Quercetin solubilisation in bile salts: A comparison with sodium dodecyl sulphate

Method development and validation for the quantitative determination of total flavonoids through the complexation of iron (III) and its application in real sample

BACKGROUND

The determination of flavonoids in real sample using UV-Vis spectrophotometer commonly uses quercetin and catechin with Al+3 complexing agent as reference materials for the calibration of the instrument. However, getting these standard materials is challenging due to its expense and unavailability in the chemical reserve of the country. Moreover, the Al+3 - quercetin complexation standard method demands high amount of quercetin in spite of its high cost. Hence, developing alternative method that can solve this problem is crucial for the determination of flavonoids in the real sample.

RESULTS

An iron-based complexation method for the determination of flavonoids in the real sample was developed that reduces the amount of quercetin by 200 times (1 mg/mL to 0.005 mg/mL) during the calibration of UV-Vis spectroscopy as an alternative method. The reaction parameters (incubation time, pH, and concentration of quercetin) were optimized using software Design Expert 11 and confirmed by the practical experiments. The kinetics of reaction between iron and quercetin was found to be pseudo first order with rate constant of kobs at 340 and 510 nm. The analysis window for the flavonoid complex was achieved with the kinetic discrimination of the interferences at its optimized time of complexation 20 min and absorbance maxima of 510 nm. The developed method was validated by evaluating its precision, accuracy, recovery test (84-117%), detection limit and quantification limit following the standard protocols. The calibration of the instrument has been developed for the new method and the linear regression coefficient (R2) of 0.998 was obtained.

SIGNIFICANCE

Applying the developed standard material (Fe3+ - quercetin complex) gives freedom for the analytical chemists to find the standard materials that is accessible and cheaper than the existing one (Al3+-quercetin complex). The developed method can also be easily applied for determination of flavonoid in the real samples without potential interferences coming from sample matrix.

Chlorine-doped MoS2 quantum dots embedded in a molecularly imprinted polymer for highly selective and sensitive optosensing of quercetin

Chlorine-doped MoS2 quantum dots (Cl-MoS2 QDs) embedded in a SiO2 molecularly imprinted polymer (Cl-MoS2 QDs@SiO2@MIP) have been successfully synthesized and can be used for highly selective and sensitive optosensing of quercetin. The novel environmentally friendly sensor integrated the advantages of the Cl-MoS2 QDs and MIP, high sensitivity and specific recognition for quercetin. The as-fabricated sensor is used to detect trace amounts of quercetin, and its fluorescence intensity showed a good linear decline with the increasing concentration of quercetin from 2 ng mL-1 to 200 ng mL-1 with a detection limit of 1.2 ng mL-1 (S/N = 3). The Cl-MoS2 QDs@SiO2@MIP probe was employed to assay the content of quercetin of real onion extract with good performance, which is in fine agreement with the result obtained by high performance liquid chromatography. The developed Cl-MoS2 QDs@SiO2@MIP sensor exhibits promising potential in the detection of quercetin.

Changes in Phenolic Profile and Total Phenol and Total Flavonoid Contents of Guadua angustifolia Kunth Plants under Organic and Conventional Fertilization

Agronomic management of a crop, including the application of fertilizers and biological inoculants, affects the phenol and flavonoid contents of plants producing these metabolites. Guadua angustifolia Kunth, a woody bamboo widely distributed in the Americas, produces several biologically active phenolic compounds. The aim of this study was to evaluate the effect of chemical and organic fertilizers together with the application of biological inoculants on the composition of phenolic compounds in G. angustifolia plants at the nursery stage. In 8-month-old plants, differences were observed in plant biomass (20.27 ± 7.68 g) and in the content of total phenols and flavonoids (21.89 ± 9.64 mg gallic acid equivalents/plant and 2.13 ± 0.98 mg quercetin equivalents/plant, respectively) when using the chemical fertilizer diammonium phosphate (DAP). No significant differences were found owing to the effect of the inoculants, although the plants with the application of Stenotrophomonas sp. on plants fertilized with DAP presented higher values of the metabolites (24.12 ± 6.72 mg gallic acid equivalents/plant and 2.39 ± 0.77 mg quercetin equivalents/plant). The chromatographic profile of phenolic metabolites is dominated by one glycosylated flavonoid, the concentration of which was favored by the application of the inoculants Azospirillum brasilense, Pseudomonas fluorescens, and Stenotrophomonas sp. In the case study, the combined use of DAP and bacterial inoculants is recommended for the production of G. angustifolia plant material with a high content of promising biologically active flavonoids or phenolics.

