Anthocyanin Solutions Research Articles

Modulation of autophagy enhances the apoptotic cell death in human T lymphoma cells treated with Anthocyanin

In the present study, the effect of modulation of autophagy induced by anthocyanin on cell death of Human T lymphoma cells (Jurkat) was studied. Anthocyanin was abstracted from dry petals of Hibiscus sabdariffa, aquous solution of anthocyanin was added to cells at different concentrations then cell viability was determined by trypan blue exclusion method. Autophagy induced by anthocyanin was inhibited by 5 mM NH4CL which halts lysosomal enzymes and accordingly preventing autolysosomes formation. On the other hand, Autophagy was enhanced by glucose starvation. In both experiments of autophagy inhibition and enhancement, cell viability was studied to investigate the effect of autophagy modulation on cell viability. The results of this work revealed that both inhibition and enhancement of autophagy induced by anthocyanin lead to massive cell death. Immuno-detection of active caspase 3, one of the major hallmark of apoptotic cell death revealed remarkable increase of active caspse3 upon autophagy inhibition or enhancement. In conclusion, modulation of autophagy induced by anthocyanin lead to increasing of apoptotic cell death.

Color Variation Assay of the Anthocyanins from Açai Fruit (Euterpe oleracea): A Potential New Dye for Vitreoretinal Surgery

The goals of this study were to determine the potential for use of the natural anthocyanins from the açai fruit (Euterpe oleracea) during vitreoretinal surgery and the ideal physicochemical properties of the dye. We evaluated the color variations of the dye at different pHs and osmolarities with or without the use of mordants as a potential new tool for internal limiting membrane peeling. The extracts of anthocyanin from the açai fruit were analyzed by spectrophotometry to determine the degree of color variations associated with various pHs and osmolarities. The experiments were conducted in test tubes filled with tryptophan soya media and Petri dishes prepared with agar media. We observed various shades of green, red, and purple in the extracts of the anthocyanin dye at different pHs and osmolarities. The assay to adjust the anthocyanin solution similar to the physiologic retinal environment (osmolarity, 300 mOsm; pH, 7.00) resulted in a shade of purple that may be useful to stain the intraocular microstructures during vitreoretinal surgery. The physicochemical property of the purple anthocyanin solutions from the açai fruit was observed at physiologic pH and osmolarity. Anthocyanins from the açai fruit may be useful to enhance visualization of the intraocular microstructures during vitreoretinal surgery.

Effects of UV‐B irradiation on poly (vinyl alcohol) and Ixora siamensis anthocyanins‐coated glass

PurposeThe purpose of this paper is to evaluate the potential of natural colourants from fruits of Ixora siamensis for coating applications, to study its glossiness and effectiveness against UV‐B irradiation.Design/methodology/approachIn this study, natural colourants from the fruits of Ixora siamensis were extracted using trifluoroacetic acid‐methanol solution. Anthocyanins and organic acid variants were mixed together to form co‐pigments. Different concentrations of ferulic and gallic acid co‐pigments were added to a blended solution of poly (vinyl alcohol), PVA and anthocyanin (from Ixora siamensis) to form a coating system. The coatings were exposed to UV‐B irradiation at room temperature in air using a UV‐lamp which emitted radiation at 312 nm. The effects of UV‐B irradiation on the coating system were evaluated using glossiness test and UV‐visible spectroscopy.FindingsAnthocyanins are unstable and can quickly lose their colour. One of the methods of preserving the stability of these pigments is by co‐pigmentation. Co‐pigmentation of anthocyanin with organic acid variants resulted in an increase in both hyperchromic effects (ΔA) and bathochromic shifts (Δλ). In this study, ferulic acids yielded better results compared to gallic acids.Research limitations/implicationsSamples with co‐pigmentation give better result compared to the untreated samples. The addition of 0.5 and 1.0 per cent ferulic acid improves the gloss properties and resistivity of the samples towards the UV irradiation. Thus, in order to study the effectiveness of ferulic acid as additive and improving the properties of the samples, the percentage of ferulic acid added and exposure time could be increased.Practical implicationsThe method developed provided a simple and efficient solution for improving the UV resistance of anthocyanin blend with poly (vinyl alcohol), PVA UV absorber. Effect of ferulic acid as UV absorber, if added in more concentration, can be further studied for optimization.Social implicationsThe social implication is the use of local plant species as a low cost source of natural pigments in coating system.Originality/valueThe method for improving the resistance towards UV irradiation of anthocyanin blend with poly (vinyl alcohol), PVA was novel and could find numerous applications for natural product based on plant pigment.

