Pigments in the Fruit of Red-Fleshed Kiwifruit ( Actinidia chinensis and Actinidia deliciosa)

Kiwifruit cultivars ( Actinidia chinensisand A. deliciosa) generally have fruit with yellow or green flesh when ripe. A small number of genotypes also have red pigments, usually restricted to the inner pericarp but varying in intensity and in distribution within the fruit. Carotenoids, chorophylls, and anthocyanins were extracted from the fruit pericarp of such red-fleshed kiwifruit selections. Pigments were analyzed by HPLC and identified by comparison with authentic standards and by liquid chromatographymass spectroscopy to obtain a tentative identification of the major anthocyanins in red-fleshed kiwifruit. The yellow and green colors of the outer fruit pericarp are due to different concentrations and proportions of carotenoids and chlorophylls. The red color found mainly in the inner pericarp is due to anthocyanins. In the A. chinensisgenotypes tested the major anthocyanin was cyanidin 3- O-xylo- (1-2)-galactoside, with smaller amounts of cyanidin 3- O-galactoside. In the A. deliciosa genotypes analyzed, cyanidin 3- O-xylo(1-2)-galactoside was not detected; instead, the major anthocyanins identified were cyanidin 3- O-galactoside and cyanidin 3- O-glucoside. However, the two species did not differ consistently in anthocyanin composition

The Flavonol Quercetin-3-Glucoside Inhibits Cyanidin-3-Glucoside Absorption in Vitro

At present, little is known about the mechanisms responsible for intestinal absorption of anthocyanins (ACNs). For example, it has not yet been established if ACNs are absorbed through an active transport mechanism, such as the sodium-dependent glucose transporter (SGLT1), or by passive diffusion. Previously, we found that the absorption of ACNs differs between regions of the digestive tract and is maximal in the jejunum, suggesting that an active transport mechanism is involved. In the present study, we examined the effect of D-glucose (main substrate of SGLT1), phloridzin (inhibitor of SGLT1), and quercetin-3-glucose (Q3G, a flavonol) on the absorption of cyanidin-3-glucoside (C3G; ~5 mol/L) by mouse jejunum mounted in Ussing chambers. We found that the presence of either D-glucose (10, 20, and 40 mmol/L) or phloridzin (50, 100, and 200 mol/L) resulted in a small but insignificant inhibition of C3G disappearance from the mucosal solution (decrease of disappearance with glucose, 33%; with phloridzin, 18%; NS). However, when the flavonol Q3G (50 mol/L) was added to the mucosal solution together with the C3G, the disappearance of C3G was significantly decreased (74%; p <0.001), and Q3G disappeared instead. In addition, we found phloretin and quercetin, the aglycones of phloridzin and Q3G, respectively, present in the mucosal solution and tissue extracts, indicating hydrolysis of these compounds by the enterocytes of the jejunum. In contrast, the aglycone cyanidin was not detected at all. Our results show that in the mouse small intestine, ACN absorption is not solely dependent on the activity of the SGLT1 transporter, as D-glucose and phloridzin had only a slight effect on uptake. Q3G, however, clearly inhibited C3G disappearance. These results suggest that there might be a competitive inhibition between C3G and Q3G absorption. It is possible that an absorption mechanism other than the SGLT1 is involved, which has a structural preference toward flavonol

Viscous Food Matrix Influences Absorption and Excretion but Not Metabolism of Blackcurrant Anthocyanins in Rats

The aim of the present study was to investigate the effect of a simultaneous intake of food and anthocyanins (ACNs) on ACN absorption, metabolism, and excretion. Blackcurrant ACNs (BcACNs) were dissolved in water with or without the addition of oatmeal and orally administered to rats, providing approximately 250 mg total ACNs per kilogram BW. Blood, urine, digesta, and tissue samples of the stomach, jejunum, and colon were subsequently collected at 0.25, 0.5, 1, 2, 3, 7, and 24 h. Identification and quantification of ACNs were carried out by Reversed phase-high-performance liquid chromatography (RP-HPLC) and liquid chromatography-mass spectrometry (LC-MS). Four major ACNs were present in the blackcurrant extract: delphinidin 3-O-glucoside, delphinidin 3-O-rutinoside, cyanidin 3-O-glucoside, and cyanidin 3-O-rutinoside. In plasma, the 4 ACNs of blackcurrant were identified and quantified. The time to reach maximal total ACN plasma concentration (Cmax BcACN/water = 0.37 ± 0.07 µmol/L; Cmax BcACN/oatmeal = 0.20 ± 0.05 µmol/L) occurred faster after BcACN/water (tmax= 0.25 h), than after BcACN/oatmeal administration (tmax= 1.0 h). In digesta and tissue samples, the 4 original blackcurrant ACNs were detected. The relative concentration of rutinosides in the digesta increased during their passage through the gastrointestinal tract, while the glucosides decreased. Maximum ACN excretion in urine occurred later after BcACN/oatmeal than after BcACN/water administration (3 compared with 2 h). The 4 original ACNs of blackcurrant in their unchanged form, as well as several metabolites, were identified in the urine samples of both groups. The simultaneous intake of food affects ACN absorption and excretion in the urine, but not metabolism

