Hydrazone-flavonol based oxidovanadium(V) complexes: Synthesis, characterization and antihyperglycemic activity of chloro derivative in vivo

Wet synthesis approach afforded four new heteroleptic mononuclear neutral diamagnetic oxidovanadium(V) complexes, comprising salicylaldehyde-based 2-furoic acid hydrazones and a flavonol coligand of the general composition [VO(fla)(L-ONO)]. The complexes were comprehensively characterized, including chemical analysis, conductometry, infrared, electronic, and mass spectroscopy, as well as 1D 1H and proton-decoupled 13C(1H) NMR spectroscopy, alongside extensive 2D 1H1H COSY, 1H13C HMQC, and 1H13C HMBC NMR analyses. Additionally, the quantum chemical properties of the complexes were studied using Gaussian at the B3LYP, HF, and M062X levels on the 6-31++g(d,p) basis sets. The interaction of these hydrolytically inert vanadium complexes and the BSA was investigated through spectrofluorimetric titration, synchronous fluorimetry, and FRET analysis in a temperature-dependent manner, providing valuable thermodynamic insights into van der Waals interactions and hydrogen bonding. Molecular docking was conducted to gain further understanding of the specific binding sites of the complexes to BSA. Complex 2, featuring a 5-chloro-substituted salicylaldehyde component of the hydrazone, was extensively examined for its biological activity in vivo. The effects of complex administration on biochemical and hematological parameters were evaluated in both healthy and diabetic Wistar rats, revealing antihyperglycemic activity at millimolar concentration. Furthermore, histopathological analysis and bioaccumulation studies of the complex in the brain, kidneys, and livers of healthy and diabetic rats revealed the potential for further development of vanadium(V) hydrazone complexes as antidiabetic and insulin-mimetic agents.

Bioisosteric heterocyclic analogues of natural bioactive flavonoids by scaffold-hopping approaches: State-of-the-art and perspectives in medicinal chemistry

The flavonoid family is a set of well-known bioactive natural molecules, with a wide range of potential therapeutic applications. Despite the promising results obtained in preliminary in vitro/vivo studies, their pharmacokinetic and pharmacodynamic profiles are severely compromised by chemical instability. To address this issue, the scaffold-hopping approach is a promising strategy for the structural optimization of natural leads to discover more potent analogues. In this scenario, this Perspective provides a critical analysis on how the replacement of the chromon-4-one flavonoid core with other bioisosteric nitrogen/sulphur heterocycles might affect the chemical, pharmaceutical and biological properties of the resulting new chemical entities. The investigated derivatives were classified on the basis of their biological activity and potential therapeutic indications. For each session, the target(s), the specific mechanism of action, if available, and the key pharmacophoric moieties were highlighted, as revealed by X-ray crystal structures and in silico structure-based studies. Biological activity data, in vitro/vivo studies, were examined: a particular focus was given on the improvements observed with the new heterocyclic analogues compared to the natural flavonoids. This overview of the scaffold-hopping advantages in flavonoid compounds is of great interest to the medicinal chemistry community to better exploit the vast potential of these natural molecules and to identify new bioactive molecules.

K+-Specification with Flavone P0 Probe in a G-Quadruplex DNA

G-quadruplex (G4) DNA is considered as a prospective therapeutic target due to its potential biological significance. To understand G4 biological roles and function, a G4-specific fluorescent probe is necessary. However, it is difficult for versatile G4 to precisely recognize without perturbing their folding dynamics. Herein, we reported that flavone P0 can be a fluorescent probe for G4 DNA-specific recognition and have developed a highly selective detection of K+ ion by dimeric G4/P0 system. When comparing various nucleic acid structures, including G4, i-motif, ss/ds-DNA, and triplex, an apparent fluorescence enhancement is observed in the presence of G4 DNA for 85-fold, but only 8-fold for non-G4 DNA. Furthermore, based on fluorescent probe of flavone P0 for G4 DNA screening, the noncovalent dimeric G4/P0 system is exploited as a K+ sensor, that selectively responds to K+ with a 513-fold fluorescence enhancement and a detection range for K+ ion concentration from 0 to 500 mM. This K+ sensor also has a remarkably anti-interference ability for other metal cations, especially for a high concentration of Na+. These results have demonstrated that flavone P0 is an efficient tool for monitoring G-quadruplex DNA and endows flavone P0 with bioanalytical and medicinal applications.

5,7-dihydroxy-3',4',5'-trimethoxyflavone mitigates lead induced neurotoxicity in rats via its chelating, antioxidant, anti-inflammatory and monoaminergic properties

Chronic exposure to lead (Pb) induces neurodegenerative changes in animals and humans. Drugs with strong antioxidant properties are effective against Pb-mediated neurotoxicity. In a prior study, we identified 5,7-dihydroxy-3',4',5'-trimethoxyflavone (TMF) from Ocimum basilicum L. leaves as a potent antioxidant and neuroprotective compound. This research explores TMF's neuroprotective effects against Pb-induced brain toxicity in rats to establish it as a therapeutic agent. Rats received lead acetate (100 mg/kg, orally, once daily) for 30 days to induce brain injury, followed by TMF treatment (5 and 10 mg/kg, oral, once daily) 30 min later. Cognitive and motor functions were assessed using Morris Water Maze and horizontal bar tests. Lead, monoamine oxidase (MAO) A and B enzymes, reduced glutathione (GSH), thiobarbituric acid reactive species (TBARS), Tumor necrosis factor-alpha (TNF-α), and IL-6 levels were measured in the hippocampus and cerebellum. Pb exposure impaired cognitive and motor functions, increased Pb, TBARS, TNF-α, and IL-6 levels, and compromised MAO A & B and GSH levels. TMF reversed Pb-induced memory and motor deficits and normalized biochemical anomalies. TMF's neuroprotective effects against lead involve chelating, antioxidant, anti-inflammatory, and monoaminergic properties, suggesting its potential as a treatment for metal-induced brain injury.

Unveiling the Antioxidative Potential of Galangin: Complete and Detailed Mechanistic Insights through Density Functional Theory Studies

A comprehensive quantum mechanical investigation delved into the antioxidative activity of galangin (Glg). Thermochemical and kinetic data were used to assess antiradical, chelating, and renewal potential under physiological conditions. A brief comparison with reference antioxidants and other flavonoids characterized Glg as a moderate antioxidative agent. The substance showed significantly lower performance in lipid compared to aqueous solvent─the reaction rates for scavenging •OOH in both media were established at 3.77 × 103 M-1 s-1 and 6.21 × 104 M-1 s-1, respectively, accounting for the molar fraction of both interacting molecules at the given pH. The impact of pH value on the kinetics was assessed. Although efficient at chelating Cu(II) ions, the formed complexes can still undergo the Fenton reaction. On the other hand, they persistently scavenge •OH in statu nascendi. The flavonoid effectively repairs oxidatively damaged biomolecules except model lipid acids. All Glg radicals are readily restored by physiologically prevailing O2•-. Given this, the polyphenol is expected to participate in antiradical and regenerating activities multiple times, amplifying its antioxidative potential.

