Flavylium Cation Research Articles

Correspondence on “Visible‐Light‐Switchable Chalcone‐Flavylium Photochromic Systems in Aqueous Media”

AbstractIn a recent Communication in this journal, Bandyopadhyay and co‐workers proposed a rational design of chalcone photoswitches that are claimed to convert into the respective flavylium cations upon irradiation with blue, green, and red light in aqueous media. Here we argue that the reported improvements on the optical/photochemical properties of the new chalcone photoswitches are not substantiated and that the proposed design and data interpretation rely on assumptions that have yet to be validated. We also identify a series of control experiments that can be performed to verify the hypotheses and better support the conclusions presented by the authors.

Potential and Simulation of Functional Compounds Recovery from Clitoria ternatea L. Extract during The Commercial Sterility Process

The butterfly pea flower (Clitoria ternatea L.) is a flower that is identical to blue to purple petals and contains various phytochemical compounds. Heat processing in butterfly pea flower extract can reduce its nutritional and sensory properties, which is indicated by a decrease in each quality parameter, namely color intensity, total anthocyanins, red flavylium cation, purple quinonoidal base, blue anionic quinonoidal base, ferrulic acid, caffeic acid, p-hydroxybenzoic acid, procatechuic acid, gallic acid, vanillic acid, vanillin, procyanidin hexamer III, and delphinidin-3-glucosse. The thermal process can deactivate bacterial spores to maintain the quality of butterfly pea flower extract. This paper will review steps that can be used as a reference for researchers or industry to optimize commercial sterilization processes using heating process kinetics. The method studied to be adopted in this article is based on the heating process kinetics of each quality parameter (k and D values) combined towards temperature (Z value). The combination of temperature and time to optimize the process is determined by referring to the D and Z values. To optimize the heating process, the sterilization heater needs to be evaluated and the kinetics of the thermal process for each quality parameter need to be prescribed. This thermal process design will contribute greatly to the functional food business with commercial sterilization standards that aim to claim functional compounds at certain concentrations after processing.

Comparing the Chemistry of Malvidin-3-O-glucoside and Malvidin-3,5-O-diglucoside Networks: A Holistic Approach to the Acidic and Basic Paradigms with Implications in Biological Studies.

The kinetics, thermodynamics, and degradation of malvidin mono- and diglucosides were studied following a holistic approach by extending to the basic medium. In acidic conditions, the reversible kinetics of the flavylium cation toward the equilibrium is controlled by the hydration and cis-trans isomerization steps, while in the basic medium, the OH- nucleophilic addition to the anionic quinoidal bases is the slowest step. There is a pH range (transition pHs), between the acidic and basic paradigms, that includes physiological pH (7.4), where degradation reactions occur faster, preventing the system from reaching the equilibrium. The transition pH of the diglucoside is narrower, and in contrast with the monoglucoside, there is no evidence for the formation of colored oligomers among the degradation products. Noteworthy, OH- addition in position 4 to form B42-, a kinetic product that decreases the overall equilibration rate, was observed only for the diglucoside.

Nonlinearity and anthocyanin colour expression: A mathematical analysis of anthocyanin association kinetics and equilibria

Anthocyanins are polyphenolic compounds that provide pigmentation in plants as reflected by pH-dependent structural transformations between the red flavylium cation, purple quinonoidal base, blue quinonoidal anion, colourless hemiketal, and pale yellow chalcone species. Thermodynamically stable conditions of hydrated plant cell vacuoles in vivo correspond to the colourless hemiketal, yet anthocyanin colour expression appears in an important variety of hues within plant organs such as flowers and fruit. Moreover, anthocyanin colour from grape berries is significant in red winemaking processes as it plays a crucial role in determining red wine quality. Here, nonlinear ordinary differential equations were developed to represent the evolution in concentration of various anthocyanin species in both monomeric (chemically reactive) and self-associated (temporally stable) forms for the first time, and simulations were verified experimentally. Results indicated that under hydrating conditions, anthocyanin pigmentation is preserved by self-association interactions, based on pigmented monomeric anthocyanins experiencing colour loss whereas colour-stable self-associated anthocyanins increase in concentration nonlinearly over time. In particular, self-association of the flavylium cation and the quinonoidal base was shown to influence colour expression and stability within Geranium sylvaticum flower petals and Vitis vinifera grape skins. This study ultimately characterises fundamental mechanisms of anthocyanin stabilisation and generates a quantitative framework for anthocyanin-containing systems.

