Improvement of the Color Stability of Cyanidin-3-glucoside by Fatty Acid Enzymatic Acylation

Effect of glycosylation, acylation and pyranylation at cyanidin C-ring on its interaction with vitamin C in apple juice beverage matrix

BACKGROUND

Synchronous degradation between anthocyanin and vitamin C was found in fruit and vegetable juice matrices. To investigate whether the C-ring of anthocyanin is the key site of this interaction, cyanidin with four different C-ring modifications (3-glucosylation, 3,5-diglucosylation, 6″-malonylation, pyranylation) was added to vitamin C-containing apple juice, and the changes of anthocyanin retention, vitamin C retention, color, antioxidative activity and differential metabolites were analyzed.

RESULTS

The anthocyanin retention was in the order of pyranylation >6″-malonylation >3,5-diglucosylation >3-glucosylation. The vitamin C retention was in the order of 6″-malonylation > pyranylation >3,5-diglucosylation >3-glucosylation. The order of color stability was the same as that of anthocyanin retention, and the order of antioxidative activity was opposite to that of vitamin C retention. The results showed that modification at the C-ring limited the activity of anthocyanin, and suggested that the C-ring was one of the key sites for anthocyanin and vitamin C interaction. The shared differential metabolite of all apple juice matrices added with different anthocyanins was trans-hinokiresinol, which was likely generated from anthocyanin skeleton reacted with certain compounds in apple juice.

CONCLUSION

This study showed that modification of the anthocyanin C-ring could affect the anthocyanin and vitamin C interaction to some extent, which provided valuable insights for the application of anthocyanin C-ring modification in shelf-life quality control of typical fruit and vegetable beverages with the coexistence of anthocyanin and vitamin C. © 2024 Society of Chemical Industry.

Progress on molecular modification and functional applications of anthocyanins

Anthocyanins have attracted a lot of attention in the fields of natural pigments, food packaging, and functional foods due to their color, antioxidant, and nutraceutical properties. However, the poor chemical stability and low bioavailability of anthocyanins currently limit their application in the food industry. Various methods can be used to modify the structure of anthocyanins and thus improve their stability and bioavailability characteristics under food processing, storage, and gastrointestinal conditions. This paper aims to review in vitro modification methods for altering the molecular structure of anthocyanins, as well as their resulting improved properties such as color, stability, solubility, and antioxidant properties, and functional applications as pigments, sensors and functional foods. In industrial production, by mixing co-pigments with anthocyanins in food systems, the color and stability of anthocyanins can be improved by using non-covalent co-pigmentation. By acylation of fatty acids and aromatic acids with anthocyanins before incorporation into food systems, the surface activity of anthocyanins can be activated and their antioxidant and bioactivity can be improved. Various other chemical modification methods, such as methylation, glycosylation, and the formation of pyranoanthocyanins, can also be utilized to tailor the molecular properties of anthocyanins expanding their range of applications in the food industry.

Esterification of black bean anthocyanins with unsaturated oleic acid, and application characteristics of the product

Esterification of anthocyanins with saturated fatty acids have been widely investigated, while that with unsaturated fatty acids is little understood. In this study, crude extract (purity ∼ 35 %) of cyanidin-3-O-glucoside (C3G) from black bean seed coat was utilized as reaction substrate, and enzymatically acylated with unsaturated fatty acid (oleic acid). Optimization of various reaction parameters finally resulted in the highest acylation rate of 54.3 %. HPLC-MS/MS and NMR analyses elucidated the structure of cyanidin-3-O-glucoside-oleic acid ester (C3G-OA) to be cyanidin-3-O-(6″-octadecene)-glucoside. Introduction of oleic acid into C3G improved the lipophilicity, antioxidant ability, and antibacterial activity. Further, the color and substance stability analyses showed that the susceptibility of C3G and C3G-OA to different thermal, peroxidative, and illuminant treatments were highly pH dependent, which suggested individual application guidelines. Moreover, C3G-OA showed lower toxicity to normal cell (QSG-7701) and better inhibitory effect on the proliferation of HepG2 cells than C3G, which indicated its potential anti-tumor bioactivity.

