Presence Of Quercetin Research Articles

Development of Quercetin Solid Dispersion-Loaded Dissolving Microneedles and In Vitro Investigation of Their Anti-Melanoma Activities.

Background: Melanoma is a skin cancer that requires early treatment to prevent metastasis. In particular, the superficial spreading melanoma, excisional surgery with local administration of anti-cancer drugs via microneedles is currently considered a potential combination therapy. Quercetin is a natural flavonoid having activities against melanoma cells. Unfortunately, the therapeutic effect is limited by its poor water solubility. Objectives: This study aimed to develop formulations of solid dispersion-loaded dissolving microneedles (SD-DMNs) of quercetin and to investigate their in vitro activities against melanoma cells. Methods: Quercetin solid dispersions (Q-SDs) were prepared using polyvinylpyrrolidone K30 (PVP) via a solvent technique. The optimized Q-SD was selected for preparing Q-SD-loaded dissolving microneedles (Q-SD-DMNs) using a mold casting method. Results: Q-SDs had higher water solubility than that of quercetin by 5-10 times depending on the ratio of quercetin-to-PVP. The presence of quercetin in the Q-SD and Q-SD-DMN were in an amorphous form. The obtained Q-SD-DMNs had pyramid-shaped microneedles. Their strength depended on the compositions, i.e., ratios of hyaluronic acid-to-sodium carboxymethylcellulose and the content of Q-SD. An optimized Q-SD-DMN increased the in vitro skin permeation of quercetin compared to that of microneedles containing quercetin (without being processed). From the molecular investigations, the optimized Q-SD-DMN reduced the viability of the A375 cells (melanoma cells) through the induction of cell apoptosis. It suppressed Bcl-2 gene expression and led to a lower content of Bcl-2 in the cells. Conclusions: The optimized Q-SD-DMN has a potential for use in further in vivo studies as a synergistic method of melanoma treatment.

Role of quercetin in permanganate oxidation of bisphenol A: Kinetics and mechanism

Potassium permanganate (Mn (VII)) oxidation, a green advanced oxidation technology, is widely used as an in-situ remediation method for groundwater contamination. Based on the complexity of organic substances in aquatic environments, many novel organic components, whose processes and mechanisms affecting the oxidative efficacy of Mn (VII), remain unknown and need to be studied systematically. Therefore, using the reducing macromolecular quercetin as the organic matter, the efficiency and mechanism of quercetin-bound, low-valent Mn enhanced Mn (VII) oxidation of bisphenol A (BPA) were studied. The pH and concentration of quercetin strongly influenced its performance. Under pH 4.0–6.0, quercetin evidently promoted the BPA degradation rate in the Mn (VII)/quercetin (Mn (VII)/Q) system. However, the presence of quercetin had little effect on the degradation efficiency of Mn (VII) at pH ≥ 7.0. This study found that at pH 4.0–5.0, quercetin could act as both a reductant and complexing ligand in the process of BPA oxidation. As a complexing ligand, quercetin stabilized the intermediate states of Mn (III) to form complexes. These stable complexes could efficiently oxidize BPA. While low concentrations of quercetin were insufficient to complex and stabilize Mn (III), Mn (III) was reduced to Mn (II). Mn (II) then reacted with Mn (VII) to form MnO2, enhancing the degradation efficiency of the Mn (VII)/Q system for BPA through its catalytic and oxidative properties. This study provides a better understanding of the degradation of organic pollutants by KMnO4 in groundwater treatment.

Hazelnut Protein and Sodium Alginate Complex Coacervates: An Effective Tool for the Encapsulation of the Hydrophobic Polyphenol Quercetin.

