed counter-current chromatography, using a biphasic mixture of tert-butyl methyl ether, n-butanol, acetonitrile, water and trifluoroacetic acid (2.5:2.0:2.5:5.0:1.0%). The anthocyanins were identified as pelargonidin-3-rutinoside, cyanidin-3-glucoside and pelargonidin-3-glucoside with purity of 95.6%, 96.2% and 99.3% respectively. Additionally, the copigmentation reaction rates between pelargonidin-3-glucoside and phenolic acids (catechin or epicatechin) at pH 1.5 and 3.6, pressure 0.1 and 500 MPa, and temperature 60 °C were calculated. The absorbance of pelargonidin-3-glucoside at pH 3.6, with high quantity of phenolic acids was significantly increased by high pressure. The complex of pelargonidin-3-glucoside/catechin has a binding energy of 78.64 kJ/mol at pH 3.6, and 39.13 kJ/mol at pH 1.5; pelargonidin-3-glucoside/epicatechin has a binding energy of 75.34 kJ/mol at pH 1.5 and 54.47 kJ/mol at pH 3.6. The hydrogen bond and van der Waals interaction were the main forces contributing to the structures of complex.

Pelargonidin-3-O-glucoside and its metabolites have modest anti-inflammatory effects in human whole blood cultures

This study hypothesized that the predominant strawberry anthocyanin, pelargonidin-3-O-glucoside (Pg-3-glc), and 3 of its plasma metabolites (4-hydroxybenzoic acid, protocatechuic acid, and phloroglucinaldehyde [PGA]) would affect phagocytosis, oxidative burst, and the production of selected pro- and anti-inflammatory cytokines in a whole blood culture model. For the assessment of phagocytosis and oxidative burst activity of monocytes and neutrophils, whole blood was preincubated in the presence or absence of the test compounds at concentrations up to 5 μmol/L, followed by analysis of phagocytic and oxidative burst activity using commercially available test kits. For the cytokine analysis, diluted whole blood was stimulated with lipopolysaccharide in the presence or absence of the test compounds at concentrations up to 5 μmol/L. Concentrations of selected cytokines (tumor necrosis factor-α, interleukin [IL]-1β, IL-6, IL-8, and IL-10) were determined using a cytometric bead array kit. There were no effects of any of the test compounds on phagocytosis of opsonized or nonopsonized Escherichia coli or on oxidative burst activity. Pg-3-glc and PGA at 0.08 μmol/L increased the concentration of IL-10 (P<.01 and P<.001, respectively), but there was no effect on tumor necrosis factor-α, IL-1β, IL-6, and IL-8, and there were no effects of the other compounds. In conclusion, this study demonstrated a lack of effect of these compounds on the opsonization, engulfment, and subsequent destruction of bacteria. Pg-3-glc and PGA, at physiologically relevant concentrations, had anti-inflammatory properties; however, effects were modest, only observed at the lowest dose tested and limited to IL-10.

The effect of dietary factors on strawberry anthocyanins oral bioavailability.

Strawberries are a dietary source of anthocyanins, particularly pelargonidin glycosides. Dietary anthocyanins have received increasing attention among researchers and consumers due to their health benefits. The oral bioavailability of anthocyanins is reported to be low and various dietary factors may influence their oral bioavailability further. Milk is suggested to reduce (poly)phenols' oral bioavailability. However, the effect of milk on anthocyanin oral bioavailability remains uncertain. Likewise, mixed nutrient meals may influence the oral bioavailability of anthocyanins. Therefore, the purpose of this study was to assess the effect of milk on the oral bioavailability and other pharmacokinetic (PK) variables of strawberry anthocyanins consumed with and without a meal. Nine healthy participants consumed a strawberry beverage prepared in milk or water with a standard meal on two occasions. On two additional occasions, the beverages were given to a subset (n = 4) of participants to determine the impact of the meal on anthocyanin PK variables, including oral bioavailability. Independent of the meal, beverages prepared in milk significantly reduced the peak plasma concentrations (Cmax) of pelargonidin-3-O-glucoside (P-3-G), pelargonidin-glucuronide (PG) and pelargonidin-3-O-rutinoside (P-3-R), as well as the PG and P-3-R area under the curve (AUC) (p < 0.05) compared to beverages prepared in water. Milk did not influence the oral relative bioavailability of pelargonidin anthocyanins under meal conditions; however, the oral relative bioavailability of pelargonidin anthocyanins was reduced by ∼50% by milk under without meal conditions (p < 0.05). Consuming strawberry beverages made with milk and consuming those made with water with and without a meal influenced different aspects of strawberry anthocyanin PKs. The significance of this effect on clinical efficacy requires additional research.

