Cyanidin-3-glucoside Research Articles

Characterization and bioaccessibility assessment of bioactive compounds from camu-camu (Myrciaria dubia) powders and their food applications

Camu-camu (Myrciaria dubia) is a tropical fruit known for its content of bioactive compounds. This study aimed to evaluate physicochemically, morphologically, andsensorialpowders from camu-camu obtained by spray-drying at two inlet temperatures (150 °C and 180 °C) with three encapsulating agents (maltodextrin, whey protein and a 50:50 mixture of both) and by freeze-drying of whole fruit. The use of maltodextrin protected bet anthocyanins (cyanidin-3-glucoside (C3G) and delphinidin-3-glucoside (D3G)), but whey protein showed a better protective effect on ascorbic and malic acids. These facts were confirmed during the storage stability test, finding that relative humidity is a critical variable in preserving the bioactive compounds of camu-camu powders. The powders with the highest content of bioactive compounds were added to a yogurt and a white grape juice, and then sensory evaluated. The bioaccessibility studies in gastric and intestinal phases showed better recovery percentages of bioactive compounds in camu-camu powders (up to 60.8 %) and beverages (up to 90 %) for C3G, D3G, ascorbic acid, and malic acid than in the fruit juice. Dehydration of camu-camu (M. dubia) is a strategy to increase the bioactive compounds stability, modulate the fruit sensory properties, and improve their bioavailability after incorporation in food matrices.

Cyanidin-3-O-glucoside and its derivative vitisin A alleviate androgenetic alopecia by exerting anti-androgen effect and inhibiting dermal papilla cell apoptosis

Androgenetic alopecia (AGA), one of the most common forms of hair loss, lacks satisfactory treatment methods in modern society. This study employed an experimental design combining in vitro and in vivo approaches to explore the effects of Cyanidin-3-O-glucoside (C3G) and Carboxypyranocyanidin-3-O-glucoside (Vitisin A) on AGA. In human dermal papilla cells (HDPCs), both anthocyanins demonstrated inhibitory effects on androgen receptors, significantly reduced dihydrotestosterone (DHT) induced apoptosis of HDPCs, and regulated the secretion of Fibroblast growth factor 7 and Transforming growth factor beta 1. In vitro transdermal experiment revealed that both C3G and Vitisin A could penetrate mice skin, aided by the application of cream. Furthermore, in vivo experiments with mice indicated that application of C3G or Vitisin A cream effectively improved hair follicles miniaturization, regression, and apoptosis caused by DHT. The repression of Wnt10b and β-catenin expression induced by DHT was prevented by C3G and Vitisin A in both cell and mouse model. Consequently, these findings suggest that C3G and Vitisin A could be considered as alternative methods for alleviating AGA.

Effects of paper pouches of different light transmittance on the phenolic synthesis and related gene expression in peach fruit

Bagging is a vital cultivation measure for producing high-quality peach fruit, which affects the appearance and internal quality of the fruit by mainly intervening in its exposure to light. However, it is not entirely clear whether bagging affects the content of phenolic compounds or which compounds are most sensitive to bagging treatment, and the regulatory role of bagging on phenolic synthetic-related genes is also unknown. In this experiment, four peach cultivars, 'BJ', 'XH', 'RG', and 'HYT', were bagged with four different types of bags at 50 days after full bloom, with no bag as control, and all fruits were harvested at the commercial maturation stage. The study found that bagged fruits had higher L*, b*, and h° values but lower a* and C* values than non-bagged fruits. Different cultivars and different phenolics exhibited different sensitivities to bagging treatments. Light intensity not only played a decisive role in the accumulation of anthocyanins in peach fruit but also had a strong and widespread impact on other phenolic substances. Overall, light not onlly significantly promoted the accumulation of cyanidin 3-glucoside, cyanidin 3-rutinoside, epicatechin, and rutin but also increased the accumulation of catechin, chlorogenic acid, and neochlorogenic acid to some extent, while shading by bagging inhibited the accumulation of these phenolics. Correspondingly, high light induced the upregulation of most structural genes and transcription factors, including PpPAL1, PpC3H1, PpC3H2, PpDFR, PpLDOX, PpUFGT, and PpMYB10.1, while low light inhibited the expression of these genes in the four varieties. In addition, PpHY5 homolog PpHYH was induced by high light, which might participate in the biosynthesis of the light-regulated phenolic in peach fruit. This study lays the foundation for further analysis of the regulation mechanism of light on the synthesis of phenolic compounds in peach fruit.

