Polyphenols as Inhibitors of Antibiotic Resistant Bacteria-Mechanisms Underlying Rutin Interference with Bacterial Virulence

The rising incidence of antibiotic resistant microorganisms urges novel antimicrobials development with polyphenols as appealing potential therapeutics. We aimed to reveal the most promising polyphenols among hesperetin, hesperidin, naringenin, naringin, taxifolin, rutin, isoquercitrin, morin, chlorogenic acid, ferulic acid, p-coumaric acid, and gallic acid based on antimicrobial capacity, antibiofilm potential, and lack of cytotoxicity towards HaCaT, and to further test its antivirulence mechanisms. Although the majority of studied polyphenols were able to inhibit bacterial growth and biofilm formation, the most promising activities were observed for rutin. Further investigation proved rutin's ability to prevent/eradicate Pseudomonas aeruginosa and MRSA urinary catheter biofilms. Besides reduction of biofilm biomass, rutin antibiofilm mechanisms included reduction of cell viability, exopolysaccharide, and extracellular DNA levels. Moderate reduction of bacterial adhesion to human keratinocytes upon treatment was observed. Rutin antivirulence mechanisms included an impact on P. aeruginosa protease, pyocyanin, rhamnolipid, and elastase production and the downregulation of the lasI, lasR, rhlI, rhlR, pqsA and mvfR genes. Rutin also interfered with membrane permeability. Polyphenols could repress antibiotic resistant bacteria. Rutin has shown wide antimicrobial and antibiofilm capacity employing a range of mechanisms that might be used for the development of novel antimicrobials

Revealing the astragalin mode of anticandidal action

Due to limited arsenal of systemically available antifungal agents, infections caused by Candida albicans are difficult to treat and the emergence of drug-resistant strains present a major challenge to the clinicians worldwide. Hence further exploration of potential novel and effective antifungal drugs is required. In this study we have explored the potential of a flavonoid, astragalin, in controlling the growth of C. albicans, in both planktonic and biofilm forms by microdilution method; and in regulating the morphological switch between yeast and hyphal growth. Astragalin ability to interfere with membrane integrity, ergosterol synthesis and its role in the regulation of genes encoding for efflux pumps has been addressed. In our study, astragalin treatment produced good antimicrobial and significant antibiofilm activity. Anticandidal activity of astragalin was not related to ERG11 downregulation, neither to direct binding to CYP51 enzyme nor was linked to membrane ergosterol assembly. Instead, astragalin treatment resulted in reduced expression of CDR1 and also affected cell membrane integrity without causing cytotoxic effect on human gingival fibroblast cells. Considering that astragalin-mediated decreased expression of efflux pumps increases the concentration of antifungal drug inside the fungal cells, a combinatorial treatment with this agent could be explored as a novel therapeutic option for candidiasis

Antibacterial and antibiofilm activity of selected polyphenolic compounds: An in vitro study on Staphylococcus aureus

Staphylococcus aureus is a human pathogen that causes serious infections with high mortality rates. The antimicrobial activities of eight phenolic compounds (caffeic acid, chlorogenic acid, ferulic acid, morin, quercetin, isoquercitrin, rutin and hesperidin) were evaluated against planktonic and biofilm forming Staphylococcus aureus cells. Their ability to prevent biofilm formation via interference with bacterial cell adhesion and to reduce biomass of 24 h old biofilms has been addressed in this study. The antibacterial activities (MIC/MBC) were demonstrated using the microdilution method and the investigated compounds showed good activity against S. aureus isolates, with MICs in the range 0.05-0.4 mg/mL. Also, they exhibited promising antibiofilm potential in dose depended manner. Among all tested compounds, morin and quercetrin showed the best antibiofilm activity at MIC values. The observed antimicrobial potential of the studied natural products can serve as a starting point towards development of novel plant-based therapeutics for the treatment of common infections such as the ones caused by S. aureus

Phlomis fruticosa l. exerts in vitro antineurodegenerative and antioxidant activities and induces prooxidant effect in glioblastoma cell line

