The health-promoting anthocyanin petanin in Lycium ruthenicum fruit: a promising natural colorant.

Acylated anthocyanins derived from dietary sources have gained significant attention due to their health-promoting properties and potential as natural colorants with high stability. However, exploration of the functional food products using acylated anthocyanins enriched in fruits and vegetables remains largely delayed in food industries. The black goji (Lycium ruthencium) fruit (LRF) is a functional food that is extensively used due to its exceptionally high levels of acylated anthocyanins, including petanin. This review provides a comprehensive summary of the functional properties and anthocyanin components of LRF. The stability, bioaccessibility, bioavailability, and bioactivities of petanin, the major anthocyanin component, are compared with those of LRF anthocyanin extracts and other food sources. Furthermore, the biosynthetic pathway and regulatory network of petanin in LRF are proposed and constructed, respectively. The key genes that could be potentially used for metabolic engineering to produce petanin are predicted. Finally, the potential application of petanin derivatives in the food industry is also discussed. This review presents comprehensive and systematic information about the dual-function of petanin as a bioactive component and a promising natural colorant for future food industrial applications.

Deciphering the interaction mechanism between soy protein isolate and fat-soluble anthocyanin on experiments and molecular simulations.

In this work, the acylated anthocyanin (Ca-An) was prepared by enzymatic modification of black rice anthocyanin with caffeic acid, and the binding mechanism of Ca-An to soybean protein isolate (SPI) was investigated by experiments and computer simulation to expand the potential application of anthocyanin in food industry. Multi-spectroscopic studies revealed that the stable binding of Ca-An to SPI induced the folding of protein polypeptide chain, which transformed the secondary structure of SPI trended to be flexible. The microenvironment of protein was transformed from hydrophobic to hydrophilic, while tyrosine played dominant role in quenching process. The binding sites and forces of the complexes were determined by computer simulation for further explored. The protein conformation of the 7S and 11S binding regions to Ca-An changed, and the amino acid microenvironment shifted to hydrophilic after binding. The results showed that more non-polar amino acids existed in the binding sites, while in binding process van der Waals forces and hydrogen bonding played a major role hydrophobicity played a minor role. Based on MM-PBSA analysis, the binding constants of 7S-Ca-An and 11S-Ca-An were 0.518 × 106 mol-1 and 5.437 × 10-3 mol-1, respectively. This information provides theoretical guidance for further studying the interaction between modified anthocyanins and biomacromolecules.

Acylated anthocyanin inhibited the formation of heterocyclic amines in hybrid chemical model system and its underlying mechanism.

Enzymatic acylation was employed to synthesize acylated anthocyanin, and a hybrid chemical model system was used for the formation of heterocyclic amines. And the inhibition effect and underline mechanism were investigated by analyzing the variations in important precursors and intermediates. Results confirmed that cyanidin-3-(6-cinnamoyl) -glycosidase (C3(6C)G) with a purity of 98.9% was obtained. HPLC identified seven types of heterocyclic amines (IQ, MeIQx, 4, 8-DimeiqX, Norharman, Harman, PhIP, and AαC) generated in the chemical model. (C3(6C)G) showed a good concentration-dependent manner for the inhibition effect on most HCAs except for MeIQx and PhIP. It also suppressed the glucose content, showed a dose-dependent manner in creatine/creatinine inhibition, and could scavenge formaldehyde, acetaldehyde, and phenylacetaldehyde. Two potential pathways might be involved: 1. by inhibiting the content of precursors (glucose and creatinine), competing with the formation of amino acids, to suppress HCAs generation; 2 through the removal of reactive carbonyl, reducing its reaction with creatinine.

Effect of Growth Stages on Anthocyanins and Polyphenols in the Root System of Sweet Potato.

The storage roots of purple-fleshed sweet potato contain a variety of anthocyanins and polyphenols. Little is known about changes in the total content and composition of anthocyanins and polyphenols in the early growth stages of the root system. In this study, we investigated the changes in anthocyanins and polyphenols in the root system of purple-fleshed sweet potato cultivars at 15, 30, 45, and 60 days after transplant (DAT). Unexpectedly, the highest percentage of acylated anthocyanins in three purple-fleshed cultivars among all growth stages was at 15 DAT. On the other hand, the total polyphenol content in the early growth stages of the root system increased rapidly toward 45 DAT, just before the beginning of storage root enlargement, and then decreased rapidly as the storage roots began to enlarge. These data indicate that the early growth stage of the root system is a critical time. This timing may present a strategy to maximize the accumulation of polyphenols with high antioxidant activity, as well as acylated anthocyanins, to protect against abiotic and biotic stresses.

Metabolic perturbations and key pathways associated with the bacteriostatic activity of Clitoria ternatea flower anthocyanin fraction against Escherichia coli.