CO2-Sourced Polymer Dyes for Dual Information Encryption

Large amounts of small molecule dyes leak into the ecosystems annually in harmful and unsustainable ways. Polymer dyes have attracted much attention because of their high migration resistance, excellent stability, and minimized leakage. However, the complex synthesis process, high cost, and poor degradability hinder their widespread application. Herein, green and sustainable polymer dyes are prepared using natural dye quercetin (Qc) and CO2 through a one-step process. The CO2-sourced polymer dyes show strong migration resistance, high stability, and can be degraded on demand. Additionally, the CO2-sourced polymer dyes showed unique responses to Zn2+, leading to significantly enhanced fluorescence, highlighting their potential for information encryption/decryption. The CO2-sourced polymer dyes can solve the environmental hazards caused by small molecule dye leakage and promote the carbon cycle process. Meanwhile, the one-step synthesis process is expected to achieve sustainable and widespread utilization of CO2-sourced polymer dyes.

Investigation on production and reaction conditions of sucrose synthase based glucosylation cascade towards flavonoid modification

Enzyme-based glycosylation is of great interest in the context of natural products decoration. Yet, its industrial application is hindered by optimisation difficulties and hard-to-standardise productivities. In this study, five sugar nucleotide-dependent glucosyltransferases from different origins (bacterial, plant and fungal) were coupled with soy sucrose synthase (GmSuSy) to create a set of diverse cascade biocatalysts for flavonoid glucosylation, which evaluation brought new insights into the field. Investigations into co-expression conditions and reaction settings enabled to define optimal induction temperature (25 °C) and uridine diphosphate (UDP) concentration (0.5 mM) for all tested pairs of enzymes. Moreover, the influence of pH and substrate concentration on the monoglucosylated product distribution was detected and analysed. The utilisation of crude protein extracts as a cost-effective source of catalysts unveiled their glycosidase activity against flavonoid glucosides, resulting in decreased productivity, which, to our knowledge, has not previously been discussed in such a context. Additionally, examination of the commercially available EziG immobilisation resins showed that selection of suitable carrier for solid catalyst production can be problematic and not only enzyme's but also reagent's properties have to be considered. Flavonoids, due to their complexation and hydrophobic properties, can adsorb on different types of surfaces, including divalent metal ions required for IMAC based immobilisation, necessitating detailed examination of the resins while the catalysis design.

EGCG-based nanoparticles: synthesis, properties, and applications

(-)-Epigallocatechin-3-gallate (EGCG) is a natural phenolic substance found in foods and beverages (especially tea) that exhibits a broad spectrum of biological activities, including antioxidant, antimicrobial, anti-obesity, anti-inflammatory, and anti-cancer properties. Its potential in cardiovascular and brain health has garnered significant attention. However, its clinical application remains limited due to its poor physicochemical stability and low oral bioavailability. Nanotechnology can be used to improve the stability, efficacy, and pharmacokinetic profile of EGCG by encapsulating it within nanoparticles. This article reviews the interactions of EGCG with various compounds, the synthesis of EGCG-based nanoparticles, the functional attributes of these nanoparticles, and their prospective applications in drug delivery, diagnosis, and therapy. The potential application of nanoencapsulated EGCG in functional foods and beverages is also emphasized. Top-down and bottom-up approaches can be used to construct EGCG-based nanoparticles. EGCG-based nanoparticles exhibit enhanced stability and bioavailability compared to free EGCG, making them promising candidates for biomedical and food applications. Notably, the non-covalent and covalent interactions of EGCG with other substances significantly contribute to the improved properties of these nanoparticles. EGCG-based nanoparticles appear to have a wide range of applications in different industries, but further research is required to enhance their efficacy and ensure their safety.

Theoretical Exploration of Enhanced Antioxidant Activity in Copper Complexes of Tetrahydroxystilbenes: Insights into Mechanisms and Molecular Interactions

A theoretical investigation was conducted using DFT/PW91/TZP/DMSO calculations on a complete set of exhaustive lists of 18 compounds resulting from the complexation of trans-2,4,3',5'-tetrahydroxystilbene (T-OXY) and cis-2,4,1',3'-tetrahydroxystilbene (C-OXY) with copper metal cations (Cu+ and Cu2+). The ligand-binding sites are the critical points of Quantum Theory of Atoms in Molecules (QTAIM) analysis on neutral and deprotonated ligands. Various mechanisms, including hydrogen atom transfer (HAT), sequential proton loss electron transfer (SPLET), single electron transfer followed by proton transfer (SET-PT), and bond dissociation energy (BDE(E0)) calculations, were employed to quantify the antioxidant activity. The BDE(E0) mechanism emerged as the most suitable approach for such analyses to evaluate the departure of hydrogen atoms since the results show the HAT mechanism is the most likely occurring. Particularly intriguing were the anionic Cu+ complexes with ligands adopting trans configurations and deprotonated conformations, displaying superior antioxidant activity compared to their counterparts. Remarkably, a single ligand within the Cu+ complex exhibited exceptional antioxidant prowess, yielding a BDE(E0) value of 91.47 kcal/mol. Furthermore, a complex involving two deprotonated ligands demonstrated antioxidant activity of 31.12 kcal/mol, signifying its potential as a potent antiradical agent, surpassing T-OXY by a factor of 3.91 and even surpassing the antioxidant efficiency of Vitamin C.

Effects of barakol from Cassia siamea on neuroblastoma SH-SY5Y cell line: A potential combined therapy with doxorubicin

Management of neuroblastoma is challenging because of poor response to drugs, chemotherapy resistance, high relapse, and treatment failures. Doxorubicin is a potent anticancer drug commonly used for neuroblastoma treatment. However, doxorubicin induces considerable toxicities, particularly those caused by oxidative-related damage. To minimize drug-induced adverse effects, the combined use of anticancer drugs with natural-derived compounds possessing antioxidant properties has become an interesting treatment strategy. Barakol is a major compound found in Cassia siamea, an edible plant with antioxidant and anticancer properties. Therefore, barakol could potentially be used in combination with doxorubicin to synergize the anticancer effect, while minimizing the oxidative-related toxicities. Herein, the potential of barakol (0.0043-43.0 μM) to synergize the anticancer effect of low-dose doxorubicin (0.5 and 1.0 μM) was investigated. Results indicated that barakol could enhance the cytotoxic effect of low-dose doxorubicin by affecting the cell viability of the treated cells. Furthermore, the co-treatment with barakol and low-dose doxorubicin decreased the levels of intracellular ROS when compared with the control. Moreover, the antimetastatic effect of the barakol itself was studied through its ability to inhibit metalloproteinase-3 (MMP-3) activity and prevent cell migration. Results revealed that the barakol inhibited MMP-3 activity and prevented cell migration in time- and dose-dependent manners. Additionally, barakol was a non-cytotoxic agent against the normal tested cell line (MRC-5), which suggested its selectivity and safety. Taken together, barakol could be a promising compound to be further developed for combination treatment with low-dose doxorubicin to improve therapeutic effectiveness but decrease drug-induced toxicities. The inhibitory effects of barakol on MMP-3 activity and cancer cell migration also supported its potential to be developed as an antimetastatic agent.

Complexation of Flavonoids: Spectral Phenomena, Regioselectivity, Interplay with Charge and Proton Transfer

The review compiles information on the spectral classification of flavonoids, the changes in their electronic structure upon complex formation, and the manifestation of these changes in the absorption and emission spectra. Part of the review is devoted to the regioselectivity of the complex formation process, including types of complexation sites, the structure of chelates and 'open' complexes, and the correlation between the structure of complexes and their spectral properties. The interplay between complex formation and other processes occurring in flavonoids during electronic excitation is also considered, such as intramolecular inter-fragment charge transfer (ICT) and intramolecular proton transfer (ESIPT). The review also contains systematic data on the study of regioselectivity and spectral properties of flavone complexes, obtained by the author and their colleagues over the past decades.