The Hypotensive and Vasodilatory Effects Observed in Rats Exposed to Chiranthodendron pentadactylon Larreat Flowers Can Be Attributed to Cyanidin 3-O-Glucoside

Chiranthodendron pentadactylon Larreat is a tree native to southeastern Mexico and Guatemala. Its flower is used in Mexican folk medicine to treat a variety of diseases, including conditions of blood pressure. However, scientific information on its usefulness in this pathology is lacking. The present study evaluates the effect of a methanolic extract (ME) from the flower and its active constituents on heart rate (HR) and mean arterial pressure (MAP) in anesthetized rats (MAPHR). The study also analyzed the effects on rat-isolated aortic rings (RIAR) and the rat mesenteric arterial bed (MABR). Active fractions were chromatographed, which led to the isolation of cyanidin 3-O-glucoside (C3G) identified through HPLC. The Chiranthodendron pentadactylon flowers produced hypotensive and vasorelaxant effects associated with C3G. The vasorelaxant effect is a mechanism underlying the synthesis and release of nitric oxide (NO). Neither cholinergic receptors nor prostaglandins are involved. ME and C3G cause cardiovascular depression in anesthetized rats via cholinergic and prostanoid mechanisms. Our research expands the scientific understanding of the flowers on the rat cardiovascular system. This amplifies the appreciation of the flower’s ethnomedicine employed to control blood pressure. However, researchers need to conduct toxicity studies to determine the safety of this plant.

The Purple leaf (Pl) Alleles, Plw and Pli, Regulate Leaf Color Development Independently from the Pb Gene of Purple pericarp (Prp) in Rice

Color development in various rice organs results from the complementary expression of genes involved in anthocyanin biosynthesis. The Purple pericarp (Prp) trait and the Purple leaf (Pl) trait both display epistasis, relying on the complement of the Pb and Pp genes for pericarp coloration and the Pl and Pp genes for leaf coloration, respectively. However, there is still genetic uncertainty in identifying the genes responsible for the various color expressions and intensities of rice grain pericarp and leaves. In this study, we characterized the inheritance patterns of color development and the mode of anthocyanin pigments in rice by crossing two parental mutant lines. YUM051, exhibiting dark purple leaves (Plw) and purple pericarp (Prp), was crossed with YUM144, which displayed light purple leaves (Pli) and a white pericarp (prp). The F1 plants exhibited dark purple leaves with purple pericarps, indicating the dominant nature of the purple leaf (Pl) and purple pericarp (Prp) traits. The rice Prp traits display a complementary interaction, reflected in a 9:7 ratio of purple to white pericarp. However, the Prp trait followed Mendelian segregation with a 3:1 ratio of purple to white pericarp in this cross, indicating homozygous dominant Pp alleles in both parental plants. Meanwhile, the segregation of the purple leaf color in the F2 generation of this cross followed complementary inheritance, exhibiting a 9:7 segregation ratio between purple leaves and greenish leaves with purple leaf margins. Moreover, the co-segregation of Prp and Pl traits in the cross between YUM051 (Plw) and YUM144 (Pli) plants did not adhere to the Mendelian 9:3:3:1 independent assortment ratio, confirming that the Pl gene and Pb gene are linked on the same chromosome. Cyanidin-3-O-glucoside (C3G) was detected in the leaves of all progeny resulting from the Plw and Pli cross. However, C3G was exclusively identified in the seeds of offspring carrying the dominant Pb gene. Therefore, the Plw and Pli alleles are Pl genes responsible for purple leaf color, while the Pb gene is responsible for purple pericarp color in rice; these genes function independently of each other.