Chitosan/Polyvinyl Alcohol-Based Biofilms Using Ternary Deep Eutectic Solvents towards Innovative Color-Stabilizing Systems for Anthocyanins

Anthocyanins are amazing plant-derived colorants with highly valuable properties; however, their chemical and color instability issues limit their wide application in different food industry-related products such as active and intelligent packaging. In a previous study, it was demonstrated that anthocyanins could be stabilized into green plasticizers namely deep eutectic solvents (DESs). In this work, the fabrication of edible films by integrating anthocyanins along with DESs into biocompatible chitosan (CHT)-based formulations enriched with polyvinyl alcohol (PVA) and PVA nanoparticles was investigated. CHT/PVA-DES films' physical properties were characterized by scanning electron microscopy, water vapor permeability, swelling index, moisture sorption isotherm, and thermogravimetry analysis. Innovative red-to-blue formulation films were achieved for CHT/PVA nanoparticles (for 5 min of sonication) at a molar ratio 1:1, and with 10% of ternary DES (TDES)-containing malvidin-3-glucoside (0.1%) where the physical properties of films were enhanced. After immersion in solutions at different pH values, films submitted to pHs 5-8 were revealed to be more color stable and resistant with time than at acidic pH values.

The chromogenic mechanism of natural pigments and the methods and techniques to improve their stability: A systematic review

Pigments have become a very important part of food research, not only adding sensory properties to food, but also providing functional properties to the food system. In this paper, we review the source, structure, modification, encapsulation and current status of the three main types of natural pigments that have been studied in recent years: polyphenolic flavonoids, tetraterpenoids and betaines. By examining the modification of pigment, the improvement of their stability and the impact of new food processing methods on the pigments, a deeper understanding of the properties and applications of the three pigments is gained, the paper reviews the research status of pigments in order to promote their further research and provide new innovations and ideas for future research in this field.

Pharmacological Activities and Chemical Stability of Natural and Enzymatically Acylated Anthocyanins: A Comparative Review

Anthocyanins (ANCs) are naturally occurring water-soluble pigments responsible for conferring red, blue, and purple colors to fruits, vegetables, flowers, and grains. Due to their chemical structure, they are highly susceptible to degradation by external factors, such as pH, light, temperature, and oxygen. Naturally acylated anthocyanins have proven to be more stable in response to external factors and exhibit superior biological effects as compared with their non-acylated analogues. Therefore, synthetic acylation represents a viable alternative to make the application of these compounds more suitable for use. Enzyme-mediated synthetic acylation produces derivatives that are highly similar to those obtained through the natural acylation process, with the main difference between these two pathways being the catalytic site of the enzymes involved in the synthesis; acyltransferases catalyze natural acylation, while lipases catalyze synthetic acylation. In both cases, their active sites perform the addition of carbon chains to the hydroxyl groups of anthocyanin glycosyl moieties. Currently, there is no comparative information regarding natural and enzymatically acylated anthocyanins. In this sense, the aim of this review is to compare natural and enzyme-mediated synthetic acylated anthocyanins in terms of chemical stability and pharmacological activity with a focus on inflammation and diabetes.

Identification and functional characterization of AcMYB113 in anthocyanin metabolism of Aesculus chinensis Bunge var. chinensis leaves

Anthocyanins can be induced by environmental factors such as low-temperature and play essential roles in plant color formation. In this study, leaves of Aesculus chinensis Bunge var. chinensis with different colors under natural low-temperature in autumn were collected and grouped into green leaf (GL) and red leaf (RL). To reveal the underlying mechanism of color formation in RL, a combined analysis of the metabolome and transcriptome was conducted with GL and RL. Metabolic analyses revealed that total anthocyanin content and primary anthocyanin components were increased RL relative to GL and cyanidin was the main anthocyanin compound in RL. Transcriptome analysis provided a total of 18720 differentially expressed genes (DEGs), of which 9150 DEGs were upregulated and 9570 DEGs were downregulated in RL relative to GL. KEGG analysis showed that DEGs were mainly enriched in flavonoid biosynthesis, phenylalanine metabolism, and phenylpropanoid biosynthesis. Furthermore, co-expression network analysis indicated that 56 AcMYB transcription factors were highly expressed in RL compared with GL, among which AcMYB113 (an R2R3-MYB TF) had a strong correlation with anthocyanins. Overexpression of AcMYB113 in apple resulted in dark-purple transgenic calluses. In addition, the transient expression experiment showed that AcMYB113 enhanced anthocyanin synthesis by activating pathways of anthocyanin biosynthesis in leaves of Aesculus chinensis Bunge var. chinensis. Taken together, our findings reveal new insights into the molecular mechanism of anthocyanin accumulation in RL and provide candidate genes for the breeding of anthocyanin-rich cultivars.