Phenanthroline and Schiff Base associated Cu(II)-coordinated compounds containing N, O as donor atoms for potent anticancer activity

As an inherent metal ion, copper has been the subject of investigation for developing a novel antitumoral compound that exhibits fewer adverse effects. Copper serves as a cofactor in multiple enzymes, generates reactive oxygen species (ROS), facilitates tumour evolution, metastasis and angiogenesis and has been detected at elevated concentrations in the serum and tissues of various human cancer types. In the given setting, utilising two methodologies in developing novel Copper-based pharmaceuticals for anti-cancer applications is standard practice. These approaches involve either the sequestration of unbound Copper ions or the synthesis of Copper complexes that induce cellular apoptosis. In the past four decades, the latter system has been used, leading to numerous reviews that have examined the anticancer characteristics of a wide range of Copper complexes. These analyses have consistently demonstrated that multiple factors frequently influence the efficacy of these compounds. This review examines the possible anticancer properties of copper and Cu(II) complexes that incorporate Schiff base ligands containing 1,10-phenanthroline. The present study will comprehensively analyse the examined cell lines and mechanistic research associated with each complex.

Effects of Fluorinated Functionalization of Linker on Quercetin Encapsulation, Release and Hela Cell Cytotoxicity of Cu-Based MOFs as Smart pH-Stimuli Nanocarriers

Controlled delivery of target molecules is required in many medical and chemical applications. For such purposes, metal-organic frameworks (MOFs), which possess desirable features such as high porosity, large surface area, and adjustable functionalities, hold great potential as drug carriers. Herein, Quercetin (QU), as an anticancer drug, was loaded on Cu2 (BDC)2 (DABCO) and Cu2 (F4 BDC)2 )DABCO) MOFs (BDC=1,4-benzenedicarboxylate and DABCO=1,4-diazabicyclo[2.2.2]octane). As these Cu-MOFs have a high surface area, an appropriate pore size, and biocompatible ingredients, they can be utilized to deliver QU. The loading efficiency of QU in these MOFs was 49.5 % and 41.3 %, respectively. The drug-loaded compounds displayed sustained drug release over 15 days, remarkably high drug loading capacities and pH-controlled release behavior. The prepared nanostructures were characterized by different characterization technics including FT-IR, PXRD, ZP, TEM, FE-SEM, UV-vis, and BET. In addition, MTT assays were carried out on the HEK-293 and HeLa cell lines to investigate cytotoxicity. Cellular apoptosis analysis was performed to investigate the cell death mechanisms. Grand Canonical Monte Carlo simulations were conducted to analyze the interactions between MOFs and QU. Moreover, the stability of MOFs was also investigated during and after the drug release process. Ultimately, kinetic models of drug release were evaluated.

Flavonoid-metal ion Complexes as Potent Anticancer Metallodrugs: A Comprehensive Review

BACKGROUND

Flavonoids and their analogous are mainly found in pink lady apples, green and black tea (catechins), celery and red peppers, onions, broccoli and spinach, berries, cherries, soybean, citrus fruits, and fungi. The different derivatives of flavonoids belonging to polyphenolic compounds such as 3,4',5,7-Tetrahydroxyflavylium (pelargonidin), 2-(3,4-Dihydroxyphenyl)chromenylium-3,5,7-triol (cyanidin), 3,3',4',5,5',7-Hexahydroxyflavylium (delphinidin), 3,3',4',5,7-Pentahydroxy-5'-methoxyflavylium (petunidin), and 3,4',5,7-Tetrahydroxy-3',5'-dimethoxyflavylium (malvidin) can act as good chelating agents for metal-chelate complex formation. These flavonoid-metal complexes have been reported to have various biomedical and pharmacological activities.

OBJECTIVE

Flavonoid-metal ion complexes display a broad spectrum of biological properties such as antioxidant, anti-inflammatory, anti-allergic, antiviral, anticarcinogenic, and cytotoxic activity. The literature survey showed that flavonoid metal complexes have potential therapeutic properties against various cancerous cells. The objective is to gain insight into the current perspective and development of novel anticancer metallodrugs.

METHODS

The flavonoid-metal ion complexes can be prepared by reacting flavonoid ligand with appropriate metal salt in aqueous or alcoholic reaction medium under stirring or refluxing conditions. In this review article, the various reported methods for the synthesis of flavonoid-metal complexes have been included. The utility of synthetic methods for flavonoid-metal complexes will support the discovery of novel therapeutic drugs.

RESULTS

In this review study, short libraries of flavonoid-metal ion complexes were studied as potential anticancer agents against various human cancer cell lines. The review report reveals that metal ions such as Fe, Co, Ni, Cu, Zn, Rh, Ru, Ga, Ba, Sn etc., when binding to flavonoid ligands, enhance the anticancer activity compared to free ligands. This review study covered some important literature surveys for the last two decades.

CONCLUSION

It has been concluded that flavonoid metal complexes have been associated with a wide range of biological properties that could be noteworthy in the medicinal field. Therefore, to develop a new anticancer drug, it is essential to determine the primordial interaction of drug with DNA under physiological or anatomical conditions. The study of numerous flavonoid metal complexes mentioned in this paper could be the future treatment against various cancerous diseases.

Buteinylated-hafnium oxide bionanoparticles for electrochemical sensing of wogonin

Hybridizing biomolecules with metal oxide nanostructures possessing inherent optical emission and electrochemical functionality is advantageous for external mediator-free analytical applications. This work demonstrates the ultrasonochemical synthesis of hafnium oxide (HfO2) nanoparticles and their combination with butein, a chalcone type polyphenol, for the direct electrochemical detection of active herbaceuticals. The underlying hybridization chemistry between HfO2 and butein within the bio-nano interface is comprehensively investigated using ultraviolet diffuse reflectance, X-ray diffraction, Fourier-transform infrared, and X-ray photoelectron spectroscopic techniques. Electron micrographs suggest the formation of elongated nano spherical particles of HfO2 with the incorporation of butein (average particle size of 17.6 ± 2.9 nm). The catecholic OH group of butein existing on the surface of hybridized HfO2 exhibits reversible redox behavior convenient for probing the selected target analyte at physiological pH. The electron diffusion kinetics, electron transfer coefficient and rate constant parameters of the prepared HfO2-butein electrode material have been studied in detail for further application in biomolecular sensing of wogonin. The as-developed sensor platform exhibits a linear detection range of 20-100 μM with a current density of 60 μA cm-2 and a detection limit of 0.63 μM, which is promising for herbaceutical analysis.

Magnetic UiO-66-NH2 Core-Shell Nanohybrid as a Promising Carrier for Quercetin Targeted Delivery toward Human Breast Cancer Cells

In this study, a magnetic core-shell metal-organic framework (MOF) nanocomposite, Fe3O4-COOH@UiO-66-NH2, was synthesized for tumor-targeting drug delivery by incorporating carboxylate groups as functional groups onto ferrite nanoparticle surfaces, followed by fabrication of the UiO-66-NH2 shell using a facile self-assembly approach. The anticancer drug quercetin (QU) was loaded into the magnetic core-shell nanoparticles. The synthesized magnetic nanoparticles were comprehensively evaluated through multiple techniques, including FT-IR, PXRD, FE-SEM, TEM, EDX, BET, UV-vis, ZP, and VSM. Drug release investigations were conducted to investigate the release behavior of QU from the nanocomposite at two different pH values (7.4 and 5.4). The results revealed that QU@Fe3O4-COOH@UiO-66-NH2 exhibited a high loading capacity of 43.1% and pH-dependent release behavior, maintaining sustained release characteristics over a prolonged duration of 11 days. Furthermore, cytotoxicity assays using the human breast cancer cell line MDA-MB-231 and the normal cell line HEK-293 were performed to evaluate the cytotoxic effects of QU, UiO-66-NH2, Fe3O4-COOH, Fe3O4-COOH@UiO-66-NH2, and QU@Fe3O4-COOH@UiO-66-NH2. Treatment with QU@Fe3O4-COOH@UiO-66-NH2 substantially reduced the cell viability in cancerous MDA-MB-231 cells. Cellular uptake and cell death mechanisms were further investigated, demonstrating the internalization of QU@Fe3O4-COOH@UiO-66-NH2 by cancer cells and the induction of cancer cell death through the apoptosis pathway. These findings highlight the considerable potential of Fe3O4-COOH@UiO-66-NH2 as a targeted nanocarrier for the delivery of anticancer drugs.