Characterisation of poly(acrylamide‐co‐acrylic acid) mixed with anthocyanin pigment from hibiscus sabdariffa l.

PurposeThe purpose of this paper is to develop a new water based coating system composed of poly(acrylamide‐co‐acrylic acid) and anthocyanin colourant extracted from Hibiscus sabdariffa L. and characterise the system.Design/methodology/approachAnthocyanin from Hibiscus sabdariffa L. (roselle) calyxes was extracted using optimised water extraction method with ratio of calyxes to water being 1:2. UV‐Vis absorption spectroscopy was conducted on the anthocyanin extract to monitor its degradation. Poly(acrylamide‐co‐acrylic acid) was mixed with the extracted anthocyanin solution in two different weight ratios. The mixtures were coated on glass substrate and let to cure for approximately one day. FTIR spectroscopy was conducted on the samples to determine their functional groups and identify the compounds in the samples. Cross hatch test was performed on the samples to determine the adhesion properties. Thermal degradation of the samples was determined through thermogravimetric analysis. Surface roughness of the samples was studied by atomic force microscopy. Colour stability was determined before and after UV irradiation.FindingsAnthocyanin pigment from roselle extracted with water was found to be stable with 6.0 per cent drop in absorbance value over the 15 day period. The reaction rate was found to be 0.000181 h−1, and the half life was calculated to be 3,850 hours. Better adhesion of the samples to the glass substrate was due to the higher concentration of poly(acrylamide‐co‐acrylic acid). Thermogravimetric analysis revealed similar thermal stability of the samples. Surface roughness study revealed that sample with higher anthocyanin content has higher surface roughness. Colour stability of the 20PBR was found to be better than 10PBR.Research limitations/implicationsUsage of poly(acrylamide‐co‐acrylic acid) as coating is limited by its weak water resistance property. Improvement could be made in this direction for future applications.Practical implicationsMixture of water‐based polymer and anthocyanin colourant from roselle has been developed into coating for the first time. Commercialisation is possible if more research is conducted towards water resistance property of poly(acrylamide‐co‐acrylic acid), storage condition for the pigment and coating, and mass production of the pigment.Originality/valueIncorporation of anthocyanin pigment into water based coating is the first of its kind.

Effect of cyclodextrins on the thermodynamic and kinetic properties of cyanidin-3-O-glucoside

In this study, the effect of α and β-cyclodextrin on cyanidin-3-O-glucoside color was investigated by UV–visible absorption techniques. The equilibrium and kinetic constants of the network of chemical reactions taking place in cyanidin-3-O-glucoside were also studied in water at 25°C by UV–visible absorption techniques. The results showed that the addition of β-cyclodextrin resulted in the fading of anthocyanin solution, and this fading effect was greater at higher pH. This anti-copigmentation effect is caused by the selective inclusion and stabilization of the anthocyanin colorless forms into the β-cyclodextrin cavity. Oppositely, no changes were observed in the cyanidin-3-O-glucoside absorption spectra with the addition of α-cyclodextrin.Direct pH jump, from thermally equilibrated solutions at pH=1.0 (flavylium cation, AH+), shows three kinetic processes: formation of the base A, hydration reaction to form the hemiketal B and the chalcone cis–trans isomerization (Cc–Ct). The results obtained clearly indicated that the equilibrium and kinetic constants of the network of chemical reactions taking place in cyanidin-3-O-glucoside were affected by the presence of β-cyclodextrin. Molecular inclusion in the β-cyclodextrin cavity resulted in the increase of the isomerization observed rate constant (kobs) at pH5.3 and in the increase of the hydration equilibrium constant Kh which is in agreement with the fading of the anthocyanin solution. For the macrocycle α-cyclodextrin, no significant changes were observed on the equilibrium and kinetic constants, which suggests that the inclusion of cyanidin-3-glucoside in the α-cyclodextrin's cavity is not favored.

