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Iron-gall inks, a vital part of our written cultural heritage, are at risk of complete loss due to degradation, a potential loss that we must urgently address. These inks are based on Fe3+-complexes with phenolic compounds, which grow to form a complex network of iron oxyhydroxides. Over time, these black inks turn into brownish tones, with extensive degradation in paper support leading to extensive breaking. The kinetics of iron-gall ink preparation explains the use of iron sulfate, FeSO4, in all ancient recipes to obtain a stable amorphous ink. The novelty of this work shows that a low ratio of Fe3+/polyphenol is a crucial factor in allowing the ink's growth without its degradation. This ratio also prevents the formation of superoxide. This was achieved through a comprehensive research methodology involving spectroscopic techniques in the visible and the near-infrared regions, stopped-flow spectrometry and electrochemical studies., (© 2024 Wiley‐VCH GmbH.)

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 B4 2- , a kinetic product that decreases the overall equilibration rate, was observed only for the diglucoside.

Different treatment options exist for localized prostate cancer. Treatments performed in high-volume hospitals are associated with better results. Our objective was to describe time trends in prostate cancer treatments in Portugal and case volume per hospital. We used the national database of diagnosis-related group of the Portuguese Central Administration of the Health System to describe the number of radical prostatectomy (RP), brachytherapy (BT) and external radiotherapy (eRT) treatments performed in all National Health System hospitals. There was a rapid increase in the annual number of RP until 2006 and then a deceleration; BT treatments augmented significantly until 2011. The utilization of eRT also increased, surpassing RP after 2010. From the 46 hospitals performing RP, only eight had a case-volume > 50 treatments/year, and from the nine hospitals performing BT, only four accomplished > 15 treatments/year. In the 11 hospitals with eRT, nine performed > 50/year. Regarding RP, there was negative correlation between the hospital volume and length of stay (r = - 0.303; p = 0.041). In the Portuguese National Health Service there was a steep increase in the number of prostate cancer treatments, and there is an ample margin for concentration of RP and BT treatments, for improvement of the hospitals case volume., (© 2023. The Author(s).)

Stopped flow corroborated by UV-vis measurements allowed for the calculation of the copigmentation constants of delphinidin 3- O -glucoside with the neutral (CP) and negatively charged CP(-) forms of chlorogenic acid. Solutions of delphinidin 3- O -glucoside in the absence and presence of the copigment were equilibrated at several pH values in the acidic region, pH < 6, and reverse pH jumps monitored by stopped flow were carried out by adding sufficient acid to give flavylium cation at pH ≤ 1. This procedure allows for the separation of three contributions: (i) all flavylium cation and quinoidal base species, (ii) all hemiketal species, and (iii) all cis -chalcone species. Reverse pH jumps can also be performed at fixed pH versus copigment addition. The contribution of trans -chalcone, minor species in the present system, requires reverse pH jumps from the equilibrium followed by a common spectrophotometer. The system was also studied by UV-vis as a function of the copigment addition at different pH values. A global fitting of all experimental data allowed for determination of the copigmentation constants with flavylium cation, K AH + CP = 167 M -1 , K AH + CP(-) = 338 M -1 ; and quinoidal base, K ACP = 1041 M -1 , K ACP(-) = 221 M -1 . No significant copigmentation was observed for hemiketal and chalcones. Computational calculations confirm different geometries for the interactions of flavylium cation and quinoidal base with the neutral or the negatively charged forms of the copigment as well as predict identical relative order for the binding energies of the four adducts.

The thermodynamics and kinetics of compound 7-diethylamino-4'-dimethylaminoflavylium were studied in water : ethanol (1 : 1) and water in the presence of SDS and CTAB micelles. The blue flavylium cation is in equilibrium with the pink protonated flavylium cation defined by p K AH 2+ /AH + and the yellow trans -chalcone, defined by p K AH + /Ct . The difference between these two p K s gives the pH domain of the flavylium cation, Δp K = 1.95 in CTAB, Δp K = 5.6 in water/ethanol (1 : 1) and Δp K = 8.5 in SDS micelles. On the other hand, the pH domain of the trans -chalcone is limited by p K AH + /Ct and p K Ct/Ct - . It is lower in SDS micelles Δp K = 2.7, increases in ethanol/water (1 : 1) Δp K = 5.1 and is maximum in CTAB micelles, Δp K = 6.8. All these effects can be explained by the electric charge present at the micellar surface. Relative energy level diagrams that allow for the explanation of the driving forces for any pH stimuli or light absorption were constructed from the calculated equilibrium constants. Irradiation of the trans -chalcone at 466 nm leads to the formation of the flavylium cation. In water : ethanol (1 : 1), the photochemistry is residual with Φ < 0.00002, while in SDS micelles at pH = 7 light increases the rate of the spontaneous conversion of trans -chalcone to the flavylium cation, with quantum yield Φ = 0.002; photochromism from trans -chalcone to give the flavylium cation with the same quantum yield is also observed in CTAB micelles.

The contribution of radiotherapy, per se , to late cardiotoxicity remains controversial. To clarify its impact on the development of early cardiac dysfunction, we developed an experimental model in which the hearts of rats were exposed, in a fractionated plan, to clinically relevant doses of ionizing radiation for oncological patients that undergo thoracic radiotherapy. Rat hearts were exposed to daily doses of 0.04, 0.3, and 1.2 Gy for 23 days, achieving cumulative doses of 0.92, 6.9, and 27.6 Gy, respectively. We demonstrate that myocardial deformation, assessed by global longitudinal strain, was impaired (a relative percentage reduction of >15% from baseline) in a dose-dependent manner at 18 months. Moreover, by scanning electron microscopy, the microvascular density in the cardiac apex was significantly decreased exclusively at 27.6 Gy dosage. Before GLS impairment detection, several tools (qRT-PCR, mass spectrometry, and western blot) were used to assess molecular changes in the cardiac tissue. The number/expression of several genes, proteins, and KEGG pathways, related to inflammation, fibrosis, and cardiac muscle contraction, were differently expressed in the cardiac tissue according to the cumulative dose. Subclinical cardiac dysfunction occurs in a dose-dependent manner as detected by molecular changes in cardiac tissue, a predictor of the severity of global longitudinal strain impairment. Moreover, there was no dose threshold below which no myocardial deformation impairment was detected. Our findings i) contribute to developing new markers and exploring non-invasive magnetic resonance imaging to assess cardiac tissue changes as an early predictor of cardiac dysfunction; ii) should raise red flags, since there is no dose threshold below which no myocardial deformation impairment was detected and should be considered in radiation-based imaging and -guided therapeutic cardiac procedures; and iii) highlights the need for personalized clinical approaches., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Ribeiro, Simões, Rocha, Vala, Pinto, Ministro, Poli, Diegues, Pina, Benadjaoud, Flamant, Tamarat, Osório, Pais, Casal, Pinto, Matthiesen, Fiuza and Constantino Rosa Santos.)