Enzymatic lipophilization of bioactive compounds with high antioxidant activity: a review

Food products contain bioactive compounds such as phenolic and polyphenolic compounds and vitamins, resulting in a myriad of biological characteristics such as antimicrobial, anticarcinogenic, and antioxidant activities. However, their application is often restricted because of their relatively low solubility and stability in emulsions and oil-based products. Therefore, chemical, enzymatic, or chemoenzymatic lipophilization of these compounds can be achieved by grafting a non-polar moiety onto their polar structures. Among different methods, enzymatic modification is considered environmentally friendly and may require only minor downstream processing and purification steps. In recent years, different systems have been suggested to design the synthetic reaction of these novel products. This review presents the new trends in this area by summarizing the essential enzymatic modifications in the last decade that led to the synthesis of bioactive compounds with attractive antioxidative properties for the food industry by emphasizing on optimization of the reaction conditions to maximize the production yields. Lastly, recent developments regarding characterization, potential applications, emerging research areas, and needs are highlighted.

Preparation of 10-(hexylcarbamoyl)pyranomalvidin-3-glucoside from 10-carboxypyranomalvidin-3-glucoside using carbodiimide chemistry

Anthocyanins and pyranoanthocyanins are appealing natural pigments for replacement of synthetic ones. However, due to instability and solubility issues, lipophilization process of anthocyanins has raised as a valuable and efficient strategy to extend their stability and affinity into liposoluble formulations and enhance their unique physicochemical and biological properties. In this work, 10-carboxypyranomalvidin-3-glucoside was functionalized with hexylamine via carbodiimide chemistry compatible with the absence of hydroxyl protecting groups. A new amide conjugate attached to an alkyl chain with better hydrophobic features was obtained and isolated from its precursor. Mass spectrometry, FTIR, and NMR spectroscopy confirmed that the lipophilization site took place at the carboxyl group and the octanol-water partition coefficient determined by UV-Vis revealed its superior affinity for non-polar media. Overall, we reported a new pyranoanthocyanin lipophilic derivative for the first time which encourage further investigation for this novel class of compounds towards their incorporation into lipid-based foods and cosmetic formulations.

Antimicrobial activity of cyanidin-3-O-glucoside-lauric acid ester against Staphylococcus aureus and Escherichia coli

Enzymatic acylation of anthocyanin with fatty acid improves its lipophilic solubility and application potential. Nevertheless, evaluation of functional properties of product is premise for application. This study investigated the antimicrobial potential and the underlying mechanisms of an acylated anthocyanin, namely, cyanidin-3-O-glucoside-lauric acid ester (C3G-LA), to provide guidelines for its application. C3G-LA exhibited outstanding antibacterial activity against Staphylococcus aureus [minimum inhibitory concentration (MIC) = 0.3125 mg/mL] and modest activity against Escherichia coli (MIC = 5 mg/mL). Moreover, C3G-LA manifested bactericide ability against S. aureus at 0.625 mg/mL. Decreases in membrane integrity (by 96% and 92% at MIC in S. aureus and E. coli, respectively), intracellular ATP concentration (by 96% and 92%) and intracellular pH (by 11% and 9%) and changes in cellular morphology altogether indicated the dysfunction of cell membrane under C3G-LA treatment. These findings demonstrated that C3G-LA could be adopted as an alternative food preservative against foodborne pathogens.