3-Hydroxyflavone is a mildly active and safe cobalt chelator while cobalt markedly enhances baicalein toxicity toward erythrocytes

Cobalt intoxication can occur after its release from metal-based prostheses, which is generally clinically severe. Therefore, there is a need for the development of a cobalt chelator since there are currently no approved drugs for cobalt intoxication. As flavonoids are known for their metal chelating properties and safety, the screening of cobalt chelating properties was performed in a total of 23 flavonoids by our recently developed new spectrophotometric assay. Further assessment of positive or negative consequences of cobalt chelation was performed both in vitro and ex vivo. Six and thirteen flavonoids significantly chelated cobalt ions at pH 7.5 and 6.8, respectively. Baicalein demonstrated a significant activity even at pH 5.5; however, none of the flavonoids showed chelation at pH 4.5. In general, baicalein and 3-hydroxyflavone were the most active. They also mildly decreased the cobalt-triggered Fenton reaction, but baicalein toxicity toward red blood cells was strongly increased by the addition of cobalt. Quercetin, tested as an example of flavonoid unable to chelate cobalt ions significantly, stimulated both the cobalt-based Fenton reaction and the lysis of erythrocytes in the presence of cobalt. Therefore, 3-hydroxyflavone can serve as a potential template for the development of novel cobalt chelators.

A Combined NMR and UV-Vis Approach to Evaluate Radical Scavenging Activity of Rosmarinic Acid and Other Polyphenols

Oxidative stress results from an imbalance between reactive oxygen species (ROS) production and the body's ability to neutralize them. ROS are reactive molecules generated during cellular metabolism and play a crucial role in normal physiological processes. However, excessive ROS production can lead to oxidative damage, contributing to various diseases and aging. This study is focused on rosmarinic acid (RA), a hydroxycinnamic acid (HCA) derivative well known for its antioxidant activity. In addition, RA has also demonstrated prooxidant behavior under specific conditions involving high concentrations of transition metal ions such as iron and copper, high pH, and the presence of oxygen. In this study, we aim to clarify the underlying mechanisms and factors governing the antioxidant and prooxidant activities of RA, and to compare them with other HCA derivatives. UV-Vis, NMR, and EPR techniques were used to explore copper(II)'s binding ability of RA, caffeic acid, and p-coumaric acid. At the same time, UV-Vis and NMR methods were exploited to evaluate the polyphenols' free radical scavenging abilities towards ROS generated by the ascorbic acid-copper(II) system. All the data indicate that RA is the most effective polyphenol both in copper binding abilities and ROS protection.

Anticancer Potential of Flavonoids: An Overview with an Emphasis on Tangeretin

Natural compounds with pharmacological activity, flavonoids have been the subject of an exponential increase in studies in the field of scientific research focused on therapeutic purposes due to their bioactive properties, such as antioxidant, anti-inflammatory, anti-aging, antibacterial, antiviral, neuroprotective, radioprotective, and antitumor activities. The biological potential of flavonoids, added to their bioavailability, cost-effectiveness, and minimal side effects, direct them as promising cytotoxic anticancer compounds in the optimization of therapies and the search for new drugs in the treatment of cancer, since some extensively antineoplastic therapeutic approaches have become less effective due to tumor resistance to drugs commonly used in chemotherapy. In this review, we emphasize the antitumor properties of tangeretin, a flavonoid found in citrus fruits that has shown activity against some hallmarks of cancer in several types of cancerous cell lines, such as antiproliferative, apoptotic, anti-inflammatory, anti-metastatic, anti-angiogenic, antioxidant, regulatory expression of tumor-suppressor genes, and epigenetic modulation.

The role of redox active copper(II) on antioxidant properties of the flavonoid baicalein: DNA protection under Cu(II)-Fenton reaction and Cu(II)-ascorbate system conditions

The antioxidant properties of flavonoids are mediated by their functional hydroxyl groups, which are capable of both chelating redox active metals such as iron, copper and scavenging free radicals. In this paper, the antioxidant vs. prooxidant and DNA protecting properties of baicalein and Cu(II)-baicalein complexes were studied under the conditions of the Copper-Fenton reaction and of the Copper-Ascorbate system. From the relevant EPR spectra, the interaction of baicalein with Cu(II) ions was confirmed, while UV-vis spectroscopy demonstrated a greater stability over time of Cu(II)-baicalein complexes in DMSO than in methanol and PBS and Phosphate buffers. An ABTS study confirmed a moderate ROS scavenging efficiency, at around 37%, for both free baicalein and Cu(II)-baicalein complexes (in the ratios 1:1 and 1:2). The results from absorption titrations are in agreement with those from viscometric studies and confirmed that the binding mode between DNA and both free baicalein and Cu-baicalein complexes, involves hydrogen bonds and van der Waals interactions. The DNA protective effect of baicalein has been investigated by means of gel electrophoresis under the conditions of the Cu-catalyzed Fenton reaction and of the Cu-Ascorbate system. In both cases, it was found that, at sufficiently high concentrations, baicalein offers some protection to cells from DNA damage caused by ROS (singlet oxygen, hydroxyl radicals and superoxide radical anions). Accordingly, baicalein may be useful as a therapeutic agent in diseases with a disturbed metabolism of redox metals such as copper, for example Alzheimer's disease, Wilson's disease and various cancers. While therapeutically sufficient concentrations of baicalein may protect neuronal cells from Cu-Fenton-induced DNA damage in regard to neurological conditions, conversely, in the case of cancers, low concentrations of baicalein do not inhibit the pro-oxidant effect of copper ions and ascorbate, which can, in turn, deliver an effective damage to DNA in tumour cells.

pH-Responsive Cobalt(II)-Coordinated Assembly Containing Quercetin for Antimicrobial Applications

The development of novel drug delivery systems (DDSs) with promising antibacterial properties is essential for facing the emergency of increasing resistance to antimicrobial agents. The antibacterial features of quercetin and its metal complexes have been broadly investigated. However, several drawbacks affect their activity and effectiveness. In this work, we propose a DDS based on a pH-responsive cobalt(II)-coordinated assembly containing quercetin and polyacrylic acid. This system is suggested to trigger the release of the model drug in a pH-dependent mode by exploiting the localized acidic environment at the bacterial infection sites under anaerobic conditions. The delivery system has been designed by accurately examining the species and the multiple equilibria occurring in solution among the assembly components. The formation of cobalt(II) complexes with quercetin in the absence or presence of the pH-responsive polyacrylic acid was investigated in buffered aqueous solution at pH 7.4 using spectrophotometric (UV-Vis) and calorimetric (ITC) techniques. The determined binding affinities and thermodynamic parameters that resulted are essential for the development of a DDS with improved binding and release capabilities. Furthermore, the affinity of the polymer-cobalt(II) complex toward the model antimicrobial flavonoid was explored at the solid-liquid interface by quartz crystal microbalance (QCM-D) experiments, which provided marked evidence for drug loading and release under pH control.