Despite the significant advances in drug development we are witnessing the inability of health systems to combat both neurodegenerative diseases and cancers, especially glioblastoma. Hence, natural products are comprehen-sively studied in order to provide novel therapeutic options. This study aimed to explore anti-neurodegenerative and anti-glioblastoma potential of extract of Phlomis fruticosa L. using in vitro model systems. It was found that the methanol extract of P. fruticosa was able to efficiently reduce activities of enzymes linked to neurodegenera-tive disease including acetylcholinesterase, butyrylcholinesterase and tyrosinase. Furthermore, P. fruticosa ex-tract has shown excellent antioxidant potential, as evidenced by six different methods. Analysis of cytotoxic ef-fect of P. fruticosa extract on A172 glioblastoma cell line revealed that the concentration of the extract necessary for 50 % inhibition of A172 growth (IC50) was 710 μg/mL. The extract did not induce changes in proliferation and morphology of A172 glioblastoma cells. On the other side, production of ROS was increased in A172 cells treated with the extract. Observed cytotoxic effect of P. fruticosa extract might be based on increase in ROS generation upon treatment. Quantitative chemical analysis revealed the presence of twelve different polyphenols with the cis 3-O-caffeoylquinic acid being the most abundant. This study provided scientific evidence for further exploration of P. fruticosa as a promising natural anti-neurodegenerative therapeutic option.This work has been supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (451-03-9/2021-14/200007 and 451-03-68/2022-14/200042). The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Program PT2020 for financial support to CIMO (UIDB/00690/2020); national funding by FCT, P.I., through the institutional scien-tific employment program-contract for M.I. Dias and L. Barros; to FEDER-Interreg España-Portugal program for financial support through the project 0377_Iberphenol_6_E and TRANSCoLAB 0612_TRANS_CO_LAB_2_P.info:eu-repo/semantics/publishedVersio

Citoarhitektura humanog paraventrikularnog jedra

Introduction. The significance of this research in terms of structure and biochemical processes in PVN contributes to further understanding of vital physiological processes from delivery and stress to delicate chemical processes that keep the hypothalamo-hypophysial axis in balance. Conclusion. Comparative studies of the human hypothalamus with the hypothalamus of other mammals enable further research, especially pharmacological and physiological ones. These are made possible with the aid of highly sophisticated equipment for examination of neurophysiological features of the brain.Ovim člankom smo želeli da ukažemo na važnost paraventrikularnog jedra pokazujući novije podele ćelijskih podgrupa, kao i podele prema hemijskom sastavu proteina koji se nalaze u njemu. Fiziološka uloga hipotalamo-hipofiznog kompleksa je svakako uslovljena njegovim vezama sa drugim delovima mozga, kao i hemijskim supstancijama od kojih zavisi prenos signala. Uvođenjem savršenijih tehnika u razvojno-neurobiološka istraživanja, možemo da pratimo i poredimo mnoge delove mozga, pa i paraventrikularno jedro s istim jedrima drugih sisara, a time omogućimo lakši rad na eksperimentalnim modelima fiziološko-farmakoloških i drugih istraživanja

The effects of biostimulants, biofertilizers and water-stress on nutritional value and chemical composition of two spinach genotypes (Spinacia oleracea L.)

In the present study, the e ect of biostimulants application on the nutritional quality and bioactive properties of spinach cultivated in protected environment under water stress conditions was evaluated. For this purpose, four commercially available biostimulant products (Megafol (MEG), Aminovert (AM), Veramin Ca (V), Twin Antistress (TA), and two spinach genotypes (Fuji F1 and Viroflay) were tested under two irrigation regimes (normal irrigation (W+), and water-holding (W–). Fat and carbohydrates content was favored by water stress when Megafol (MEGW+) and Veramin (VW+) were applied on Fuji plants, while calorific value was also increased by MEGW+ treatment. In contrast, protein and ash content increased when AMW– and TAW+ were applied on Viroflay plants. Ra nose and glucose were the most abundant sugars, followed by sucrose and fructose, with the highest contents recorded for Fuji plants when AMW+ (fructose, glucose and total carbohydrates), CW– (sucrose), and TAW– (ra nose) treatments were applied. Regarding organic acids, oxalic and malic acid which had the highest contents for the TAW– (Viroflay plants) and AMW– (Fuji plants) treatments, respectively. - and -tocopherol were the only isoforms detected with MEGW– and VW– inducing the biosynthesis of -tocopherol, while AMW+ increased -tocopherol content in Fuji plants. The main fatty acids were -linolenic and linoleic acids which were detected in the highest amounts in AMW–, AMW+, and TAW+ the former and in AMW–, VW–, and CW+ the latter. Regarding phenolic compounds content, peak 12 (5,30,40-Trihydroxy-3-methoxy-6:7-methylenedioxyflavone-40-glucuronide) was the most abundant compound, especially in Viroflay plants under normal irrigation and no biostimulants added (CW–). The antioxidant and cytotoxic activity of the tested samples did not show promising results when compared with the positive controls, while a variable antibacterial activity was recorded depending on the tested biostimulant, irrigation regime and genotype. In conclusion, a variable e ect of the tested biostimulants and irrigation regimes was observed on bioactive properties and chemical composition of both spinach genotypes which highlights the need for further research in order to make profound conclusions regarding the positive effects of biostimulants under water stress conditions.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2019); national funding by FCT, P.I., through the institutional scientific employment program-contract for M.I.D., R.C.C. and L.B.; C.P. contract though the celebration of program-contract foreseen in No. 4, 5 and 6 of article 23º of Decree-Law No. 57/2016, of 29th August, amended by Law No. 57/2017, of 19th July; to FEDER-Interreg España-Portugal programme for financial support through the project 0377_Iberphenol_6_E and TRANSCoLAB 0612_TRANS_CO_LAB_2_P.info:eu-repo/semantics/publishedVersio