Intermolecular copigmentation of malvidin-3- O -glucoside with caffeine was studied using a holistic procedure that includes the extension to basic pH values. In moderately basic solutions (7.5 < pH < 9.5) and independently of the copigment presence, there is a pH region where degradation of the quinoidal base and anionic quinoidal bases is faster than hydration and OH - nucleophilic addition, preventing the system from reaching the equilibrium. Intermolecular copigmentation with caffeine reduces significantly the degradation rate of quinoidal bases. In a more basic medium, the equilibrium is reached and degradation occurs from the anionic chalcones. In this case, the addition of caffeine also reduces the degradation rate in the interval 10 < pH < 11.5., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The kinetics and thermodynamics of the pH-dependent reversible and irreversible processes leading to color fading of pelargonidin-3- O -glucoside, peonidin-3- O -glucoside, malvidin-3- O -glucoside, and cyanidin-3- O -glucoside dyes in aqueous solutions are reported. Following the addition of base to the flavylium cation, the quinoidal bases disappear by three distinct steps: (i) in an acidic medium by a biexponential process, in which the faster step is controlled by the hydration reaction and the slower one by cis-trans isomerization; the degradation process occurs essentially from the anionic quinoidal base; (ii) in a basic medium (pH > 9.5), in which the disappearance of the anionic bases is monoexponential, with the rate proportional to the hydroxyl concentration (hydroxyl attack), leading to anionic chalcones ( cis and trans ) at equilibrium─the slower degradation step occurs from the di- and trianionic chalcones; and (iii) in the pH region circa 7.7 < pH < 9.5, in which hydration and hydroxyl attacks are much slower than anionic quinoidal base degradation (which is the rate-controlling step) and the equilibrium cannot be attained.

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.

A linear double pyridinium-terminated thread comprising a central chalcone moiety is shown to provide two independent binding sites with similar affinity for cucurbit[7]uril (CB7) macrocycles in water as judged from NMR, UV-Visible and fluorescence spectroscopies. Association results in [2] and [3]pseudorotaxanes, which are both pH and photosensitive. Switching from the neutral chalcone to the cationic flavylium form upon irradiation at 365 nm under acidic conditions provided an enhanced CB7 association (K 1:1 increases from 1.2×10 5  M -1 to 1.5×10 8  M -1 ), limiting spontaneous on-thread cucurbituril shuttling. This co-conformational change in the [2]pseudorotaxane is reversible in the dark with k obs =4.1×10 -4  s -1 . Threading the flavylium moiety into CB7 leads to a dramatic increase in the fluorescence quantum yield, from 0.29 in the free axle to 0.97 in the [2]pseudorotaxane and 1.0 in the [3]pseudorotaxane., (© 2021 Wiley-VCH GmbH.)

While identified by the respective flavylium cation, anthocyanins are much more than this molecule. The flavylium cation (generally appearing only at very acidic pH values) is one of the molecules of a complex sequence of pH dependent molecular species reversibly interconnected by different chemical reactions. These species include the red flavylium cation, purple quinoidal base and blue or bluish anionic quinoidal bases. At the common pH of the vacuoles of simpler anthocyanins, the red flavylium cation is present only at very acidic pH values and at moderately acidic pHs there is no significant colour of the purple quinoidal base. Moreover, the blue or bluish anionic quinoidal base appearing around neutral pH values is not stable. Intermolecular (copigmentation) and intramolecular (in acylated anthocyanins) interactions increase the colour hue and yield bathochromic shifts in the absorption bands, permitting to extend the pH domain of the flavylium cation and increase the mole fraction of the quinoidal bases. Metal complexation is another strategy. In particular, the Al 3+ cation plays an essential role in the blue colour of hydrangea. The most sophisticated structures are however the metaloanthocyanins, such as the one that gives the blue colour of commelina communis , constituted of six anthocyanins, six flavanones and two metals. In this work we discuss how physical chemical tools are indispensable to account for the chemical behaviour of these complex systems. The experimental procedures and the equations needed to calculate all equilibrium constants of anthocyanins and the consequent pH dependent mole fraction distributions in the absence or presence of copigments are described in detail. Reverse pH jumps monitored by stopped flow have been shown to be an indispensable tool to calculate these parameters.