For valorization purposes of hazelnut byproducts, complex coacervation of hazelnut protein isolate (HPI) with sodium alginate (NaAlg) was investigated by turbidimetric analysis and zeta potential determination as a function of pH and protein/alginate mixing ratio. HPI-NaAlg complex coacervates were used as an encapsulating material of quercetin (QE) at different concentrations. The optimal pH and mixing ratio resulting in the highest turbidity and neutral charge were 3.5 and 6:1, respectively. The coacervation yield was 74.9% in empty capsules and up to 90.0% in the presence of QE. Under optimal conditions, HPI-NaAlg complex coacervates achieved an encapsulation efficiency higher than 99% in all coacervate/QE formulations. Fourier transform infrared spectroscopy (FTIR) results revealed the occurrence of electrostatic interactions between different functional groups within the ternary complex in addition to hydrogen and hydrophobic interactions between QE and HPI. HPI-NaAlg complex coacervates can serve as an alternative matrix for the microencapsulation of bioactive ingredients with low water solubility in food formulations, which adds an additional valorization of hazelnut byproducts.

Erythrina subumbrans (Hassk) Merr. (Fabaceae) Inhibits Insulin Resistance in the Adipose Tissue of High Fructose-Induced Wistar Rats.

The twigs and roots of Erythrina subumbrans (Hassk). Merr. Was reported to possess antidiabetic activity by reducing the activity of α-glucosidase and α-amylase. TNF-α is a pro-inflammatory cytokine in obesity and diabetes mellitus (DM). It inhibits the action of insulin, causing insulin resistance. Adiponectin is an anti-inflammatory peptide synthesized in white adipose tissue (WAT) and its high levels are linked with a decreased risk of DM. However, information about the effect of Erythrina subumbrans (Hassk). Merr. on insulin resistance are still lacking. To obtain the effects of the ethanol extract of E. subumbrans (Hassk) Merr. leaves (EES) in improving insulin resistance conditions. The leaves were collected at Ciamis, West Java, Indonesia, and were extracted using ethanol 96%. The effects of EES were studied in fructose-induced adult male Wistar rats by performing the insulin tolerance test (ITT) and assessing blood glucose, TNF-α, adiponectin, and FFA levels. The number of WAT and BAT of the adipose tissues was also studied. The total phenols and flavonoids in EES were determined by the spectrophotometric method and the presence of quercetin in EES was analyzed using the LC-MS method. EES significantly reduced % weight gain, TNF-α levels, and increased adiponectin levels in fructose-induced Wistar rats. EES significantly reduced the FFA levels of fructose-induced Wistar rats and significantly affected the formation of BAT similar to that of metformin. All rats in EES and metformin groups improved insulin resistance as proven by higher ITT values (3.01 ± 0.91 for EES 100 mg/kg BW; 3.01 ± 1.22 for EES 200 mg/kg BW; 5.86 ± 3.13 for EES 400 mg/kg BW; and 6.44 ± 2.58 for metformin) compared with the fructose-induced group without treatment (ITT = 2.62 ± 1.38). EES contains polyphenol compounds (2.7638 ± 0.0430 mg GAE/g extract), flavonoids (1.9626 ± 0.0152 mg QE/g extract), and quercetin 0.246 µg/mL at m/z 301.4744. Erythrina subumbrans (Hassk). Merr. extract may have the potential to be further explored for its activity in improving insulin resistance conditions. However, further studies are needed to confirm its role in alleviating metabolic disorders.

Novel polydopamine-based composites with adjustable antioxidant activity

It is obtained here that dopamine and quercetin, not easily miscible compounds, can form stable quercetin – polydopamine (Q:PDA) composite systems under special conditions: oxidative polymerization of dopamine in the presence of quercetin in mixed water/ethanol solution at both, acidic and alkaline pH, by using NaIO4 as oxidant. The structure of the Q:PDA composites in bulk and as coating layers on SiO2 nanoparticles has been characterized by solid-state NMR spectroscopy, which directly confirms the incorporation of quercetin in the PDA matrix. Indirectly, it was also proved by HPTLC by monitoring quercetin released during Q:PDA disassembling in strongly acidic 0.1 M HCl solution. The morphology of Q:PDA coating layers has been characterized by AFM on glass substrates. It was found that, compared to PDA alone, layer thickness is increased in the presence of quercetin, reaching the highest value of about 190 nm for 1:1 quercetin/dopamine relative concentration, at pH 5.5 and 24 h deposition time. Sine quercetin is one of the most widely consumed natural antioxidant, and PDA has been reported with interesting antioxidant activity, the free radical scavenging properties of the Q:PDA composites was investigated. The free radicals bleaching activity was found dependent on the specific Q:PDA synthesis/deposition conditions, which might be of interest in biomedical applications that require adjustable antioxidant activity.