Exploring the Colonic Metabolism of Grape and Strawberry Anthocyanins and Their in Vitro Apoptotic Effects in HT-29 Colon Cancer Cells.

Beneficial properties attributed to the intake of fruit and red wine have been associated with the presence of significant amounts of anthocyanins. However, their low absorption and consequent accumulation in the gut have generated the suspicion that colonic metabolites of anthocyanins are probably involved in these protective effects. Grape pomace and strawberry extracts, rich in malvidin- and pelargonidin-glucoside, respectively, were fermented in vitro using human feces as microbial inoculum. After 8 h of anaerobic incubation, the anthocyanins were almost completely degraded, whereas their microbial metabolite concentrations were highest at 24 h. Syringic acid and tyrosol were the main metabolites of grape and strawberry extracts, respectively. On the basis of the metabolites detected, metabolic pathways of malvidin- and pelargonidin-glucosides were proposed. Anthocyanin-rich grape and strawberry extracts and their generated metabolites such as hydroxyphenylacetic acid showed apoptotic effects in HT-29 colon cancer cells and may suggest their possible contribution as anticarcinogenic agents.

Pharmacokinetic Characterization and Bioavailability of Strawberry Anthocyanins Relative to Meal Intake.

Plasma strawberry anthocyanins were characterized in overweight (BMI: 26 ± 2 kg/m(2)) adults (n = 14) on the basis of meal timing. At each visit, subjects ingested three study drinks: two control and one strawberry drink. A strawberry drink was given at either 2 h before the breakfast meal (BM), with the meal (WM), or 2 h after the meal (AM), and control drinks were given at the alternative time points. Plasma anthocyanins and their metabolic conjugates were assessed hourly for 10 h using a triple-quadrupole liquid chromatography mass spectrometer. Maximum concentrations (Cmax), area under the curve (AUC), and bioavailability of pelargonidin-based anthocyanins determined from the main conjugated metabolite (pelargonidin glucuronide) were greater when a strawberry drink was consumed 2 h before the meal (BM) compared to consumption WM or AM (p < 0.05). Our results indicate that the timing of strawberry consumption relative to a meal impacts anthocyanin pharmacokinetic variables.

Investigating the effect of different soilless substrates on strawberry productivity and fruit composition

The effect of different soiless substrates (viz. agrotextile, coir fibre, perlite and rock wool) on strawberry productivity and fruit composition of three strawberry cultivars (‘Camarosa’, ‘Candonga’ and ‘Festival’) was investigated.Plant productivity and berry composition was mainly affected by differences between cultivars rather than by the nature of the different growing substrates. However, regardless of the cultivar, plants grown on agrotextile-type substrate produced significantly more fruit (1018.2g plant−1) than those grown in other substrates (average 892.3g plant−1). In addition, accompanying greater fruit production, fruit from plants grown on agrotextile generally had the lowest concentrations of the main strawberry anthocyanins perlargonidin-3-glucoside (0.74-fold) and pelargonidin derivative 1 (0.85-fold). Nor sugars, organic acids or any other health-related compounds were significantly affected by the nature of the soilless substrate.Overall, the present study demonstrates that despite some minor differences in fruit yield and the health-related composition of fruit grown on agrotextile, a number of different substrates with different physico-chemical characteristics may be employed during soilless cultivation of strawberry fruit without detrimentally affecting final fruit quality.