A Study on the Use of the Phyto-Courier Technology in Tobacco Leaves Infected by Agrobacterium tumefaciens

Climate change results in exceptional environmental conditions and drives the migration of pathogens to which local plants are not adapted. Biotic stress disrupts plants' metabolism, fitness, and performance, ultimately impacting their productivity. It is therefore necessary to develop strategies for improving plant resistance by promoting stress responsiveness and resilience in an environmentally friendly and sustainable way. The aim of this study was to investigate whether priming tobacco plants with a formulation containing silicon-stabilised hybrid lipid nanoparticles functionalised with quercetin (referred to as GS3 phyto-courier) can protect against biotic stress triggered by Agrobacterium tumefaciens leaf infiltration. Tobacco leaves were primed via infiltration or spraying with the GS3 phyto-courier, as well as with a buffer (B) and free quercetin (Q) solution serving as controls prior to the biotic stress. Leaves were then sampled four days after bacterial infiltration for gene expression analysis and microscopy. The investigated genes increased in expression after stress, both in leaves treated with the phyto-courier and control solutions. A trend towards lower values was observed in the presence of the GS3 phyto-courier for genes encoding chitinases and pathogenesis-related proteins. Agroinfiltrated leaves sprayed with GS3 confirmed the significant lower expression of the pathogenesis-related gene PR-1a and showed higher expression of peroxidase and serine threonine kinase. Microscopy revealed swelling of the chloroplasts in the parenchyma of stressed leaves treated with B; however, GS3 preserved the chloroplasts' mean area under stress. Furthermore, the UV spectrum of free Q solution and of quercetin freshly extracted from GS3 revealed a different spectral signature with higher values of maximum absorbance (Amax) of the flavonoid in the latter, suggesting that the silicon-stabilised hybrid lipid nanoparticles protect quercetin against oxidative degradation.

Natural photosensitizers potentiate the targeted antimicrobial photodynamic therapy as the Monkeypox virus entry inhibitors: An in silico approach

BACKGROUND

Monkeypox is a viral zoonotic disease that has emerged as a threat to public health. Currently, there is no treatment approved specifically targeting Monkeypox disease. Hence, it is essential to identify and develop therapeutic approaches to the Monkeypox virus. In the current in silico paper, we comprehensively involve using computer simulations and modeling to insights and predict hypotheses on the potential of natural photosensitizers-mediated targeted antimicrobial photodynamic therapy (aPDT) against D8L as a Monkeypox virus protein involved in viral cell entry.

MATERIALS AND METHODS

In the current study, computational techniques such as molecular docking were combined with in silico ADMET predictions to examine how Curcumin (Cur), Quercetin (Qct), and Riboflavin (Rib) as the natural photosensitizers bind to the D8L protein in Monkeypox virus, as well as to determine pharmacokinetic properties of these photosensitizers.

RESULTS

The three-dimensional structure of the D8L protein in the Monkeypox virus was constructed using homology modeling (PDB ID: 4E9O). According to the physicochemical properties and functional characterization, 4E9O was a stable protein with the nature of a hydrophilic structure. The docking studies employing a three-dimensional model of 4E9O with natural photosensitizers exhibited good binding affinity. D8L protein illustrated the best docking score (-7.6 kcal/mol) in relation to the Rib and displayed good docking scores in relation to the Cur (-7.0 kcal/mol) and Qct (-7.5 kcal/mol).

CONCLUSIONS

The findings revealed that all three photosensitizers were found to obey the criteria of Lipinski's rule of five and displayed drug-likeness. Moreover, all the tested photosensitizers were found to be non-hepatotoxic and non-cytotoxic. In summary, our investigation identified Cur, Qct, and Rib could efficiently interact with D8L protein with a strong binding affinity. It can be concluded that aPDT using these natural photosensitizers may be considered an adjuvant treatment against Monkeypox disease.

