Flavonols, belonging to a subgroup of secondary plant metabolites, have a high therapeutic potential. To compare molecular parameters of the flavonols and their interactions with membranes, we performed quantum chemical modeling of structure and electronic characteristics of some flavonols such as quercetin, fisetin, kaempferol, and myricetin and considered the effects of the flavonols on liposomal membranes, using fluorescence spectroscopy, an electric-kinetical method and differential scanning calorimetry. Quercetin was more effective in increasing liposomal membrane stiffness and hydration, while fisetin increased zeta potential and destabilized the membrane to a greater extent. We hypothesize that a modification of the biological membrane structure, stability, reduction of fluidity and enhancement of bilayer hydration by the flavonols underlie their biochemical and pharmacological effects.

The high metastatic potential of melanoma and its poor prognosis in advanced stages motivate the search for innovative therapeutic approaches. Therefore, this study aimed to assess the effects of phytocannabinoids (cannabidiol-CBD, and cannabigerol-CBG) on the structure and function of the melanoma cell membrane, phospholipid metabolism, and the respective metabolites generated in ROS- and enzyme-dependent reactions. Biochemical and physicochemical parameters were analyzed in melanoma cells (SK-MEL-5) cultured for 24 h with CBD (5 µM), CBG (1 µM), and their combination applied either alone or after UVA irradiation (365 nm) at a dose of 18 J/cm². Phytocannabinoids have been shown to partially counteract changes in the levels of cell membrane components, including phospholipid polyunsaturated fatty acids (PUFAs) and sialic acid, consequently affecting surface charge density and lipid rafts, which may be a potential target for anticancer therapy. Furthermore, by changing the activity of lipolytic enzymes (PLA2/COX1/2/LOX-5), phytocannabinoids partially enhanced the UVA-induced decrease in free PUFAs. Consequently, the levels of lipid mediators, including endocannabinoids and eicosanoids, were altered. The use of phytocannabinoids led to a significant increase in 2-AG levels, while the combined action of CBD/CBG reduced the levels of pro-inflammatory eicosanoids. UVA radiation increased the expression of G-protein-coupled receptors in melanoma cells (CB1/2/TRPV1/PPARγ), while the combined use of CBD/CBG reduced their expression. Therefore, the results have shown that CBD and CBG modulate the metabolism of phospholipids and PUFAs by altering the functions of melanoma cell membranes, potentially offering options for the use of these phytocannabinoids in the integrative biomedicine treatment of melanoma.

The study investigates the effect of the presence of a chlorine atom in the 2'-hydroxychalcone molecule on its interaction with model lipid membranes, in order to discern its potential pharmacological activity. Five chlorine derivatives of 2'-hydroxychalcone were synthesized and evaluated against liposomes composed of POPC and enriched with cationic (DOTAP) or anionic (POPG) lipids. The physicochemical properties of the compounds were initially simulated using SwissAdame software, revealing high lipophilicity (ilogP values: 2.79-2.90). The dynamic light scattering analysis of liposomes showed that chloro chalcones induce minor changes in the diameter of different surface charges. Fluorescence quenching assays with a TMA-DPH probe demonstrated the strong ability of the compounds to interact with the lipid bilayer, with varying quenching capacities based on chlorine atom position. FTIR studies indicated alterations in carbonyl, phosphate, and choline groups, suggesting a transition area localization rather than deep penetration into the hydrocarbon chains. Additionally, dipole potential reduction was observed in POPC and POPC-POPG membranes, particularly pronounced by derivatives with a chlorine atom in the B ring. Antibacterial and antibiofilm assays revealed enhanced activity of derivatives with a chlorine atom compared to 2’-hydroxychalcone, especially against Gram-positive bacteria. The MIC and MBIC50 values showed increased efficacy in the presence of chlorine with 3’-5’-dichloro-2’-hydroxychalcone showing optimal antimicrobial and antibiofilm activity. Furthermore, antiproliferative assays against breast cancer cell lines indicated higher activity of B-ring chlorine derivatives, particularly against MDA-MB-231 cells. In general, the presence of a chlorine atom in 2’-hydroxychalcone improves its pharmacological potential, with derivatives showing improved antimicrobial, antibiofilm, and antiproliferative activities, especially against aggressive breast cancer cell lines. These findings underscore the importance of molecular structure in modulating biological activity and highlight chalcones with a chlorine as promising candidates for further drug development studies.

