The kinetics of quorum sensing in Saccharomyces cerevisiae were studied using a mini-fermentation platform. The quorum-sensing molecules were monitored using our previous HPLC approach that is here supported by quantitative real-time PCR analysis of the quorum-sensing genes. We thus initially confirm correlations between peak production rates of the monitored quorum-sensing molecules 2-phenylethanol, tryptophol, and tyrosol and peak expression of the genes responsible for their synthesis: ARO8, ARO9, and ARO10. This confirms the accuracy of our previously implemented kinetic model, thus favoring its use in further studies in this field. We also show that the quorum-sensing kinetics are precisely dependent on the population growth phase and that tyrosol production is also regulated by cell concentration, which has not been reported previously. Additionally, we show that during wine fermentation, ethanol stress reduces the production of 2-phenylethanol, tryptophol, and tyrosol, which opens new challenges in the control of wine fermentation.

Digital image analysis of high time resolution video microscopy was used to investigate hyphal growth dynamics in different Candida albicans strains. The effects of the quorum sensing molecules tyrosol and farnesol, the deletion of the fungus specific protein phosphatase Z1 CaPPZ1), and the hypha-specific cyclin (HGC1) genes were analyzed by this method. Our system monitored cell growth in a CO2 incubator under near-physiological conditions and measured three major parameters under the following stringent conditions: (a) the time of yeast cell adherence, (b) the time of hyphal outgrowth, and (c) the rate of hyphal growth. This method showed that hyphal extension of wild-type SC5314 cells was accelerated by tyrosol and inhibited by farnesol. Hyphal growth rate was moderately lower in cappz1 and strongly reduced in hgc1 mutants. In addition, tyrosol treatment caused a firm adherence, while farnesol treatment and hgc1 mutation prevented the adherence of yeast cells to the surface of the culture flask. Transition from yeast-to-hyphal state was faster after tyrosol treatment, while it was reduced in farnesol-treated cells as well as in the cappz1 and hgc1 mutants. Our data confirm the notion that the attachment of yeast cells, the yeast-to-hyphal transition, and hyphal growth rate are closely related processes. Time-lapse video microscopy combined with image analysis offers a convenient and reliable method of testing chemicals, including potential drug candidates, and genetic manipulations on the dynamic morphological changes in C. albicans strains.

Roseroot (Rhodiola rosea L.) belongs to plants revealing adaptogenic properties, which are attributed to the presence of specific phenolic compounds and are reflected mainly as antioxidant activity. The aim of the present study was to determine the antioxidant and antibacterial activity of various products obtained from R. rosea (underground organs as well as their aqueous and ethanolic dry extracts) in relation to the chemical profiles of phenolic and essential oil compounds. The chemical profiles were determined by High-performance Liquid Chromatography with a diode-array detector (HPLC-DAD) and Gas chromatography-mass spectrometry (GC-MS), antioxidant activity by (1,1-Diphenyl-2-picrylhydrazyl) Scavenging Capacity Assay (DPPH), (2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) Scavenging Capacity Assay (ABTS) and Ferric Reducing Antioxidant Power Assay (FRAP) and antimicrobial properties were expressed as minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) values following the broth microdilutions method. The results show that the investigated samples differed in terms of their chemical compositions and biological activities. The extracts were more abundant in phenolic compounds (salidroside, tyrosol, and rosavin derivatives) in comparison to dried underground organs. The content of the determined phenolics in the analyzed extracts was affected by the solvent used for extraction. The ethanolic extract was characterized by the highest content of these substances in comparison to the aqueous one and the dried raw material, especially with regard to rosavin (969.71 mg/100 g). In parallel, this extract showed the strongest antioxidant and antibacterial activity. However, dried R. rosea underground organs also revealed strong antibacterial effects against, for example, Staphylococcus strains.