Purpose: New biomarkers may contribute to avoid unnecessary biopsies resulting from the suboptimal performance of prostate-specific antigen (PSA) testing. This study aimed to assess serum endoglin as a prostate cancer (PCa) diagnostic tool among biopsy candidates., Methods: A total of 262 consecutive patients referred for prostate biopsy based on abnormal digital rectal examination and/or elevated total PSA (tPSA) who had serum endoglin assessed by solid-phase enzyme-linked immunosorbent assay were selected. Receiver operating characteristic curves were used to compare the predictive accuracy of different combinations of biomarkers to distinguish between PCa and benign prostatic conditions, and to identify cut-offs that maximize the ability of endoglin to rule out patients for biopsy (highest sensitivities)., Results: Serum endoglin levels were higher in patients with PCa (median: 7.86 vs. 5.88 pg/mL, P < 0.001). Among patients with baseline tPSA ≤ 10 ng/mL the area under the curve was 0.69 for endoglin. Approximately one-quarter of the patients had serum endoglin < 4.92 ng/mL (sensitivity: 90.3%; specificity: 32.8%), and the probability of PCa varied from 37.7% before testing to 15.2% among those with low endoglin levels [negative predictive value (NPV) = 84.8%]. When restricting the analyses to patients with free/total PSA ratio > 0.25, the probability of cancer was less than 5% among those with serum endoglin < 6.04 ng/mL (sensitivity: 93.8%; specificity: 56.1%), corresponding to a NPV of 95.8%; this could allow sparing approximately 40% of patients from biopsy., Conclusions: Serum endoglin may be useful in clinical practice to distinguish between PCa and non-cancer patients among prostatic biopsy candidates., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The concept of molecular metamorphosis is described. A molecule (flavylium cation) generates a sequence of other different molecules by means of external stimuli. The reversibility of the system allows for the flavylium cation to be recovered by other external stimuli, completing one cycle. Differently from supramolecular chemistry, molecular metamorphosis is not a bottom-up approach. All events occur at the bottom. The procedures to characterize the kinetics and thermodynamics of the cycles are summarized. They are based on direct pH jumps (addition of a base to the flavylium cation) and reverse pH jumps (addition of an acid to equilibrated solutions at higher pH values). Stopped flow is an indispensable tool to characterize these systems. The following metamorphic cycles will be described to illustrate the concept: (i) introducing the flavanone in the metamorphic system and illustrating the concept of a timer at the molecular level; (ii) response of the flavylium-based metamorphosis to light inputs and the write-lock-read-unlock-erase molecular system; (iii) a one-way cycle of direct-reverse pH jumps; (iv) interconversion of the flavylium cation with 2,2'-spirobis[chromene] derivatives; (v) 6,8 A-ring substituent rearrangements., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Flavylium-based compounds in their acidic and cationic form bring color to aqueous solutions, while under slightly acidic or neutral conditions they commonly bring discoloration. Selective host-guest complexation between water-soluble p -sulfonatocalix[n]arenes (SCn) macrocycles and the flavylium cationic species can increase the stability of the colored form, expanding its domain over the pH scale. The association constants between SCn and the cationic (acid) and neutral basic forms of flavylium-based compounds were determined through UV-Vis host-guest titrations at different pH values. The affinity of the hosts for synthetic chromophore was found to be higher than for a natural anthocyanin (Oenin). The higher affinity of SC4 for the synthetic flavylium was confirmed by 1 H NMR showing a preferential interaction of the flavylium phenyl ring with the host cavity. In contrast with its synthetic counterpart, the flavylium substitution pattern in the anthocyanin seems to limit the inclusion of the guest in the host's binding pocket. In this case, the higher affinity was observed for the octamer (SC8) likely due to its larger cavity and higher number of negatively charged sulfonate groups.

Anthocyanins are the basis of the color of angiosperms, 3-deoxyanthocyanins and sphagnorubin play the same role in mosses and ferns, and auronidins are responsible for the color in liverworts. In this study, the color system of cyanidin-3- O -glucoside (kuromanin) as a representative compound of simpler anthocyanins was fully characterized by stopped flow. This type of anthocyanin cannot confer significant color to plants without intra- or intermolecular interactions, complexation with metals or supramolecular structures as in Commelina communis. The anthocyanin's color system was compared with those of 3-deoxyanthocyanins and riccionidin A, the aglycone of auronidins. The three systems follow the same sequence of chemical reactions, but the respective thermodynamics and kinetics are dramatically different.

Anthocyanins co-pigmentation models with application on 1:1 complexes were revisited, and their limitations were critically commented. The flavylium multistate of species is dramatically simplified to a single acid-base equilibrium between flavylium cation and its conjugated base CB, equal to the sum of quinoidal base, hemiketal, and cis and trans -chalcones. Bearing this, a new equation that simultaneously allows calculation of the co-pigmentation constant with flavylium cation ( K AH + CP ) and with its conjugated base CB ( K CBCP ) was deduced. This equation can be used at a fixed co-pigment concentration with pH as a variable or at fixed pH and co-pigment concentration variable. A global fitting of all data allows us to calculate both association constants with good accuracy. The model was applied to the co-pigmentation of malvidin-3-glucoside with caffeine and pentagalloyl glucose (PGG). Caffeine gives rise to complexes not only with flavylium cation K AH + CP = 125 ± 7 M -1 but also with CB with K CBCP = 23 ± 3 M -1 . PGG complexes exclusively with flavylium cation, K AH + CP = 914 ± 10 M -1 , and the possible interaction with quinoidal base is lower than the detection limits that the inherent experimental error permits.

The endoplasmic reticulum (ER) is one of the largest cytoplasmic organelles in eukaryotic cells and plays a role in many cellular processes, such as the production and quality control of secretory protein, lipid synthesis, and calcium homeostasis. The ER cannot be generated de novo , and thus its proper inheritance during cell division is paramount to the health and survival of the daughter cells. Although previous work has uncovered the cytoskeletal components involved, we still lack a comprehensive understanding of the intricate steps of and the cytoplasmic and membrane-bound components involved in ER inheritance. To directly address these issues, we utilized microfluidics and genetic analyses to show that before nuclear migration, early ER inheritance can be further divided into three distinctive steps. Moreover, we demonstrated that perturbing each of these steps affects the cell's ability to mitigate ER stress. Thus, proper ER inheritance is essential to ensuring a healthy, functional cell.

Introduction: Adverse health effects related with chronic exposure to waste anesthetic gases remain controversial. Strict threshold values are recommended to minimize possible health risks. The objective of our study was to measure the concentration of waste anesthetic gases in different hospital settings in an 11-year period., Materials and Methods: Six-monthly assessment of nitrous oxide, sevoflurane, and desflurane was made between 2005 and 2016 in different hospital departments. Trace gas analysis was performed by infrared spectroscopy., Results: An anesthetic gas concentration above the upper limit of the threshold value was found in computed tomography/magnetic resonance imaging (CT/MRI) (45.5%), ambulatory operating room (34.5%), and in the burn unit (31.6%). Desflurane assessment was more frequently above the upper limit of threshold value (12.37%)., Discussion: In the CT/MRI department, the small number of air cycling per hour and the frequent use of a face mask with the associated risk of leakage may explain the results. In burn unit patients inhalatory route is also frequent. Desflurane is widely used for its rapid elimination and rapid recovery, which is compatible with the results. Being odorless, it may be connected to undetected escape., Conclusion: The places with more anesthetic agents exposure were the CT/MRI, the ambulatory operating room, and the burn unit. Desflurane was the anesthetic agent more frequently above the upper limit of threshold value. To complement environmental surveillance, it is essential to establish a health surveillance system for professionals exposed to anesthetic agents., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2020 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of PBJ-Associação Porto Biomedical/Porto Biomedical Society. All rights reserved.)