Cyanidin-3-O-glucoside protects the brain and improves cognitive function in APPswe/PS1ΔE9 transgenic mice model

Cyanidin-3-O-glucoside (C3G) is a natural anthocyanin with antioxidant, anti-inflammatory, and antitumor properties. However, as the effects of C3G on the amyloidogenic pathway, autophagy, tau phosphorylation, neuronal cell death, and synaptic plasticity in Alzheimer’s disease models have not been reported, we attempted to investigate the same in the brains of APPswe/PS1ΔE9 mice were analyzed. After oral administration of C3G (30 mg/kg/day) for 16 weeks, the cortical and hippocampal regions in the brains of APPswe/PS1ΔE9 mice were analyzed. C3G treatment reduced the levels of soluble and insoluble Aβ (Aβ40 and Aβ42) peptides and reduced the protein expression of the amyloid precursor protein, presenilin-1, and β-secretase in the cortical and hippocampal regions. And C3G treatment upregulated the expression of autophagy-related markers, LC3B-II, LAMP-1, TFEB, and PPAR-α and downregulated that of SQSTM1/p62, improving the autophagy of Aβ plaques and neurofibrillary tangles. In addition, C3G increased the protein expression of phosphorylated-AMPK/AMPK and Sirtuin 1 and decreased that of mitogen-activated protein kinases, such as phosphorylated-Akt/Akt and phosphorylated-ERK/ERK, thus demonstrating its neuroprotective effects. Furthermore, C3G regulated the PI3K/Akt/GSK3β signaling by upregulating phosphorylated-Akt/Akt and phosphorylated-GSK3β/GSK3β expression. C3G administration mitigated tau phosphorylation and improved synaptic function and plasticity by upregulating the expression of synapse-associated proteins synaptophysin and postsynaptic density protein-95. Although the potential of C3G in the APPswe/PS1ΔE9 mouse models has not yet been reported, oral administration of the C3G is shown to protect the brain and improve cognitive behavior.Graphical

Enhancing the storage stability of mulberry anthocyanin extract through ternary complex with whey protein isolate and ferulic acid at neutral pH: Investigation of binding mechanisms

Mulberry anthocyanin extract (MAE) is a valuable natural pigment with potential applications in the food industry. However, its storage stability remains a challenge, as it is prone to degradation over time. To tackle this issue, the present study focuses on investigating the efficacy of utilizing whey protein isolate (WPI) and ferulic acid (FA) in combination at pH 6.3. The addition of FA reduced the ΔE values and the degradation of anthocyanin within MAE solution in the presence of WPI. Notably, the combination of WPI and FA exhibited a remarkable stabilizing effect on the MAE solution. Multi-spectroscopic analysis revealed the occurrence of non-covalent interactions mediated by hydrophobic interaction between β-lactoglobulin (β-LG) and cyanidin-3-O-glucoside (C3G) in the presence of FA, with improved binding affinity. While FA did not exhibit a copigmentation effect on the C3G solution, it enhanced the protective action of β-LG on the chromophoric structural form of C3G. Moreover, although the introduction of FA to the β-LG complex with C3G resulted in minor modifications to the secondary structure, in contrast to the binary complexes, its particle size increased. The molecular dynamics simulations also revealed that FA enhances the binding affinity between β-LG and C3G. These findings provide a foundation for enhancing the storage stability of anthocyanins and expanding the utilization of MAE pigment in the food industry.

Antioxidant Properties and Geroprotective Potential of Wheat Bran Extracts with Increased Content of Anthocyanins.

In recent years, there has been a focus on breeding wheat with high anthocyanin levels in order to improve food quality and human health. The objective of this study was to examine the antioxidant and geroprotective properties of wheat bran extracts using both in vitro and in vivo research methods. Two wheat lines were used: one with uncolored pericarp (anthocyanin-free) and another with colored pericarp (anthocyanin-containing). These lines differed in a specific region of chromosome 2A containing the Pp3/TaMyc1 gene, which regulates anthocyanin production. High-performance liquid chromatography-mass spectrometry revealed the presence of cyanidin glucoside and cyanidin arabinoside in the anthocyanin-containing wheat bran extract (+AWBE), while no anthocyanins were found in the anthocyanin-free wheat bran extract (-AWBE). The +AWBE showed higher radical scavenging activity (DPPH and ABTS assays) and membrane protective activity (AAPH oxidative hemolysis model) compared to the -AWBE. Both extracts extended the lifespan of female Drosophila, indicating geroprotective properties. This study demonstrates that wheat bran extracts with high anthocyanin levels have antioxidant and geroprotective effects. However, other secondary metabolites in wheat bran can also contribute to its antioxidant and geroprotective potential.