Dental caries (DC) is the most common oral pathology. The main bacteria responsible for DC is Streptococcus mutans. One of the strategies that can decrease or eliminate the risk of DC development is using compounds that will inhibit both the growth and virulence factors of S. mutans. Tannins are plant polyphenols that have strong antibacterial activity. The purpose of this study was to assess the antibacterial activity of three tannins against S. mutans. In this investigation, microbiological tests (MIC and MBC) and physicochemical techniques like the fluorescence measurements of tannins’ interaction with S. mutans cell membrane and membrane proteins, zeta potential, and thermodynamic analyses were used to obtain knowledge about the antibacterial potential of the investigated compounds against S. mutans as well as about the mechanisms associated with antibacterial activity. The obtained results demonstrate that the used compounds exhibit high antibacterial activity against S. mutans. The mechanisms of their antibacterial activity are linked to the strong change in the S. mutans membrane fluidity and potential, and to their interaction with membrane proteins that can result in great disturbance of bacterial physiology and ultimately the inhibition of bacterial growth, triggering their death. Therefore, it can be concluded that the investigated compounds can be potentially used as natural factors in the prevention of dental caries.

The use of dendrimers as drug and nucleic acid delivery systems requires knowledge of their interactions with objects on their way to the target. In the present work, we investigated the interaction of a new class of carbosilane dendrimers functionalized with polyphenolic and caffeic acid residues with human serum albumin, which is the most abundant blood protein. The addition of dendrimers to albumin solution decreased the zeta potential of albumin/dendrimer complexes as compared to free albumin, increased density of the fibrillary form of albumin, shifted fluorescence spectrum towards longer wavelengths, induced quenching of tryptophan fluorescence, and decreased ellipticity of circular dichroism resulting from a reduction in the albumin α-helix for random coil structural form. Isothermal titration calorimetry showed that, on average, one molecule of albumin was bound by 6–10 molecules of dendrimers. The zeta size confirmed the binding of the dendrimers to albumin. The interaction of dendrimers and albumin depended on the number of caffeic acid residues and polyethylene glycol modifications in the dendrimer structure. In conclusion, carbosilane polyphenolic dendrimers interact with human albumin changing its structure and electrical properties. However, the consequences of such interaction for the efficacy and side effects of these dendrimers as drug/nucleic acid delivery system requires further research.

The interactions of flavonols with biological membranes underlie their beneficial biochemical effects. In the present work, we performed quantum chemical modeling of the molecular structure and electronic characteristics of some flavonols such as fisetin, kaempferol, and myricetin and compared our findings with those for quercetin obtained earlier. We considered the effects of the flavonols on liposomal membranes, using the methods of fluorescence probe spectroscopy, an electric-kinetical method and differential scanning calorimetry. The AC and B rings in the molecules of all the flavonols studied were located in the same plane. All the flavonols (5–25µM) increased the lipid bilayer order both in the surface zone and the hydrophobic area of the membrane. Quercetin was more effective in changing the liposomal membrane mobility and fisetin modulated markedly the thermotropic behavior of the membrane. Myricetin was located predominantly in the surface zone, whereas quercetin penetrated into the deeper zone of the bilayer. Using the fluorescent probe Laurdan we showed that all the flavonols studied increased the hydration of the lipid bilayer. The incorporation of effector molecules into the liposomal membrane bilayer resulted in an increase in the absolute value of zeta potential and induced an increase in the liposomal diameter. Destabilization and enhanced heterogeneity of liposomal membranes in the presence of all the flavonols studied were revealed.