Acylation of Anthocyanins and Their Applications in the Food Industry: Mechanisms and Recent Research Advances

Anthocyanins are extensively used as natural non-toxic compounds in the food industry due to their unique biological properties. However, the instability of anthocyanins greatly affects their industrial application. Studies related to acylated anthocyanins with higher stability and increased solubility in organic solvents have shown that the acylation of anthocyanins can improve the stability and fat solubility of anthocyanins. However, relevant developments in research regarding the mechanisms of acylation and applications of acylated anthocyanins are scarcely reviewed. This review aims to provide an overview of the mechanisms of acylation and the applications of acylated anthocyanins in the food industry. In the review, acylation methods, including biosynthesis, semi-biosynthesis, and chemical and enzymatic acylation, are elaborated, physicochemical properties and biological activities of acylated anthocyanins are highlighted, and their application as colourants, functionalizing agents, intelligent indicators, and novel packaging materials in the food industry are summarized. The limitations encountered in the preparation of acylated anthocyanins and future prospects, their applications are also presented. Acylated anthocyanins present potential alternatives to anthocyanins in the food industry due to their functions and advantages as compared with non-acylated analogues. It is hoped that this review will offer further information on the effective synthesis and encourage commercialization of acylated anthocyanins in the food industry.

Research progress of anthocyanin prebiotic activity: A review

BACKGROUND

Anthocyanins are a kind of flavonoids and natural water-soluble pigments, which endow fruits, vegetables, and plants with multiple colors. They are important source of new products with prebiotic activity. However, there is no systematic review documenting prebiotic activity of anthocyanins and their structural analogues. This study aims to fill this gap in literature.

PURPOSE

The objective of this review is to summarize and evaluate the prebiotic activity of anthocyanin's, and discuss the physical and molecular modification methods to improve their biological activities.

STUDY DESIGN AND METHODS

In this review, the databases (PubMed, Google Scholar, Web of Science, Researchgate and Elsevier) were searched profoundly with keywords (anthocyanin's, prebiotics, probiotics, physical embedding and molecular modification).

RESULTS

A total of 34 articles were considered for reviewing. These studies approved that anthocyanins play an important role in promoting the proliferation of probiotics, inhibiting the growth of harmful bacteria and improving the intestinal environment. In addition, physical embedding and molecular modification have also been proved to be effective methods to improve the prebiotic activity of anthocyanins. Anthocyanins could promote the production of short chain fatty acids, accelerate self degradation and improve microbial related enzyme activities to promote the proliferation of probiotics. They inhibited the growth of harmful bacteria by inhibiting the expression of harmful bacteria genes, interfering with the role of metabolism related enzymes and affecting respiratory metabolism. They promoted the formation of a complete intestinal barrier and regulated the intestinal environment to keep the body healthy. Physical embedding, including microencapsulation and colloidal embedding, greatly improved the stability of anthocyanins. On the other hand, molecular modification, especially enzymatic modification, significantly improved the biological activities (antioxidant, prebiotic activity and so on) of anthocyanins.

CONCLUSION

All these research results displayed by this review indicate that anthocyanins are a useful tool for developing prebiotic products. The better activities of the new anthocyanins formed by embedding and modification may make them become more effective raw materials. Our review provides a scientific basis for the future research and application of anthocyanins.

Dietary polyglycosylated anthocyanins, the smart option? A comprehensive review on their health benefits and technological applications

Over the years, anthocyanins have emerged as one of the most enthralling groups of natural phenolic compounds and more than 700 distinct structures have already been identified, illustrating the exceptional variety spread in nature. The interest raised around anthocyanins goes way beyond their visually appealing colors and their acknowledged structural and biological properties have fueled intensive research toward their application in different contexts. However, the high susceptibility of monoglycosylated anthocyanins to degradation under certain external conditions might compromise their application. In that regard, polyglycosylated anthocyanins (PGA) might offer an alternative to overcome this issue, owing to their peculiar structure and consequent less predisposition to degradation. The most recent scientific and technological findings concerning PGA and their food sources are thoroughly described and discussed in this comprehensive review. Different issues, including their physical-chemical characteristics, consumption, bioavailability, and biological relevance in the context of different pathologies, are covered in detail, along with the most relevant prospective technological applications. Due to their complex structure and acyl groups, most of the PGA exhibit an overall higher stability than the monoglycosylated ones. Their versatility allows them to act in a wide range of pathologies, either by acting directly in molecular pathways or by modulating the disease environment attributing an added value to their food sources. Their recent usage for technological applications has also been particularly successful in different industry fields including food and smart packaging or in solar energy production systems. Altogether, this review aims to put into perspective the current state and future research on PGA and their food sources.