Clitoria ternatea flowers are rich in anthocyanins and possess various biological activities. Specifically, the antibacterial mechanism of action of C. ternatea anthocyanins remains unknown and was investigated in Escherichia coli . A time-kill assay was used to assess the antibacterial activity and the metabolic perturbations in E. coli were investigated utilizing liquid chromatography-mass spectrometry (LC-MS)-based metabolomics. Pathway analyses were carried out for metabolites showing ≥2-fold changes. The anthocyanin fraction remarkably reduced the growth of E. coli at 4 h by 95.8 and 99.9 % at minimum inhibitory concentration (MIC) and 2× MIC, respectively. The anthocyanin fraction (MIC) had a bacteriostatic effect and was shown to have perturbed glycerophospholipids (1-acyl-sn-glycero-3-phosphoethanolamine, phosphatidylglycerol, diacylglycerol and cardiolipin), amino acids (valine, tyrosine and isoleucine) and energy (ubiquinone and NAD) metabolites at 1 and 4 h. This study demonstrated significant metabolic perturbations of the glycerophospholipid, amino acid and energy metabolism, with these being the key pathways involved in the bacteriostatic activity of anthocyanins from C. ternatea, which may have promise as bacteriostatic agents for E. coli -related infections.

Intramolecular copigmentation in malvidin-3-O-(6-O-p-coumaryl)-glucoside: Insights from experimental and theoretical study.

Intramolecular copigmentation, a natural phenomenon occurring widely in acylated anthocyanins, can stabilize anthocyanins to a great extent and produce color changes. In this study, the mechanism underlying the intramolecular copigmentation of malvidin-3-O-(6-O-p-coumaryl)-glucoside (MvCG) was systematically elucidated using experimental and theoretical approaches. Color analysis by UV-vis spectroscopy revealed an obvious bathochromic shift for MvCG compared to its non-acylated form, as well as higher thermostability of the former. Two dimensional NOESY spectra indicated close proximity between the coumaryl group and anthocyanin B ring in space. Deeper insights into the relationship between the conformational features and optical properties were acquired through TDDFT calculations. Based on the results, the most reasonable conformation of MvCG was proposed: the coumaryl group folded over the anthocyanin B ring in an aslant-parallel arrangement, generating intramolecular copigmentation interactions.

Effects of organic acids on color intensification, thermodynamics, and copigmentation interactions with anthocyanins.

Anthocyanins are attractive alternatives to synthetic colorants, but their low stability impedes practical applications. Intermolecular copigmentation can enhance both color intensity and stability. Herein, the copigmentation interactions of Kyoho grape skin anthocyanins (KSA) or cyanidin-3-O-glucoside (Cy-G) with organic acids were investigated. Color enhancement was evaluated at different acid molar ratios and treatment temperatures. The optimal copigmentation effects were observed for KSA/tannic acid (1:150) and Cy-G/tannic acid (1:100). Based on enthalpy variation, KSA/ferulic acid and Cy-G/ferulic acid exhibited the highest stability. The distinct color differences observed in the presence of different acids were attributed to structural effects. The influence of ferulic acid on various anthocyanins was also evaluated using theoretical approaches. Owing to steric hindrance, the acyl groups in KSA affected the spatial conformation, hydrogen bonding, and van der Waals interactions of the complexes. Further, hydroxyl groups decreased complex stability. These findings contribute to furthering the understanding of copigmentation effects.

Inhibitory effect of acylated anthocyanins on heterocyclic amines in grilled chicken breast patty and its mechanism.

Heterocyclic amines (HCAs) are a group of carcinogenic substances produced in protein-rich poultry meat under high-temperature. Enzymatic acylation of anthocyanins (ACNs) is a reliable way to improve their stability, and we recently found the acylated cyaniding-3-O-glucose (cyanidin-3-6-cinnamoyl-glucoside, C3(6C)G) could effective inhibit the HCAs formation, but the underline mechanism was still obscure. Thus, the present study investigated the inhibitory effect ofC3(6C)G on HCAs formation in the food system (chicken breast) and to explore the potential mechanism. The results showed that C3(6C)G with different concentrations (0.1, 0.5 and 1.0 mg/mL) could significantly inhibit lipid oxidation and decrease the total HCAs content (P<0.05) in chicken breast meat patty after roasting. The samples with 0.1 mg/mL C3(6C)G had the best inhibition effect on total HCAs, with an inhibition rate of 28%, and the inhibition rates for IQ, Harman, TRP-P-2, PhIP and AαC were 34%, 46%, 100%, 54% and 41%, respectively.

Matrix-assisted laser desorption/ionization mass spectrometry-guided visualization analysis of intestinal absorption of acylated anthocyanins in Sprague-Dawley rats.