Extraction of anthocyanins from red cabbage and purification using adsorption

There is an increasing interest in anthocyanins, as natural food colorants, in food products and also in pharmaceutical products due to their antioxidative potential. The present study deals with extraction and purification of anthocyanins from red cabbage. Conventional extraction methods of anthocyanin from plant material are non-selective and yield pigment solutions with large amounts of byproducts such as sugars, organic acids and proteins. Some of these impurities may accelerate anthocyanin degradation. Different extracting media were used and the mixture of 50% (v/v) ethanol and acidified water resulted in maximum anthocyanin content (390.6mg/L). In order to obtain anthocyanins in a purified form, adsorption was carried out with six different adsorbents. Among these, non-ionic acrylic ester adsorbent, namely Amberlite XAD-7HP, showed the highest adsorption capacity (0.84mg/mL of resin) and desorption ratio (92.85%). Adsorption results were found to be correlated best using the Langmuir isotherm equation especially at low temperature. The resulting anthocyanin solution after purification was free from sugars, which are the major cause for degradation of anthocyanin. No browning was observed and chroma increased by 27% compared to crude anthocyanin.

Comprehensive Colorimetric Study of Anthocyanic Copigmentation in Model Solutions. Effects of pH and Molar Ratio

New colorimetric variables have been defined in the uniform CIELAB color space to assess the quantitative and qualitative color changes induced by copigmentation and their incidence on visual perception. The copigmentation process was assayed in model solutions between malvidin 3-glucoside and three phenolic compounds (catechin, epicatechin, and caffeic acid) as a function of the pH and the pigment/copigment molar ratio. Along the pH variation, the greatest magnitude of copigmentation was obtained at pH 3.0, being significantly higher with epicatechin and caffeic acid. At high acidic pH, the main contribution of copigmentation to the total color was qualitative, whereas between pH 2.0 and 4.0, the main colorimetric contribution was quantitative. The contribution of epicatechin and caffeic acid to the color changes was more marked for the quantitative characteristics. On contrast, particularly at higher pH values, the qualitative contribution was more important in catechin copigmented solutions. Increasing copigment concentration induced perceptible color changes at molar ratios higher than 1:2, consisting in a bluish and darkening effect of the anthocyanin solutions. Among the different CIELAB attributes, hue difference was the best correlated parameter with the increase of copigment concentration, proving the relevance of this physicochemical phenomenon on the qualitative changes of anthocyanin color.

TiO2/Chitosan-NH4I(+I2)-BMII-Based Dye-Sensitized Solar Cells with Anthocyanin Dyes Extracted from Black Rice and Red Cabbage

Dye sensitized solar cells (DSSCs) were fabricated using anthocyanin dye and polymer electrolyte with ammonium iodide (NH4I) salt. The study was designed to focus on increasing the efficiency of the DSSC. DSSC using 26.9 wt. % chitosan-22 wt. % NH4I(+2.2 wt.% I2)-48.9 wt. % IL solid electrolyte, black rice anthocyanin with Pt counter electrode showedJscof 172 μA cm−2andVocof 195 mV. The performance of the cell with Pt electrode was further improved by coating a blocking layer on the indium tin oxide (ITO) substrate. The black rice DSSC using 11 wt. % (chitosan:PEO, wt. ratio 30:70)-9 wt. % NH4I-80 wt. % BMII gel electrolyte exhibitedJscof 1213 μA cm−2,Vocof 400 mV,FFof 0.47, andηof 0.23%. The red cabbage anthocyanin DSSC containing (phthaloyl chitosan-PEO)-NH4I-BMII gel electrolyte using tartaric acid to adjust the pH of anthocyanin solution showed the best performance with the fill factor of 0.39,Jscof 3503 μA cm−2,Vocof 340 mV, and an overall conversion efficiency of 0.46%.