Pomegranate and its by-products contain a broad spectrum of phytochemicals, such as flavonoids, phenolic acids and tannins, having pleiotropic preventive and prophylactic properties in health disorders related to oxidative stress and microbial contamination. Here, we examined the biological effects of a pomegranate peel ellagitannins-enriched (>90%) extract, PETE. In vitro studies revealed that PETE has a strong antiradical action towards synthetic radicals and biologically relevant ROS surpassing or comparable to that of Trolox. In cellular models, it showed concentration-dependent (25–100 µg/mL) yet opposing effects depending on the cell membrane type and exposure conditions. In erythrocytes, PETE protected membrane integrity in the presence of the strong oxidant HClO and restored reduced glutathione levels to up to 85% of the control value while having much weaker acute and long-term intrinsic effects. Such protection persisted even after the removal of the extract from cells, indicating strong membrane interaction. In HeLa cancer cells, and at concentrations lower than those used for red blood cells, PETE induced robust potentiation of ROS production and mitochondrial potential dissipation, leading to autophagy-like membrane morphology changes and cell death. In S. aureus, the growth arrest and bacterial death in the presence of PETE (with MIC = 31.25 µg/mL and MBC = 125 µg/mL, respectively) can be linked to the tripled ROS induction by the extract in the same concentration range. This study indicates a specificity of ROS production by the pomegranate extract depending on the type of cell, the concentration of the extract and the time of incubation. This specificity witnesses a strong potential of the extract components as candidates in antioxidant and pro-oxidant therapy.

Treatment of infections caused by Pseudomonas aeruginosa presents a challenge due to its ability to adapt and acquire drug resistance rapidly. Therefore, a key challenge is identifying and investigating new compounds with antibacterial and anti-virulence activity. Tannins, a group of plant polyphenolic compounds, can interact with bacterial cells and their virulence factors. The purpose of this study was to assess the antibacterial potential of using 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-β-D-glucose (C55H40O34) isolated from Rhus typhina against P. aeruginosa ATCC BAA-1744. The investigation involved viability analyses using the INT assay, fluorescence analyses of the tannins’ interaction with the cell membrane and membrane proteins of P. aeruginosa, and analysis of changes in the Zeta potential. The results obtained allowed us to conclude that C55H40O34 exhibits antimicrobial activity by inducing changes in the biophysical properties of P. aeruginosa’s cell membrane. The thermodynamic parameters indicated that C55H40O34 binds to bacterial membrane proteins through hydrophobic interactions. These interactions with proteins may impact their structure and disrupt their functions, such as disturbing or inhibiting the efflux pumps, which are part of P. aeruginosa’s resistance mechanisms. Therefore, C55H40O34 may be a new, natural agent and could potentially be used against P. aeruginosa.

Tannins are natural plant origin polyphenols that are promising compounds for pharmacological applications due to their strong and different biological activities, including antibacterial activity. Our previous studies demonstrated that sumac tannin, i.e., 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-β-D-glucose (isolated from Rhus typhina L.), possesses strong antibacterial activity against different bacterial strains. One of the crucial factors of the pharmacological activity of tannins is their ability to interact with biomembranes, which may result in the penetration of these compounds into cells or the realization of their activity on the surface. The aim of the current work was to study the interactions of sumac tannin with liposomes as a simple model of the cellular membrane, which is widely used in studies focused on the explanation of the physicochemical nature of molecule–membrane interactions. Additionally, these lipid nanovesicles are very often investigated as nanocarriers for different types of biologically active molecules, such as antibiotics. In the frame of our study, using differential scanning calorimetry, zeta-potential, and fluorescence analysis, we have shown that 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-β-D-glucose interacts strongly with liposomes and can be encapsulated inside them. A formulated sumac–liposome hybrid nanocomplex demonstrated much stronger antibacterial activity in comparison with pure tannin. Overall, by using the high affinity of sumac tannin to liposomes, new, functional nanobiomaterials with strong antibacterial activity against Gram-positive strains, such as S. aureus, S. epidermitis, and B. cereus, can be formulated.