The extraction of Rhodiola rosea rhizomes using natural deep eutectic solvent (NADES) consisting of lactic acid, glucose, fructose, and water was investigated. A two-level Plackett-Burman design with five variables, followed by the steepest ascent method, was undertaken to determine the optimal extraction conditions. Among the five parameters tested, particle size, extraction modulus, and water content were found to have the highest impact on the extrability of phenyletanes and phenylpropanoids. The concentration of active compounds was analyzed by HPLC. The predicted results showed that the extraction yield of the total phenyletanes and phenylpropanoids (25.62 mg/g) could be obtained under the following conditions: extraction time of 154 min, extraction temperature of 22 °C, extraction modulus of 40, molar water content of 5:1:11 (L-lactic acid:fructose:water, mol/mol), and a particle size of rhizomes of 0.5-1 mm. These predicted values were further verified by validation experiments in predicted conditions. The experimental yields of salidroside, tyrosol, rosavin, rosin, cinnamyl alcohol and total markers (sum of phenyletanes and phenylpropanoids in mg/g) were 11.90 ± 0.02, 0.36 ± 0.02, 12.23 ± 0.21, 1.41 ± 0.01, 0.20 ± 0.01, and 26.10 ± 0.27 mg/g, respectively, which corresponded well with the predicted values from the models.

OBJECTIVE

This study examined the antifungal activity of the combination of tyrosol and farnesol against Candida albicans and Candida glabrata in the planktonic state or forming biofilms.

RESULTS

The effect of drug association against Candida planktonic cells was assessed by the fractional inhibitory concentration index. Mono- and dual-species biofilms were developed during 24 h and then treated with the compounds for 3 days, with two daily treatments of 1 min each. After, the total biomass, metabolic activity and the number of cultivable cells were quantified. Planktonic cells of the two species showed a similar susceptibility to the drug combination, however, a synergistic effect was only verified for C. glabrata. Regarding biofilm susceptibility, significant reductions in C. glabrata biomass, metabolism of C. albicans and mixed biofilms, and cultivable cells of single biofilms were verified for the drug combination, indicating an additive effect. For all other experiments, the effects were classified as indifferent.

CONCLUSIONS

The combined use of tyrosol and farnesol was advantageous for some of the analysed parameters against Candida species.

CONCLUSIONS

These findings may contribute to the development of oral care products containing tyrosol and farnesol to combat oral infections caused by Candida species.

A validated HPLC method with fluorescence detection for the simultaneous quantification of hydroxytyrosol and tyrosol in red wines is described. Detection conditions for both compounds were optimized (excitation at 279 and 278 and emission at 631 and 598 nm for hydroxytyrosol and tyrosol, respectively). The validation of the analytical method was based on selectivity, linearity, robustness, detection and quantification limits, repeatability, and recovery. The detection and quantification limits in red wines were set at 0.023 and 0.076 mg L(-1) for hydroxytyrosol and at 0.007 and 0.024 mg L(-1) for tyrosol determination, respectively. Precision values, both within-day and between-day (n = 5), remained below 3% for both compounds. In addition, a fractional factorial experimental design was developed to analyze the influence of six different conditions on analysis. The final optimized HPLC-fluorescence method allowed the analysis of 30 nonpretreated Spanish red wines to evaluate their hydroxytyrosol and tyrosol contents.

Hydroxytyrosol, a naturally occurred o-phenolic compound exhibiting antioxidant properties, was synthesized by a three-step high-yielding procedure from natural and low-cost compounds such as tyrosol or homovanillyl alcohol. First, the efficient chemoselective protection of the alcoholic group of these compounds was performed by using dimethyl carbonate (DMC) as reagent/solvent; second, the oxidation with 2-iodoxybenzoic acid (IBX) or Dess-Martin periodinane reagent (DMP) and in situ reduction with sodium dithionite (Na2S2O4) allowed the preparation of carboxymethylated hydroxytyrosol; finally, by a mild hydrolytic step, hydroxytyrosol was obtained in high yield and purity, as confirmed by NMR spectra and HPLC profile. By using a similar methodology, lipophilic hydroxytyrosol derivatives, utilized as additives in pharmaceutical, food, and cosmetic preparations, were prepared. In fact, at first the chemoselective protection of the alcoholic group of tyrosol and homovanillyl alcohol was performed by using acyl chlorides without any catalyst to obtain the corresponding lipophilic derivatives, and then these compounds were converted in good yield and high purity into the hydroxytyrosol derivatives by oxidative/reductive pathway with IBX or DMP and Na2S2O4.