CTRP3/AMPK pathway plays a key role in the anti-hypertrophic effects of cyanidin-3-O-glucoside by inhibiting the inflammatory response.

Cardiac hypertrophy can be a pathological process that impairs heart function. Anthocyanins are a well-characterized type of natural antioxidant, and recent studies have shown that this type of compound has potential cardioprotective effects against different disorders, such as cardiac hypertrophy. We assessed the anti-hypertrophy potential of cyanidin-3-O-glucoside (C3G) and the mechanism associated with any observed effects. Hypertrophy symptoms were induced using the transverse aortic constriction (TAC) operation in vivo and angiotensin II (Ang II) in vitro. The effect of C3G on the development of hypertrophic symptoms was then determined. Moreover, we examined the influence of CTRP3 inhibition on the anti-hypertrophy function of C3G. The TAC operation induced cardiac fibrosis and heart weight increase, which was associated with increased production of cytokines and suppressed activity of the CTRP3/AMPK pathway. The impairments of heart structure and function were attenuated by C3G. Angiotensin II induced size increases of neonatal rat cardiomyocytes (NRCMs) in vitro, and this effect was inhibited by C3G. Furthermore, the inhibition of CTRP3 counteracted the function of C3G by promoting NRCM hyperplasia and inflammation. The results of the current study showed that the activation of CTRP3 contributed to the anti-hypertrophy effects of C3G.

The Role of Cyanidin-3-O-glucoside in Modulating Oxaliplatin Resistance by Reversing Mesenchymal Phenotype in Colorectal Cancer.

Epithelial-mesenchymal transition (EMT) plays an important role in the biological and biochemical processes of cells, and it is a critical process in the malignant transformation, and mobility of cancer. Additionally, EMT is one of the main mechanisms contributing to chemoresistance. Resistance to oxaliplatin (OXA) poses a momentous challenge in the chemotherapy of advanced colorectal cancer (CRC) patients, highlighting the need to reverse drug resistance and improve patient survival. In this study, we explored the response of cyanidin-3-O-glucoside (C3G), the most abundant anthocyanin in plants, on the mechanisms of drug resistance in cancer, with the purpose of overcoming acquired OXA resistance in CRC cell lines. We generated an acquired OXA-resistant cell line, named HCT-116-ROx, by gradually exposing parental HCT-116 cells to increasing concentrations of OXA. To characterize the resistance, we performed cytotoxicity assays and shape factor analyses. The apoptotic rate of both resistant and parental cells was determined using Hoechst 33342/Propidium Iodide (PI) fluorescence staining. Migration capacity was evaluated using a wound-healing assay. The mesenchymal phenotype was assessed through qRT-PCR and immunofluorescence staining, employing E-cadherin, N-cadherin, and Vimentin markers. Resistance characterization announced decreased OXA sensitivity in resistant cells compared to parental cells. Moreover, the resistant cells exhibited a spindle cell morphology, indicative of the mesenchymal phenotype. Combined treatment of C3G and OXA resulted in an augmented apoptotic rate in the resistant cells. The migration capacity of resistant cells was higher than parental cells, while treatment with C3G decreased the migration rate of HCT-116-ROx cells. Analysis of EMT markers showed that HCT-116-ROx cells exhibited loss of the epithelial phenotype (E-cadherin) and gain of the mesenchymal phenotype (N-cadherin and Vimentin) compared to HCT-116 cells. However, treatment of resistant cells with C3G reversed the mesenchymal phenotype. The morphological observations of cells acquiring oxaliplatin resistance indicated the loss of the epithelial phenotype and the acquisition of the mesenchymal phenotype. These findings suggest that EMT may contribute to acquired OXA resistance in CRC. Furthermore, C3G decreased the mobility of resistant cells, and reversed the EMT process, indicating its potential to overcome acquired OXA resistance.