Host-Guest Chemosensor Ensembles based on Water-Soluble Sulfonated Calix[n]arenes and a Pyranoflavylium Dye for the Optical Detection of Biogenic Amines.

Biogenic amines (BAs) are biologically active nitrogen-containing compounds formed during the food spoilage process and are often related as key markers of food quality, safety, and freshness. Because their presence in foods at high levels can cause significant health problems, researchers have been focused on developing novel strategies and methods for early detection and capture of these analytes. Herein, water-soluble sulfonated calix[n]arene macrocycles (SC4, SC6, and SC8) and a pH-sensitive dye (4'-hydroxy-10-methylpyranoflavylium) were investigated as host-guest systems for BA sensing. The hosts were able to bind the flavylium cation of the dye with association constants of 103 to 104 M-1. The dye complexation also allowed tuning its pKa from 6.72 (free) toward high values: 7.68 (SC4), 7.79 (SC6), and 8.45 (SC8). These data were crucial to optimize the host-guest complexes as optical sensing systems for putrescine/tyramine (pH 7.2-7.6), yielding a colorimetric redshift from yellow to red. The BA sensing was also demonstrated by fluorescence quenching for the calix[n]arene/dye complexes and fluorescence recovery after the addition of BAs. 1H NMR spectroscopy was used to demonstrate the interaction mode, confirming an encapsulation-driven mechanism. Overall, these host-guest systems demonstrated great potential for the detection of BAs, one of the main key markers of food spoilage.

Chemical and colorimetric study of the influence of grape soluble polysaccharides on the color and stability of malvidin 3-O-glucoside solutions

Red wine color is mainly due to anthocyanins’ flavylium cation. In wine, these pigments are involved in a pH-dependent equilibrium involving other forms, both colored and non-colored. This equilibrium is affected by the presence of other phenolic compounds, the so-called copigments. Moreover, other non-phenolic compounds that can be found in wine, such as polysaccharides, can also affect wine color. In this work, molecular dynamics simulations, tristimulus colorimetry and HPLC-DAD analyses have been performed to assess the effect of soluble polysaccharides (P) on the color and stability of malvidin 3-O-glucoside (Mv) solutions at different pH values, both in presence and absence of other compounds that can establish copigmentation interactions with the pigment. Results showed that P shifts the color of flavylium solutions towards a more intense color with bluer hues, which can be related to a stabilization of the blue quinoidal forms of anthocyanins. This effect is similar to that observed for quercetin 3-β-glucopyranoside (QG), although, in the case of P, it seems to be more relevant. This behavior could be due to the presence of hydrophobic regions in P that allows the interaction with the quinoidal forms, which in the case of the polysaccharide might be related to the type I rhamnogalacturonans.