Structural identification of the main ellagitannins of a boysenberry (Rubus loganbaccus × baileyanus Britt.) extract by LC–ESI-MS/MS, MALDI-TOF-MS and NMR spectroscopy

Four ellagitannins from boysenberry, a cross between Rubus loganbaccus and Rubus baileyanus Britt., were isolated by preparative HPLC and the exact structures determined by a combination of LC–ESI-MS/MS, MALDI-TOF-MS and NMR spectroscopy. The two most abundant ellagitannins were identified as sanguiin H-6, which is known to be abundant in Rubus species, and the other was identified as an isomer of sanguiin H-10, which has not previously been reported in Rubus. The two less abundant ellagitannins were identified as sanguiin H-2 and [galloyl–bis-HHDP–glucose]2-gallate. Sanguiin H-2 has been previously reported in Rubus, whereas both sanguiin H-2 and [galloyl–bis-HHDP–glucose]2-gallate have been previously reported as hot-water degradation products of lambertianin C. Even though lambertianin C is reported to be a major ellagitannin in other Rubus species, it was not found in any of the fractions, suggesting that both sanguiin H-2 and [galloyl–bis-HHDP–glucose]2-gallate are present naturally in boysenberry

The in vivo antioxidant action and the reduction of oxidative stress by boysenberry extract is dependent on base diet constituents in rats

Dietary antioxidants are often defined by in vitro measures of antioxidant activity. Such measures are valid indicators of the antioxidant potential, but provide little evidence of activity as a dietary antioxidant. This study was undertaken to assess the in vivo antioxidant efficacy of a berry fruit extract by measuring biomarkers of oxidative damage to protein (carbonyls), lipids (malondialdehyde), and DNA (8-oxo-2'-deoxyguanosine urinary excretion) and plasma antioxidant status (antioxidant capacity, vitamin E) in rats when fed basal diets containing fish and soybean oils, which are likely to generate different levels of oxidative stress. Boysenberry (Rubus loganbaccus x baileyanus Britt) extract was used as the dietary antioxidant. The basal diets (chow, synthetic/soybean oil, or synthetic/fish oil) had significant effects on the biomarkers of oxidative damage and antioxidant status, with rats fed the synthetic/fish oil diet having the lowest levels of oxidative damage and the highest antioxidant status. When boysenberry extract was added to the diet, there was little change in 8-oxo-2'-deoxyguanosine excretion in urine, oxidative damage to proteins decreased, and plasma malondialdehyde either increased or decreased depending on the basal diet. This study showed that boysenberry extract functioned as an in vivo antioxidant and raised the antioxidant status of plasma while decreasing some biomarkers of oxidative damage, but the effect was highly modified by basal diet. Our results are further evidence of complex interactions among dietary antioxidants, background nutritional status as determined by diet, and the biochemical nature of the compartments in which antioxidants functio

An R2R3 MYB transcription factor determines red petal colour in an Actinidia (kiwifruit) hybrid population

Background\ud \ud Red colour in kiwifruit results from the presence of anthocyanin pigments. Their expression, however, is complex, and varies among genotypes, species, tissues and environments. An understanding of the biosynthesis, physiology and genetics of the anthocyanins involved, and the control of their expression in different tissues, is required. A complex, the MBW complex, consisting of R2R3-MYB and bHLH transcription factors together with a WD-repeat protein, activates anthocyanin 3-O-galactosyltransferase (F3GT1) to produce anthocyanins. We examined the expression and genetic control of anthocyanins in flowers of Actinidia hybrid families segregating for red and white petal colour. \ud \ud Results\ud \ud Four inter-related backcross families between Actinidia chinensis Planch. var. chinensis and Actinidia eriantha Benth. were identified that segregated 1:1 for red or white petal colour. Flower pigments consisted of five known anthocyanins (two delphinidin-based and three cyanidin-based) and three unknowns. Intensity and hue differed in red petals from pale pink to deep magenta, and while intensity of colour increased with total concentration of anthocyanin, no association was found between any particular anthocyanin data and hue. Real time qPCR demonstrated that an R2R3 MYB, MYB110a, was expressed at significant levels in red-petalled progeny, but not in individuals with white petals. \ud \ud A microsatellite marker was developed that identified alleles that segregated with red petal colour, but not with ovary, stamen filament, or fruit flesh colour in these families. The marker mapped to chromosome 10 in Actinidia. \ud \ud The white petal phenotype was complemented by syringing Agrobacterium tumefaciens carrying Actinidia 35S::MYB110a into the petal tissue. Red pigments developed in white petals both with, and without, co-transformation with Actinidia bHLH partners. MYB110a was shown to directly activate Actinidia F3GT1 in transient assays. \ud \ud Conclusions\ud \ud The transcription factor, MYB110a, regulates anthocyanin production in petals in this hybrid population, but not in other flower tissues or mature fruit. The identification of delphinidin-based anthocyanins in these flowers provides candidates for colour enhancement in novel fruits