Modification of flavonoids: methods and influences on biological activities

Flavonoids are important active ingredients in plant-based food, which have many beneficial effects on health. But the low solubility, poor oral bioavailability, and inferior stability of many flavonoids may limit their applications in the food, cosmetics, and pharmaceutical industries. Structural modification can overcome these shortcomings to improve and extend the application of flavonoids. The study of how to modify flavonoids and the influence of various modifications on biological activity have drawn great interest in the current literature. In this review, the working principles and operating conditions of modification methods were summarized along with their potential and limitations in terms of operational safety, cost, and productivity. The influence of various modifications on biological activities and the structure-activity relationships of flavonoids derivatives were discussed and highlighted, which may give guidance for the synthesis of highly effective active agents. In addition, the safety of flavonoids derivatives is reviewed, and future research directions of flavonoid modification research are discussed.

Enzymatic acylation of raspberry anthocyanin: Evaluations on its stability and oxidative stress prevention

Raspberry anthocyanins were isolated and purified by XAD-7HP macroporous resin and silica gel column chromatography. Anthocyanins were then acylated with methyl salicylate as catalyzed by lipase under reduced pressure, and the conversion rate was 84.26%. LC-MS and NMR were used to identify the structure, and the stability, antioxidant capacity and protective ability of the acylated anthocyanins against oxidative damage were determined. The results showed that cyanindin-3-O-glucoside (C3G) was the primary anthocyanin in raspberry, and the binding site of acylation was on the glucoside C-6, and the product was cyanidin-3-(6-salicyloyl) glucoside (C3-6(S) G). After acylation, its stability in light, heat and oxidation environments could be significantly improved, and acylated ACN showed insignificant changes in antioxidant capacities to scavenge DPPH and ABTS free radicals, as well as oxygen free radical absorptive capacity (ORAC). And it could also effectively prevent the release of ROS caused by oxidative damage and alleviate oxidative stress damage.

A review on enzymatic acylation as a promising opportunity to stabilizing anthocyanins

Anthocyanins are naturally occurring bioactive compounds found mainly in fruits, vegetables, and grains. They are usually extracted due to their biological properties and great potential for technological applications. These compounds have characteristic pH-dependent colorations that are natural dyes since they come in different colors. However, they are susceptible to processing conditions, remarkably light, temperature, and oxygen. The acylated anthocyanins showed better stability characteristics, and therefore, an acylation process of these compounds could improve their applications. The enzymatic acylation was effective and showed promising results. The current review provides an overview of the works that performed enzymatic acylation of anthocyanins and studies on the stability, antioxidant activity, and lipophilicity. In general, enzymatically acylated anthocyanins showed better stability to light and temperature than non-acylated compounds. In addition, they were liposoluble, a characteristic that allows their addition to products with lipid matrices. The results showed that these compounds formed by enzymatic acylation have perspectives of application mainly as natural colorants in food products. Therefore, the enzymatic acylation of anthocyanins appears viable to increase the industrial applicability of anthocyanins. There are still some gaps to be filled in process optimization, the reuse of enzymes, and toxicity analysis of the acylated compounds formed.

Natural and Synthetic Flavylium-Based Dyes: The Chemistry Behind the Color

Flavylium compounds are a well-known family of pigments because they are prevalent in the plant kingdom, contributing to colors over a wide range from shades of yellow-red to blue in fruits, flowers, leaves, and other plant parts. Flavylium compounds include a large variety of natural compound classes, namely, anthocyanins, 3-deoxyanthocyanidins, auronidins, and their respective aglycones as well as anthocyanin-derived pigments (e.g., pyranoanthocyanins, anthocyanin-flavan-3-ol dimers). During the past few decades, there has been increasing interest among chemists in synthesizing different flavylium compounds that mimic natural structures but with different substitution patterns that present a variety of spectroscopic characteristics in view of their applications in different industrial fields. This Review provides an overview of the chemistry of flavylium-based compounds, in particular, the synthetic and enzymatic approaches and mechanisms reported in the literature for obtaining different classes of pigments, their physical-chemical properties in relation to their pH-dependent equilibria network, and their chemical and enzymatic degradation. The development of flavylium-based systems is also described throughout this Review for emergent applications to explore some of the physical-chemical properties of the multistate of species generated by these compounds.