Studies on α-amylase inhibition by acarbose and quercetin using fluorescence, circular dichroism, docking, and dynamics simulations

This study looked at the effects of acarbose (ACA) and quercetin (QUE) on α-amylase activity, employing QUE and ACA to measure enzyme activity. The study observed that both drugs suppressed α-amylase activity, with greater inhibition reported at higher concentrations. The use of tryptophan residues as an intrinsic fluorescence probe permitted the observation of conformational changes in α-amylase, with CD measurements utilized to explore the secondary structure in the presence of QUE and ACA. Docking studies revealed an effective interaction between α-amylase, quercetin and acarbose, with a higher binding energy. Finally, a trajectory analysis was done to establish the stability and volatility of these complexes. These findings have potential significance for the development of new α-amylase-related therapeutics.

Novel in vitro evidence on the beneficial effect of quercetin treatment in vascular calcification.

Vascular calcification is a pathological chronic condition characterized by calcium crystal deposition in the vessel wall and is a recurring event in atherosclerosis, chronic kidney disease, and diabetes. The lack of effective therapeutic treatments opened the research to natural products, which have shown promising potential in inhibiting the pathological process in different experimental models. This study investigated the anti-calcifying effects of Quercetin and Berberine extracts on vascular smooth muscle cells (VSMCs) treated with an inorganic phosphate solution for 7days. Quercetin has shown the highest anti-calcifying activity, as revealed by the intracellular quantitative assay and morphological analysis. Confocal microscopy revealed downregulation of RUNX2, a key marker for calcified phenotype, which was otherwise upregulated in calcified VSMCs. To investigate the anti-inflammatory activity of Quercetin, culture media were subjected to immunometric assays to quantify the levels of IL-6 and TNF-α, and the caspase-1 activity. As expected, calcified VSMCs released a large quantity of inflammatory mediators, significantly decreasing in the presence of Quercetin. In summary, our findings suggest that Quercetin counteracted calcification by attenuating the VSMC pathological phenotypic switch and reducing the inflammatory response. In our opinion, these preliminary in vitro findings could be the starting point for further investigations into the beneficial effects of Quercetin dietary supplementation against vascular calcification.

Quercetin inhibits SARS-CoV-2 infection and prevents syncytium formation by cells co-expressing the viral spike protein and human ACE2

BackgroundSeveral in silico studies have determined that quercetin, a plant flavonol, could bind with strong affinity and low free energy to SARS-CoV-2 proteins involved in viral entry and replication, suggesting it could block infection of human cells by the virus. In the present study, we examined the ex vivo ability of quercetin to inhibit of SARS-CoV-2 replication and explored the mechanisms of this inhibition.MethodsGreen monkey kidney Vero E6 cells and in human colon carcinoma Caco-2 cells were infected with SARS-CoV-2 and incubated in presence of quercetin; the amount of replicated viral RNA was measured in spent media by RT-qPCR. Since the formation of syncytia is a mechanism of SARS-CoV-2 propagation, a syncytialization model was set up using human embryonic kidney HEK293 co-expressing SARS-CoV-2 Spike (S) protein and human angiotensin converting enzyme 2 (ACE2), [HEK293(S + ACE2) cells], to assess the effect of quercetin on this cytopathic event by microscopic imaging and protein immunoblotting.ResultsQuercetin inhibited SARS-CoV-2 replication in Vero E6 cells and Caco-2 cells in a concentration-dependent manner with a half inhibitory concentration (IC50) of 166.6 and 145.2 µM, respectively. It also inhibited syncytialization of HEK293(S + ACE2) cells with an IC50 of 156.7 µM. Spike and ACE2 co-expression was associated with decreased expression, increased proteolytic processing of the S protein, and diminished production of the fusogenic S2’ fragment of S. Furin, a proposed protease for this processing, was inhibited by quercetin in vitro with an IC50 of 116 µM.ConclusionThese findings suggest that at low 3-digit micromolar concentrations of quercetin could impair SARS-CoV-2 infection of human cells partly by blocking the fusion process that promotes its propagation.