Phenolic Compounds Stability of Grumixama (Eugenia brasiliensis) Juice during Processing and Storage

Grumixama is an anthocyanin-rich berry commonly found in South America, yet not widely consumed by Brazilians due to the lack of studies covering its technological properties. Therefore, the stability of anthocyanins and the activity of oxidoreductase enzymes in grumixama juice during thermal treatment (60 °C to 100 °C) and storage (at 25 °C and 7 °C) were evaluated. As a result, the pasteurization of grumixama juice at 80 °C for 60 s completely inactivated peroxidase (POD) and polyphenol oxidase (PPO), eliminated microorganisms, and induced low degradation of the total anthocyanins (40%) and minimal degradation of the total phenolic compounds. Four anthocyanins were monitored in the pasteurized juice, namely delphinidin 3-glucoside, cyanidin 3-glucoside, and two unidentified anthocyanins. Despite the temperature range, the qualitative chromatographic profile of the anthocyanins did not change, while the contents were affected. The binominal temperature/time of 80 °C/60 s effectively inactivated PPO and POD enzymes, promoted moderate alterations in the contents of total anthocyanins and total phenolic compounds, and ensured the microbiological quality of grumixama juice. Grumixama juice can be used as a health food due to its high content of antioxidant phenolic compounds, especially anthocyanins.

In Vitro Antioxidant Activity, Bioaccessibility, and Thermal Stability of Encapsulated Strawberry Fruit (Fragaria × ananassa) Polyphenols.

Bioactive compounds in red fruits, such as strawberries, are vulnerable to digestion, and encapsulation has become an alternative for their protection. This study aims at encapsulating strawberry juice (SJ) by freeze-drying with pea protein and okra mucilage (SJPO), pea protein and psyllium mucilage (SJPP), and pea protein, psyllium mucilage, and okra mucilage (SJPPO) and investigating the in vitro release. The highest encapsulation efficiency was observed in capsule SJPPO (95.38%) and the lowest efficiency in SJPO (82.45%). Scanning electron microscopy revealed an amorphous glassy structure for the structure of the strawberry microcapsules, and X-ray diffraction confirmed that observation. However, X-ray diffraction further showed that SJPPO was crystalline, indicating a tighter crosslinking density than the other microcapsules. Fourier transform infrared spectroscopy showed peaks at 3390 and 1650 cm-1, confirming the presence of polyphenols and polysaccharides in the strawberry microcapsules. Thermal stability was higher for SJPPO, and the observed thermal transitions were due to the bonds formed between the polymers and polyphenols. Pelargonidin 3-glucoside, cyanidin 3-glucoside, cyanidin, delphinidin, malvidin 3-glucoside, ellagic acid, chlorogenic acid, catechin, and kaempferol were identified in the strawberry microcapsules. Digestion affected the compounds' content; the bioaccessibility for SJ was 39.26% and 45.43% for TPC and TAC, respectively. However, encapsulation improved the bioaccessibility of both TPC (SJPP, 51.54%; SJPO, 48.52%; and SJPPO, 54.39%) and TAC (SJPP, 61.08%; SJPO, 55.03%; and SJPPO, 71.93%). Thus, encapsulating pea protein isolate, psyllium mucilage, and okra mucilage is an effective method to facilitate targeted release and preserve the biological activities of fruits.

Cyanidin-3-O-glucoside from blueberry anthocyanin extracts protects ARPE-19 cells against high glucose damage via REDD1/GSK3β pathway

The retinal pigment epithelium (RPE) serves dual roles: it acts as a selective barrier and also as a regulator for the photoreceptor layer situated above it. The RPE is considered a crucial target for halting the development and progression of diabetic retinopathy (DR). This study focuses on understanding the protective role of blueberry anthocyanin extracts (BAEs), particularly its anti-oxidant constituent, cyanidin-3-O-glucoside (C3G), against damage to RPE cells induced by high glucose (HG) levels. The findings revealed that the BAEs mitigated damage to HG-induced ARPE-19 cells by decreasing the intracellular reactive oxygen species (ROS) levels, which improved cell morphology and cell viability (p < 0.01). Importantly, these cytoprotective effects were linked to the C3G rich in BAEs. The underlying mechanism may involve C3G interrupting the ROS generation feedback loop by downregulating REDD1 expression, which in turn enhanced the retinal Nrf2 antioxidant response to HG through the promotion of the GSK3β phosphorylation at Ser-9. Moreover, C3G suppressed VEGFA expression by inhibiting REDD1 levels in HG-induced ARPE-19 cells, subsequently preventing an increase in vascular permeability. In conclusion, this study suggested that the C3G relieved HG-induced oxidative stress damage in ARPE-19 cells via REDD1/GSK3β pathway and inhibited an increase in vascular permeability by downregulating VEGFA expression. These insights could shed light on how this natural bioactive compound can help manage HG-associated eye disorders like DR.