Dendrimers as Color-Stabilizers of Pyranoanthocyanins: The Dye Concentration Governs the Host-Guest Interaction Mechanisms

Anionic dendrimers have recently emerged as hosts (H) for the color stabilization of the flavylium cation of anthocyanin guests (G). The interaction with a promising, more hydrophobic pyranoanthocyanin illustrates how the structure and concentration of the dye modulate the host-guest interaction mechanisms. NMR and UV-vis titrations (host over guest, from G/H ratio 2089 to 45) showed that at relatively low dendrimer-to-dye concentrations, ion pairs at the dendrimer periphery prevail over dye encapsulation. This promotes the deaggregation of the dye, not previously observed with anthocyanins, and related to the more hydrophobic nature of this dye (deshielding of the dye ¹H signals, higher T ₂ relaxation times, constant diffusion coefficient). As the dendrimer concentration increases, the dye encapsulation, earlier unseen with structurally simpler flavylium dyes, becomes dominant (shielding and broadening of the dye ¹H signals and lower T ₂ and diffusion coefficient). The interaction parameters of the encapsulation process (K ∼ 4.51 × 10⁴ M^-1, n ∼ 150) indicate the binding of ca. one pyranoanthocyanin molecule by each sulfate terminal group. Our results provide insights into the ability of dendrimers to host structurally diverse pyranoflavylium-based dyes and how the structure of the latter modulates the range of interactions involved. The encapsulation ability of this dendrimer to such pH-sensitive dyes is envisioned for the host-guest sensing applications such as pH-responsive systems used for example in food smart packaging.

Cyanidin-3-glucoside Lipophilic Conjugates for Topical Application: Tuning the Antimicrobial Activities with Fatty Acid Chain Length

Background: Natural anthocyanins present a low solubility in lipophilic media, which compromises their effective application in lipophilic systems. In this work, cyanidin-3-O-glucoside (Cy3glc) was esterified by the addition of fatty acids with increasing chain-lengths and a structure-activity relationship was performed towards the description of the best analog for skin-care applications. Methods: By enzymatic hemi-synthesis, it was possible to obtain 5 structurally related derivatives of cyanidin-3-O-glucoside with successive C2 increments in the aliphatic chain. The stability in hanks buffer and DMEM with or without FBS was followed by HPLC. The cytotoxicity against keratinocytes was evaluated by MTT assay. The antioxidant capacity was determined by using the fluorescent probe DCF-DA. The effect on enzyme activity was evaluated towards tyrosinase, collagenase, and elastase enzymes by colorimetric assays. MIC and MBC values were obtained against reference strains and against multidrug-resistant isolates. Results: In physiological conditions, cy3glc−fatty acid derivatives are more stable and may be converted to the native anthocyanin. The 5 conjugates showed lower antioxidant capacity and enzymatic inhibitory activities in comparison to the anthocyanin precursor. However, concerning the antibacterial activity, the insertion of a fatty acid chain sprouted the antibacterial activity, showing a clear biphasic effect and a more effective effect on Gram-positive bacteria. Conclusions: Cy3glc-C10 was the most effective compound considering the antimicrobial activity, although a general reduction was observed among the other activities evaluated. This work prompt further assays with a different panoply of derivatives ranging other features including saturation vs. unsaturation, even vs. odd carbon content and linear vs. branched.

Investigation of acute, subacute and subchronic toxicities of anthocyanin derived acylation reaction products and evaluation of their antioxidant activities in vitro

Previously, anthocyanins were successfully acylated with lauric acid using Novozym 435 lipase, and the corresponding products were confirmed to have higher stability. As novel synthetic compounds, their toxicological safety has not been evaluated. Therefore, acute, subacute and subchronic toxicities of anthocyanin-lauric acid derivatives (ALDs) were investigated while their antioxidant activities were also evaluated in vitro. The acute toxicity results showed that the 50% lethal dose (LD₅₀) of ALDs in mice was >10 g kg^-1. Subsequently, the subacute toxicity test was conducted by oral administration of ALDs at doses of 0.63, 1.25 and 2.50 g kg^-1 for 28 days. No adverse effect of ALDs on body weight, food/water intake, organ coefficient and histology was observed. Though there were some fluctuations in AST and ALT, the tested biochemical parameters were maintained within the normal ranges. The subchronic toxicity test results demonstrated that less than 0.60 g of ALDs per kg BW intake did not affect mortality, body weight, food/water intake, gross pathology, histology, hematology and serum biochemistry. Furthermore, cyanidin-3-(6''-dodecanoyl)-glucoside, the main component of ALDs, had a beneficial reducing power and a strong DPPH˙, ABTS⁺˙, and O^2-˙ scavenging activity. This study provides an imperative reference to the safety of ALDs, suggesting their application as novel colorants or antioxidants in food and therapeutics.