Complexes of β-cyclodextrin (β-CD) and caffeine (Caf) with biophenols present in olive and olive oil (tyrosol, hydroxytyrosol, homovanillic acid, 3,4-dihydroxyphenylacetic acid, and protocatechuic acid) were investigated by NMR spectroscopy and thermodynamical-molecular dynamic studies to verify the formation of supermolecular aggregates. The obtained results indicated that the investigated biophenols form inclusion complexes with β-CD in a molar ratio of 1:1 in aqueous solution having binding constant values from 10- to 40-fold bigger than those of the corresponding complexes with Caf. Then, β-CD preferentially encloses the biophenol molecule, decreasing its bitter taste and, at the same time, preserving it against chemical and physical decomposition reactions that occur during storage.

2-(4-Hydroxyphenyl)ehyl-β-D-glucopyranoside (salidroside) and 4-(2-hydroxyethyl)phenol (p-tyrosol) are famous food and medicine additives originally derived from alpine Rhodiola plants. Salidroside or p-tyrosol production by the endophytic fungus Rac56 (Phialocephala fortinii) was confirmed by UPLC/Q-TOF-MS and ¹H-NMR. The fermentation conditions were optimized by orthogonal design using data processing system software. The broth fermentation results showed that salidroside and p-tyrosol extraction yields from Rac56 were stable and reached 1.729 ± 0.06 mg and 1.990 ± 0.05 mg per mL of culture medium, respectively. The optimal conditions for salidroside and p-tyrosol production in fermentation culture of Rac56 were determined to be 25 °C, pH values of 7 and 5, Czapek-Dox culture medium volumes of 150 mL and 50 mL in 250 mL flasks, rotation speeds of 100× g and 200× g, and fermentation durations of 7 and 15 days, respectively. Under these optimal conditions, stable yields of 2.339 ± 0.1093 mg and 2.002 ± 0.0009 mg per mL of culture medium of salidroside and p-tyrosol, respectively, were obtained, indicating that the P. fortinii Rac56 strain is a promising source of these compounds.

OBJECTIVE

Altered inflammatory response characterizes chronic immunemediated inflammatory diseases (IMID) such as rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, systemic lupus erythematosus, and psoriasis. Accumulating evidence indicates that regular consumption of extra virgin olive oil (EVOO), the main source of fat in the Mediterranean diet, is associated with a reduced risk of developing chronic degenerative disorders such as cardiovascular diseases, type 2 diabetes and cancer. The beneficial effects on health of EVOO have been attributed, besides to the monounsaturated fats content, to the presence of phenolic compounds that have antioxidant, anti-inflammatory and immunomodulatory properties. The purpose of this review is to provide an overview of the effects of EVOO polyphenols on IMID highlighting the potential mechanisms of action.

METHODS

Scientific papers were found by searching in PubMed up to May 2017 using the following key words: rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, systemic lupus erythematosus, and psoriasis also in combination with EVOO, phenolic compounds, oleuropein, oleocantal, hydroxytyrosol,tyrosol and oleochantal.

RESULTS

In vitro and in vivo studies indicate that EVOO and its polyphenols can improve diseases symptoms in IMID, by acting both at local and systemic levels and by modulating several molecular pathways. Nevertheless, there are not sufficient data to achieve specific nutritional guidelines.

CONCLUSIONS

Further research is needed to evaluate the real contribution of EVOO and its phenolic compounds in modulating the IMID-associated inflammatory perturbations, in order to develop appropriate nutritional recommendations.