It is unknown whether intestinal absorption of acylated anthocyanins occurs in their intact or metabolized form. In this study, with the aid of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) imaging, intestinal absorption of acylated anthocyanins was visually investigated. Anthocyanin extracts from purple carrots were orally administered to Sprague-Dawley rats. Acylated cyanidins were absorbed into portal and circulating blood systems in their intact form, and aglycon; cyanidin 3-O-(6-O-feruloyl-ß-d-glucopyranosyl)-(1 â†’ 6)-[ß-d-xylopyranosyl-(1 â†’ 2)]-ß-d-galactopyranoside (Cy3XFGG), and showed a high absorption of 39.3 ± 0.1 pmol/mL-plasma at 60 min after administration. MALDI-MS imaging analysis of the rat jejunum membranes showed that an organic anion transporting polypeptide (OATP) transporter was involved in Cy3XFGG transport, while deacylated anthocyanins were incorporated through both the glucose transporter 2 and OATP routes. In conclusion, acylated anthocyanin, Cy3XFGG, can be absorbed in its intact form through intestinal OATP.

Bioactive Compounds and Antioxidant Capacity in Anthocyanin-Rich Carrots: A Comparison between the Black Carrot and the Apulian Landrace "Polignano" Carrot.

The carrot is one of the most cultivated vegetables in the world. Black or purple carrots contain acylated anthocyanins which are of special interest to the food industry for their stability and nutraceutical characteristics. Anthocyanin-rich fruits and vegetables have gained popularity in the last ten years, due to the health benefits they provide. In this paper, the characterizations of the bioactive compounds and antioxidant capacities of different anthocyanin-containing carrots (a black carrot-BC, and a local purple carrot, the "Polignano" carrot-PC), compared to the commercial orange carrot (OC) (lacking of anthocyanins), are reported. The anthocyanin profiles of the polyphenolic extracts of BC and PC were similar, but differences were observed at quantitative levels. The total anthocyanin content in BC was more than twice that in PC (13.84 ± 0.61 vs. 5.64 ± 0.48 mg K Eq. g-1 DW). Phenolic acids (mostly chlorogenic acid) were also present at high level in anthocyanin-rich carrots compared to OC. High polyphenol content accounted also for a high reducing capacity (evaluated by Folin-Ciocalteu reagent, FCR), and antioxidant capacity (evaluated by TEAC and ORAC assays) which were the highest for BC (FCR value: 16.6 ± 1.1 mg GAE. g-1 DW; TEAC: 76.6 ± 10.6 µmol TE. g-1 DW; ORAC: 159.9 ± 3.3 µmol TE. g-1 DW). All carrot genotypes (mostly OC) were rich in carotenoids (BC 0.14 ± 0.024; PC 0.33 ± 0.038; OC 1.29 ± 0.09 mg. g-1 DW), with predominance of α and ß-carotene, in OC, and lutein in BC. PC showed the highest malic acid and sugar (glucose plus fructose) content. In conclusion, while BC is remarkable for nutraceutical features, the local genotype ("Polignano" carrot) is worth considering in genetic biodiversity conservation programme.

New acylated cyanidin glycosides extracted from underutilized potential sources: Enzymatic synthesis, antioxidant activity and thermostability.

Interest in anthocyanins has increased remarkably in recent decades, although their wider application has been hampered by instability problems. Thus, this study aimed at developing a strategy to gain access to more stable anthocyanins via enzymatic esterification. For that purpose, three cyanidin derivatives were obtained from underutilized, but easily accessible sources, and their total anthocyanin content was quantified. The purity of cyanidins obtained ranged from 40% to 88% depending on their source. Subsequently, the critical enzymatic reaction conditions were established, and the best results were found using tert-butanol as a solvent, 20 g/L of lipase B from Candida Antarctica, and vinyl cinnamate as acyl donor at ratio 250:1 (acyl donor to anthocyanin). Finally, five new acylated anthocyanin derivatives were synthesized with improved antioxidant activity and thermostability, in comparison to the cyanidin-3-glucoside, which is an advantageous feature for industrial applications.

Variation in anthocyanin profiles of 27 genotypes of red cabbage over two growing seasons.

Acylated anthocyanins, such as those found in red cabbage, are more heat-, light-, and alkaline pH-stable than non-acylated anthocyanins, making them attractive for a variety of commercial applications. A UPLC-DAD-MSE method with an optimized chromatographic strategy was used to identify 29 red cabbage anthocyanins, predominantly acylated and glucosylated cyanidin derivatives. Anthocyanin profiles of 27 red cabbage genotypes harvested in consecutive growing seasons were measured and assessed for variation. Three unique anthocyanin profile fingerprints were identified through hierarchical clustering analysis. PCA analysis identified anthocyanin accumulation traits and genotypes with high diversity which can be utilized in future investigations into the genetic and molecular basis for anthocyanin production, acylation, and diversity.