Cyanidin-3-O-glucoside Mitigates the Ovarian Defect Induced by Zearalenone via p53-GADD45a Signaling during Primordial Follicle Assembly.

Zearalenone (ZEN) is well known as a kind of endocrine disruptor whose exposure is capable of causing reproductive toxicity in animals. Cyanidin-3-O-glucoside (C3G) is a derivative of cyanidin and owns multiple biofunctions, and prior efforts have suggested that C3G has therapeutic actions for reproductive diseases. In this article, a ZEN exposure model during primordial follicle assembly was constructed using the in vitro culture platform of neonatal mouse ovaries. We investigated the protective effect of C3G on ZEN-induced ovarian toxicity during primordial follicle assembly in mice, as well as its potential mechanism. Interestingly, we observed that C3G could effectively protect the ovary from ZEN damage, mainly by restoring primordial follicle assembly, which upregulated the expression of LHX8 and SOHLH1 proteins and relieved ZEN-induced DNA damage. Next, to explore the mechanism by which C3G rescued ZEN-induced injury, we performed RNA sequencing (RNA-seq). The bioinformatic analysis illustrated that the rescue pathway of C3G was associated with p53-Gadd45a signaling and cell cycle. Then, western blotting and flow cytometry results revealed that C3G restored the expression levels of cyclin-dependent kinase 6 (CDK6) and cyclin D2 (CCND2) and regulated the ovarian cell cycle to normal. In conclusion, our findings manifested that C3G could alleviate ZEN-induced primordial follicle assembly impairment by restoring the cell cycle involved in p53-GADD45a signaling.

Cyanidin-3-glucoside protects the photooxidative damage of retinal pigment epithelium cells by regulating sphingolipid signaling and inhibiting MAPK pathway

Cyanidin-3-glucoside (C3G) is the most common anthocyanin in dark grains and berries and is a food functional factor to improve visual health. However, the mechanisms of C3G on blue light-induced retinal pigment epithelial (RPE) cell photooxidative damage needs further exploration. We investigated the effects of C3G on blue light-irradiated A2E-containing RPE cells and explored whether sphingolipid, mitogen-activated protein kinase (MAPK), and mitochondria-mediated pathways are involved in this mechanism. Blue light irradiation led to mitochondria and lysosome damage in RPE cells, whereas C3G preserved mitochondrial morphology and function and maintained the lysosomal integrity. C3G suppressed the phosphorylation of JNK and p38 MAPK and mitochondria-mediated pathways to inhibit RPE cell apoptosis. Lipidomics data showed that C3G protected RPE cells against blue light-induced lipid peroxidation and apoptosis by maintaining sphingolipids balance. C3G significantly inhibited ceramide (Cer d18:0/15:0, Cer d18:0/16:0 and Cer d18:0/18:0) accumulation and elevated galactosylceramide (GalCer d18:1/15:0 and GalCer d18:1/16:0) levels in the irradiated A2E-containing RPE cells. Furthermore, C3G attenuated cell membrane damage by increasing phosphatidylcholine and phosphatidylserine levels. C3G inhibited apoptosis and preserved the structure of mitochondria and lysosome by regulating sphingolipid signaling and suppression of MAPK activation in RPE cells. Thus, dietary supplementation of C3G prevents retinal photooxidative damage.