Formulation and In Vitro-In Vivo Evaluation of Black Raspberry Extract-Loaded PLGA/PLA Injectable Millicylindrical Implants for Sustained Delivery of Chemopreventive Anthocyanins

The objective of this study was to formulate and evaluate freeze-dried black raspberry (FBR) ethanol extract (RE) loaded poly(DL-lactic-co-glycolic acid) (PLGA) and poly(DL-lactic acid) (PLA) injectable millicylindrical implants for sustained delivery of chemopreventive FBR anthocyanins (cyanidin-3-sambubioside (CS), cyanidin-3-glucoside (CG) and cyanidin-3-rutinoside (CR)). Identification and quantitation of CS, CG, and CR in RE was performed by mass spectroscopy and HPLC. RE:triacetyl-beta-cyclodextrin (TA-beta-CD) inclusion complex (IC) was prepared by a kneading method and characterized by X-ray diffraction (XRD), nuclear magnetic resonance spectroscopy (NMR) and UV-visible spectroscopy. RE or RE:TA-beta-CD IC-loaded PLGA or PLA implants were prepared by a solvent extrusion method. In vitro and in vivo controlled release studies were conducted in phosphate-buffered saline Tween-80 (pH 7.4, 37 degrees C) and after subcutaneous administration in male Sprague-Dawley rats, respectively. Anthocyanins were quantified by HPLC at 520 nm. The content of CS, CG, and CR in RE was 0.2, 1.5, and 3.5 wt%, respectively. The chemical stability of anthocyanins in solution was determined to be pH-dependent, and their degradation rate increased with an increase in pH from 2.4 to 7.4. PLGA/PLA millicylindrical implants loaded with 5 or 10 wt% RE exhibited a high initial burst and short release duration of anthocyanins (35-52 and 80-100% CG + CR release after 1 and 14 days, respectively). The cause for rapid anthocyanins release was linked to higher polymer water uptake and porosity associated with the high osmolytic components of large non-anthocyanin fraction of RE. XRD, (1)H NMR and UV-visible spectroscopy indicated that the non-anthocyanin fraction molecules of RE formed an IC with TA-beta-CD, decreasing the hydrophilicity of RE. Formation of an IC with hydrophobic carrier, TA-beta-CD, provided better in vitro/in vivo sustained release of FBR anthocyanins (16-24 and 97-99% CG + CR release, respectively, after 1 and 28 days from 20 wt% RE:TA-beta-CD IC/PLA implants) over 1 month, owing to reduced polymer water uptake and porosity. PLA injectable millicylindrical implants loaded with RE:TA-beta-CD IC are optimal dosage forms for 1-month slow and continuous delivery of chemopreventive FBR anthocyanins.

The effect of ascorbic acid and H_2O_2 treatment on the stability of anthocyanin pigments in berries

Anthocyanins are natural pigments widely distributed in nature. Anthocyanin pigment molecules are a subclass of flavonoids. They are responsible for the red, purple, and blue colors observed in many flowers, fruits, and vegetables. Fruits and berries are the main sources of anthocyanins in nature. Anthocyanins are thought to contribute to the nutritive value of fruits and berries due to their antioxidative, anti-carcinogenic, anti-inflammatory, and anti-angiogenic properties. Anthocyanins can also improve the nutritional value of processed foods by preventing the oxidation of lipids and proteins. As such, identification of agents that can affect the stability of anthocyanins and the protective effect of anthocyanins is very important. In the present study anthocyanin pigment was extracted from 3 different berries (Morus nigra L., Morus alba var. nigra, and Fragaria L.). After soaking and wetting in ethanol (1% acidified), the extracted anthocyanin pigments were exposed to 3 different concentrations of ascorbic acid (AA) (10%, 25%, and 50%) and H_2O_2 (9.31, 18.61, and 27.92 mmol/L). Six groups of anthocyanin solutions were refrigerated and kept in darkness for 63 days, and every 3 weeks anthocyanin absorbance was recorded at 526 nm. AA absorbance decreased relative to the blank in all the treated samples. These results indicate the destructive effect of AA on anthocyanins. In the samples treated with H_2O_2 anthocyanin degradation increased and the intensity of color decreased as the concentration of H_2O_2 increased.