A chemoselective procedure for MCPBA oxidation of 26-thiodiosgenin to corresponding sulfoxides and sulfone was elaborated. An unusual equilibration of sulfoxides in solution was observed. Moreover, α-alkylation of sulfoxide and sulfone was investigated. Finally, the biological activity of obtained compounds was examined.

The goal of this study is to obtain and characterize the complex of quercetin with glycyrrhizic acid, which is known to serve as a drug delivery system. Quercetin is a flavonoid with a wide range of biological activities, including an antimicrobial effect. However, quercetin instability and low bioavailability that limits its use in medical practice makes it necessary to look for new nanoformulations of it. The formation of the GAQ complex (2:1) was confirmed by using UV and FT-IR spectroscopies. It was found that the GAQ exhibited antimicrobial and antihemolytical activities against S. aureus bacteria and its main virulent factor-α-hemolysin. The IC50 value for the antihemolytical effect of GAQ was 1.923 ± 0.255 µg/mL. Using a fluorescence method, we also showed that the GAQ bound tightly to the toxin that appears to underlie its antihemolytic activity. In addition, another mechanism of the antihemolytic activity of the GAQ against α-hemolysin was shown, namely, its ability to increase the rigidity of the outer layer of the erythrocyte membrane and thus inhibit the incorporation of α-hemolysin into the target cells, increasing their resistance to the toxin. Both of these effects of GAQ were observed at concentrations below the MIC value for S. aureus growth, indicating the potential of the complex as an antivirulence agent.

The technology of lipid nanoparticles has a long history in drug delivery, which begins with the discovery of liposomes by Alec D Bangham in the 1960s. Since then, numerous studies have been conducted on these systems, and several nanomedicinal products that utilize them have entered the market, with the latest being the COVID19 vaccines. Despite their success, many aspects of their biophysical behavior are still under investigation. At the same time, their combination with other classes of biomaterials to create more advanced platforms is a promising endeavor. Herein, we developed mixed lipid-polymer nanoparticles with incorporated curcumin as a drug delivery system for therapy, and we studied its interactions with various biosystems. Initially, the nanoparticle physicochemical properties were investigated, where their size, size distribution, surface charge, morphology, drug incorporation and stability were assessed. The incorporation of the drug molecule was approximately 99.8 % for a formulated amount of 10 % by weight of the total membrane components and stable in due time. The association of the nanoparticles with human serum albumin and the effect that this brings upon their properties was studied by several biophysical techniques, including light scattering, thermal analysis and circular dichroism. As a biocompatibility assessment, interactions with erythrocyte membranes and hemolysis induced by the nanoparticles were also studied, with empty nanoparticles being more toxic than drug-loaded ones at high concentrations. Finally, interactions with bacterial membrane proteins of Staphylococcus aureus and the antibacterial effect of the nanoparticles were evaluated, where the effect of curcumin was improved when incorporated inside the nanoparticles. Overall, the developed mixed nanoparticles are promising candidates for the delivery of curcumin to infectious and other types of diseases.

Search for novel antimicrobial agents, including plant-derived flavonoids, and evaluation of the mechanisms of their antibacterial activities are pivotal objectives. The goal of this study was to compare the antihemolytic activity of flavonoids, quercetin, naringenin and catechin against sheep erythrocyte lysis induced by α-hemolysin (αHL) produced by the Staphylococcus aureus strain NCTC 5655. We also sought to investigate the membrane-modifying action of the flavonoids. Lipophilic quercetin, but not naringenin or catechin, effectively inhibited the hemolytic activity of αHL at concentrations (IC50 = 65 ± 5 µM) below minimal inhibitory concentration values for S. aureus growth. Quercetin increased the registered bacterial cell diameter, enhanced the fluidity of the inner and surface regions of bacterial cell membranes and raised the rigidity of the hydrophobic region and the fluidity of the surface region of erythrocyte membranes. Our findings provide evidence that the antibacterial activities of the flavonoids resulted from a disorder in the structural organization of bacterial cell membranes, and the antihemolytic effect of quercetin was related to the effect of the flavonoid on the organization of the erythrocyte membrane, which, in turn, increases the resistance of the target cells (erythrocytes) to αHL and inhibits αHL-induced osmotic hemolysis due to prevention of toxin incorporation into the target membrane. We confirmed that cell membrane disorder could be one of the direct modes of antibacterial action of the flavonoids.