An Integrated Approach to Skeletal Muscle Health in Aging

A decline in muscle mass and function represents one of the most problematic changes associated with aging, and has dramatic effects on autonomy and quality of life. Several factors contribute to the inexorable process of sarcopenia, such as mitochondrial and autophagy dysfunction, and the lack of regeneration capacity of satellite cells. The physiologic decline in muscle mass and in motoneuron functionality associated with aging is exacerbated by the sedentary lifestyle that accompanies elderly people. Regular physical activity is beneficial to most people, but the elderly need well-designed and carefully administered training programs that improve muscle mass and, consequently, both functional ability and quality of life. Aging also causes alteration in the gut microbiota composition associated with sarcopenia, and some advances in research have elucidated that interventions via the gut microbiota-muscle axis have the potential to ameliorate the sarcopenic phenotype. Several mechanisms are involved in vitamin D muscle atrophy protection, as demonstrated by the decreased muscular function related to vitamin D deficiency. Malnutrition, chronic inflammation, vitamin deficiencies, and an imbalance in the muscle-gut axis are just a few of the factors that can lead to sarcopenia. Supplementing the diet with antioxidants, polyunsaturated fatty acids, vitamins, probiotics, prebiotics, proteins, kefir, and short-chain fatty acids could be potential nutritional therapies against sarcopenia. Finally, a personalized integrated strategy to counteract sarcopenia and maintain the health of skeletal muscles is suggested in this review.

Interaction between oxidised state of quercetin and bovine serum albumin in presence of surfactant aggregates with different charges

The present investigation focuses on the role of surfactant and its charge on the interaction of flavonoid Quercetin (QCT) and Bovine serum albumin (BSA). QCT is known to undergo autoxidation in many chemical environments which has different characteristics compared to its non-oxidised structure. In this experiment, two ionic surfactants used. They are anionic surfactant, Sodium dodecyl sulfate (SDS) and Cationic surfactants Cetyl pyridinium bromide (CPB). The characterizations employed are conductivity, FT-IR, UV-visible spectroscopy, Dynamic light scattering (DLS) and Zeta potential measurements. The critical micellar concentration (CMC) as well as the counter-ion binding constant (β) have been calculated by making use of specific conductance values, in aqueous medium at 300 K. Various thermodynamic parameters, ΔG0m, standard free energy of micellization, ΔH0m, standard enthalpy of micellization and ΔS0m, standard entropy of micellization are calculated. The negative value of ΔG0m in all systems is indicative of spontaneous binding occurring in both QCT + BSA + SDS (-23.35 kJ mol-1) and QCT + BSA + CPB (-27.18 kJ mol-1). The higher negative value infers the latter is a more stable system with greater spontaneity. The UV-visible spectroscopy study points at stronger binding of QCT and BSA in presence of surfactants and also there is stronger binding of CPB in ternary mixture with higher binding constant compared to SDS ternary mixture. Which is evident from the binding constant calculated from Benesi-Hildebrand plot (QCT + BSA + SDS, 244.46 M-1; QCT + BSA + CPB, 336.53 M-1). Further, the structural alterations occurring in the above systems has been observed by FT-IR spectroscopy. The DLS and Zeta potential measurements also support the above finding.Communicated by Ramaswamy H. Sarma.

Self-assembly of bile salts and their mixed aggregates as building blocks for smart aggregates

The present communication offers a comprehensive overview of the self-assembly of bile salts emphasizing their mixed smart aggregates with a variety of amphiphiles. Using an updated literature survey, we have explored the dissimilar interactions of bile salts with different types of surfactants, phospholipids, ionic liquids, drugs, and a variety of natural and synthetic polymers. While assembling this review, special attention was also provided to the potency of bile salts to alter the size/shape of aggregates formed by several amphiphiles to use these aggregates for solubility improvement of medicinally important compounds, active pharmaceutical ingredients, and also to develop their smart delivery vehicles. A fundamental understanding of bile salt mixed aggregates will enable the development of new strategies for improving the bioavailability of drugs solubilized in newly developed potential hosts and to formulate smart aggregates of desired morphology for specific targeted applications. It enriches our existing knowledge of the distinct interactions exerted in mixed systems of bile salts with variety of amphiphiles. By virtue of this, researchers can get innovative ideas to construct novel nanoaggregates from bile salts by incorporating various amphiphiles that serve as a building block for smart aggregates for their numerous industrial applications.