Several extracts of Olea europaea wood (Picual olive cultivar) were obtained with solvents of different polarity and their antioxidant activities determined. The active compounds were detected in fractions of an ethyl acetate extract using HPLC with on-line radical scavenging detection. After applying different separation techniques, hydroxytyrosol, tyrosol, cycloolivil, 7-deoxyloganic acid, oleuropein and ligustroside were isolated and characterized. Hydroxytyrosol showed a higher activity than the natural antioxidant rosmarinic acid in scavenging the DPPH model radical. Cycloolivil and oleuropein showed stronger activities than the synthetic antioxidant BHT against the same radical. Ligustroside, tyrosol and 7-deoxyloganic acid showed little activity. The latter compound has not been previously identified in the genus Olea.

The phenolic fraction of extra virgin olive oil (EVOO) concentrates before absorption in the intestinal lumen, where it may contribute to the modulation of enterocytes response to oxidative and inflammatory stimuli. We evaluated the ability of two monovarietal EVOOs phenolic extracts, Bosana and Nera di Gonnos/Tonda di Cagliari, typical and widespread varieties in Sardinia (Italy), to counteract in enterocytes like Caco-2 cells the pro-oxidant action of oxidized lipids, tert-butyl hydroperoxide (TBH) or a mixture of oxysterols of dietary origin. We confirmed that TBH treatment causes a significant increase of ROS production, GSH depletion, increase of MDA, fatty acids hydroperoxides and 7-ketocholesterol, and showed first evidence of oxidative imbalance and cell damage due to oxysterols exposure. Preincubation of cells with the phenolic extracts significantly attenuated oxidative modifications. Bosana extract showed the highest concentration of total phenols, mainly hydroxytyrosol and tyrosol, and was the most active in presence of TBH, where the free radical scavenging activity of these simple phenols seems to be a determining factor. The two extracts were equally effective, in spite of the different composition, in presence of oxysterols, where ROS production probably occurs according to different and more complex mechanisms.

Iridoids, which have beneficial health properties, include a wide group of cyclopentane [c] pyran monoterpenoids present in plants and insects. The cleavage of the cyclopentane ring leads to secoiridoids. Mainly, secoiridoids have shown a variety of pharmacological effects including anti-diabetic, antioxidant, anti-inflammatory, immunosuppressive, neuroprotective, anti-cancer, and anti-obesity, which increase the interest of studying these types of bioactive compounds in depth. Secoiridoids are thoroughly distributed in several families of plants such as Oleaceae, Valerianaceae, Gentianaceae and Pedialaceae, among others. Specifically, Olea europaea L. (Oleaceae) is rich in oleuropein (OL), dimethyl-OL, and ligstroside secoiridoids, and their hydrolysis derivatives are mostly OL-aglycone, oleocanthal (OLE), oleacein (OLA), elenolate, oleoside-11-methyl ester, elenoic acid, hydroxytyrosol (HTy), and tyrosol (Ty). These compounds have proved their efficacy in the management of diabetes, cardiovascular and neurodegenerative disorders, cancer, and viral and microbial infections. Particularly, the antioxidant, anti-inflammatory, and immunomodulatory properties of secoiridoids from the olive tree (Olea europaea L. (Oleaceae)) have been suggested as a potential application in a large number of inflammatory and reactive oxygen species (ROS)-mediated diseases. Thus, the purpose of this review is to summarize recent advances in the protective role of secoiridoids derived from the olive tree (preclinical studies and clinical trials) in diseases with an important pathogenic contribution of oxidative and peroxidative stress and damage, focusing on their plausible mechanisms of the action involved.

BACKGROUND

Acer tegmentosum, which contains salidroside and tyrosol, has been used for the treatment of hepatic disorders in eastern Asia. However, little is known about its safety.

OBJECTIVE

To determine the safety of Acer tegmentosum, we evaluated its acute oral toxicity and genotoxicity profiles.