Enzymatic acylation of cyanidin-3-glucoside with fatty acid methyl esters improves stability and antioxidant activity

Cyanidin-3-glucoside is a major anthocyanin in legumes, black rice, and purple potato, and has anti-inflammatory and antioxidant properties. In the present study, the effect of acylation on cyanidin-3-glucoside lipophilicity, stability, and antioxidant capacity was investigated. Cyanidin-3-glucoside was enzymatically acylated through transesterification with fatty acid esters to produce three monoacylated cyanidin-3-glucoside esters, cyanidin-3-(6″-n-octanoyl)-glucoside, cyanidin-3-(6″-lauroyl)-glucoside, and cyanidin-3-(6″-myristoyl)-glucoside. Cyanidin-3-(6″-n-octanoyl)-glucoside had the highest thermostability and photostability of the three cyanidin-3-glucoside esters. While the in vitro antioxidant activity of cyanidin-3-(6″-n-octanoyl)-glucoside was 7.5%-14.3% lower than that of cyanidin-3-glucoside (p < 0.05), its cellular antioxidant activity increased by 33.3% (p < 0.05). Further, while cyanidin-3-(6″-lauroyl)-glucoside had lower stability and in vitro antioxidant activity than that of cyanidin-3-(6″-n-octanoyl)-glucoside, its cellular antioxidant capacity was 125.9% and 69.4% higher than cyanidin-3-glucoside and cyanidin-3-(6″-n-octanoyl)-glucoside, respectively (p < 0.05). This study demonstrated that transesterification can be used to improve the stability and in vivo antioxidant activity of cyanidin-3-glucoside.

Kinetics of Enzymatic Synthesis of Cyanidin-3-Glucoside Lauryl Ester and Its Physicochemical Property and Proliferative Effect on Intestinal Probiotics

The interest in anthocyanins used in food, cosmetic, and pharmaceutical industries has increased the research in order to improve their stability while maintaining bioactivity. In this work, cyanidin-3-glucoside lauryl ester (Cy3glc-C12) was enzymatically synthesized, using Novozym 435 as a catalyst, as well as to obtain a kinetic model for the bioprocess. Its liposolubility, UV–VIS absorbance property, thermostability, and potential proliferative effect on intestinal probiotics were also studied. The maximum conversion yield (68.7 ± 2.1%) was obtained with a molar ratio (substrate:donor) of 1:56, 435 16.5 g/L Novozym, temperature of 56 °C, and a time of 28 h via the acylation occurred at 6′′-OH position of the glucoside. The kinetics of the reaction is consistent with a ping-pong bi-bi mechanism and the parameters of the respective kinetic equations are reported. Compared with native Cy3glc, the liposolubility, pH resistivity and thermostability of Cy3glc-C12 were significantly improved. The growth kinetics of Bifidobacteria and Lactobacillus was established based on the Logistic equation, and Cy3glc-C12 could promote their proliferation especially during the logarithmic growth, in which lower pH and more bacteria population were found compared with those of media without anthocyanins. This research provided a reference for the industrial production of Cy3glc-C12 and extended its application to natural products in lipophilic systems.