The kinetics and thermodynamics (in acidic solutions) of the five chemical species reversibly interconnected by external stimuli (a multistate), such as pH and light, generated by the liverworts colorant riccionidin A were investigated. The degradation products of the multistate formed after 10 days at neutral pH were identified. The behaviour of riccionidin A multistate was compared with previous results reported for the equivalent systems based on 3-deoxyanthocyanidins (found in mosses and ferns) and anthocyanins (ubiquitous in angiosperms). The five chemical species have mutatis mutandis similar structures in the three multistates. The most dramatic difference is the extremely slow interconversion rate between flavylium cation and trans-chalcone in riccionidin A and related compounds multistates (tens of days) when compared with deoxyanthocyanins (a few days) and anthocyanins (several hours), at room temperature. The mole fraction distribution of the five species that constitute the multistate as a function of pH is also different in the three families of compounds. Some considerations regarding the chemical evolution of the three systems are given., Competing Interests: Declaration of competing interest There are no conflicts of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Introduction: Opportunistic screening for prostate cancer has been widely used, though organized programs are not recommended. We aimed to estimate the prevalence of prostate cancer screening and the perception of potential benefits and harms of screening, among the Portuguese general population., Methods: A representative sample of Portuguese-speaking inhabitants in mainland Portugal was selected, using a stratified probabilistic sampling procedure; men above 40 were considered for analysis (n = 414). Data on sociodemographic characteristics, lifetime use and usual frequency of prostate cancer screening (prostate-specific antigen test or digital rectal examination) and perception of potential benefits and adverse effects of cancer screening were assessed using face-to-face interviews, by structured questionnaire., Results: The proportion of participants who reported having been submitted to prostate cancer screening at least once in their lifetime was 44.2% (95% confidence interval: 37.5-51.0; 13.8% only digital rectal examination, 12.2% only prostate-specific antigen test, and 18.2% digital rectal examination and prostate-specific antigen test). As potential benefits of cancer screening, the options "knowledge of not having the disease", "earlier detection" and "more effective treatment" were selected by 55.8%, 12.9% and 31.3% of the participants, respectively. Regarding potential adverse effects, the most and least frequently identified were 'anxiety while waiting for the results' (55.1%) and 'false negatives' (38.0%), respectively., Conclusions: Almost half of the men between 40 and 79 years old declared that they have been screened for prostate cancer. Nearly one-third of the participants considered that reassurance of a negative result was the main potential benefit of screening, whereas most failed to identify the most frequent adverse effects.

The molecular structure of the medieval watercolor known as folium has finally been solved in the 21st century. The interdisciplinary approach taken was the key to producing extracts that had been prepared following medieval instructions, and shows the blue/purple chromophore as the major dye in Chrozophora tinctoria fruits (shell). A multi-analytical characterization of its structure was made using HPLC-DAD-MS, GC-MS, NMR ( 1 H, 13 C, COSY, HSQC, HMBC, INADEQUATE), and computational studies. The results demonstrate that the blue compound corresponds to 6'-hydroxy-4,4'-dimethoxy-1,1'-dimethyl-5'-{[3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2 H -pyran-2-yl]oxy}-[3,3'-bipyridine]-2,2',5,6(1 H ,1' H )-tetraone, a hermidin derivative, which we named chrozophoridin. Experimental data and computational modeling studies show that this mono-glycosylated dimer is represented by two stable isomers (atropisomers). This is an indispensable piece of knowledge for the characterization of this medieval dye in works of art such as medieval manuscript illuminations and for testing its stability and contributes to the preservation of our cultural heritage., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Low doses of ionizing radiation (LDIR) activate endothelial cells inducing angiogenesis. In zebrafish, LDIR induce vessel formation in the sub-intestinal vessels during post-embryonic development and enhance the inter-ray vessel density in adult fin regeneration. Since angiogenesis is a crucial process involved in both post-embryonic development and regeneration, herein we aimed to understand whether LDIR accelerate these physiological conditions. Our data show that LDIR upregulate the gene expression of several pro-angiogenic molecules, such as flt1, kdr, angpt2a, tgfb2, fgf2 and cyr61in sorted endothelial cells from zebrafish larvae and this effect was abrogated by using a vascular endothelial growth factor receptor (VEGFR)-2 tyrosine kinase inhibitor. Irradiated zebrafish present normal indicators of developmental progress but, importantly LDIR accelerate post-embryonic development in a VEGFR-2 dependent signaling. Furthermore, our data show that LDIR do not accelerate regeneration after caudal fin amputation and the gene expression of the early stages markers of regeneration are not modulated by LDIR. Even though regeneration is considered as a recapitulation of embryonic development and LDIR induce angiogenesis in both conditions, our findings show that LDIR accelerate post-embryonic development but not regeneration. This highlights the importance of the physiological context for a specific phenotype promoted by LDIR.

In the present work, five 2-styryl-1-benzopyrylium salts and their relative self-assembly processes towards TiO 2 nanocrystalline layers were evaluated as photosensitizers in dye-sensitized solar cells (DSSCs). Integration of these 2-styryl-1-benzopyrylium salts with the semiconductor allow for the performance of highly specific functions suitable for smart applications in material science. Spectroscopic and photoelectrochemical measurements conducted on these five bio-inspired dyes, in solution and upon adsorption onto titanium dioxide films, allowed detailed discussion of the anchoring ability of the different donor groups decorating the 2-styryl-1-benzopyrylium core and have demonstrated their ability as photosensitizers. Our results suggest that the introduction of a dimethylamino group in position 4' of the 2-styryl-1-benzopyrylium skeleton can alter the conjugation of the molecule leading to larger absorption in the visible region and a stronger electron injection of the dye into the conduction band of TiO 2 . Moreover, our experimental data have been supported by theoretical calculations with the aim to study the energy of the excited states of the five compounds. In this specific case, the simulations reported contributed to better describe the properties of the compounds used and to help create the necessary basis for the design of new and targeted bio-inspired molecules.