METHODS

Salidroside and tyrosol present in Acer tegmentosum were quantified using high-performance liquid chromatography. Acute oral toxicity testing of Acer tegmentosum was performed in rats. Genotoxicity of Acer tegmentosum was assessed by bacterial reverse mutation, chromosomal aberration, and bone marrow micronucleus tests. All the tests were conducted in accordance with the good laboratory practices.

RESULTS

The amounts of salidroside and tyrosol in Acer tegmentosum were found to be 85.01±1.21mg/g and 3.12±0.04mg/g, respectively. In the bacterial reverse mutation test, Acer tegmentosum increased the number of revertant Salmonella typhimurium TA98 colonies, regardless of metabolic activation by S9 mixture. In contrast, Acer tegmentosum application did not significantly increase the number of chromosomal aberrations in Chinese hamster ovary (CHO)-K1 cells and micronucleated polychromatic erythrocytes in mice. In the acute oral toxicity test, the median lethal dose (LD50) of Acer tegmentosum was found to be >2000mg/kg in rats.

CONCLUSIONS

Take together, Acer tegmentosum exhibits mutagenicity, which was evident from the bacterial reverse mutation test. Further studies are needed to identify the components responsible for such an effect and the underlying mechanisms.

This mini-review synthesises the present knowledge of microbial quorum-sensing, with a specific focus on quorum-sensing in yeast, and especially in wine yeast. In vine and wine ecosystems, yeast co-interact with a large variety of microorganisms, thereby affecting the fermentation process and, consequently, the flavour of the wine. The precise connections between microbial interactions and quorum-sensing remain unclear, but we describe here how and when some species start to produce quorum-sensing molecules to synchronously adapt their collective behaviour to new conditions. In Saccharomyces cerevisiae, the quorum-sensing molecules were identified as 2-phenylethanol and tryptophol. However, it was recently shown that also a quorum-sensing molecule formerly identified only in Candida albicans, tyrosol, appears to be regulated in S. cerevisiae according to cell density. This review describes the methods for detection and quantification of those quorum-sensing molecules, their underlying mechanisms of action, and their genetic background. It also examines the external stimuli that evoke the quorum-sensing mechanism in the wine-processing environment. The review closes with insight into the biotechnological applications that are already making use of the advantages of quorum-sensing systems and indicates the important questions that still need to be addressed in future research into quorum-sensing.

Although it is known that Mediterranean diet plays an important role in maintaining human health, the underlying molecular mechanisms remain largely unknown. The aim of this investigation was to elucidate the potential role of ortho-dihydroxy group containing natural compounds in H2O2-induced DNA damage and apoptosis. For this purpose, the main phenolic alcohols of olive oil, namely hydroxytyrosol and tyrosol, were examined for their ability to protect cultured cells under conditions of oxidative stress. A strong correlation was observed between the ability of hydroxytyrosol to mitigate intracellular labile iron level and the protection offered against H2O2-induced DNA damage and apoptosis. On the other hand, tyrosol, which lacks the ortho-dihydroxy group, was ineffective. Moreover, hydroxytyrosol (but not tyrosol), was able to diminish the late sustained phase of H2O2-induced JNK and p38 phosphorylation. The derangement of intracellular iron homeostasis, following exposure of cells to H2O2, played pivotal role both in the induction of DNA damage and the initiation of apoptotic signaling. The presented results suggest that the protective effects exerted by ortho-dihydroxy group containing dietary compounds against oxidative stress-induced cell damage are linked to their ability to influence changes in the intracellular labile iron homeostasis.