Preparation of metal-organic framework combined with Portulaca oleracea L. extract electrostatically spun nanofiber membranes delayed release wound dressing

In this study, we prepared a polyacrylonitrile (PAN) composite nanofiber membrane comprising Portulaca oleracea L. extract (POE) and a zinc-based metal-organic framework (MOF) by an in situ growth method as a potentially new type of wound dressing with a slow drug-release effect, to solve the problem of the burst release of drugs in wound dressings. The effects of the MOF and POE doping on the nanofiber membranes were examined using scanning electron microscopy (SEM) and FTIR spectroscopy. SEM analysis revealed the dense and uniform attachment of MOF particles to the surface of the nanofiber membrane, while FTIR spectroscopy confirmed the successful fusion of MOF and POE. Furthermore, investigations into the water contact angle and swelling property demonstrated that the incorporation of the MOF and POE enhanced the hydrophilicity of the material. The results of the in vitro release test showed that the cumulative release rate for PAN/MOF/POE60 decreased from 66.5 ± 2.34% to 32.18 ± 1.31% in the initial 4 h and from 90.54 ± 0.79% to 65.92 ± 1.95% in 72 h compared to PAN/POE, indicating a slowing down of the drug release. In addition, the antimicrobial properties of the fiber membranes were evaluated by the disc diffusion method, and it was evident that the PAN/MOF/POE nanofibers exhibited strong inhibition against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The antioxidant properties of the nanofiber membranes loaded with POE were further validated through the DPPH radical scavenging test. These findings highlight the potential application of the developed nanofiber membranes in wound dressings, offering controlled and sustained drug-release capabilities.

Interactions of Natural Flavones with Iron Are Affected by 7-O-Glycosylation, but Not by Additional 6″-O-Acylation

In iron-fortified bouillon, reactivity of the iron ion with (acylated) flavone glycosides from herbs can affect product color and bioavailability of iron. This study investigates the influence of 7-O-glycosylation and additional 6″-O-acetylation or 6″-O-malonylation of flavones on their interaction with iron. Nine (6″-O-acylated) flavone 7-O-apiosylglucosides were purified from celery (Apium graveolens), and their structures were elucidated by mass spectrometry (MS) and nuclear magnetic resonance (NMR). In the presence of iron, a bathochromic shift and darker color were observed for the 7-O-apiosylglucosides compared to the aglycon of flavones that only possess the 4-5 site. Thus, the ability of iron to coordinate to the flavone 4-5 site is increased by 7-O-glycosylation. For flavones with an additional 3'-4' site, less discoloration was observed for the 7-O-apiosylglucoside compared to the aglycon. Additional 6″-O-acylation did not affect the color. These findings indicate that model systems used to study discoloration in iron-fortified foods should also comprise (acylated) glycosides of flavonoids.

Novel Pyrazole-Based Transition Metal Complexes: Spectral, Photophysical, Thermal and Biological Studies

A novel bioactive Schiff base (HL) named 3-methyl-1-phenyl-5-((5-nitrosalicylidene)amino)pyrazole was prepared by condensing 5-amino-3-methyl-1-phenylpyrazole with 5-nitrosalicyldehyde in methanol on a heating mantle in refluxing condition for 1 h. Some transition metal complexes of the ligand in (1 : 1) and (1 : 2) have also been prepared by condensing the metal acetate salt with the synthesized Schiff base. The Schiff base and metal complexes were characterized by different physiochemical techniques, i. e., 1 H-NMR, InfraRed, mass spectroscopy, elemental analysis, Ultraviolet-Visible, Cyclic voltammetry, electronic spectra and Electron spin resonance. The presence of water molecules in the complexes have been calculated with the help of thermogravimetric analysis. Kinetic parameters such that entropy change, enthalpy change and activation energy have been calculated with the help of Coats-Redfern equations. Fluorescence spectra showed enhancement in the fluorescence signal of the metal complexes. Square planar geometry for the copper complexes and octahedral geometry for the other metal complexes have been proposed with help of various methods. Biological activities of all the compounds have been carried out and the results disclosed that the metal complexes have high biological activity than the Schiff base having MIC value in the range 25-3.12 μg/mL and mycelial growth inhibition 60.82-96.98 %.

Reactivity of Fe(III)-containing pyrophosphate salts with phenolics: complexation, oxidation, and surface interaction

Mixed pyrophosphate salts with the general formula Ca_2(1-x)Fe_4x(P₂O₇)_(1+2x) potentially possess less iron-phenolic reactivity compared to ferric pyrophosphate (FePP), due to decreased soluble Fe in the food-relevant pH range 3-7. We investigated reactivity (i.e., complexation, oxidation, and surface interaction) of FePP and mixed salts (with x = 0.14, 0.15, 0.18, and 0.35) in presence of structurally diverse phenolics. At pH 5-7, increased soluble iron from all salts was observed in presence of water-soluble phenolics. XPS confirmed that water-soluble phenolics solubilize iron after coordination at the salt surface, resulting in increased discoloration. However, color changes for mixed salts with x ≤ 0.18 remained acceptable for slightly water-soluble and insoluble phenolics. Furthermore, phenolic oxidation in presence of mixed salts was significantly reduced compared to FePP at pH 6. In conclusion, these mixed Ca-Fe(III) pyrophosphate salts with x ≤ 0.18 can potentially be used in designing iron-fortified foods containing slightly water-soluble and/or insoluble phenolics.

Cytotoxicity and Antibacterial Potentials of Mixed Ligand Cu(II) and Zn(II) Complexes: A Combined Experimental and Computational Study

[Cu(C₁₅H₉O₄)(C₁₂H₈N₂)O₂C₂H₃]·3H₂O (1) and [Zn(C₁₅H₉O₄)(C₁₂H₈N₂)]O₂C₂H₃ (2) have been synthesized and characterized by ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, mass spectrometry, thermogravimetric analysis/differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), and molar conductance, and supported by density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. Square pyramidal and tetrahedral geometries are proposed for Cu(II) and Zn(II) complexes, respectively, and the XRD patterns showed the polycrystalline nature of the complexes. Furthermore, in vitro cytotoxic activity of the complexes was evaluated against the human breast cancer cell line (MCF-7). A Cu(II) centered complex with an IC₅₀ value of 4.09 μM was more effective than the Zn(II) centered complex and positive control, cisplatin, which displayed IC₅₀ values of 75.78 and 18.62 μM, respectively. In addition, the newly synthesized complexes experienced the innate antioxidant nature of the metal centers for scavenging the DPPH free radical (up to 81% at 400 ppm). The biological significance of the metal complexes was inferred from the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy band gap, which was found to be 2.784 and 3.333 eV, respectively for 1 and 2, compared to the ligands, 1,10-phenathroline (4.755 eV) and chrysin (4.403 eV). Moreover, the molecular docking simulations against estrogen receptor alpha (ERα; PDB: 5GS4) were strongly associated with the in vitro biological activity results (E _B and K _i are -8.35 kcal/mol and 0.76 μM for 1, -7.52 kcal/mol and 3.07 μM for 2, and -6.32 kcal/mol and 23.42 μM for cisplatin). However, more research on in vivo cytotoxicity is suggested to confirm the promising cytotoxicity results.