A dye–fibre system from food waste: Dyeing casein fibres with anthocyanins

AbstractRegenerated protein fibres manufactured from food side‐streams offer significant potential as circular and sustainable fibres, but greater knowledge of their dyeing properties is required. In this research, coloration of casein fibres with dyes also extracted from blackcurrant skins left over from juice pressing is explored. Casein fibre was dyed with blackcurrant extract, rich in anthocyanins, from pH 2 to pH 6 and from 40 to 80°C, with and without alum. Casein fibres could be dyed with blackcurrant extract across all conditions tested, and under optimal conditions, dyeing is achieved with medium depths of colour with good wash fastness. Highest sorption of anthocyanins onto casein is observed at pH 4, where anthocyanins are a mixture of 60% neutral purple quinonoidal base form and 40% flavylium cation form; under these conditions dye–fibre interaction is optimal. At pH 2, casein fibre has a highly positively charged surface and anthocyanin is in the flavylium cation form, leading to some dye–fibre repulsion. At pH 6, the slightly negatively charged casein fibre demonstrates lower sorption of the mixture of 40% purple quinonoidal base form and 60% the anionic quinonoidal base form, again leading to some dye–fibre repulsion. Presence of alum in the dyebath enhances sorption of anthocyanins onto fibre at pH 4 due to formation of Al–anthocyanin complexes. Wash fastness of the dyeings is better as pH increases and as temperature increases.

Effects of sunflower pectin on thermal stability of purple sweet potato anthocyanins at different pH

The present study aimed to examine the impact of sunflower pectin (SFP) on the thermal stability and antioxidant activity of purple sweet potato anthocyanins (PSPA) at varying pH levels. It was observed that the pH value significantly influenced the ability of pectin to protect anthocyanins from thermal degradation, which was found to be associated with the rate of binding between PSPA and SFP. The binding rate of PSPA-SFP was observed to be highest at pH 4.0, primarily due to the influence of electrostatic interaction and hydrogen bonding. Monoacylated anthocyanins exhibited a binding rate approximately 2–4 % higher than that of diacylated anthocyanins. The PSPA-SFP demonstrated its highest thermal stability at pH 4.0, with a corresponding half-life of 14.80 h at 100 °C. Molecular dynamics simulations indicated that pectin had a greater affinity for the flavylium cation and hemiketal form of anthocyanins. The antioxidant activity of anthocyanins in PSPA and PSPA-SFP increased with increasing pH, suggesting that anthocyanins at high pH had higher antioxidant activity than anthocyanins at low pH.

Relationship between Chemical Structure and Biological Activity Evaluated In Vitro for Six Anthocyanidins Most Commonly Occurring in Edible Plants.

Numerous studies have provided evidence that diets rich in anthocyanins show a broad spectrum of health benefits. Anthocyanins in nature are usually found in the form of glycosides. Their aglycone forms are called anthocyanidins. The chemical structure of anthocyanins is based on the flavylium cation, but they differ in the position and number of substituents. However, the bioactives and foods that contain them are frequently treated as a uniform group of compounds exhibiting the same biological activity, without paying attention to the structural differences between individual anthocyanidins. The aim of this study was to find out how structural differences impact the biological activity of the six most common dietary anthocyanidins, i.e., delphinidin (Dp), petunidin (Pt), cyanidin (Cd), malvidin (Mv), pelargonidin (Pg) and peonidin (Po). The study concentrated on redox-related phenomena and compared the following parameters: antioxidant activity (measured using various methods: spectrophotometric tests (ABTS, DPPH), ORAC assay and CAA test (cellular antioxidant activity)), the ability to inhibit growth of human colon cancer cells (HT29; determined using MTT assay), and the ability of studied compounds to protect DNA from oxidative damage (comet assay). Based on the obtained results, the relationship between the structure of studied anthocyanidins and their biological activity was assessed. The obtained results revealed that the number and position of the hydroxyl and methoxy groups in the anthocyanidin structure strongly influenced not only the color of anthocyanidins but most of all their antioxidant and biological activities.