Purpose: During radiotherapy the peritumoral tissues are daily exposed to subtherapeutic doses of ionizing radiation. Herein, the biological and molecular effects of doses lower than 0.8 Gy per fraction (LDIR), previously described as angiogenesis inducers, were assessed in human peritumoral tissues., Material and Methods: Paired biopsies of preperitoneal adipose tissue were surgically collected from 16 patients diagnosed with locally advanced rectal cancer who underwent neo-adjuvant radiotherapy. One of the biopsies is located in the vicinity of the region where the tumor received the prescribed dose of radiation, and thus exposed to LDIR; the other specimen, outside all beam apertures, was used as an internal calibrator (IC). Microvessel density (MDV) was quantified by immunohistochemistry and the expression of several pro-angiogenic genes was assessed by quantitative RT-PCR using exclusively endothelial cells (ECs) isolated by laser capture microdissection microscopy., Results: LDIR activated peritumoral ECs by significantly up-regulating the expression of several pro-angiogenic genes such as VEGFR1, VEGFR2, ANGPT2, TGFB2, VWF, FGF2, HGF and PDGFC. Accordingly, the MVD was significantly increased in peritumoral tissues exposed to LDIR, compared to the IC. The patients that yielded a larger pro-angiogenic response, also showed the highest MVD., Conclusions: LDIR activate ECs in peritumoral tissues that are associated with increased MVD. Although the technological advances in radiotherapy have contributed to reduce the damage to healthy tissues over the past years, the anatomical regions receiving LDIR should be taken into account in the treatment plan report for patient follow-up and in future studies to correlate these doses with tumor dissemination., (Copyright © 2019. Published by Elsevier B.V.)

At low doses, ionizing radiation activates endothelial cells and promotes angiogenesis. However, it is still unknown if other cells may contribute to this process. In this study, the effect of low-dose ionizing radiation (LDIR) in modulating the pro-angiogenic potential of adipocytes was investigated. Adipocytes are known to secrete multiple angiogenic factors and adipokines that induce angiogenesis. In this work, a confluent monolayer of 3T3-L1 pre-adipocytes was exposed to low doses (0.1 and 0.3 Gy) and to higher doses (0.5, 0.8 and 1.0 Gy), as control. Our data show that the adipocyte-conditioned media (A-CM) from mature adipocytes differentiated from low-dose irradiated pre-adipocytes presented a higher angiogenic potential, compared to mature adipocytes differentiated from sham-irradiated control preadipocytes. The vascular endothelial growth factor (VEGF)-A levels were significantly increased in A-CM from the 0.1 Gy ( P < 0.05) and 0.3 Gy ( P < 0.01) experimental conditions and a significant increase was found in response to 0.3 Gy dose of radiation for VEGF-C, angiopoietin-2 (ANG-2) and hepatocyte growth factor (HGF). Moreover, 0.3 Gy dose of radiation significantly increased the expression of matrix metalloproteinase (MMP)-2 active forms. In vitro , the A-CM from the 0.1 and 0.3 Gy doses experimental conditions significantly accelerated endothelial cell migration after an in vitro wound healing assay. Importantly, in vivo , the A-CM corresponding to the 0.3 Gy experimental condition significantly induced the growth of more blood vessels towards the inoculation area in the chick embryo chorioallantoic membrane (CAM). In conclusion, this work reveals a new mechanism by which low-dose radiation might promote angiogenesis, enhancing the angiogenic potential of A-CM.

The comparison of the ground-state reactivity of anthocyanins and aurone model compounds (i.e. with and without the furano bridge) has shown that the kinetic paradigm does not depend on the bridge but only on the hydroxyl substituent pattern, independently of the presence of the bridge: (i) bell shaped kinetics for those with two hydroxyl substituents in position 4' and 7, and (ii) four distinct kinetic steps for the mono substituted compounds with a hydroxyl in position 4'. The excited state proton transfer (ESPT) properties of these compounds were also investigated using steady-state and time-resolved spectroscopic techniques. It was found that the ESPT efficiency is significantly higher for the bridged compounds. Interestingly, pH-dependent steady-state fluorescence emission experiments show that in 4',7-dihydroxyfuranoflavylium the hydroxyl group in position 7 is the more acidic one in the excited state, while 1 H NMR titration curves indicate a higher acidity constant in the ground state for the proton at the hydroxyl group in position 4'. Differently, the fluorescence emission spectrum of the quinoidal base deprotonated at position 7 is only observed upon excitation of the flavylium cation while the one from the base deprotonated at 4' is observed upon direct excitation.

Two anthocyanins from purple-fleshed sweet potato were isolated and characterized by LC-MS and NMR analysis. They were identified as peonidin-3-(6'-hydroxybenzoyl)-sophoroside-5-glucoside and peonidin-3-(6'-hydroxybenzoyl-6″-caffeoyl)-sophoroside-5-glucoside. The acid-base dynamics of these acylated anthocyanins was evaluated by means of pH jump techniques. Equilibrium and kinetic constants were determined and, in general, these anthocyanins demonstrated a higher capacity in retaining the red and blue colors at acidic and basic pH values, suggesting a higher resistance to pH variations compared to the parent anthocyanin, peonidin-3-O-glucoside. The presence of acyl groups and additional glucoside moieties seems to determine this particular characteristic. The fluorescence properties of these anthocyanins were evaluated. Overall, the species present at higher pH values (7-9) showed higher fluorescence intensity for both anthocyanins, with an optimum λ ex /λ em pair at λ ex 610 nm/λ em 640 nm. The fluorescence characteristics of these anthocyanins were used to evaluate their location in gastric and intestinal cells by fluorescence microscopy., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

A new experimental procedure to calculate all equilibrium constants of the multistate of species of anthocyanins and related compounds, including those in basic medium, is reported. The procedure is based on a series of pH jumps monitored by stopped flow from an extended pH range of solutions at pseudo-equilibrium (when there is no significant formation of trans -chalcones) or at equilibrium to pH = 1.0. The experimental procedure is described for the anthocyanin model compound 4'-hydroxyflavylium, which exhibits a peculiar behavior in moderately acidic medium, because the quinoidal base, hemiketal, and cis -chalcone have similar mole fractions at pseudo-equilibrium, permitting good discrimination among these species. The experimental procedure can be extended to the copigmentation phenomenon and allow the calculation of the 1:1 copigmentation constants of the flavylium cation, quinoidal base, hemiketal, and cis - and trans -chalcones (this last from the equilibrium) and their respective ionized forms. The method was applied to calculate the copigmentation constants of the model compound 4'-hydroxyflavylium as well as malvidin-3-glucoside with caffeine. In the last compound, the strongest interaction takes place with the quinoidal base ( K = 303 M -1 ) and flavylium cation ( K = 134 M -1 ) and, to a lesser extent, with the ionized quinoidal base ( K = 43 M -1 ) and cis -chalcone ( K = 17 M -1 ). The caffeine interaction with the hemiketal and the other ionized species is negligible., Competing Interests: The authors declare no competing financial interest.