OsGSTU34, a Bz2-like anthocyanin-related glutathione transferase transporter, is essential for rice (Oryza sativa L.) organs coloration

Anthocyanins are a flavonoid compound known as one of the most important chromogenic substances. They play several functions, including health promotion and sustaining plants during adverse conditions. They are synthesized at the endoplasmic reticulum and sequestered in the vacuole. In this work, we generated knock-out lines of OsGSTU34, a glutathione transporter's tau gene family, with no transgene line and off-target through CRISPR/Cas9 mutagenesis and highlighted the loss of pigmentation in rice flowers, leaves, stems, shoots, and caryopsis. The anthocyanin quantification in the wild-type BLWT and mutant line BLG34-8 caryopsis showed that cyanidin-3-O-glucoside (C3G) and peonidin-3-O-glucoside (P3G) were almost undetectable in the mutant line. A tandem mass tag (TMT) labeling proteomic analysis was conducted to elucidate the proteomic changes in the BLWT and BLG34-8. The result revealed that 1175 proteins were altered, including 408 that were down-regulated and 767 that were upregulated. The accumulation of the OsGSTU34-related protein (Q8L576), along with several anthocyanin-related proteins, was down-regulated. The enrichment analysis showed that the down-regulated proteins were enriched in different pathways, among which the phenylpropanoid biosynthesis pathway, flavonoid biosynthesis metabolites, and anthocyanin biosynthesis pathway. Protein interaction network prediction revealed that glutathione-S-transferase (Q8L576) was connected to the proteins involved in the flavonoid and anthocyanin biosynthesis pathways, such as flavanone 3-dioxygenase 1 (Q7XM21), leucoanthocyanidin dioxygenase 1 (Q93VC3), 4-coumarate-CoA ligase 2 (Q42982), phenylalanine ammonia-lyase (P14717), chalcone synthase 1 (Q2R3A1), and 4-coumarate-CoA ligase 5 (Q6ZAC1). However, the expression of the most important anthocyanin biosynthesis gene was not altered, suggesting that only the transport mechanism was affected. Our findings highlight new insight into the anthocyanin pigmentation in black rice and provide new perspectives for future research.

Covalent and non-covalent interaction of myofibrillar protein and cyanidin-3-O-glucoside: focus on structure, binding sites and in vitro digestion properties.

The aim of this study was to investigate the effects of covalent and non-covalent interactions between myofibrillar protein (MP) and cyanidin-3-O-glucoside (C3G) on protein structure, binding sites, and digestion properties. Four methods of inducing covalent cross-linking were used in the preparation of MP-C3G conjugates, including tyrosinase-catalyzed oxidation, alkaline pH shift treatment, free radical grafting, and ultrasonic treatment. A comparison was made between MP-C3G conjugates and complexes, and the analysis included sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), C3G binding ratio, liquid chromatography-tandem mass spectrometry (LC-MS/MS), protein side-chain amino acids, circular dichroism spectroscopy, three-dimensional fluorescence, particle size, and in vitro simulated digestion. Covalent bonding between C3G and amino acid side chains in MP was confirmed by LC-MS/MS. In covalent bonding, tryptophan residues, free amino groups and sulfhydryl groups were all implicated. Among the 22 peptides covalently modified by C3G, 30 modification sites were identified, located in lysine, histidine, tryptophan, arginine and cysteine. In vitro simulated digestion experiments showed that the addition of C3G significantly reduced the digestibility of MP, with the covalent conjugate showing lower digestibility than the non-covalent conjugate. Moreover, the digestibility of protein decreased more during intestinal digestion, possibly because covalent cross-linking of C3G and MP further inhibited trypsin targeting sites (lysine and arginine). Covalent cross-linking of C3G with myofibrillar proteins significantly affected protein structure and reduced protein digestibility by occupying more trypsin binding sites. © 2023 Society of Chemical Industry.