Water-soluble propolis extract as a natural preservative for jaboticaba juice

This study was focused on the preparation of water-soluble propolis extract as the natural preservative for perishable jaboticaba juice. A successive extraction and alkaline hydrolysis were performed to produce water-soluble propolis extract. The propolis extract was found to have a high content of phenolics and flavonoids, but a low concentration of wax. The hydrolysed propolis extract was added into jaboticaba juice and the treated juice quality was monitored for 2 weeks at 4 °C. The results found that the performance of propolis extract was comparable with chemical preservative, sodium benzoate in similar amount (0.035%) used in the present study. The comparison was performed based on the physiochemical properties such as pH, titratable acidity, browning index and ascorbic acid content of juice. Ascorbic acid was the most reliable parameter to monitor the kinetic degradation of jaboticaba juice. Its degradation followed a first order kinetic model with a lower kinetic constant (0.1912 mg/mL/day) than that of non-treated juice (0.2073 mg/mL/day). The second reliable parameter was titratable acidity which could be used to monitor the rate of acid formation resulting from the breakdown of fruit sugars during degradation. The acidity of juice was slightly increased with storage time following zero order kinetics. The browning index was not suitable for juice quality monitoring as the addition of propolis would reduce flavylium cations of anthocyanins to be colourless. This non-thermal extraction followed by mild alkaline hydrolysis at pH 7.5 could produce good quality propolis extract, possibly as an alternative to chemical preservatives for jaboticaba juice.

Thermal and photochemical reactions of n-pyridinebenzopyrylium multistate of species (n = 2′,3′,4′). Exploring the synthetic potentialities from the unique reactivity of position 2′

The kinetics and thermodynamics of the pH-dependent multistate of species generated by the trans-chalcone of n-pyridinebenzopyrylium (n = 2′, 3′) were studied by UV–vis spectroscopy, 1H NMR and HPLC-MS, and the results compared with those reported for n = 4′. Due to the slow kinetics of the multistate species interconversion, the conjugation of these techniques has shown to be a powerful tool to investigate the behaviour of these systems. The species involved in the multistate are mutatis mutandis the same observed in anthocyanins and related compounds except for the flavylium cation, which was not observed in these systems even in very acidic medium. The rates of the interconversion of the multistate species upon pH stimuli are much slower than in anthocyanins. The compound bearing the pyridine nitrogen in position 2′ gives two novel products absorbing in the visible. Formation of the new products is particularly efficient from the thermal evolution of the photochemical products obtained upon light irradiation of the protonated trans-chalcone in a mixture of methanol:acidic water (1:1). This confirms the unique capacity of the substituents in position 2′ in giving intramolecular reactions involving the benzopyrylium core. Crystal structures for the three pyridine chalcone compounds (n = 2′, 3′, 4′) were obtained and the respective structures discussed.

New insights into the pH dependence of anthocyanin-protein interactions by a case study of cyanidin-3-O-glucoside and bovine serum albumin

Anthocyanins are natural pigments that can undergo structural transformations depending on pH, and their interactions with proteins have received considerable attention in recent decades. This work intended to unravel the pH-dependence of anthocyanin-protein binding mechanisms by examining interactions between cyandin-3-O-glucoside (C3G) and bovine serum albumin (BSA) at different pH. Fluorescence quenching (FQ) and microscale thermophoresis (MST) demonstrated that their binding affinity was pH 7 > pH 5 > pH 3, with dissociation constant (Kd) at pH 7 of 43.1 μM for FQ and 33.0 μM for MST. The predominant C3G forms were determined by measuring UV–Vis absorption spectra with pH-jump experiments. Additionally, circular dichroism, Trp fluorescence, zeta potential and particle size measurements demonstrated the “molten globule” state of BSA at pH 3, and C3G had a negligible effect on BSA conformation. The binding mechanisms were investigated using molecular dynamics simulation, which revealed the importance of electrostatic interaction. Flavylium cation rarely bound to BSA due to electrostatic repulsion at pH 3, whereas the uncharged forms of C3G at all pH values bound to BSA surface due to hydrophobic interactions and hydrogen bonds, but possibly in a weak and nonspecific manner. Anionic quinoidal bases, the most common C3G forms at pH 7, mostly bound to the positively charged pockets of BSA and formed several hydrogen bonds with surrounding amino acids, resulting in higher binding affinity. These findings provide insights into the interactions of proteins with different anthocyanin forms, which may guide the future research and applications in this field.