Use of Modified Phenolic Thyme Extracts (Thymus vulgaris) with Reduced Polyphenol Oxidase Substrates as Anthocyanin Color and Stability Enhancing Agents.

Residual enzymatic activity in certain foods, particularly of polyphenoloxidase (PPO), is responsible for the majority of anthocyanin degradation in food systems, causing also parallel losses of other relevant nutrients. The present work explored the feasibility of modifying phenolic profiles of thyme extracts, by use of chromatographic resins, to obtain phenolic extracts capable of enhancing anthocyanin colour and stability in the presence of PPO activity. Results indicated that pretreatment of thyme extracts with strong-anion exchange resins (SAE) enhanced their copigmentation abilities with strawberry juice anthocyanins. Phenolic chromatographic profiles, by HPLC-PDA, also demonstrated that thyme extracts subjected to SAE treatments had significantly lower concentrations of certain phenolic compounds, but extracts retained their colour enhancing and anthocyanin stabilization capacities though copigmentation. Additional testing also indicated that SAE modified extract had a lower ability (73% decrease) to serve as PPO substrate, when compared to the unmodified extract. Phenolic profile modification process, reported herein, could be potentially used to manufacture modified anthocyanin-copigmentation food and cosmetic additives for colour-stabilizing applications with lower secondary degradation reactions in matrixes that contain PPO activity.

ABA and UV-C effects on quality, antioxidant capacity and anthocyanin contents of strawberry fruit (Fragaria ananassa Duch.)

Effects of 1mM abscisic acid (ABA) and 4.1kJ/m2 UV-C radiation on quality, antioxidant capacity, anthocyanin contents, and anthocyanin biosynthetic enzyme activities of large green strawberry fruit stored at 20°C were evaluated. Results showed that ABA promoted color formation, firmness decrease, soluble solids content and anthocyanin accumulation while UV-C inhibited these processes. Activities of phenylalanine ammonia-lyase, tyrosine ammonia-lyase and p-coumarate ligase were immediately upregulated by approximately 50% with UV-C radiation but were inhibited, including dihydroflavonol 4-reductase especially on day 3 or 4. UV-C radiation had little effect on activity of cinnamate 4-hydroxylase (C4H). ABA enhanced activities of anthocyanin biosynthetic enzymes except C4H. These data indicated that the stimulatory effect of ABA on strawberry anthocyanin accumulation was related to enhancement of biosynthetic enzyme activities, while the effects of UV-C were more transient. In addition, it appeared that C4H was not a rate-limiting enzyme in the strawberry anthocyanin biosynthesis pathway.

Stabilisation of strawberry (Fragaria x ananassa Duch.) anthocyanins by different pectins

The objective of the present study was to evaluate the effects of different pectins on strawberry anthocyanins in viscous model solutions at pH 3.0. For this purpose, low esterified amidated, low and high methyl esterified citrus and apple pectins, and a sugar beet pectin (SBP), respectively, were added to strawberry extracts. The latter were predominantly composed of pelargonidin-glycosides, containing either reduced (E-1) or original amounts of non-anthocyanin phenolics (E-2). Model systems were stored for 18weeks at 20±0.5°C protected from light, and anthocyanins were quantitated in regular intervals by HPLC-DAD analyses. Half-life (t1/2) and destruction (D) values were calculated based on first-order kinetics. Generally, significant differences in pigment retention could be ascribed to differing pectin sources, while variation in the degree of esterification and amidation, respectively, had negligible effects. Compared to systems without added pectin, apple pectins and SPB enhanced anthocyanin stability moderately, while stabilising effects of citrus pectins were poor or even imperceptible. Generally, the amount of non-anthocyanin phenolics and the addition of citrate did not markedly affect anthocyanin stability. However, pectins had no influence on total phenolic contents (Folin-Ciocalteu assay) and antioxidant capacities (FRAP and TEAC assay) of strawberry phenolics over time. For pelargonidin-3-glucoside and -rutinoside largely consistent stabilities were found in all model systems. In contrast, pelargonidin-3-malonylglucoside was less stable in the blank, and stabilisation by pectins was always negligible. The findings of the present study are contrary to results reported previously for the stabilisation of cyanidin- and delphinidin-glycosides in similar model systems prepared with black currant extracts, indicating a high impact of the number of hydroxyl groups in the anthocyanin B-ring.