The action of UVA radiation (both that derived from solar radiation and that used in the treatment of skin diseases) modifies the function and composition of keratinocyte membranes. Therefore, this study aimed to assess the effects of phytocannabinoids (CBD and CBG), used singly and in combination, on the contents of phospholipids, ceramides, lipid rafts and sialic acid in keratinocyte membranes exposed to UVA radiation, together with their structure and functionality. The phytocannabinoids, especially in combination (CBD+CBG), partially prevented increased levels of phosphatidylinositols and sialic acid from occurring and sphingomyelinase activity after the UVA exposure of keratinocytes. This was accompanied by a reduction in the formation of lipid rafts and malondialdehyde, which correlated with the parameters responsible for the integrity and functionality of the keratinocyte membrane (membrane fluidity and permeability and the activity of transmembrane transporters), compared to UVA-irradiated cells. This suggests that the simultaneous use of two phytocannabinoids may have a protective effect on healthy cells, without significantly reducing the therapeutic effect of UV radiation used to treat skin diseases such as psoriasis.

In this study, using bilayer lipid membrane technique, we report a novel facet of antihemolytic activity of two tannins (1,2,3,4,5-penta-O-galloyl-β-D-glucose (PGG) and 1,2-di-O-galloyl-4,6-valoneoyl-β-D-glucose (dGVG)), which consists in inhibiting the formation of α-hemolysin channels and blocking the conductivity of already formed channels. These effects were observed at tannin concentrations well below minimal inhibitory concentration values for S. aureus growth. Using spectroscopic methods, we show that these two tannins differing in molecular structure but having the same number of -OH groups and aromatic rings form firm complexes with hemolysin in aqueous solutions, which may underlie the disruption of its subsequent interaction with the membrane, thus preventing hemolysis of erythrocytes. In all experimental settings, PGG was the more active compound compared to dGVG, that indicates the important role of the flexibility of the tannin molecule in interaction with the toxin. In addition, we found that PGG, but not dGVG, was able to block the release of the toxin by bacterial cells. This toxin is a strong pathogenic factor causing a number of diseases and therefore is considered as a virulence target for treatment of S. aureus infection, so the data obtained suggest that PGG and possibly other tannins of similar structure have therapeutic potential in fighting the virulence of S. aureus.

Polyphenols, including tannins, are phytochemicals with pronounced antimicrobial properties. We studied the activity of two hydrolysable tannins, (i) gallotannin—1,2,3,4,5-penta-O-galloyl-β-D-glucose (PGG) and (ii) ellagitannin—1,2-di-O-galloyl-4,6-valoneoyl-β-D-glucose (dGVG), applied alone and in combination with antibiotics against Staphylococcus aureus strain 8324-4. We also evaluated the effect of these tannins on bacterial membrane integrity and fluidity and studied their interaction with membrane proteins and lipids. A correlation between the antimicrobial activity of the tannins and their membranotropic action depending on the tannin molecular structure has been demonstrated. We found that the antibacterial activity of PGG was stronger than dGVG, which can be associated with its larger flexibility, dipole moment, and hydrophobicity. In addition, we also noted the membrane effects of the tannins observed as an increase in the size of released bacterial membrane vesicles.

A four-step synthesis of five-and six-membered E/F ring spiroethers from tigogenin has been developed. An efficient strategy that features bis-Grignard reaction of dinorcholanic lactone with appropriate bis(bromo-magnesio)alkanes followed by acid-mediated spirocyclization was employed to construct a new class of steroid compounds having E and F ring junction as an oxa-carbacyclic system. The synthesized carbaanalogs interact with liposomes and albumin, and also exhibit antibacterial and antifungal activity, demonstrating their phar-macological potential.