Supramolecular Study of the Interactions between Malvidin-3-O-Glucoside and Wine Phenolic Compounds: Influence on Color.

Supramolecular study of the interactions between the major wine anthocyanin, malvidin-3-O-glucoside (Mv3G) and different wine phenolic compounds (quercetin 3-O-β-glucopyranoside (QG), caffeic acid, (-)-epicatechin, (+)-catechin, and gallic acid) has been performed at two different molar ratios (1:1 and 1:2) in acidic medium where flavylium cation predominates (pH ≤ 2). Color variations have been evaluated by differential colorimetry using CIELAB color space. These studies have been complemented with isothermal titration calorimetry assays and molecular dynamics simulations. The color of Mv3G flavylium cation is modified by the interaction with QG toward more bluish and intense colors. Interaction constants between the anthocyanin and the different phenolic compounds were obtained, ranging from 9.72 × 108 M-1 for QG to 1.50 × 102 M-1 for catechin. Hydrophobic interactions and H-bonds are the main driving forces in the pigment/copigment aggregation, except for the interactions where caffeic acid is involved, in which hydrophobic interactions acquire greater preponderance.

First insights into the binding mechanism and colour effect of the interaction of grape seed 11S globulin with malvidin 3-O-glucoside by fluorescence spectroscopy, differential colorimetry and molecular modelling

Recently, the search for alternative proteins endogenous to grapes to be used as wine colour protecting agents became an important research trend. In this study, the molecular interaction between the grape seed 11S globulin from winemaking by-product and malvidin-3-O-glucoside was investigated by fluorescence, differential colorimetry and molecular modelling. Fluorescence studies revealed the formation of grape seed protein- pigment complex whose KS was 8.5 × 104 M−1 and binding sites, n = 1.3. Malvidin-3-O-glucoside showed darker and more vivid bluish colour of in the presence of 11S globulin, suggesting the flavylium cation protection in a hydrophobic region of the protein. Docking analysis and molecular dynamics simulation indicated that malvidin-3-O-glucoside interacts mainly with the acidic subunit (40 kDa) of the 11S globulin monomer (60 kDa). An average of two hydrogen bonds and Van der Wall forces were the main interaction forces found for the protein-pigment complex, whose stability was confirmed by root-means-square deviation.

A novel all-natural (collagen+pectin)/chitosan aqueous two-phase microcapsule with improved anthocyanin loading capacity

Microcapsules based on an aqueous two-phase system (ATPS) have attracted increasing interest due to their all-aqueous biocompatible microenvironment, but the undesirable use of high concentrations of synthetic poly(ethylene glycol) and dextran (Dex) in conventional ATPSs has severely hindered their application in the food industry. In this study, a new type of ATPS microcapsule was developed by taking advantage of the spontaneous phase separation and simultaneous interfacial self-assembly of natural pectin, chitosan, and collagen. Chitosan (1 wt%) and collagen (4 wt%)+pectin (0.5 wt%) were used to form ATPS to replace poly(ethylene glycol) (15∼30 wt%) and Dex (15∼20 wt%) in conventional ATPSs. The (collagen + pectin)/chitosan microcapsules exhibited the plumpest morphology and highest stability at pH 6, and the smoothest interfacial membrane texture was achieved through interfacial self-assembly of pectin, chitosan, and collagen via electrostatic interactions and hydrogen bonds. Notably, anthocyanin could be stabilized by pectin in the inner phase, and the (collagen + pectin)/chitosan microcapsules had an improved anthocyanin encapsulation efficiency and loading capacity of 92.58% and 12.34 g/100 g, respectively, which was attributed to the electrostatic attractions between the flavylium cation form of anthocyanin and anionic pectin. This study yielded a strategy for constructing a new type of food-grade ATPS microcapsule using all-natural polysaccharides and proteins, and provided a novel all-aqueous template for loading hydrophilic bioactive components. • Natural chitosan and collagen + pectin generate a spontaneous aqueous two-phase system. • The novel (collagen + pectin)/chitosan microcapsules developed were stable at pH 6. • Chitosan, pectin, and collagen could be self-assembled at the microcapsule interface. • Anthocyanin could be stabilized by pectin in the inner phase via electrostatic attraction. • (Collagen + pectin)/chitosan microcapsules had excellent anthocyanin loading capacity.