Advances on nanoformulation approaches for delivering plant-derived antioxidants: A case of quercetin

Oxidative stress has been implicated in tumorigenic, cardiovascular, neuro-, and age-related degenerative changes. Antioxidants minimize the oxidative damage through neutralization of reactive oxygen species (ROS) and other causative agents. Ever since the emergence of COVID-19, plant-derived antioxidants have received enormous attention, particularly in the Indian subcontinent. Quercetin (QCT), a bio-flavonoid, exists in the glycosylated form in fruits, berries and vegetables. The antioxidant potential of QCT analogs relates to the number of free hydroxyl groups in their structure. Despite presence of these groups, QCT exhibits substantial hydrophobicity. Formulation scientists have tested nanotechnology-based approaches for its improved solubilization and delivery to the intended site of action. By the virtue of its hydrophobicity, QCT gets encapsulated in nanocarriers carrying hydrophobic domains. Apart from passive accumulation, active uptake of such formulations into the target cells can be facilitated through well-studied functionalization strategies. In this review, we have discussed the approaches of improving solubilization and bioavailability of QCT with the use of nanoformulations.

Supramolecular Vector/Drug Coassemblies of Polyglycerol Dendrons and Rutin Enhance the pH Response

A coassembly strategy for a supramolecular vector/drug was proposed with a biocompatible ternary dodecyl-bi(third-generation polyglycerol (PG) dendrons) (C₁₂-(G3)₂) amphiphile, dodecyl sulfobetaine (SB3-12) surfactant, and poorly water-soluble drug rutin. C₁₂-(G3)₂ and rutin will mutually enhance their pH response by protonation and deprotonation of dendritic PG and rutin's ionization as the pH changes from the acidic gastric lumen to the weakly alkaline intestine. SB3-12 may increase the payload and bring about sustained release for rutin by intermolecular interactions. Self-assembling behaviors of C₁₂-(G3)₂, SB3-12, sodium dodecyl sulfate (SDS), and dodecyl trimethylammonium bromide (DTAB) and their hybrids with rutin were characterized by UV-vis spectroscopy, a fluorescence probe, and ¹H NMR. UV-vis and ¹H NMR were used to identify the position and orientation of rutin in the vectors. The functions of the vector/drug were confirmed by measuring the solubility and in vitro release of rutin. The ternary coassembling vector/drug easily imparted functions of pH-responsive and sustained release without complex synthetic processes. The nanocaves framed by PG dendrons in the micelles provide pH-responsive compartments for rutin and SB3-12 in the supramolecular vector/drug anchors that accommodate rutin by weak interactions. The finely matched supramolecular vector/drug coassemblies exhibit the pH-responsive function for a potential application in the treatment of inflammatory bowel disease.

Chitosan/PEO nanofibers containing Calendula officinalis extract: Preparation, characterization, in vitro and in vivo evaluation for wound healing applications

Wound healing is a complex pathophysiological process, highlighting the importance of effective and thorough wound care along with the prevention of wound infection, a major barrier that can slow down or even disrupt the healing process. To date, there are plenty of herbal plants well known and historically supernatural, showing profound wound healing effects. Application of such herbal extracts/ingredients in electrospun nanofiber platforms has shown promising outcomes in improving wound healing process. Based on these facts, we loaded Calendula officinalis extract (CO) in chitosan/polyethylene oxide scaffolds (CS/PEO) by electrospinning. Using SEM, morphology of electrospun scaffolds showed a narrow range of fiber diameter, around 143--252 nm, with uniform and bead-free appearance. FT-IR spectroscopy confirmed the presence of CO extract in nanofibrous scaffolds. Of importance, incorporation of CO extract improved mechanical properties of CS/PEO nanofibers. A 1602 cP reduction in viscosity and a 0.892 ms/cm increase in the conductivity of the solution was observed after addition of the CO extract. CO extract showed strong antibacterial properties with 96% and 94% reduction in Gram positive and Gram negative bacteria, respectively. In vitro studies with fibroblast cells confirmed enhanced proliferation, growth and attachment of the cells. The in vivo and histological analysis of rat wounds, revealed excellent wound healing ability of CS/PEO/CO dressings (87.5 % wound closure after 14 days) via improving collagen synthesis, re-epithelization and remodeling of the tissue. In sum, our findings show that CS/PEO/CO scaffolds can be used as a promising dressing for the treatment of skin wounds.