Unexpected Value of Honey Color for Prediction of a Non-Enzymatic H2O2 Production and Honey Antibacterial Activity: A Perspective

Hydrogen peroxide is the principal antibacterial compound of honey and its concentration determines honey bacteriostatic (MIC) and bactericidal (MBC) potencies. Levels of H₂O₂ produced are highly relevant to honey therapeutic potential, but they vary extensively among honey with reasons not immediately apparent. According to a traditional view, H₂O₂ is produced as a by-product of glucose oxidation by the honey bee enzyme, glucose oxidase; however, significant levels of H₂O₂ could be produced in a non-enzymatic way via polyphenol autooxidation. The aim of this study was to evaluate the potential for such an alternative pathway by re-examining evidence from many experimental and correlative studies in order to identify factors and compounds required for pro-oxidant activity. Unexpectedly, the color intensity was found to be the main indicator separating honey varieties based on the quantitative differences in the polyphenolic content, antioxidant activity and the content of transition metals, Fe, Cu and Mn, the main factors required for pro-oxidant effects. The color-impeding polyphenolics and their oxidation products (semiquinones and quinones) further contributed to color development through multiple chemical conjugations with proteins, phenolic oxidative polymerization, chelation or the reduction of metal ions. Moreover, quinones, as an intrinsic part of polyphenol redox activity, play an active role in the formation of higher-order structures, melanoidins and colloids in honey. The latter structures are also known to chelate metal ions, potentially contributing to H₂O₂ production. Thus, the color intensity appears as a major parameter that integrates polyphenol-dependent pro-oxidant reactions resulting in H₂O₂ generation.

Synthesis and Characterization of Quercetin-Iron Complex Nanoparticles for Overcoming Drug Resistance

Quercetin, one of the major natural flavonoids, has demonstrated great pharmacological potential as an antioxidant and in overcoming drug resistance. However, its low aqueous solubility and poor stability limit its potential applications. Previous studies suggest that the formation of quercetin-metal complexes could increase quercetin stability and biological activity. In this paper, we systematically investigated the formation of quercetin-iron complex nanoparticles by varying the ligand-to-metal ratios with the goal of increasing the aqueous solubility and stability of quercetin. It was found that quercetin-iron complex nanoparticles could be reproducibly synthesized with several ligand-to-iron ratios at room temperature. The UV-Vis spectra of the nanoparticles indicated that nanoparticle formation greatly increased the stability and solubility of quercetin. Compared to free quercetin, the quercetin-iron complex nanoparticles exhibited enhanced antioxidant activities and elongated effects. Our preliminary cellular evaluation suggests that these nanoparticles had minimal cytotoxicity and could effectively block the efflux pump of cells, indicating their potential for cancer treatment.

The Chelating Ability of Plant Polyphenols Can Affect Iron Homeostasis and Gut Microbiota

In the past decades, many studies have widely examined the effects of dietary polyphenols on human health. Polyphenols are well known for their antioxidant properties and for their chelating abilities, by which they can be potentially employed in cases of pathological conditions, such as iron overload. In this review, we have highlighted the chelating abilities of polyphenols, which are due to their structural specific sites, and the differences for each class of polyphenols. We have also explored how the dietary polyphenols and their iron-binding abilities can be important in inflammatory/immunomodulatory responses, with a special focus on the involvement of macrophages and dendritic cells, and how they might contribute to reshape the gut microbiota into a healthy profile. This review also provides evidence that the axes “polyphenol–iron metabolism–inflammatory responses” and “polyphenol–iron availability–gut microbiota” have not been very well explored so far, and the need for further investigation to exploit such a potential to prevent or counteract pathological conditions.

Polymeric Systems for the Controlled Release of Flavonoids

Flavonoids are natural compounds that are attracting great interest in the biomedical field thanks to the wide spectrum of their biological properties. Their employment as anticancer, anti-inflammatory, and antidiabetic drugs, as well as for many other pharmacological applications, is extensively investigated. One of the most successful ways to increase their therapeutic efficacy is to encapsulate them into a polymeric matrix in order to control their concentration in the physiological fluids for a prolonged time. The aim of this article is to provide an updated overview of scientific literature on the polymeric systems developed so far for the controlled release of flavonoids. The different classes of flavonoids are described together with the polymers most commonly employed for drug delivery applications. Representative drug delivery systems are discussed, highlighting the most common techniques for their preparation. The flavonoids investigated for polymer system encapsulation are then presented with their main source of extraction and biological properties. Relevant literature on their employment in this context is reviewed in relationship to the targeted pharmacological and biomedical applications.

In vitro and in vivo investigation of chrysin chelated copper complex as biocompatible materials for bone tissue engineering applications

Flavonoid metal complexes have interesting properties and are widely explored for bone regeneration owing to their potent biological activity. In the present study, we investigated the biocompatibility and osteogenic properties of the Copper(II)-chrysin complex (C/Cu). The biocompatibility of C/Cu was assessed in vitro with human osteoblastic cells and in vivo using chick embryo and zebrafish models. The C/Cu complex was found to be cytofriendly with good biocompatibility. The osteogenic property of C/Cu was studied at cellular and molecular levels. C/Cu promoted mineralization in osteoblastic cultures by increasing ALP activity. At the molecular level, C/Cu significantly promoted the mRNA levels of osteoblast differentiation marker genes such as runt-related transcription factor 2 (Runx2), Type 1 collagen and ALP. In addition to this, secretory proteins, osteonectin (ON) and osteocalcin (OC) levels were also stimulated. We have also identified that C/Cu exhibited enhanced osteogenic properties and antibacterial activity compared with Chrysin. Thus, C/Cu can be used as an osteogenic agent in bone tissue engineering.

Antioxidant conjugated metal complexes and their medicinal applications

Antioxidants are naturally available and man-made substances have the ability to protect cells from damage due to a number of intracellular redox activities. Moreover, Antioxidants such as α-lipoic acid, curcumin and catechin are good anticancer agents. In recent years, the usage of metal complexes as therapeutic agents is gaining importance due to their useful biological properties. Most of the metal ions act as the essential components in building drug molecules that serve as medicines for cancer and neurodegenerative diseases. In particular, metals like copper, gold, ruthenium, and platinum have adequate anticancer properties at both micro- and nano-levels. Hence, conjugation of antioxidants with metals and metal-based compounds results in hybrid bioactive materials with improved anticancer properties. In this chapter, medicinal applications of antioxidant conjugated metal complexes are reviewed and discussed.

An efficient ethylcellulose fluorescent probe for rapid detection of Fe3+ and its multi-functional applications

Fe³⁺ is the most abundant essential transition metal ion in the human body, plays a vital role in biological and environmental systems. Ethyl cellulose is one of the derivatives of cellulose. Herein, a novel ethylcellulose fluorescent probe EC-HPCB for detecting Fe³⁺ was prepared by grafting a flavonol derivative as both fluorophore and selective recognition group. The probe exhibited a highly specific "turn-off" fluorescence response to Fe³⁺, and the fluorescence color changed from yellow to colorless in the presence of Fe³⁺. The detection limit of EC-HPCB for Fe³⁺ was 2.65 × 10^-7 mol/L, and the response time was as quick as 2 min. The detection mechanism was confirmed by ¹H NMR and DFT calculations. Based on the good solubility and processability in organic solvent, EC-HPCB was made into coating and film with favorable fluorescent performances. Furthermore, EC-HPCB probe was successfully applied to monitor Fe³⁺ in real water samples, and the EC-HPCB-loaded filter paper provided a solid-state platform for detecting Fe³⁺ by naked eye and fluorescence method.