A pilot study to investigate bioavailability of strawberry anthocyanins and characterize postprandial plasma polyphenols absorption patterns by Q-TOF LC/MS in humans

BACKGROUND: Information on absorption and metabolism of strawberry polyphenols is limited. OBJECTIVE: The aim of this study was to characterize and quantify plasma polyphenols/anthocyanins across 4 doses of strawberry using Q-TOF LC/MS and LC-MS/MS analysis. METHOD: Plasma was collected from 5 subjects (n = 5) every 30–60 min for 6 h after consuming beverages containing 0, 10, 20 or 40 g freeze-dried strawberry powder with a meal. RESULTS: Q-TOF LC/MS and LC-MS/MS analysis of plasma revealed 33 compounds; 7 not reported previously. Pelargonidin-O-glucuronide (PG) was the most abundant metabolite. Maximum concentrations (Cmax) of PG were achieved at 148 ± 31 min and were significantly different among beverages containing 0, 10, 20, 40 g strawberry powder: 0, 93.4 ± 21.9, 166.5 ± 16.2 and 226.7 ± 36.7 nmol/L, respectively (P < 0.05). Area under the concentration curve (AUC) also increased with dose (P < 0.05); however, Cmax and AUC of PG was reduced as a percent of pelargonidin-3-O-glucoside (P3G) delivered in the strawberry beverages (P < 0.05). CONCLUSION: Use of both Q-TOF LC/MS and LC-MS/MS allowed for detection of compounds in plasma not previously reported, which may be a useful approach for characterizing postprandial plasma metabolites of lesser known plant foods. Additionally, higher concentrations of key strawberry compounds/metabolites are achieved with eating more strawberry; however, saturation of absorptive capacity of pelargonidin-based anthocyanins was suggested.

Strawberry extract attenuates glucose and free fatty acid‐mediated impaired insulin signaling in vitro in skeletal muscle cells

Elevated glucose and free fatty acids (FFA) are evident in individuals with insulin resistance (IR) and are associated with oxidative stress. Anthocyanins are suggested to have favorable effects on human health due to their ability to modulate oxidative stress and cell signaling pathways in peripheral tissues. We hypothesized that strawberry anthocyanins (ST) will improve oxidative stress‐mediated impaired insulin signaling in vitro in human skeletal muscle cells (HSMCs). Oxidative stress was generated using physiologically high glucose, FFA or a combination of both for 2–6 h with and without ST (0.1–1.0 mg/mL) in vitro in HSMCs. Cell viability was not affected by any of the above treatments/time. At the end of treatments, cells were treated with insulin (100 nM) for 20 min. Phosphorylation of Akt (p‐Akt/Akt) was studied using AlphaScreen® Surefire® assay as a measure of insulin signaling. Our results indicate that FFA (2 mM) or combination of Glucose (15 mM) + FFA (2 mM) significantly decreased p‐Akt/Akt compared to control cells treated with phosphate buffered saline (P&lt;0.05). ST extract restored FFA and Glucose + FFA‐induced reductions in p‐Akt/Akt levels (P&lt;0.05). These in vitro data suggest a role of strawberry in improving insulin sensitivity having potentially important implications for people with IR.Grant Funding Source : California Strawberry Commission, California Department of Food &amp; Agriculture

Strawberry anthocyanin and its association with postprandial inflammation and insulin

The present study investigates the effect of strawberry antioxidants in beverage form on meal-induced postprandial inflammatory and insulin responses in human subjects. Overweight adults (n 24) consumed a high-carbohydrate, moderate-fat meal (HCFM) accompanied by either a strawberry or a placebo beverage in a cross-over design. Postprandial changes in plasma anthocyanins, their metabolites, insulin, glucose and inflammatory markers were assessed for 6h. The postprandial concentrations of pelargonidin sulfate and pelargonidin-3-O-glucoside were significantly increased when the strawberry beverage was consumed concurrently with the HCFM compared with the placebo beverage (P<0·001). The strawberry beverage significantly attenuated the postprandial inflammatory response as measured by high-sensitivity C-reactive protein and IL-6 (P<0·05) induced by the HCFM. It was also associated with a reduction in postprandial insulin response (P<0·05). Collectively, these data provide evidence for favourable effects of strawberry antioxidants on postprandial inflammation and insulin sensitivity.