Photoacoustic characterization of wheat bread mixed with Moringa oleifera

Photoacoustic spectroscopy is applied to evaluate the impact of Moringa at different concentrations (0, 1.25, 2.5, 5 and 10%) on the elaboration, sanity, texture, and color of wheat bread. It was found that: i) Photoacoustic signal amplitude values of bread significantly increase from 37 to 90% when moringa powder concentration raises from 1.25% to 10%, at 300 nm wavelength. ii) Comparing the photoacoustic signal values at 300, 330, and 370 nm wavelengths, produced by the different bread types, there were statistically significant differences. iii) The sanitary quality of bread mixed with a 2.5% of moringa is relatively higher than the ones obtained for other concentrations, such that the number of fungal colonies were reduced by 99% in comparison with the control bread without moringa, after six days of storage. Moringa at 2.5% of concentration could thus improve the sanitary quality of wheat bread. iv) The addition of moringa for making bread slows down its textural changes (hardness, elasticity, cohesiveness, resilience, and chewiness) during storage. v) Finally, the highest correlation between the photoacoustic amplitude and the moringa concentration occurs at the wavelengths of 300 and 330 nm, which could be related to significant changes in the content of flavonoids and phenolic acids.

Absorption Coefficients of Phenolic Structures in Different Solvents Routinely Used for Experiments

Phenolic structures are of great interest due to their antioxidant properties and various postulated benefits on human health. However, the quantification of these structures in fruits and vegetables, as well as in vivo or in vitro experiments, is demanding, as relevant concentrations are often low, causing problems in exactly weighing the respective amounts. Nevertheless, the determination of used concentrations is often a prerequisite for accurate results. A possibility to quantify polyphenol is the use of UV/vis spectroscopy. Therefore, the absorption coefficients of selected phenolic structures were determined in three different solvents relevant for polyphenol research (water/methanol (50/50, v/v), water, and phosphate buffer at pH 7.5). To confirm the values based on weight and to avoid errors due to impurities, hygroscopic effects, and inadequate balance care, the mass concentrations were additionally determined by quantitative NMR (q-NMR). The coefficients presented in this article can help to quickly and easily determine accurate concentrations in a laboratory routine without wasting the often-precious standard compounds.

In Vitro Gastrointestinal Stability of Lipophilic Polyphenols is Dependent on their Oil-Water Partitioning in Emulsions: Studies on Curcumin, Resveratrol, and Quercetin

Many lipophilic polyphenols have low bioavailability because of their poor solubility and chemical stability within the human gut. The encapsulation of these polyphenols within digestible lipid droplets can improve their solubility and stability. However, there is currently a poor understanding of how the molecular and physicochemical properties of specific polyphenols impact these characteristics. In this study, the factors influencing the solubility and stability of different polyphenols (curcumin, resveratrol, and quercetin) under simulated gastrointestinal conditions were examined when they were delivered in the form of soybean oil-in-water nanoemulsions containing quillaja saponin-coated droplets (d₃₂ ≈ 0.15 μm; ζ = -63 mV; pH 5). The polyphenols were loaded into the lipid droplets using a pH-driven method, which is based on the pH-dependent electrical charge, oil-water partitioning, and water-solubility of these molecules. The encapsulation efficiency of all three polyphenols was relatively high (75-87%). However, their chemical stability under gastrointestinal conditions (i.e., the % remaining after exposure to gastrointestinal conditions) differed considerably: quercetin (44%), curcumin (92%), and resveratrol (100%). This effect was mainly attributed to the lower logD value of quercetin (2.17) than those of resveratrol (3.39) and curcumin (4.12). As a result, a high fraction (>50%) of quercetin was located within the aqueous gastrointestinal fluids, where it would be more prone to chemical degradation or precipitation. The fraction of the polyphenols solubilized in the gastrointestinal fluids (bioaccessibility) followed a different trend: curcumin (57%) < quercetin (73%) < resveratrol (76%). This effect was attributed to the chemical instability and/or binding of curcumin with other molecules in the simulated intestinal conditions. These results provide useful information for designing nanoemulsion-based delivery systems to improve the efficacy of lipophilic polyphenols.