Novel Liposomal Formulation of Baicalein for the Treatment of Pancreatic Ductal Adenocarcinoma: Design, Characterization, and Evaluation

Pancreatic cancer (PC) is one of the deadliest cancers so there is an urgent need to develop new drugs and therapies to treat it. Liposome-based formulations of naturally-derived bioactive compounds are promising anticancer candidates due to their potential for passive accumulation in tumor tissues, protection against payload degradation, and prevention of non-specific toxicity. We chose the naturally-derived flavonoid baicalein (BAI) due to its promising effect against pancreatic ductal adenocarcinoma (PDAC) and encapsulated it into a liposomal bilayer using the passive loading method, with an almost 90% efficiency. We performed a morphological and stability analysis of the obtained BAI liposomal formulation and evaluated its activity on two-dimensional and three-dimensional pancreatic cell models. As the result, we obtained a stable BAI-encapsulated liposomal suspension with a size of 100.9 nm ± 2.7 and homogeneity PDI = 0.124 ± 0.02, suitable for intravenous administration. Furthermore, this formulation showed high cytotoxic activity towards AsPC-1 and BxPC-3 PDAC cell lines (IC₅₀ values ranging from 21 ± 3.6 µM to 27.6 ± 4.1 µM), with limited toxicity towards normal NHDF cells and a lack of hemolytic activity. Based on these results, this new BAI liposomal formulation is an excellent candidate for potential anti-PDAC therapy.

Organic-inorganic hybrid salt and mixed ligand Cr(III) complexes containing the natural flavonoid chrysin: Synthesis, characterization, computational, and biological studies

Organic-inorganic hybrid salt and mixed ligand Cr(III) complexes (Cr1 and Cr2) containing the natural flavonoid chrysin were synthesized. The metal complexes were characterized using UV-Vis, Fourier-transform infrared, MS, SEM-EDX, XRD, and molar conductance measurements. Based on experimental and DFT/TD-DFT calculations, octahedral geometries for the synthesized complexes were suggested. The powder XRD analysis confirms that the synthesized complexes were polycrystalline, with orthorhombic and monoclinic crystal systems having average crystallite sizes of 21.453 and 19.600 nm, percent crystallinities of 51% and 31.37%, and dislocation densities of 2.324 × 10^-3 and 2.603 × 10^-3 nm^-2 for Cr1 and Cr2, respectively. The complexes were subjected to cytotoxicity, antibacterial, and antioxidant studies. The in vitro biological studies were supported with quantum chemical and molecular docking computational studies. Cr1 showed significant cytotoxicity to the MCF-7 cell line, with an IC₅₀ value of 8.08 μM compared to 30.85 μM for Cr2 and 18.62 μM for cisplatin. Cr2 showed better antibacterial activity than Cr1. The higher E _HOMO (-5.959 eV) and dipole moment (10.838 Debye) values of Cr2 obtained from the quantum chemical calculations support the observed in vitro antibacterial activities. The overall results indicated that Cr1 is a promising cytotoxic drug candidate.

The Synthesis, Characterization and Anti-Tumor Activity of a Cu-MOF Based on Flavone-6,2'-dicarboxylic Acid

A novel two-dimensional copper(II) framework (LDU-1), formulated as {[Cu₂(L)₂·2NMP}n (H₂L = flavone-6,2'-dicarboxylic acid, NMP = N-Methyl pyrrolidone), has been constructed under solvothermal conditions and characterized by single-crystal X-ray diffraction, infrared spectroscopy (IR), thermogravimetric analysis and powder X-ray diffraction (PXRD). In the crystal structure, the Cu(II) shows hex-coordinated with the classical Cu paddle-wheel coordination geometry, and the flavonoid ligand coordinates with the Cu(II) ion in a bidentate bridging mode. Of particular interest of LDU-1 is the presence of anti-tumor activity against three human cancer cell lines including lung adenocarcinoma(A549), Michigan cancer foundation-7 (MCF-7), erythroleukemia (K562) and murine melanoma B16F10, indicating synergistic enhancement effects between metal ions and organic linkers. A cell cycle assay indicates that LDU-1 induces cells to arrest at S phase obviously at a lower concentration.

Tunable physics through coordination chemistry: formation on oxide surface of Ti and Al chelates with 3-hydroxyflavone capable of electron injection and light emission

The optoelectronic features of 3-hydroxyflavone (3HF) self-assembled on the surface of an n-type semiconducting metal oxide (TiO₂) and an insulator (Al₂O₃) are herein investigated. 3HF molecules use the coordinatively unsaturated metal ions present on the oxide surface to form metal complexes, which exhibit different behaviors upon light irradiation, depending on the nature of the metal ion. Specifically, we show that the photoluminescence of the surface species can be modulated according to the chemical properties of the complex (i.e. the binding metal ion), resulting in solid-state emitters in a high quantum yield (about 15%). Furthermore, photoinduced charge injection can be promoted or inhibited, providing a multifunctional hybrid system.

Spectrophotometric Fluoride Determination Using St. John's Wort Extract as a Green Chromogenic Complexant for Al(III)

In this study, we applied an innovative approach of green analytical chemistry to develop a novel and eco-friendly chromogenic agent for fluoride determination by making use of the nontoxic Al(III)-flavonoid complex in a natural extract from St. John's wort plant. The initial intensely yellow-colored Al(III)-flavonoid complex formed in the plant extract was converted to a colorless AlF₆ ^3- complex with increasing amounts of fluoride, and color bleaching of the Al-flavonoid chromophore (measured as absorbance decrement) was proportional to fluoride concentration. The developed method gave a linear response within the F^- concentration range of 0.11-1.32 mM with the LOD and LOQ values of 0.026 mM (0.5 mg L^-1) and 0.079 mM (1.5 mg L^-1), respectively. The LOD value for fluoride was below the WHO-permissible limit (1.5 mg L^-1) and the US-EPA-enforceable limit (4 mg L^-1) in water. The possible interference effects of common anions (Cl^-, Br^-, I^-, NO₃ ^-, HCO₃ ^-, SO₄ ^2-, and PO₄ ^3-) and cations (K⁺, NH₄ ⁺, Ag⁺, Ca²⁺, Mg²⁺, Mn²⁺, Fe²⁺, and Fe³⁺) were investigated; the observed interferences from Fe²⁺, Fe³⁺, and PO₄ ^3- were easily eliminated by masking iron with the necessary amount of Na₂EDTA without affecting the blank absorbance of the Al(III)-flavonoid complex, precipitating phosphate with Ag(I) salt, and partly neutralizing alkaline water samples to pH 4 with acetic acid. The developed method was applied to real water samples and also validated against a reference spectroscopic method at the 95% confidence level.

A combination therapy for androgenic alopecia based on quercetin and zinc/copper dual-doped mesoporous silica nanocomposite microneedle patch

A nanocomposite microneedle (ZCQ/MN) patch containing copper/zinc dual-doped mesoporous silica nanoparticles loaded with quercetin (ZCQ) was developed as a combination therapy for androgenic alopecia (AGA). The degradable microneedle gradually dissolves after penetration into the skin and releases the ZCQ nanoparticles. ZCQ nanoparticles release quercetin (Qu), copper (Cu²⁺) and zinc ions (Zn²⁺) subcutaneously to synergistically promote hair follicle regeneration. The mechanism of promoting hair follicle regeneration mainly includes the regulation of the main pathophysiological phenomena of AGA such as inhibition of dihydrotestosterone, inhibition of inflammation, promotion of angiogenesis and activation of hair follicle stem cells by the combination of Cu²⁺ and Zn²⁺ ions and Qu. This study demonstrates that the systematic intervention targeting different pathophysiological links of AGA by the combination of organic drug and bioactive metal ions is an effective treatment strategy for hair loss, which provides a theoretical basis for development of biomaterial based anti-hair loss therapy.