It is well known that accumulation of advanced glycation ends products (AGEs) lead to various diseases such as diabetes and diabetic complications. In this study we showed that hydrolysable tannin from Sumac (Rhus typhina L.)—3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-β-d-glucose (C55H40O34) inhibited generation of glycation markers in bovine serum albumin such as AGEs, dityrosine, N′-formylkynurenine and kynurenine under high glucose treatment. This effect was accompanied by stabilization of the protein structure, as was shown using ATR-FT-IR spectroscopy and fluorescence methods. C55H40O34 exhibited also a neuroprotective effect in high glucose-exposed Neuro2A cells suppressing ROS formation and expression of phospho NF-κβ and iNOS. At the same time C55H40O34 increased expression of heme oxygenase-1 and NAD(P)H: quinone oxidoreductase and mitochondrial complex I and V activities. Results from this study demonstrates a potent antiglycation activity of C55H40O34 in vitro and indicates its possible therapeutic application in glycation related diseases.

Phenolic acids represent a class of drugs with mild antibacterial properties. We have synthesized iodinated gallic and ferulic acids and together with commercially available iodinated forms of salicylic acids studied their cytotoxicity, bacteriostatic and anti-virulence action. Out of these, iodogallic acid had lowest minimal inhibitory concentration (MIC) against Staphylococcus aureus (MIC = 0.4 mM/118.8 μg/ml). Yet, it had strong effect on erythrocyte membrane lipid ordering and on α-hemolysin secretion by the bacteria at lower non-bacteriostatic and non-cytotoxic concentrations (<0.1 mM). Iodogallic acid formed static complexes with α-hemolysin in solutions (logKb = 4.69 ± 0.07) and inhibited its nano-pore conduction in artificial lipid bilayers (IC50 = 37.9 ± 5.3 μM). These effects of iodogallic acid converged on prevention of hemolysis induced by α-hemolysin (IC50 = 41.5 ± 4.2 μM) and pointed to enhanced and diverse anti-virulence properties of some aryl iodides. The analysis of molecular surface electrostatic charge distribution, molecular hydrophilicity, electronegativity, and dipole moment of studied compounds suggested the importance of the number of hydroxyl groups and their proximity to iodine in anti-virulence activity manifestation. In iodogallic acid, charge redistribution resulted in higher hydrophilicity without concomitant change in overall molecular electronegativity and dipole moment compared to non-iodinated gallic acid. This study shows new directions for the development of antibacterial/antivirulence therapeutics.

Tannins belong to plant secondary metabolites exhibiting a wide range of biological activity. One of the important aspects of the realization of the biological effects of tannins is the interaction with lipids of cell membranes. In this work we studied the interaction of two hydrolysable tannins: 1,2,3,4,6-penta-O-galloyl-β-d-glucose (PGG) and 1,2-di-O-galloyl-4,6-valoneoyl-β-d-glucose (T1) which had the same number of both aromatic rings (5) and hydroxyl groups (15) but differing in flexibility due to the presence of valoneoyl group in the T1 molecule with DMPC (dimyristoylphosphatidylcholine) lipid nano-vesicles (liposomes). Tannins-liposomes interactions were investigated using fluorescence spectroscopy, differential scanning calorimetry, laser Doppler velocimetry, dynamic light scattering and Fourier Transform Infra-Red spectroscopy. It was shown that more flexible PGG molecules stronger decreased the microviscosity of the liposomal membranes and increased the values of negative zeta potential in comparison with the more rigid T1. Both compounds diminished the phase transition temperature of DMPC membranes, interacted with liposomes via PO groups of head of phospholipids and their hydrophobic regions. These tannins neutralized DPPH free radicals with the stoichiometry of the reaction equal 1:1. The effects of the studied compounds on liposomes were discussed in relation to tannin quantum chemical parameters calculated by molecular modeling.