Crystalline WO3 nanoparticles for No2 sensing

This study shows excellent NO2-sensing properties of tungsten oxide nanoparticles, prepared using a facile procedure which includes dissolution of metallic tungsten in hydrogen peroxide with subsequent low-temperature (400 °C) heating. We also conducted a thorough literature survey on sensor properties of tungsten oxide prepared by various means and found that the sensor response towards NO2 registered in this work achieved the highest level. The most intriguing feature of the material obtained was a highly reproducible sensor signal at room temperature which was more than 100 times higher than any reported previously for WO3. The probable reason for such high sensor response was the presence of two WO3 polymorphs (-WO3 and h-WO3) in the material synthesized using a peroxide-assisted route. In order to further investigate synthesizedWO3 materials, sophisticated experimental (XRD, SEM, TEM, BET) and theoretical (B3LYP, HSE) methods have been used, as well as resistance and sensor response measurements at various temperatures

Chicory Extracts and Sesquiterpene Lactones Show Potent Activity against Bacterial and Fungal Pathogens

Chicory (Cichorium intybus L.) is an important industrial crop cultivated mainly to extract the dietary fiber inulin. However, chicory also contains bioactive compounds such as sesquiterpene lactones and certain polyphenols, which are currently discarded as waste. Plants are an important source of active pharmaceutical ingredients, including novel antimicrobials that are urgently needed due to the global spread of drug-resistant bacteria and fungi. Here, we tested different extracts of chicory for a range of bioactivities, including antimicrobial, antifungal and cytotoxicity assays. Antibacterial and antifungal activities were generally more potent in ethyl acetate extracts compared to water extracts, whereas supercritical fluid extracts showed the broadest range of bioactivities in our assays. Remarkably, the chicory supercritical fluid extract and a purified fraction thereof inhibited both methicillin-resistant Staphylococcus aureus (MRSA) and ampicillin-resistant Pseudomonas aeruginosa IBRS P001. Chicory extracts also showed higher antibiofilm activity against the yeast Candida albicans than standard sesquiterpene lactone compounds. The cytotoxicity of the extracts was generally low. Our results may thus lead to the development of novel antibacterial and antifungal preparations that are both effective and safe for human use

Water soluble biomolecules from Nepeta nuda regulate microbial growth: A case study of apple juice preservation

The following study was designed to explore antimicrobial properties of the by-product obtained in a hydro-distillation process of essential oil from Nepeta nuda L. Based on the obtained decoction of N. nuda and apple juice, we strived to develop a novel drink that would have antimicrobial self-preserving properties. By using 96-well plate microdilution assay it was shown that the N. nuda decoction has antimicrobial potential towards 8 bacterial and 6 fungal species, with the range of minimal inhibitory concentrations 10 mg/mL - 300 mg/mL. By using actual food system, such as apple juice, in combination with and without short thermal treatment, we have shown that the decoction of N. nuda can inhibit the growth of food contaminant fungus Penicillium aurantiogriseum. It was determined that 3 volumes of decoction (500 mg/mL) and 22 volumes of apple juice should be mixed in order to obtain self-preserving drink resistant to P. aurantiogriseum contamination. Likewise, when thermal treatment (80 °C for 10s) is included, self-preserving mixture of decoction and apple juice should be made in volume ratios 3:47, respectively. The designed product maintained the pleasant taste as determined by panelists during the sensorial evaluation. Chemical investigations (UHPLC–Orbitrap MS analysis) of N. nuda decoction showed that the most abundant compound was 1,5,9-epideoxyloganic acid (0.410 mg/g of dried decoction). Since N. nuda is traditionally used as a tea, we presented the novel formulation of the antimicrobial self-preserving drink based on the N. nuda decoction and apple juice