Objectives: To evaluate salivary adiponectin and adenosine deaminase (ADA) in women suffering from Sjögren's syndrome (SS)., Methods: Salivary adiponectin and ADA were measured in patients with SS (n = 17) and compared to their values in healthy controls (n = 13) and patients suffering from drug-induced xerostomia (non-SS sicca group; n = 19). A clinical history was made for each patient, patients were examined clinically, and xerostomia inventory (XI) was performed., Results: Salivary adiponectin corrected by total protein was higher in patients with SS than in healthy individuals (P < 0.05) or patients with non-SS sicca (P < 0.01) and correlated with XI (r = 0.555; P < 0.05). Salivary ADA was higher in patients with SS and non-SS sicca compared to controls (P < 0.05 in both cases)., Conclusion: The results of the present study indicate that adiponectin and ADA are increased in the saliva of patients with SS., Clinical Relevance: Salivary adiponectin corrected by total protein can be a potential biomarker of SS., Trial Registration: NCT03156569.

The multistate of chemical species generated by 4'-hydroxy-3,2'-furanoflavylium is similar to that of anthocyanins and related compounds. This furanoflavylium multistate system was fully characterized by UV-visible and NMR spectroscopy, allowing determination of the respective equilibrium and rate constants. In contrast to the multistate generated by flavylium cations derived from anthocyanins and related compounds, the furanoflavylium multistate is characterized by much slower hydration and tautomerization (pyran ring opening-closing). In addition, the cis-trans isomerization of the chalcones of this system (2'-hydroxyaurones) is extremely slow when compared with anthocyanins. The observed similar order of magnitude for tautomerization and isomerization rate constants leads to peculiar kinetics from the flavylium cation (pH = 1) to the stable trans -chalcone (higher pH values). The hemiketal appears and disappears during the first stages of the kinetics, which gives the intermediate cis -chalcone (pseudo-equilibrium). This last species disappears in a much slower process, as fully characterized by 1 H NMR, to give the final trans -chalcone., Competing Interests: The authors declare no competing financial interest.

As in supramolecular chemistry, complexity could also be achieved through a bottom-up approach. Anthocyanins and related compounds such as the compound ( E )-6-(dimethylamino)-4-(4-(dimethylamino)-2-hydroxybenzylidene)-1,2,3,4-tetrahydroxanthylium chloride ( 1 ), here reported, exhibit this type of complexity. The thermodynamics and kinetics of the complex multistate of species of compound 1 were studied by conventional and stopped-flow UV-visible spectrophotometry as well as by NMR. The system follows the same multistate of species of anthocyanins, except for the presence at moderately basic pH values of a species possessing a spiro carbon. The introduction of two dimethylamino substituents in positions 4' and 7, modulates deeply the thermodynamic and kinetics of the system. A beautiful pH-dependent palette of colors is obtained, including a blue flavylium cation at unusually high pH values. The protonation of the dimethylamino substituents is the key aspect for explaining the details of the spiro opening kinetics. The system was fully characterized by representing the mole fraction distribution and the relative energy level diagram of all multistate species as a function of pH., Competing Interests: The authors declare no competing financial interest.

A convenient method to synthesize A-type proanthocyanidin analogues from flavylium salts and π-nucleophiles has been developed. It was found that the thermodynamic stability of the starting flavylium salt, assessed by the measurement of the apparent acidity constant ( K' a ), was the key parameter to design effective one-pot reactions between flavylium salts and nucleophiles such as phloroglucinol and (+)-catechin. When flavylium salts have a p K' a value of 1.7 or lower, the synthesis of the corresponding 2,8-dioxabyciclo[3.3.1]nonane derivative was properly achieved.

The interaction of malvidin-3- O-glucoside (1) and a lignosulfonate was studied by UV-visible spectroscopy, and the results obtained showed the formation of a complex between the negatively charged lignosulfonate and the flavylium cation form (AH + ) of this anthocyanin at pH 1. The thermodynamic and kinetic parameters of 1 in the presence of a lignosulfonate were determined by UV-visible spectroscopy and stopped-flow techniques. The main differences were observed in the flavylium cation (AH + )/quinoidal base (A) equilibrium, the AH + form being more stabilized than A (p K a1 = 4.4 ± 0.1) compared with 1 in the absence of the lignosulfonate (p K a1 = 3.9 ± 0.1). Furthermore, comparing the hydration ( k h = 0.028 s -1 ) and dehydration ( k -h = 40 M -1 s -1 ) processes of 1 in the presence of the lignosulfonate with the processes of 1 ( k h = 0.12 s -1 and k -h = 35 M -1 s -1 ) show that the hydration process is slower while the dehydration process is practically unaffected in the presence of the lignosulfonate.

All equilibrium and rate constants of heavenly blue anthocyanin (HBA 1) as well as the derivatives with two (HBA 2) or none (HBA 3) acylated units were determined. The three acylated units of the sugar in position 3 of the peonidin chromophore of HBA 1 are essential to confer the peculiar stability of its purple and blue colors. The sugars generate an efficient protective environment around position 2 (and 4) of the flavylium cation, through an intramolecular sandwich-type stacking that retards 35-fold the hydration reaction ( k h ) and increases 8.8-fold the dehydration reaction ( k -h ), when compared with the peonidin chromophore HBA 3. The conjugation of these two rates lowers 308-fold the hydration equilibrium constant ( K h ), corresponding to a raise of the energy level of the hemiketal by 14.2 kJ mol -1 . Conversely, the p K a of the quinoidal base in HBA 1 is only slightly stabilized in comparison with that of HBA 2 and HBA 3. The energy level of hemiketal increases with the number of acylated units, but the inversion of energies between hemiketal and quinoidal base takes place exclusively for HBA 1 (three acylated units), permitting in moderately acidic solutions the stabilization of the purple quinoidal base. Identical inversion of energy was observed for the corresponding ionized species, allowing the stabilization of the blue ionized quinoidal base in slightly basic solutions. At pH values higher than 8, the hydroxyl groups of the hydroxycinnamic acid units start to deprotonate disrupting the intramolecular sandwich-type stacking and the more or less slow degradation of the anthocyanin is observed.