Temporal Changes in Flavonoid Components, Free Radical Scavenging Activities and Metabolism-Related Gene Expressions during Fruit Development in Chinese Dwarf Cherry (Prunus humilis)

Temporal changes in total flavonoid content (TFC), composition, free radical scavenging activity and metabolism-related gene expression of three Prunus humilis cultivars with distinctively different fruit colors were investigated in this study. The highest fruit TFCs of all three cultivars were observed at the initial sampling stage (young-fruit stage, YFS), which then declined gradually until fruit ripening. The dark-red-fruited cultivar ‘Jinou 1’ had the highest TFC, followed by the yellow-red-fruited cultivar ‘Nongda 3’ and the yellow-fruited cultivar ‘Nongda 5’. Thirteen flavonoid compounds were found in the three cultivars by using high-performance liquid chromatography (HPLC), and the content of most flavonoid compounds gradually decreased throughout the fruit-ripening process, with the exception of cyanidin-3-O-glucoside (C3G). C3G, as the main anthocyanin in P. humilis fruits, increased drastically during the fruit-coloring process of cultivars ‘Jinou 1’ and ‘Nongda 3’, while it was not detected in the developing fruits of cultivar ‘Nongda 5’. The antioxidant activity assay (DPPH, FRAP and ABTS) revealed that fruits of all three cultivars at YFS also had the highest antioxidant activities, and cultivar ‘Jinou 1’ had the highest antioxidant activities. Correlation analysis revealed that the antioxidant activities were significantly positively correlated with the TFCs and contents of the main compounds such as catechin, proanthocyanidin B1 and phloretin-2′,4-O-diglucoside (p &lt; 0.01). Moreover, gene expression analysis showed that the flavonoid biosynthetic genes had different expression patterns in the three cultivars. The expression levels of ChCHS, ChCHI, ChF3H, ChDFR, ChLDOX and ChUFGT increased gradually with fruit ripening in cultivar ‘Jinou 1’, while all flavonoid-related genes in cultivar ‘Nongda 5’ decreased gradually during fruit development. The results from our study could significantly contribute to the deeper understanding of flavonoid accumulation mechanisms in P. humilis fruits and also help facilitate the targeted cultivar development and the utilization as a functional food of this fruit species.

Effect of high pressure homogenization on the interaction between corn starch and cyanidin-3-O-glucoside

The effects of high pressure homogenization (HPH) at different pressures (50, 100, 150 and 200 MPa) and temperatures (4, 20, 40, 60 and 80 °C) on the interaction between corn starch (CS) and cyanidin-3-O-glucoside (C3G) were investigated. Based on analyses of zeta potential, attenuated total reflection-flourier transformed infrared spectroscopy and binding rate after adding shielding agents, the main interaction force changed from electrostatic interaction to hydrogen bonds. In comparison, the interaction between CS and C3G exhibited greater strength at low temperatures and pressures. Especially, 4 °C/50 MPa HPH caused the most significant enhancement in binding rate and binding amount, from 9.56 % to 25.16 % and 0.96 μg/mg CS to 2.52 μg/mg CS, respectively. At this condition, the specific surface area of CS-C3G increased from 433.57 ± 0.91 m2/kg to 440.93 ± 1.01 m2/kg. Surface fluorescence reduction was observed by confocal laser scanning microscopy, further X-ray diffraction patterns indicated the retention of partial spatial structure. Therefore, HPH opened the entry channels, increased contact area and preserved steric hindrance, which increased hydrogen bonding sites. At high temperatures and high pressures (> 40 °C, > 100 MPa), the increasing free starch chains provided new hydrogen bonding sites. Overall, HPH was an effective method to enhance the interaction by affecting starch structure.

Unravelling the anthocyanin-binding capacity of native starches from different botanical origins

In this study, the cyanidin-3-O-glucoside (C3G)-binding capacities of three native starches were investigated. While potato starch had the largest binding capacity of 0.34 mg/100 mg, corn and pea starch had binding capacities of 0.17 and 0.06 mg/100 mg. Confocal microscopy confirmed the binding results and revealed close associations between the surface properties and binding capacities. These findings were further substantiated with wettability and gelatinization results. The morphological observations showed that corn starch had advantageous particle sizes and more surface gullies, providing more opportunities to bind C3G. The zeta potential results, however, indicated that potato starch had the highest negative surface charges (−24 mV). These favorable electronic characteristics were believed to be responsible for the strongest electrostatic interactions. Hydrogen bonds, however, had a negligible effect on the formation of complexes. Overall, the negative surface charges and specific surface areas of the native starches were the most important factors determining C3G-binding capacities.