Kinetic study on the thermal and pressure degradation of anthocyanins in strawberries

The degradation of anthocyanins (pelargonidin-3-glucoside) in a strawberry paste during high-temperature/high-pressure treatments was investigated over a temperature range of 80–130 °C and a pressure range of 200–700 MPa, compared to 0.1 MPa. A first-order kinetic model fitted well to all data. At constant pressure, anthocyanin concentration decreased as a function of time and the degradation was accelerated at higher temperatures. At constant temperature, anthocyanins were more rapidly degraded as the pressure increased, but the effect of increasing pressure was smaller than the effect of increasing temperature. Temperature dependence of the degradation rate constants, described by the Arrhenius equation, was higher at atmospheric pressure than at elevated pressures, where all activation energies were comparable. Activation volumes, estimated by the Eyring equation, demonstrated a small pressure dependence of the reaction rate constants. Finally, a model to describe the combined temperature–pressure dependence of the degradation rate constants was proposed.

Urinary excretion of strawberry anthocyanins is dose dependent for physiological oral doses of fresh fruit

There is considerable interest in coloured fruits and berries as sources of biologically active anthocyanins. To examine the relationship between the oral dose and the amount excreted for anthocyanins from a food source across a physiological range of doses, volunteers were fed, in random order, four portions (100-400 g) of fresh strawberries as part of a standard breakfast. Urine was collected at 2 h intervals up to 8 h, and for the period 8-24 h. Fresh strawberries contained pelargonidin-3-glucoside as the major anthocyanin with smaller amounts of cyanidin-3-glucoside and pelargonidin-3-rutinoside. Anthocyanins were detected in the urine of all volunteers for all doses, predominantly as pelargonidin glucuronide and sulphate metabolites. There was a strong, linear relationship between oral dose and anthocyanin excretion (Pearson's product moment correlation coefficient = 0.692, p < 0.001, n = 40) which indicated that on an average, every additional unit of dose caused 0.0166 units of excretion. Within individuals, dose -- excretion data fitted a linear regression model (median R(2) = 0.93). We conclude that strawberry anthocyanins are partially bioavailable in humans with a linear relationship between oral dose and urinary excretion for doses up to 400 g fresh fruit.

Cover Picture – Mol. Nutr. Food Res. 10/2008

AbstractRegular issues provide a wide range of research and review articles covering all aspects of Molecular Nutrition &amp; Food Research.Selected topics of issue 10 are:Urinary excretion of strawberry anthocyanins .Isoflavone‐Poor Soy Protein &amp; Reduced mammary tumor progression Effects of gastrointestinal digestion and heating on the allergenicity of the kiwi allergens Mediterranean diet and cardioprotection Meat‐based functional foods for dietary equilibrium omega‐6/omega‐3 Modulation of Endothelial Cell Gene Expression by Green Tea

CZE separation of strawberry anthocyanins with acidic buffer and comparison with HPLC