Antimicrobial evaluation of silver nanoparticles using extracts of Crescentia cujete L.

New natural reducing agents with a lower negative impact on the environment and with a high antimicrobial potential are required for the process of obtaining silver nanoparticles through the chemical reduction method. The use of plant extracts can be a fast track in the formation of nanoparticles. In this case, organic compounds such as terpenes, flavonoids, enzymes, proteins, and cofactors present in plants act as reducing agents for nanomaterials. This research evaluated the antimicrobial property of silver nanoparticles from extracts of Crescentia cujete L. The presence of quercetin (flavonoid) was determined by high-performance liquid chromatography (HPLC); the production of silver nanoparticles (AgNPs) was established by green synthesis; the size and morphology of the nanomaterials were evaluated by scanning electron microscope (SEM). The antimicrobial capacity was studied by two analysis methods: modified culture medium and surface seeding. The presence of quercetin (26.55 mg L-1) in the crude extract of Crescentia cujete L., identified by HPLC, was evidenced. Nanoparticle formation was spherical, with an average size of 250 ± 3 and 460 ± 6 nm. Microbiological cultures with treatment showed 94% microbial inhibition. It was concluded that the Crescentia cujete L., leaves shoed an acceptable concentration of quercetin to be used as a useful adjuvant to enhance the reduction of NPs synthesis. The nanoparticles produced by green synthesis proved to have a positive effect to combat pathogenic microorganisms.

Hemijski sastav infuzije divlje jabuke (Malus sylvestris (L.) Mill.)

Wild apples leaves are under-utilized biomaterial, containing various bioactive compounds. The aim of this work was to determine the components and mineral composition of the wild apple leaf infusion. The leaves originated from Svrljig, Nišava District, Southern Serbia. The screening of bioactive components in the infusion was performed by the UHPLC-DAD-MS/MS method, while its mineral content was analyzed by the ICP-OES method. The results indicated the presence of quercetin, isoquercetin, hyperoside, rutin, citric and quinic acids, protocatechuic acid, 3-O-p-coumaroylquinic acid, chlorogenic acid, procyanidin B2, phloretin and phloretin-pentosyl-hexoside, while the most abundant elements were Ca, K, Mg and Na. Therefore, wild apple leaves may be utilized for isolation of polyphenolic antioxidants and minerals and production of extracts with antioxidant activity.

Quercetina inibe a liberação das armadilhas extracelulares dos neutrófilos e a atividade tóxica delas sobre células A549

Abstract Neutrophil extracellular traps (NETs) were first reported as a microbicidal strategy for activated neutrophils. Through an immunologic response against several stimuli, neutrophils release their DNA together with proteins from granules, nucleus, and cytoplasm (e.g., elastase and myeloperoxidase). To date, NETs have been implicated in tissue damage during intense inflammatory processes, mainly when their release is dependent on oxygen radical generation. Flavonoids are antioxidant and anti-inflammatory agents; of these, quercetin is commonly found in our daily diet. Therefore, quercetin could exert some protective activity against tissue damage induced by NETs. In our in vitro assays, quercetin reduced NETs, myeloperoxidase (MPO), and elastase release from neutrophils stimulated with phorbol 12-myristate 13-acetate (PMA). The activity of these enzymes also decreased in the presence of quercetin. Quercetin also reduced the cytotoxic effect of NETs on alveolar cells (A549 cell line). Further, in silico assays indicated favorable interactions between quercetin and NET proteins (MPO and elastase). Overall, our results demonstrate that quercetin decreases deleterious cellular effects of NETs by reducing their release from activated neutrophils, and diminishing the enzymatic activity of MPO and elastase, possibly through direct interaction.