Substrate specificity of Myriococcum thermophilum cellobiose dehydrogenase on mono-, oligo-, and polysaccharides related to in situ production of H2O2

Cellobiose dehydrogenase from the ascomycete fungus Myriococcum thermophilum (MtCDH) was tested for the ability to generate bleaching species at a pH suitable for liquid detergents. The catalytic properties of MtCDH were investigated for a large variety of carbohydrate substrates using oxygen as an electron receptor. MtCDH produces H2O2 with all substrates tested (except fructose) but only in the presence of a chelant. Insoluble substrates like cellulose and cotton could as well be oxidized by MtCDH. To enhance the amount of cello-oligosaccharides in solution, different cellulases on cotton were used and in combination with MtCDH an increased H2O2 concentration could be measured. Additionally, the degradation of pure anthocyanins in solution (as model substrates for bleaching) was investigated in the absence and presence of a horseradish peroxidase. MtCDH was able to produce a sufficient amount of H2O2 to decolorize the anthocyanins within 2 h.

Stabilisation of the colour of anthocyanins in solutions by admixture with phytocomponents from apple

SummaryThe colour of anthocyanins can be enhanced by planar chemical complex formation, or stabilised by the formation of adducts. We investigated these properties using fruit extracts. Delphinidine and its glucoside, myrtilline, at 0.1 mM were mixed with 10 mM caffeoylquinic acid (CQA; chlorogenic acid) or 6 mM ferulic acid (FeA). In a second experiment CQA, ferulic acid, and a CQA-rich apple extract were added in variable concentrations to a blackcurrant pigment preparation and incubated at 37°C in 0.02 M citrate buffer at pH 1.5, pH 3.0, or pH 4.5. The colour change was followed by measuring the absorbance at 540 nm and the composition of the solutions was assayed by HPLC using diode array detection. Deglycosylation of anthocyanins leads to a loss of colour and chemical stability. It is therefore of major importance that the enzyme preparations used during juice extraction be devoid of glycosidases. Addition of phenolic acids to an anthocyanin solution increases and stabilises the colour, which is accompanied by an acceleration of the loss of the native anthocyanins and the formation of coloured adducts, presumably based on the pyranoanthocyanin structure. The glycosyl residue in anthocyanins is necessary for colour stabilisation, which appears to be due to the formation of new pigments. Caffeoylquinic acid appeared to be more efficient than ferulic acid, and a CQA-rich extract from apple also resulted in stabilisation of the colour of a blackcurrant extract.

Studies on the copigmentation between anthocyanins and flavan-3-ols and their influence in the colour expression of red wine

With the aim of evaluating the importance of the copigmentation process between anthocyanins and flavanols on the colour expression of red wine, assays were carried out in wine model systems with mixtures of compounds obtained from two Vitis vinifera grape varieties (Graciano and Tempranillo). Spectrophotometric and chromatic analyses were performed to evaluate the magnitude of the copigmentation and the modifications induced in the colour of the solutions. Measurement of the changes in the anthocyanin hydration constant ( K h) was also used to determine the strength of the copigmentation process. All the flavanols assayed induced significant changes in the colour, perceptible to the human eye, of the wine-like anthocyanin solutions at concentrations similar to those that can exist in red wines. The percentage contribution of the copigmentation with flavanols to the colour of the anthocyanin solutions was found to range from 2% to 20%. The extent of this effect was related not only to the concentration of flavanols but also to the qualitative composition of the flavanol preparations, as influenced by the part of the grape (either skin or seed) and the variety considered. Divergences were found between the evaluation of the copigmentation based on chromatic parameters in the CIELAB colour space and that based on the measurement at visible λ max, as the latter does not consider the integral colour changes produced in the visible spectrum. The results obtained confirmed the importance of the qualitative phenolic composition, determined in the wine by the type of grape and winemaking practices, to the production of an effective copigmentation process.