Anthocyanins, the major colourants of strawberries, are polar pigments that are positively charged at low pH. Herein, we have assessed a new analytical method for the separation of anthocyanins using CZE. Acidic buffer solutions (pH <2) were employed in order to maintain pigments in the cation flavylium form and achieve high molar absorptivity at 510 nm. These spectral properties enabled us to identify strawberry anthocyanins in a preliminary stage by detection in the visible range, although the method was optimised at 280 nm to obtain the best S/N. The effects of buffer composition highlighted the necessity of adding an organic modifier to the running buffer to obtain a suitable separation. The electrophoretic method permitted the separation of the three main anthocyanins of strawberry extracts, namely pelargonidin 3-glucoside (Pg-glu), pelargonidin 3-rutinoside and cyanidin 3-glucoside. The electrophoretic results, expressed as retention time and separation efficiency of the major anthocyanin (Pg-glu), were compared to those achieved in HPLC, the analytical technique traditionally used for the investigation of anthocyanins in vegetable matrix. The content of Pg-glu in strawberries (cv. Camarosa), calculated with HPCE and HPLC methods, resulted respectively in 11.41 mg/L and 11.37 mg/L.

Heat Stability of Strawberry Anthocyanins in Model Solutions Containing Natural Copigments Extracted from Rose (Rosa damascena Mill.) Petals

Thermal degradation and color changes of purified strawberry anthocyanins in model solutions were studied upon heating at 85 degrees C by HPLC-DAD analyses and CIELCh measurements, respectively. The anthocyanin half-life values increased significantly due to the addition of rose (Rosa damascena Mill.) petal extracts enriched in natural copigments. Correspondingly, the color stability increased as the total color difference values were smaller for anthocyanins upon copigment addition, especially after extended heating. Furthermore, the stabilizing effect of rose petal polyphenols was compared with that of well-known copigments such as isolated kaempferol, quercetin, and sinapic acid. The purified rose petal extract was found to be a most effective anthocyanin-stabilizing agent at a molar pigment/copigment ratio of 1:2. The results obtained demonstrate that the addition of rose petal polyphenols slows the thermal degradation of strawberry anthocyanins, thus resulting in improved color retention without affecting the gustatory quality of the product.

Anthocyanin Excretion by Humans Increases Linearly with Increasing Strawberry Dose

A clinical study was conducted to investigate the dose response and metabolism of strawberry anthocyanins. In a crossover study design, 12 healthy adults consumed each of 3 strawberry treatments. The treatments were 100 g, 200 g, and 400 g of pureed strawberries, delivering 15μmol, 30μmol, and 60μmol anthocyanin, respectively. Urine samples were collected for 24 h after each dose and samples were analyzed by HPLC with diode array detection and ion trap MS. Pelargonidin 3-glucoside was the major anthocyanin form in the treatments, and pelargonidin 3-glucoside and 3 metabolites of pelargonidin 3-glucoside (detected as monoglucuronides) were excreted in urine after ingestion. One predominant monoglucuronide form was detected in urine in masses 10-fold higher than the other 2 monoglucuronide forms. Increasing dose resulted in increasing appearance of anthocyanins in urine, and the mass of each pelargonidin monoglucuronide increased in urine with increasing dose. These results suggest that pelargonidin 3-glucoside absorption and metabolism are not saturated at masses ≤ 60μmol, thus showing that more strawberry anthocyanin can be absorbed with increasing dose.

Strawberry pelargonidin glycosides are excreted in urine as intact glycosides and glucuronidated pelargonidin derivatives in rats

Anthocyanins are natural dietary pigments with a wide array of biological properties that are possibly involved in the prevention of various diseases. These properties depend on their absorption and metabolism in the body. In the present study we first examined the gastric and intestinal absorption of pelargonidin 3-glucoside (Pg 3-glc) using rat in situ models. A high proportion of Pg 3-glc was rapidly absorbed from both the stomach (23 %) and small intestine (24 %). Its metabolism was further studied by feeding rats during 8 d with a diet enriched in freeze-dried strawberries. Only low amounts of total anthocyanins were recovered in 24 h urine (0.163 (SEM 0.013) % of ingested anthocyanins; n 8). Strawberry anthocyanins were analysed in urine by HPLC-electrospray ionisation-tandem MS. Similar proportions of intact glycosides (about 53 %) and glucuronidated metabolites (about 47 %) were found. Pg 3-glc was thus glucuronidated to a larger extent than cyanidin 3-glucoside. These results highlight the influence of the aglycone structure on anthocyanin metabolism.