The Mechanism of Anxiolytic Effects of Moringa oleifera Leaf Extracts Associated with Significant Differential Expression of Crhb, Faah2a, Mao, and Pah Genes in Danio rerio

The search and development of new therapeutic agents from medicinal plants to alleviate anxiety is well justified due to the increasing cases of anxiety disorder and lack of effective treatment. Moringa oleifera has been used traditionally to treat anxiety. However, there is still lack of understanding on the mechanism for its anxiolytic effect. The purpose of this study was to investigate the anxiolytic effects and the mechanism of ethanolic extracts of the leaves of M. oleifera (MOLE) by observing behavioural changes of the Danio rerio and the differential gene expression analysis using custom RT2 Profiler PCR array. A 14-day chronic behaviour study was conducted using three concentrations of MOLE (500 mg/L, 1000 mg/L and 2000 mg/L) fluoxetine as the positive control. Stress-induced D. rerio treated with 1000 mg/L MOLE showed the lowest level of anxiety compared to other groups as evidenced by a decrease in freezing episodes and freezing time, increased entries into the light region. The fish also showed significant changes in the expression of crhb, faah2a, mao, and pah genes. MOLE with the presence of quercetin and kaempferol are believed to exert its anxiolytic effects through differential expression of gene (i) modulating the function of GABAA receptor (crhb), (ii) inhibiting the expression of nitric oxide synthase (NOS) and the production of nitric oxide, (iii) increasing the AEA levels in the brain (faah2a), (iv) increasing the level of dopamine levels in the brain (mao). These findings provide valuable insights into the potential use of MOLE as a treatment for anxiety-related disorders as well as the significance of the molecular pathways involved in its anxiolytic properties.

Decontamination efficiency of poly(hydroxybutyrate‐co‐valerate)‐based food packaging material: The role of the chemical structure of contaminants and additive

AbstractRecycled plastic materials can only be placed in the market if they are free from contaminants at harmful levels. This work studies the thermal decontamination of poly(hydroxybutyrate‐co‐valerate) (PHBV) intended for food contact. PHBV was first contaminated with gallic acid, catechin, ferulic acid, and PEG 200, at 500 mg/kg. Thermal decontamination was then applied at 160°C for 6 and 48 h. Due to the low volatility of these molecules and their hydrogen bonding interactions with the polymer, decontamination efficiency was well below safety limits. Indeed, only 25.9% of gallic acid, 68.5% of catechin, 67% of ferulic acid, and 86.8% of PEG 200 were removed. In addition, a strong degradation of the polymer was observed (Mw decrease of 57%). To try to prevent polymer degradation, while enhancing decontamination conditions, quercetin (a natural polyphenol) was used as a stabilizer at 0.5 wt%. After 6 h of decontamination, hydrogen bonds, and π‐stacking interactions were formed between quercetin and the contaminants, reducing their removal (−8.5% for gallic acid, −57.4% for catechin, −18.7% for ferulic acid, and −31.9% for PEG200). After 48 h, strong PHBV degradation was observed (−83% Mw and −45% Xc), particularly in the presence of quercetin.

Quercetin protects against Aspergillus fumigatus keratitis by reducing fungal load and inhibiting TLR-4 induced inflammatory response

PurposeTo investigate the antifungal and anti-inflammatory effects of quercetin in Aspergillus fumigatus (A. fumigatus) keratitis. MethodsDraize eye test was performed in mice to evaluate the toxicity of quercetin, and the antifungal effects on A. fumigatus were assessed via scanning electron microscopy (SEM), propidium iodide uptake, and adherence assay. In fungal keratitis (FK) mouse models, immunostaining was performed for investigating toll-like receptor 4 (TLR-4) expression and macrophage infiltration. Real-time PCR, ELISA, and Western blot were used to evaluate the expression of pro-inflammatory factors IL-1β, TNF-α, and IL-6 in infected RAW264.7 cells. Cells were also treated with TLR-4 siRNA or agonist CRX-527 to investigate mechanisms underlying the anti-inflammatory activity of quercetin. ResultsQuercetin at 32 μM was non-toxic to corneal epithelial and significantly inhibited A. fumigatus growth and adhesion, and also altered the structure and reduced the number of mycelia. Quercetin significantly reduced macrophage infiltration in the mouse cornea, and attenuated the expression of TLR-4 in the corneal epithelium and stroma of mice with keratitis caused by A. fumigatus. In RAW264.7 cells infected by A. fumigatus, quercetin downregulated TLR-4 along with pro-inflammatory factors IL-1β, TNF-α, and IL-6. RAW cells with TLR-4 knockdown had reduced expression of factors after A. fumigatus infection, which was decreased even further with quercetin treatment. In contrast, cells with CRX-527 had elevated inflammatory factors compared to control, which was significantly attenuated in the presence of quercetin. ConclusionQuercetin plays a protective role in mouse A. fumigatus keratitis by inhibiting fungal load, disrupting hyphae structure, macrophage infiltration, and suppressing inflammation response in macrophages via TLR-4 mediated signaling pathway.