The high ascorbic acid content is the main cause of the low stability of anthocyanin extracts from acerola

Acerola is considered to be one of the best natural sources of ascorbic acid (AA) and, for this reason, the influence of this component on the stability of anthocyanins from acerola extracts was determined and compared to those from açai, which have no detectable AA. The addition of three different levels of AA to the solution of açai anthocyanins resulted in a 110-fold increase in the degradation rate ( k obs) at the highest fortification level (276 mg/ml). The fact that the flavonoid concentration of the açai anthocyanin extract was 10 times higher than that of the acerola was probably responsible for the three times higher stability of the AA-fortified açai system compared to the acerola system, both at the same AA concentration and similar total polyphenol levels. The higher the level of AA addition to açai anthocyanin solutions, the greater was the colour fading, indicated by increase of L ∗ and decrease of a ∗ and C ∗ values.

Stability and Antioxidant Activity of Black Currant Anthocyanins in Solution and Encapsulated in Glucan Gel

The effects of ferric and ferrous ions, pH, and temperature on the stability and antioxidant activity of black currant anthocyanins (BCA) were studied, and the recovery of BCA from glucan gel [mixed linked (1-->3,1-->4)-beta-D-glucan] after using different encapsulating procedures was determined. The degradation of individual anthocyanins follows first-order kinetics and shows Arrhenius temperature dependence. The activation energies of individual anthocyanins, evaluated over the temperature range 60-100 degrees C, decrease with an increase in pH. While the antioxidant activity of BCA, measured by the ferric reducing antioxidant power assay, decreased with the degradation of anthocyanins, the completely degraded products still exhibited approximately 30% of the initial antioxidant activity. Ferric ions have a detrimental effect on the stability of BCA, especially for delphinidins. Freeze drying of encapsulated BCA gives approximately 20% higher recovery of individual anthocyanins than infrared drying.

Influence of Different Phenolic Copigments on the Color of Malvidin 3-Glucoside

The effectiveness of seven phenolic compounds (catechin, epicatechin, procyanidin B2, caffeic acid, p-coumaric acid, myricitrin, and quercitrin) as copigments of malvidin 3-glucoside, the major anthocyanin in red wines from Vitis vinifera, using a copigment/pigment molar ratio of 1:1 was assayed in model wine solutions under the same conditions (pH=3.6, 12% ethanol). The stability of the copigment-pigment complexes formed was studied during a storage period of 60 days at 25 degrees C. Tristimulus colorimetry was applied for color characterization of the copigmentation process, and HPLC-DAD-MS was used to monitor changes in the composition of the samples. Copigmentation has been found to occur in all cases despite the low copigment/pigment molar ratio used, although the effect was different depending on the compound. Flavan-3-ols appeared as the less effective copigments, procyanidin B2 being even worse than monomeric flavanols, whereas flavonols behaved as the best ones. These latter copigments also induced the most statistically significant bathochromic shift in lambdamax. In the colorimetric analysis, it was observed that the lightness L* of the copigmented solutions increased with time, chroma C*ab decreased, and the hue hab increased. The copigments that produced a greater increase in the hue angle were the monomeric flavan-3-ols, which therefore showed to be the least protective cofactors against browning of the anthocyanin solution during the storage. With the time of storage, the formation of new pigments was observed in the solutions containing flavanols (xanthylium structures) and hydroxycinnamic acids (pyranoanthocyanins), which explains some of the color modifications produced in these solutions. Another relevant observation was that the stability of the anthocyanin was not much improved by most of the assayed copigments, since quite similar degradation rates were observed in the presence and absence of those cofactors.