Molecular Mechanism of Cyanidin-3-O-Glucoside Disassembling Aβ Fibril In Silico

The deposition of β-amyloid (Aβ) in the brain leads to neurotoxic effects and subsequent Alzheimer's disease (AD). While AD is becoming more and more prevalent in modern society, therapeutic efforts targeting Aβ could be a promising solution. Currently, two natural products are reported to disintegrate preformed Aβ fibril in vitro. Meanwhile, the chemical driving force behind this phenomenon remains unknown. Taking cyanidin-3-O-glucoside (Cy-3G) as an example, here we studied its interaction with different Aβ polymorphs in silico. Negative charges on different Aβ polymorphs draw the interaction with the flavylium cation on Cy-3G. Our results show that Aβ in a single peptide form in solution exposed more hydrophobic solvent accessible surface area than its fibril structure (per protomer), and Cy-3G interacts more intensively with the single peptide form than fibril as indicated by more hydrogen bonding formed and more amino acid residues involved in their hydrophobic interactions. Thus, the single Aβ peptide aggregation into fibril and fibril dissociation into single peptide equilibrium could be disturbed by the preferential binding of Cy-3G to the monomeric Aβ peptide, which leads to the disassembly of the pathogenic Aβ fibril. This study offers a novel perspective of Cy-3G alleviated AD syndrome beyond its dogmatic antioxidant activity.

The Use of Flavylium Salts as Dynamic Inhibitor Moieties for Human Cb5R

Cytochrome b5 reductase (Cb5R) is a flavoprotein that participates in the reduction of multiple biological redox partners. Co-localization of this protein with nitric oxide sources has been observed in neurons. In addition, the generation of superoxide anion radical by Cb5R has been observed. A search for specific inhibitors of Cb5R to understand the role of this protein in these new functions has been initiated. Previous studies have shown the ability of different flavonoids to inhibit Cb5R. Anthocyanins are a subgroup of flavonoids responsible for most red and blue colors found in flowers and fruits. Although usually represented by the flavylium cation form, these species are only stable at rather acidic pH values (pH ≤ 1). At higher pH values, the flavylium cation is involved in a dynamic reaction network comprising different neutral species with the potential ability to inhibit the activities of Cb5R. This study aims to provide insights into the molecular mechanism of interaction between flavonoids and Cb5R using flavylium salts as dynamic inhibitors. The outcome of this study might lead to the design of improved specific enzyme inhibitors in the future.

Brain Effects of SC-Nanophytosomes on a Rotenone-Induced Rat Model of Parkinson's Disease-A Proof of Concept for a Mitochondria-Targeted Therapy.