Quercetin induces dual specificity phosphatase 5 via serum response factor

The phytochemical quercetin has gained attention for its anti-inflammatory and anti-tumorigenic properties in various types of cancer. Tumorigenesis involves aberrant regulation of kinase/phosphatase, highlighting the importance of maintaining homeostasis. Dual Specificity Phosphatase (DUSPs) plays a crucial role in controlling the phosphorylation of ERK. The current study aimed to clone the DUSP5 promoter and investigate its transcriptional activity in the presence of quercetin. The results revealed that quercetin-induced DUSP5 expression is associated with the serum response factor (SRF) binding site located in the DUSP5 promoter. The deletion of this site abolished luciferase activity induced by quercetin, indicating its vital role in quercetin-induced DUSP5 expression. SRF protein is a transcription factor that potentially contributes to quercetin-induced DUSP5 expression at the transcriptional level. Additionally, quercetin enhanced SRF binding activity without changing its expression. These findings provide evidence of how quercetin affects anti-cancer activity in colorectal tumorigenesis by inducing SRF transcription factor activity, thereby increasing DUSP5 expression at the transcriptional level. This study highlights the importance of investigating the molecular mechanisms underlying the anti-cancer properties of quercetin and suggests its potential use in cancer therapy.

Obtaining of Silver Nanoparticles in the Presence of Quercetin and Rutin Flavonoids

Obtaining of Silver Nanoparticles in the Presence of Quercetin and Rutin Flavonoids

Regional distributions of curcumin and tetrahydrocurcumin in the liver and small intestine of rats when orally co-administered with quercetin and paeoniflorin.

Curcumin (CUR), derived from the dietary spice turmeric, is a polyphenolic compound with various biological and pharmacological activities. Tetrahydrocurcumin (THC) is one of the major reductive metabolites of curcumin. A pharmacokinetic study using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for the simultaneous determination of curcumin, THC, quercetin (QR), and paeoniflorin (PF) in rat plasma had been performed. In this study, the regional distributions of curcumin and tetrahydrocurcumin in the liver and the three segments of small intestine (duodenum, jejunum, and ileum) of rats when orally co-administered with quercetin and paeoniflorin were carried out. Drug concentrations were determined using UHPLC-MS/MS. The results showed that curcumin was well distributed in the small intestine, while the distributions of tetrahydrocurcumin in the liver, duodenum, jejunum were similar, but much more abundant in the ileum. When orally co-administered with quercetin and paeoniflorin, the tissue to plasma concentration ratios (Kp values) of curcumin in the three segments of the small intestine were increased, indicating that the presence of quercetin and paeoniflorin increases the distribution of curcumin in these regions. Moreover, the half-life (t1/2 ) of THC in the liver was significantly prolonged, and the Kp value of THC in the liver was increased and the Kp values in the small intestine were decreased, suggesting that the combination of quercetin and paeoniflorin might suppress the metabolism of curcumin in the small intestine. In brief, the combination had an effect on the distributions of curcumin and tetrahydrocurcumin in the liver and small intestine of rats.

LC-HRMS for the Identification of Quercetin and Its Derivatives in Spiraea hypericifolia (Rosaceae) and Anatomical Features of Its Leaves.