Microwave-Assisted Synthesis and Ionic Liquids: Green and Sustainable Alternatives toward Enzymatic Lipophilization of Anthocyanin Monoglucosides

Anthocyanins recycling and transformations into novel compounds have been of great interest of the scientific community to improve the circular economy and enhance their technological applications. The enzymatic acylation of anthocyanins into lipophilic derivatives by conjugation with fatty acids emerged as one of the approaches; however, the literature describes only the use of organic solvents and conventional heating. In this work, the production of cyanidin-3-glucoside-octanoic acid conjugate combining ionic liquids (ILs), microwave (MW) irradiation, and Candida antarctica lipase B as a biocatalyst was attempted for the first time. Overall, the use of MW irradiation could reduce drastically the reaction time, allowing the formation of an acylated product with similar concentrations to the conventional method. On the other hand, the study of the lipophilic conjugate synthesis using different ILs showed that their composition is crucial to achieve the desired enzymatic reaction, and in this case, the combination of an imidazolium derivative as the cation with the triflate as the anion was suitable for the production of this derivative. These promising results achieved through the combination of greener alternatives to those reported in the literature are a starting point for further developments to produce this kind of anthocyanin derivatives exploring such sustainable and ecofriendly conditions.

The Colors of Health: Chemistry, Bioactivity, and Market Demand for Colorful Foods and Natural Food Sources of Colorants

There is an increasing consumer demand for natural colors in foods. However, there is a limited number of available natural food sources for use by the food industry because of technical and regulatory limitations. Natural colors are less stable and have less vibrant hues compared to their synthetic color counterparts. Natural pigments also have known health benefits that are seldom leveraged by the food industry. Betalains, carotenoids, phycocyanins, and anthocyanins are major food colorants used in the food industry that have documented biological effects, particularly in the prevention and management of chronic diseases such as diabetes, obesity, and cardiovascular disease. The color industry needs new sources of stable, functional, and safe natural food colorants. New opportunities include sourcing new colors from microbial sources and via the use of genetic biotechnology. In all cases, there is an imperative need for toxicological evaluation to pave the way for their regulatory approval.

Antioxidant activity and absorption of cyanidin-3-O-glucoside liposomes in GES-1 cells in vitro

The use of anthocyanins are limited by their chemical properties. Recent evidence suggests Cyanidin-3-O-glucoside (C3 G) liposomes via the ethanol injection method exhibit improved stability. In the current study, the characterization and cell absorption of C3 G liposomes were explored via transmission electron microscopy and flow cytometry. The internalization of the C3 G liposomes across the gastric epithelial cell monolayer (GES-1 cells) were investigated. Results showed that the particle size and encapsulation efficiency were 234 ± 9.35 nm and 75.0% ± 0.001, respectively. The total antioxidant capacity (T-AOC) and malondialdehyde (MDA) content were used to evaluate the antioxidant activity of C3 G liposomes. The C3 G liposomes can obviously increased T-AOC and decreased the MDA content.Collectively, C3 G liposomes protected human GES-1 cells from gastric mucosal injury induced by H₂O₂ by activating the related antioxidant pathway. Our research could provide a new effective treatment strategy for the absorption of stomach drugs.Abbreviations: C3G: Cyanidin-3-O-glucoside; LP: Liposome; GES-1 cells: Human gastric epithelial cell lines; FBS: Fetal Bovine Serum; PBS: Phosphate-buffered saline; PC: Phosphatidylcholine; CH: Cholesterol; MDA: Malondialdehyde; TEM: Transmission electron microscope; FCM: Flow cytometry; FITC: Fluorescein isothiocyanate; DAPI: 4', 6-diamidino-2phenylidole; FT-IR: Fourier Transform infrared spectroscopy; PFA: Paraformaldehyde.

Cyanidin-3-o-glucoside liposome: Preparation via a green method and antioxidant activity in GES-1 cells

Cyanidin-3-O-glucoside (C3G) liposomes was used to improve the stability and antioxidant activity of C3G through a green thin-film dispersion method. The characteristics, stability and the effect of C3G liposomes on GES-1 cells were explored. Results showed that the particle size and encapsulation efficiency (EE%) of C3G liposomes were 258.9 ± 5.06 nm and 77.5%, respectively. DPPH assay showed that liposomes encapsulation can improve the antioxidant of C3G, while the ABTS assay was opposite. Stability study showed the C3G liposome were unstable under extended storage time. The effects of C3G liposomes on GES-1 cells showed that C3G liposomes can decrease the ROS levels of GES-1 and had negligible effects on cell viability and mitochondrial structure. These findings suggested that liposomes could be used as a carrier system to improve the stability of C3G.