Utilizing polymer-conjugate albumin-based ultrafine gas bubbles in combination with ultra-high frequency radiations in drug transportation and delivery

Ultrafine bubbles stabilized by human serum albumin conjugate polyethylene glycol ameliorates the stability of complex as well as the drug payload. Polyethylene glycol presents the crucial role in releasing drug by means of acoustic sound.

Anti-Oxidative Activity of Alcohol-Water Extracts from Field Horsetail (Equisteum arvense) in Elastomer Vulcanizates Subjected to Accelerated Aging Processes

The article aimed to highlight the antioxidant potential of natural extracts obtained from Equisteum arvense in elastomer vulcanizatec made of natural rubber. Horsetail extracts were prepared using four solvent systems at different volume ratios: methanol–water (50/50 and 70/30) and ethanol–water (50/50 and 70/30), which were then lyophilized and added to the polymer matrix. A deep characterization of the obtained bio-additives was performed. The obtained vulcanizates were subjected to various aging processes: thermo-oxidative, ultraviolet and solar. Then, the resistance and susceptibility of vulcanizates to selected processes of accelerated, simulated degradation were determined based on the changes in the spatial structure (network nodes), material strength and physical properties (color). The research showed the presence of polyphenols in the extracts of horsetail, which resulted in their high anti-oxidative activity. Moreover, the extracts were able to absorb UV radiation. As a consequence, they were active additives that protected rubber vulcanizates against the damaging effects of the aging processes, securing their functional properties. Samples containing natural extracts were characterized by better stability of: mechanical strength parameters, the increase in cross-linking density and color changes after simulating aging processes in comparison with the control sample.

Morphology of bile salts micelles and mixed micelles with lipolysis products, from scattering techniques and atomistic simulations

HYPOTHESES

Bile salts (BS) are biosurfactants released into the small intestine, which play key and contrasting roles in lipid digestion: they adsorb at interfaces and promote the adsorption of digestive enzymes onto fat droplets, while they also remove lipolysis products from that interface, solubilising them into mixed micelles. Small architectural variations on their chemical structure, specifically their bile acid moiety, are hypothesised to underlie these conflicting functionalities, which should be reflected in different aggregation and solubilisation behaviour.

EXPERIMENTS

The micellisation of two BS, sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC), which differ by one hydroxyl group on the bile acid moiety, was assessed by pyrene fluorescence spectroscopy, and the morphology of aggregates formed in the absence and presence of fatty acids (FA) and monoacylglycerols (MAG) - typical lipolysis products - was resolved by small-angle X-ray/neutron scattering (SAXS, SANS) and molecular dynamics simulations. The solubilisation by BS of triacylglycerol-incorporating liposomes - mimicking ingested lipids - was studied by neutron reflectometry and SANS.

FINDINGS

Our results demonstrate that BS micelles exhibit an ellipsoidal shape. NaTDC displays a lower critical micellar concentration and forms larger and more spherical aggregates than NaTC. Similar observations were made for BS micelles mixed with FA and MAG. Structural studies with liposomes show that the addition of BS induces their solubilisation into mixed micelles, with NaTDC displaying a higher solubilising capacity.

Quercetin as an anticancer agent: Focus on esophageal cancer

Esophageal cancer (EC) is regarded as the sixth highest contributor to all cancer-related mortality, worldwide. In spite of advances in the treatment of EC, currently used methods remain ineffective. Quercetin, as a dietary antioxidant, is a plant flavonol from the flavonoid group of polyphenols, and can be found in numerous vegetables, fruits, and herbs. Quercetin can affect the processes of cancer-related diseases via cell proliferation inhibitory effects, potential apoptosis effects, and antioxidant properties. Of the various types of cancer, the use of quercetin has now become prominent in the treatment of EC. In this review, we discuss how quercetin may be an important supplement for the prevention, treatment, and management of EC, owing to its natural origin, and low-cost relative to synthetic cancer drugs. However, most findings cited in the current study are based on in vitro and in vivo studies, and thus, further human-based research is necessitated. PRACTICAL APPLICATIONS: In spite of advances in the treatment of esophageal cancer, currently used methods remain ineffective, therefore, an alternative or complementary therapy is required. Quercetin, as a dietary antioxidant, can affect the processes of cancer-related diseases via cell proliferation inhibitory effects, potential proapoptotic functions, and antioxidant properties. Quercetin may be an important supplement for the prevention, treatment, and management of EC, owing to its natural origin. The low cost of quercetin as supplement or dietary intake, relative to synthetic cancer drugs, is an advantage of the compound which should be considered.