Mitochondria are an attractive target to fight neurodegenerative diseases due to their important functions for cells and the particularly close relationship between the functional connectivity among brain regions and mitochondrial performance. This work presents a mitochondria-targeted therapy designed to modulate the functionality of the mitochondrial respiratory chain and lipidome, parameters that are affected in neurodegeneration, including in Parkinson’s disease (PD). This therapy is supported by SC-Nanophytosomes constructed with membrane polar lipids, from Codium tomentosum, and elderberry anthocyanin-enriched extract, from Sambucus nigra L. SC-Nanophytosomes are nanosized vesicles with a high negative surface charge that preserve their properties, including anthocyanins in the flavylium cation form, under conditions that mimic the gastrointestinal tract pH changes. SC-Nanophytosomes, 3 µM in phospholipid, and 2.5 mg/L of EAE-extract, delivered by drinking water to a rotenone-induced PD rat model, showed significant positive outcomes on disabling motor symptoms associated with the disease. Ex vivo assays were performed with two brain portions, one comprising the basal ganglia and cerebellum (BG-Cereb) and the other with the cerebral cortex (C-Cortex) regions. Results showed that rotenone-induced neurodegeneration increases the α-synuclein levels in the BG-Cereb portion and compromises mitochondrial respiratory chain functionality in both brain portions, well-evidenced by a 50% decrease in the respiratory control rate and up to 40% in complex I activity. Rotenone-induced PD phenotype is also associated with changes in superoxide dismutase and catalase activities that are dependent on the brain portion. Treatment with SC-Nanophytosomes reverted the α-synuclein levels and antioxidant enzymes activity to the values detected in control animals. Moreover, it mitigated mitochondrial dysfunction, with positive outcomes on the respiratory control rate, the activity of individual respiratory complexes, and the fatty acid profile of the membrane phospholipids. Therefore, SC-Nanophytosomes are a promising tool to support mitochondria-targeted therapy for neurodegenerative diseases.

2-Hydroxychalcone-β-Cyclodextrin Conjugate with pH-Modulated Photoresponsive Binding Properties.

Stimuli-responsive supramolecular receptors are important building blocks for the construction of self-assembled functional materials. We report the design and synthesis of a pH- and light-responsive 2-hydroxychalcone-β-cyclodextrin conjugate (1-Ct) and its characterization by spectroscopic and computational methods. 1-Ct follows the typical reaction network of trans-chalcone-flavylium photoswitches. Upon light irradiation, 1-Ct can be photochemically converted into the cis-chalcone/hemiketal forms (1-Cc/1-B) under neutral pH conditions or to the flavylium cation (1-AH+) at acidic pH values. This stimuli-responsive β-cyclodextrin host, 1-Ct, was found to form stronger intramolecular self-inclusion complexes (Kintra = 14) than 1-AH+ (Kintra = 3) and weaker than 1-Cc/1-B (overall Kintra = 179), allowing control over their stability and binding properties by combinations of pH and light stimuli.

Experimental and Computational Studies on Bio-Inspired Flavylium Salts as Sensitizers for Dye-Sensitized Solar Cells.

Six new bio-inspired flavylium salts were synthesized and investigated by a combined computational and experimental study for dye-sensitized solar cell applications. The compounds were characterized by FT–IR, UV–Vis, NMR spectroscopy, and LC–MS spectrometry techniques. The pH-dependent photochromic properties of the flavylium dyes were investigated through a UV–Vis spectroscopy study and revealed that they follow the same network of chemical reactions as anthocyanins upon pH changes. The structural and electronic properties of the dyes were investigated using density functional theory (DFT) and time-dependent density functional theory (TD–DFT). Geometry optimization calculation revealed that all dyes, regardless of the specie, flavylium cations or quinoidal bases, present a planar geometry. The photovoltaic performances of the dyes, in both flavylium and quinoidal base forms, were evaluated by the HOMO and LUMO energies and by calculating the light-harvesting efficiencies, the free energy change of electron injection, and the free energy change regeneration. The MO analysis showed that all dyes can inject electrons into the conduction band of the TiO2 upon excitation and that the redox couple can regenerate the oxidized dyes. The results obtained for the free energy change of electron injection suggest that the quinoidal bases should inject electrons into the semiconductor more efficiently than the flavylium cations. The values for the free energy change regeneration showed that the redox electrolyte can easily regenerate all dyes. Dipole moment analysis was also performed. DSSCs based on the dyes, in both flavylium and quinoidal base forms, were assembled, and their photovoltaic performances were evaluated by measuring the open-circuit voltage, the short circuit current density, the fill factor, and the energy conversion efficiency. Results obtained by both experimental and computational studies showed that the overall performances of the DSSCs with the quinoidal forms were better than those obtained with the flavylium cations dyes.