Inherited deletions of α-globin genes and/or their upstream regulatory elements (MCSs) give rise to α-thalassemia, an autosomal recessive microcytic hypochromic anemia. In this study, multiplex ligation-dependent probe amplification performed with commercial and synthetic engineered probes, Gap-PCR, and DNA sequencing were used to characterize lesions in the sub-telomeric region of the short arm of chromosome 16, possibly explaining the α-thalassemia/HbH disease phenotype in ten patients. We have found six different deletions, in heterozygosity, ranging from approximately 3.3 to 323 kb, two of them not previously described. The deletions fall into two categories: one includes deletions which totally remove the α-globin gene cluster, whereas the other includes deletions removing only the distal regulatory elements and keeping the α-globin genes structurally intact. An indel was observed in one patient involving the loss of the MCS-R2 and the insertion of 39 bp originated from a complex rearrangement spanning the deletion breakpoints. Finally, in another case, no α-globin gene cluster deletion was found and the patient revealed to be a very unusual case of acquired α-thalassemia-myelodysplastic syndrome. This study further illustrates the diversity of genomic lesions and underlying molecular mechanisms leading to α-thalassemia.

Introduction: HTLV-1 infection is endemic in Japan, Caribbean, Africa, and South America. It is transmitted from mother to child, sexual contact, blood transfusions, or sharing needles. Tropical Spastic paraparesis (TSP) is a chronic degenerative neurological disease associated with this infection. It results from a spinal cord symmetrical degeneration at the thoracic level and is characterized by progressive motor weakness in the lower limbs, hyperreflexia, sensitivity changes, urinary incontinence, and bladder dysfunction., Clinical Case: Female, 53 years old, HTLV-1 infection and TSP. She had decreased strength in the lower limbs and hyperreflexia, paretic gait, spasticity, and neurogenic bladder symptoms, with recurrent urinary infections. She was scheduled for cystectomy. The patient was monitored according to standard ASA. Due to severe coagulopathy and the possibility of neurological worsening, epidural catheter was not placed. The induction of general anesthesia was performed with midazolam and fentanyl, followed by etomidate and cisatracurium. She was intubated with a tube size seven and maintained with desflurane and oxygen. Anesthesia was uneventful; the surgery lasted 1 hour and 50minutes. There were no complications in the immediate postoperative period, during hospitalization, nor deterioration of the neurological examination. The patient was discharged 20 days later., Discussion/conclusion: There are reports of decreased electromyographic response and neurological deterioration associated with propofol in these patients, etomidate was used. The hepatic metabolism of rocuronium posed a risk, we chose to use cistracurium. It was concluded that the anesthesia chosen did not affect the course of the disease., (Copyright © 2015 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.)

We present here a complete study on four synthetic environmentally friendly flavylium salts employed as sensitizers for dye-sensitized solar cells (DSSCs). The effect of several donor groups on the molecular structure of flavylium ions was investigated by combining electrochemical, spectroscopic and computational means. The computational investigation indicated that these molecules can interact strongly with the TiO 2 surface by a single OH group of the dihydroxybenzene moiety, and can efficiently inject electrons into the TiO 2 following the excitation of their lowest singlet states exhibiting charge transfer (CT) character. In general, all dyes within the explored series exhibited quite good regeneration efficiencies, often ≥70%, in the presence of an iodide electron donor, explaining the high IPCEs and photocurrents recorded in the presence of high lithium content electrolytes. The combination of molecular orbital calculations and electrochemical measurements has also revealed that the introduction of donor groups on the benzopyrylium ring has a generally positive effect resulting in an extended low energy light harvesting and in a potential improvement of the photoinduced charge separation at the semiconductor/dye/electrolyte interface. It also increases the reversibility of the oxidative redox processes of these bio-inspired species, a feature in favour of their long-term stability. At present the best dye within the explored series is 7-(N,N-diethylamino)-3',4'-dihydroxyflavylium chloride based on a dialkylamine donor which is capable of delivering, under optimized conditions, a short-circuit current density of 15 mA cm -2 . This is the highest value so far obtained for synthetic analogues of anthocyanins.

Symmetrical and nonsymmetrical oxobis(bipyridinium) cations combined with iodide and bistriflimide anions were prepared. In the case of the bistriflimide-based bis(bipyridinium) salts, two room-temperature ionic liquids (RTILs) with a combination of linkers and terminal ethers, [(C 3 O)bpy(C 4 O)bpy(C 3 O)][NTf 2 ] 4 and [(C 10 )bpy(C 4 O)bpy(C 3 O)][NTf 2 ] 4 , were obtained, with glass transition temperatures (between -6.9 and 6.0 °C) higher than those reported previously for salts of dication bipyridinium scaffolds (-17.5 to -30.0 °C). The prepared salt containing [(C 10 )bpy(C 4 O)bpy(C 10 )][NTf 2 ] can form an ionic liquid crystal structure. The most promising salts were tested as efficient and reversible multicolored electrochromic devices through cyclic voltammetry studies and detailed characterizations of their electrochromic performances. In general, tetracations based on oxobis(bipyridinium) salts show higher chromatic contrast and lower coloration efficiency than similar dication salts. Exchange of the anion from iodide to [NTf 2 ] increases the transition times and coloration efficiencies for all the prepared di- and tetracation salts. The electrochromic device stability of [(C 3 O)bpy(C 4 O)bpyC 3 O]I 4 was tested by on/off cycling; this device loses around 23 % of the initial color after 8640 redox cycles and shows very good cycling stability compared with previously reported diiodide salts., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

There is a large geographical variability in prostate cancer incidence and mortality trends, mostly because of heterogeneity in control efforts across regions. We aimed to describe the time trends in prostate cancer incidence and mortality in Portugal, overall and by region, and to estimate the number of incident cases and deaths in 2020. The number of cases and incidence rates in 1998-2009 were collected from the Regional Cancer Registries. The number of deaths and mortality rates were obtained from the WHO mortality database (1988-2003 and 2007-2013) and Statistics Portugal (2004-2006; 1991-2013 by region). JoinPoint analyses were used to identify significant changes in trends in age-standardized incidence and mortality rates. Incidence and mortality predictions for 2020 were performed using Poisson regression models and population projections provided by Statistics Portugal. In Portugal, prostate cancer incidence has been increasing since 1998 (1.8%/year), with the exception of the North Region, with a decrease since 2006 (-3.2%/year). An overall mortality decline has been observed since 1997 (-2.2%/year), although there were two patterns of mortality variation at the regional level: one with an inflection point or significant variation in the rates and the other without significant variation. If these trends are maintained, ∼8600 incident cases and 1700 deaths may be expected to occur in Portugal in 2020. Despite the overall increasing incidence and decreasing mortality, there is a large heterogeneity across regions. Future studies should address regional differences in the trends of prostate specific antigen screening and in the effective management of prostate cancer.