Induction of Apoptosis in Cultured Human Stomach Cancer Cells by Potato Anthocyanins and Its Inhibitory Effects on Growth of Stomach Cancer in Mice

Anthocyanins prepared from colored potatoes induce apoptosis in cultured human stomach cancer KATO III cells. Morphological change indicating apoptotic bodies and DNA fragmentations were observed in cells treated with potato anthocyanins.Feeding with steamed red potato alone and purple potato alone suppressed by 46.2% and 38.5%, respectively, the growth of mouse stomach cancer as compared with the feeding with Irish Cobbler. Feeding with a 1% solution of red or purple potato anthocyanin with standard food suppressed by 47.6% and 38.1%, respectively, growth of mouse stomach cancer. So, eating of potatoes containing large amounts of anthocyanin to maintain the presence of potato anthocyanin in the stomach is recommended as a possible method for protecting humans from stomach cancer.

Charge-Transfer Complexation as a General Phenomenon in the Copigmentation of Anthocyanins

Color intensification of anthocyanin solutions in the presence of natural polyphenols (copigmentation) is re-interpreted in terms of charge transfer from the copigment to the anthocyanin. Flavylium cations are shown to be excellent electron acceptors (E(red) approximately -0.3 V vs SCE). It is also demonstrated, for a large series of anthocyanin-copigment pairs, that the standard Gibbs free energy of complex formation decreases linearly with EA(Anthoc) - IP(Cop), the difference between the electron affinity of the anthocyanin, EA(Anthoc), and the ionization potential of the copigment, IP(Cop). Based on this correlation, copigmentation strengths of potential candidates for copigments can be predicted.

Hepatic uptake of grape anthocyanins and the role of bilitranslocase

Anthocyanins are water-soluble compounds that pigment berries, grapes and vegetables. Their flavonoid backbone endows them with oxygen radical scavenging activity. Thus, they could play a role in protecting the human organism from various degenerative and proliferative diseases, that are currently believed to result from an oxygen radical-mediated disruption of cellular components. Their great potential as functional food ingredients is, however, restricted by the incomplete knowledge of their bioavailability. In order to contribute to filling this gap, we looked for their presence in the liver, after administration of a solution of pure grape anthocyanins into the stomach of anaesthetised rats. We found that the liver contained both malvidin 3-glucoside and its p-coumarate ester, the main and the minor component of the mixture, respectively. Isolated, cultured liver cells were also found to be permeable to malvidin 3-glucoside and bilitranslocase was identified as the carrier protein involved, by using two different specific antibodies.

Antioxidative Activity of Anthocyanins from Purple Sweet Potato,Ipomoera batatasCultivar Ayamurasaki

We evaluated the antioxidative activity of anthocyanins from an extract of the tuber of purple sweet potato (PSP) (Ipomoea batatas cultivar Ayamurasaki). Anthocyanins from PSP showed stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity than anthocyanins from red cabbage, grape skin, elderberry, or purple corn, and eight major components of the anthocyanins from PSP showed higher levels of activity than ascorbic acid. In PSP anthocyanin-injected rats and PSP beverage-administered volunteers, DPPH radical-scavenging activity in the urine increased. The elevation of plasma transaminase activities induced by carbon tetrachloride was depressed in rats administered PSP anthocyanin solution. Two components, cyanidin 3-O-(2-O-(6-O-(E)-caffeoyl-beta-D-glucopyranocyl)-beta-D-glucopyranoide)-5-O-beta-D-glucopyranoside and peonidin 3-O-(2-O-(6-O-(E)-caffeoyl-beta-D-glucopyranocyl)-beta-D-glucopyranoide)-5-O-beta-D-glucopyranoside, which were detected in the plasma, protected low density lipoprotein from oxidation at a physiological concentration. These results indicate that PSP anthocyanins have antioxidative activity in vivo as well as in vitro.