Interaction of alkyl chain containing pyrene derivatives with different micellar media: Synthesis and photophysical study

The present work describes the synthesis and photophysical studies of four newly synthesized alkyl chain containing pyrene derivatives and their applications in micellization process of different types of surfactants e.g. CTAB and SDS. The fluorescent properties of these pyrene derivatives were utilized to understand the micellization process of CTAB and SDS. The length of alkyl chain affects the hydrophobicity of pyrene fluorophore which also affects the sensitivity of fluorophore towards the micellization of CTAB and SDS surfactants. The longest alkyl tail containing, PBBU showed more sensitivity whereas moderate alkyl chain containing, PABU and PBME showed moderate sensitivity and finally PAME contained smallest alkyl tail, showed no sensitivity towards the micellization of CTAB and SDS. The alkyl tail of fluorophore make it more hydrophobic and it could easily bind with the hydrophobic inner core of micelles. In both surfactants, PBBU showed LE emission at ~400 nm and aggregate emission at ~470 nm, whereas, PABU and PBME showed LE emission band at ~400 nm. Before CMC, the aggregates band of PBBU increased with increasing the surfactant concentrations, but after CMC the individual PBBU present into the water medium could binds with the inner core of micelles. Thus PBBU senses the formation of premicellar aggregates of CTAB and SDS. The LE emission of the fluorophore gradually increases while increasing the CTAB and SDS concentrations. The change in fluorescence emission of PABU, PBME and PBBU with increasing concentration of CTAB and SDS were used to calculate the CMC of CTAB and SDS surfactants.

Solubilization of phloretin via steviol glycoside-based solid dispersion and micelles

In this study, the solubility of phloretin (PT) was enhanced via steviol glycoside (STE)-based micelle (MC) and solid dispersion (SD). Computer simulation, characterization, interaction with serum albumin (SA) and in vitro release were carried out to investigate the solubilization mechanisms and the difference in their solubilization capacities. For PT-loaded MC (STE-PT MC), PT was encapsulated into the hydrophobic core of a spherical micelle with a droplet diameter of 5 nm. For PT-loaded SD (STE-PT SD), PT was completely dispersed with the amorphous state in STE. Most of those PTs were directly dissolved in water, and few were encapsulated by STE micelles. The amorphous state combined with relatively large micelles contributed to the high solubilization capacity of STE-PT SD. In addition, PT of STE-PT SD exhibited a higher dissolution rate and more effective interaction with SA than that of STE-PT MC. No undesirable chemical interaction between PT and STE occurred.

Characterization of xylitol or citric acid:choline chloride:water mixtures: Structure, thermophysical properties, and quercetin solubility

The industrial implementation of new eco-friendly solvents has highlighted the need to analyse both the structures and thermophysical properties of these solvents. Here, two deep eutectic solvents (DESs) used in the agro-food field were studied: xylitol:choline chloride:water (1:2:3 M ratio), XoCH, and citric acid:choline chloride:water (1:1:6 M ratio), CiCH. The H-bond network between the components of each DES was evaluated and the diffusion coefficients at 298.15 K were calculated using NMR spectroscopy. In addition, seven thermophysical properties were determined from 278.15 to 338.15 K. Also, the solubility of quercetin in water and in the two eutectic mixtures was measured and the interactions between components were studied. NMR experiments revealed the presence of water within the supramolecular structure of XoCH, but CiCH is a "DES-in-water" solution. Based on the results, XoCH is the most compact mixture. Finally, quercetin was remarkably more soluble in the studied DESs than in pure water.