Spiraea hypericifolia L. is affiliated with the section Chamaedryon Ser. of the genus Spiraea L. (Rosaceae). Similar to many other Spiraea species, S. hypericifolia most often accumulates flavonols among other flavonoids, in particular quercetin and its derivatives. An ethanol-water extract from the aerial part of S. hypericifolia collected in the vicinity of the Ilyichovo settlement (Krasnoyarsk Krai, Russia) was analyzed by liquid chromatography with high-resolution mass spectrometry. Primary and secondary metabolites were found in the extract; structural interpretation consistent with quercetin and its derivatives was proposed for 10 of them. Major compounds were various glycosides of quercetin containing glucose (four compounds), galactose (one compound), xylose (two compounds), arabinose (one compound), or rutinose (one compound) as a carbohydrate residue. Isorhamnetin and 3-O-methylquercetin-3'-O-β-D-glucopyranoside were identified among methyl-containing compounds. The latter compound and reynoutrin, rhamnetin-3-O-β-D-xylopyranosyl-β-D-glucopyranoside, and quercetin-3-O-(6″-O-malonyl)-β-D-glucoside have not been previously found in S. hypericifolia. Data on the presence of quercetin and its derivatives in the extract of S. hypericifolia expand the understanding of the possible practical use of this plant. In addition, the microscopic features of S. hypericifolia leaves were studied. The diagnostic features of the leaf blade necessary for the authentication of raw materials were revealed: straight-walled epidermis cells, stomata located on both sides of the leaf blade (amphistomatic type), two types of trichomes, and wrinkled cuticula with nodi. The main anatomical diagnostic features of the leaves of S. hypericifolia were determined, which makes it possible to assess the authenticity of the raw material.

The Mechanisms of Lipid Vesicle Fusion Inhibition by Extracts of Chaga and Buckthorn Leaves.

The ability of extracts of grapefruit seeds (ESG), sea buckthorn leaves (ESBL), and chaga (EC) to inhibit membrane fusion was evaluated. It was found that ESBL and EC inhibited Ca2+-mediated fusion of phosphatidylglycerol-enriched lipid vesicles; the inhibition indexes were about 90 and 100%, respectively. ESG did not inhibit the fusion of negatively charged liposomes induced by calcium. In addition to calcium-mediated liposome fusion, EC inhibited the fusion of vesicles from a mixture of phosphatidylcholine and cholesterol under the action of polyethylene glycol with a molecular weight of 8000 Da (the inhibition index was 80%). The other two extracts had no effect on polymer-induced fusion of uncharged membranes. The effect of some major components of the tested extracts on the fusion of vesicles was evaluated. It has been shown that flavonols, quercetin and myricetin, which are major components of ESBL, inhibited the fusion of negatively charged membranes under the action of calcium (the inhibition indexes were about 85 and 60%, respectively). Another flavonol of ESBL, the glycoside of quercetin rutin, did not have such an effect. The data obtained made it possible to relate the ESBL suppression of calcium-induced fusion of lipid vesicles with the presence of quercetin and myricetin in its composition. These flavonols had virtually no effect on polyethylene glycol-induced vesicle fusion, which is consistent with the absence of ESBL action on liposome fusion under the action of polymer. The ability of quercetin and myricetin to reduce the melting temperature of phosphatidylglycerol with saturated hydrocarbon chains and to increase the half-width of the peak corresponding to melting has been demonstrated. The observed correlation between the parameters characterizing the thermotropic behavior of the lipid in the presence of quercetin and myricetin and the index of inhibition of calcium-mediated liposome fusion by these compounds may indicate a relationship between the ability of flavonols to influence the packaging of membrane lipids and inhibit vesicle fusion. Pentacyclic triterpenoids, betulin and lupeol, which are part of EC, did not inhibit the fusion of vesicles under the action of both calcium and polyethylene glycol, and their presence in EC cannot be responsible for the antifusogenic activity of EC.

Antioxidant activity of Moringa oleifera Lam

The leaves of Moringa oleifera Lam were extracted in Methanol, Petroleum ether, and ethyl acetate, and chemical detection of biotic compounds in extracts was carried out. The TLC indicates the presence of quercetin, rutin, and luteolin, and the total flavonoid and antioxidant activity of the extract show high antioxidant activity.