The effect of β-cyclodextrin on the mole fraction distribution of the multistate species of the anthocyanin model compound, 3-methoxy-4',7-dihydroxyflavylium, was studied by NMR, stopped flow, circular dichroism, and UV-visible absorption spectroscopy. The formation of inclusion complexes with hemiketal and trans-chalcone, possessing transition dipole moments in a parallel orientation to the cyclodextrin n-fold axis, was unequivocally proved by means of the positive-induced circular dichroism signal. The discrimination of the two hemiketal enantiomers was achieved by the splitting of 1 H NMR peaks in the presence β-cyclodextrin. The spectroscopic data shows that the β-cyclodextrin has only moderate enantioselectivity, slightly favoring one of the optical isomers. The observed binding affinity of β-cyclodextrin for the 3-methoxy-4',7-dihydroxyflavylium multistate species increases in the order flavylium cation < quinoidal base < hemiketal < trans-chalcone < cis-chalcone. As a result of this selectivity and the dynamic nature of the network, the equilibrium is displaced toward the formation of the chalcone species.

Aims: We have previously shown that low-dose ionizing radiation (LDIR) induces angiogenesis but there is no evidence that it induces neovascularization in the setting of peripheral arterial disease. Here, we investigated the use of LDIR as an innovative and non-invasive strategy to stimulate therapeutic neovascularization using a model of experimentally induced hindlimb ischemia (HLI)., Methods and Results: After surgical induction of unilateral HLI, both hindlimbs of female C57BL/6 mice were sham-irradiated or irradiated with four daily fractions of 0.3 Gy, in consecutive days and allowed to recover. We demonstrate that LDIR, significantly improved blood perfusion in the murine ischemic limb by stimulating neovascularization, as assessed by laser Doppler flow, capillary density, and collateral vessel formation. LDIR significantly increased the circulating levels of VEGF, PlGF, and G-CSF, as well as the number of circulating endothelial progenitor cells (EPCs) mediating their incorporation to ischemic muscles. These effects were dependent upon LDIR exposition on the ischemic niche (thigh and shank regions). In irradiated ischemic muscles, these effects were independent of the recruitment of monocytes and macrophages. Importantly, LDIR induced a durable and simultaneous up-regulation of a repertoire of pro-angiogenic factors and their receptors in endothelial cells (ECs), as evident in ECs isolated from the irradiated gastrocnemius muscles by laser capture microdissection. This specific mechanism was mediated via vascular endothelial growth factor (VEGF) receptor signaling, since VEGF receptor inhibition abrogated the LDIR-mediated gene up-regulation and impeded the increase in capillary density. Finally, the vasculature in an irradiated non-ischemic bed was not affected and after 52 week of LDIR exposure no differences in the incidence of morbidity and mortality were seen., Conclusions: These findings disclose an innovative, non-invasive strategy to induce therapeutic neovascularization in a mouse model of HLI, emerging as a novel approach in the treatment of critical limb ischemia patients., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions please email: journals.permissions@oup.com.)

The chemistry of 2,2'-spirobis[chromene] derivatives is intimately related to the one of anthocyanins and similar compounds. The 2,2'-spirobis[chromene] species plays a central role in the network of chemical reactions connecting two different flavylium-based multistate systems. In the present work, a new asymmetric 2,2'-spirobis[chromene] intermediate possessing a constrained propylenic bridge between carbons 3 and 3' was isolated and its role as a pivot in the anthocyanins-type multistate of chemical reactions was investigated by the conjugation of absorption spectroscopy, stopped-flow, NMR, and X-ray crystallography. It was confirmed that the propylenic bridge is essential to stabilize the spirobis[chromene] species. Furthermore, under acidic conditions, two cis-trans styrylflavylium isomers were identified, which could be interconverted directly into one another with light. This is the first report of styrylflavylium cations with photoisomerization on the styryl moiety.

Cucurbit[7]uril inclusion complexes with guests bearing dimethylamino groups show the expected upward p K a shifts, whereas their diethylamino counterparts display a decrease in p K a due to the preferential stabilization of the unprotonated form. These results identify the diethylamino group as the substituent of choice to avoid receptor-assisted protonation of guest molecules and present new evidence for the role of the hydrophobic effect as a driving force in cucurbituril complexation., Competing Interests: The authors declare no competing financial interest.

A structurally constrained derivative of 4',7-dihydroxyflavylium was studied in aqueous solution and in CTAB micelles by pH jumps, flash photolysis and continuous irradiation with spectroscopic details assessed as well by theoretical calculations. In water, up to pH = 8, the compound shows only acid base chemistry with deprotonation of the flavylium cation to form a quinoidal base that further deprotonates with pK a s of 4.8 and 7.4. In the basic region, unprotonated trans-chalcones are formed. No neutral trans-chalcone (Ct) is formed in water preventing the establishment of the well-known photochromism involving photoisomerization of this species with subsequent formation of the flavylium cation. Addition of 0.02 M CTAB drastically changes the mole fraction distribution of species, leading to the formation of Ct (χ Ct = 1 at pH = 5) and unveiling a photochromic behavior with a pH-tunable colour contrast in a large pH range (2 < pH < 8). The Ct species can be hidden again (irreversibly) upon addition of α-cyclodextrin that disrupts the CTAB micelles, reverting the system to its initial mole fraction distribution of species. These supramolecular inputs work atop the molecular reaction networks by modifying their species' mole fraction distribution.