Enhanced Natural Dyeing and Antibacterial Properties of Cotton by Physical and Chemical Pretreatments

In this study, pomegranate peel extract was used to dye cotton fabrics. Generally, natural dyes have low affinity for cellulosic fibers and therefore need treatment for attachment. Air atmospheric plasma was applied to lower the concentrations of mordants needed and enhance dyeability. The outcomes showed that the residual concentrations of metallic ions decreased when applying the plasma treatment. ATR-FTIR and SEM analysis were performed to evaluate the effect of plasma modification on the surface chemistry and topography of the cellulosic fibers. The traces of metals released from finished fabric were quantified using ICP OES spectrometry. Color fastnesses (wash, rubbing and light) were evaluated to assess the mordanting step effect and the durability of the color. All tested fastnesses were good to very good. The concentrations of metal ions in finished fabrics were 32.4 for Fe, 0.28 for Al, 0.29 for Cr and 1.21 for Cu. Plasma treatment can be considered an efficient strategy to reduce the concentration of toxic metallic mordants.

A simple, cost-effective colorimetric assay for aluminum ions via complexation with the flavonoid rutin

Aluminum has been linked to deleterious health effects with high concentration, chronic exposure, creating a need for innovative detection techniques. Colorimetric assays are an ideal approach since they are simple, cost-effective, and field adaptable. Yet, commercially available colorimetric assays for aluminum are limited since it forms few colored chelation complexes. Flavonoids, a class of polyphenolic compounds, are one of the few examples that create colored aluminum complexes. Aluminum ions (Al3+) are the main constituent in colorimetric assays for flavonoid detection in food or plant samples. Our assay design was based on colorimetric flavonoid assays, where the assay reported herein was optimized. Specifically, the flavonoid rutin concentration and sample-to-rutin volume ratio (295:5 µL) were optimized to detect Al3+ at low µM concentrations in samples. The assay performed comparably, and in some instances better, than those requiring advanced instrumentation and previously reported colorimetric assays, with a linear range (1–8 µM), sensitivity (7.6 nM), limit of detection (79.8 nM), and limit of quantification (266 nM) for Al3+. The colorimetric assay was accurate (99 ≤ 108 ± 4 ≤ 6% Al3+ recovery), precise (low intra- and inter-assay coefficient of variation (CV) of 3.1 ≤ 5.9% and 4.4%, respectively), and selective for Al3+ ions compared to solutions containing a variety of other mono-, di-, and tri-cations at much higher concentrations (10- to 100-fold higher). Lastly, the colorimetric assay was applicable to complex analysis. It was used to generate a chelation curve depicting the Al3+ chelation capacity of sodium alginate, a biologically derived polymer used as a bioink for 3D bioprinting.

The neuroprotective effects of fisetin, a natural flavonoid in neurodegenerative diseases: Focus on the role of oxidative stress

Oxidative stress (OS) disrupts the chemical integrity of macromolecules and increases the risk of neurodegenerative diseases. Fisetin is a flavonoid that exhibits potent antioxidant properties and protects the cells against OS. We have viewed the NCBI database, PubMed, Science Direct (Elsevier), Springer-Nature, ResearchGate, and Google Scholar databases to search and collect relevant articles during the preparation of this review. The search keywords are OS, neurodegenerative diseases, fisetin, etc. High level of ROS in the brain tissue decreases ATP levels, and mitochondrial membrane potential and induces lipid peroxidation, chronic inflammation, DNA damage, and apoptosis. The subsequent results are various neuronal diseases. Fisetin is a polyphenolic compound, commonly present in dietary ingredients. The antioxidant properties of this flavonoid diminish oxidative stress, ROS production, neurotoxicity, neuro-inflammation, and neurological disorders. Moreover, it maintains the redox profiles, and mitochondrial functions and inhibits NO production. At the molecular level, fisetin regulates the activity of PI3K/Akt, Nrf2, NF-κB, protein kinase C, and MAPK pathways to prevent OS, inflammatory response, and cytotoxicity. The antioxidant properties of fisetin protect the neural cells from inflammation and apoptotic degeneration. Thus, it can be used in the prevention of neurodegenerative disorders.

Metallophenolomics: A Novel Integrated Approach to Study Complexation of Plant Phenolics with Metal/Metalloid Ions

Plant adaptive strategies have been shaped during evolutionary development in the constant interaction with a plethora of environmental factors, including the presence of metals/metalloids in the environment. Among adaptive reactions against either the excess of trace elements or toxic doses of non-essential elements, their complexation with molecular endogenous ligands, including phenolics, has received increasing attention. Currently, the complexation of phenolics with metal(loid)s is a topic of intensive studies in different scientific fields. In spite of the numerous studies on their chelating capacity, the systemic analysis of phenolics as plant ligands has not been performed yet. Such a systematizing can be performed based on the modern approach of metallomics as an integral biometal science, which in turn has been differentiated into subgroups according to the nature of the bioligands. In this regard, the present review summarizes phenolics–metal(loid)s’ interactions using the metallomic approach. Experimental results on the chelating activity of representative compounds from different phenolic subgroups in vitro and in vivo are systematized. General properties of phenolic ligands and specific properties of anthocyanins are revealed. The novel concept of metallophenolomics is proposed, as a ligand-oriented subgroup of metallomics, which is an integrated approach to study phenolics–metal(loid)s’ complexations. The research subjects of metallophenolomics are outlined according to the methodology of metallomic studies, including mission-oriented biometal sciences (environmental sciences, food sciences and nutrition, medicine, cosmetology, coloration technologies, chemical sciences, material sciences, solar cell sciences). Metallophenolomics opens new prospects to unite multidisciplinary investigations of phenolic–metal(loid) interactions.

Smart Multifunctional UiO-66 Metal-Organic Framework Nanoparticles with Outstanding Drug-Loading/Release Potential for the Targeted Delivery of Quercetin

Herein, UiO-66 and its two functional analogs (with -NO₂ and -NH₂ functional groups) were synthesized, and their potential ability as pH stimulus nanocarriers of quercetin (QU), an anticancer agent, was studied. UiO-66 is a low-toxicity, biocompatible metal-organic framework with a large surface area and good stability, which can be prepared through a facile and inexpensive method. Before and after drug loading, various analyses were conducted to characterize the synthesized nanocarriers. Moreover, Monte Carlo simulations were performed to investigate their structures and interactions with quercetin. The most promising drug loading potential and prolonged drug release (over 25 days) were observed in QU@UiO-66-NO₂ with 37% drug loading content, which was the best-tested sample that exhibited a higher release rate under acidic conditions (pH = 5) than that in normal cells (pH = 7.4). This behavior is known as pH-stimulus-controlled ability. The cell treatment with free QU, UiO-66-R, and QU@UiO-66-R (R = -H, -NO₂, and -NH₂) was performed, and an MTT assay was conducted on HEK-293 and MDA-MB-231 cells for the cytotoxicity study. Additionally, the kinetic modeling of drug release was investigated on the basis of the analysis of the drug release profiles.