Gastrointestinal Fate of Fluid and Gelled Nutraceutical Emulsions: Impact on Proteolysis, Lipolysis, and Quercetin Bioaccessibility

Fluid and gelled nutraceutical emulsions were formulated from quercetin-loaded caseinate-stabilized emulsions by the addition of gellan gum with or without acidification with glucono-δ-lactone. Gellan gum addition increased the viscosity or gel strength of the fluid and gelled emulsions, respectively. The behavior of the nutraceutical emulsions in a simulated gastrointestinal tract depended upon their initial composition. Fluid emulsions containing different gellan gum levels (0-0.2%) had similar protein and lipid hydrolysis rates as well as similar quercetin bioaccessibility (∼51%). Conversely, proteolysis, lipolysis, and quercetin bioaccessibility decreased with an increasing gellan gum level in the gelled emulsions. In comparison to gelled emulsions, fluid emulsions were digested more rapidly and led to higher quercetin bioaccessibility. There was a good correlation between quercetin bioaccessibility and the lipolysis rate. These findings are useful for designing nutraceutical-loaded emulsions that can be used in a wide range of food products with different rheological properties.

Facile, environmentally benign and scalable approach to produce pristine few layers graphene suitable for preparing biocompatible polymer nanocomposites

The success of developing graphene based biomaterials depends on its ease of synthesis, use of environmentally benign methods and low toxicity of the chemicals involved as well as biocompatibility of the final products/devices. We report, herein, a simple, scalable and safe method to produce defect free few layers graphene using naturally available phenolics i.e. curcumin/tetrahydrocurcumin/quercetin, as solid-phase exfoliating agents with a productivity of ∼45 g/batch (D/G ≤ 0.54 and D/D' ≤ 1.23). The production method can also be employed in liquid-phase using a ball mill (20 g/batch, D/G ≤ 0.23 and D/D' ≤ 1.12) and a sand grinder (10 g/batch, D/G ≤ 0.11 and D/D∼ ≤ 0.78). The combined effect of π-π interaction and charge transfer (from curcumin to graphene) is postulated to be the driving force for efficient exfoliation of graphite. The yielded graphene was mixed with the natural rubber (NR) latex to produce thin film nanocomposites, which show superior tensile strength with low modulus and no loss of % elongation at break. In-vitro and in-vivo investigations demonstrate that the prepared nanocomposite is biocompatible. This approach could be useful for the production of materials suitable in products (gloves/condoms/catheters), which come in contact with body parts/body fluids.

Nanoconjugates of a calixresorcinarene derivative with methoxy poly(ethylene glycol) fragments for drug encapsulation

In order to obtain a non-toxic amphiphilic calixresorcinarene capable to form nanoconjugates for drug encapsulation, tetraundecylcalixresorcinarene functionalized by methoxy poly(ethylene glycol) chains has been synthesized. The macrocycle obtained is characterized by low hemotoxicity. In aqueous solution it forms nanoassociates that are able to encapsulate organic substrates of different hydrophobicity, including drugs (doxorubicin, naproxen, ibuprofen, quercetin). The micelles of the macrocycle slowed down the release of the hydrophilic substrates in vitro. In physiological sodium chloride solution and phosphate-buffered saline, the micelles of the macrocycle acquire thermoresponsive properties and exhibit a temperature-controlled release of doxorubicin in vitro. The combination of the low toxicity and the encapsulation properties of the obtained calixresorcinarene-mPEG conjugate shows promising potential for the use as a supramolecular drug-delivery system.

Towards an Understanding of the Low Bioavailability of Quercetin: A Study of Its Interaction with Intestinal Lipids

We have studied the uptake of quercetin aglycone into CaCo-2/TC7 cells in the presence and absence of mixed micelles that are present in the human small intestine. The micelles inhibited the transport of quercetin into the cells. To gain an understanding of why this is the case we examined the solubilisation of quercetin in micelles of differing composition and into pure lipid phases. We did this by using the environmental sensitivity of quercetin’s UV-visible absorption spectra and measurement of free quercetin by filtration of the micellar solutions. The nature of the micelles was also studied by pyrene fluorescence. We found that the partitioning of quercetin into simple bile salt micelles was low and for mixed micelles was inhibited by increasing the bile salt concentration. The affinity of quercetin decreased in the order egg phosphatidylcholine (PC) = lysoPC > mixed micelles > bile salts. These results, together with the innate properties of quercetin, contribute to an understanding of the low bioavailability of quercetin.

Mango-bagasse functional-confectionery: vehicle for enhancing bioaccessibility and permeability of phenolic compounds

Study on bioaccessibility and absorption path of mango bagasse phenolics.