The prevention of adhesion of Candida cells to acrylic surfaces can be regarded as an alternative to prevent denture stomatitis. The use of quorum sensing molecules, such as tyrosol, could potentially interfere with the adhesion process. Therefore, the aim of this study was to assess the effect of tyrosol on adhesion of single and mixed cultures of Candida albicans and Candida glabrata to acrylic resin surfaces. Tyrosol was diluted in each yeast inoculum (10(7) cells/ml in artificial saliva) at 25, 50, 100, and 200 mM. Then, each dilution was added to wells of 24-well plates containing the acrylic specimens, and the plates were incubated at 37°C for 2 h. After, the effect of tyrosol was determined by total biomass quantification, metabolic activity of the cells and colony-forming unit counting. Chlorhexidine gluconate (CHG) was used as a positive control. Data were analyzed using analysis of variance (ANOVA) and the Holm-Sidak post hoc test (α = 0.05). The results of total biomass quantification and metabolic activity revealed that the tyrosol promoted significant reductions (ranging from 22.32 to 86.16%) on single C. albicans and mixed cultures. Moreover, tyrosol at 200 mM and CHG significantly reduced (p < 0.05) the number of adhered cells to the acrylic surface for single and mixed cultures of both species, with reductions ranging from 1.74 to 3.64-log10. In conclusion, tyrosol has an inhibitory effect on Candida adhesion to acrylic resin, and further investigations are warranted to clarify its potential against Candida infections.

The yeast Debaryomyces hansenii was investigated for its production of alcohol-based quorum sensing (QS) molecules including the aromatic alcohols phenylethanol, tyrosol, tryptophol and the aliphatic alcohol farnesol. Debaryomyces hansenii produced phenylethanol and tyrosol, which were primarily detected from the end of exponential phase indicating that they are potential QS molecules in D. hansenii as previously shown for other yeast species. Yields of phenylethanol and tyrosol produced by D. hansenii were, however, lower than those produced by Candida albicans and Saccharomyces cerevisiae and varied with growth conditions such as the availability of aromatic amino acids, ammonium sulphate, NaCl, pH and temperature. Tryptophol was only produced in the presence of tryptophane, whereas farnesol in general was not detectable. Especially, the type strain of D. hansenii (CBS767) had good adhesion and sliding motility abilities, which seemed to be related to a higher hydrophobicity of the cell surface of D. hansenii (CBS767) rather than the ability to form pseudomycelium. Addition of phenylethanol, tyrosol, tryptophol and farnesol was found to influence both adhesion and sliding motility of D. hansenii.

BACKGROUND

Phenolic compounds, the biggest group of natural antioxidants, have attracted much attention due to their known and wide-ranging biological activities, as well as to their health effects. In particular, regardless their antioxidant activity, they play a key role in the control of several inflammation-associated processes as well as in improving antioxidant defense system. In an our previous work we have demonstrated the ability of Hydroxytyrosol, an ortho-diphenolic compound, essential component of oleuropein, in preventing apoptotic cell death induced by UVB radiation in HaCaT cell lines in vitro. In olive oil, besides Hydroxytyrosol, there are appreciable amounts of Tyrosol and its secoiridoid derivatives.

OBJECTIVE

It has been well established that Tyrosol has a significantly lower antioxidant activity than Hydroxytyrosol, but despite this, recent studies suggest that Tyrosol exerts a powerful protective effect against oxidative injuries in cell systems and that it is able to improve the intracellular antioxidant defenses.

METHODS

Here, Tyrosol effect has been evaluated in HaCaT cells exposed to UVB radiation by means of morphological and molecular analyses.

RESULTS

Our study revealed the polyphenol ability in reducing apoptotic markers and in protecting HaCaT cells from damage.

CONCLUSIONS

These findings suggest an important role of Tyrosol in protecting cells from apoptotic cell death and encourage the use of this phytochemical as biological ingredient in topical preparations as possible tool to prevent skin damage.

Hydroxytyrosol (HTyr), a natural ortho-diphenolic antioxidant with health-beneficial properties that mainly occurs in virgin olive oil and olive oil mill waste waters (also known as vegetative waters), has been enzymatically synthesized using mushroom tyrosinase. This o-diphenol (not commercially available) was obtained from its monophenolic precursor tyrosol (commercially available) in the presence of both tyrosinase and ascorbic acid. The reaction synthesis is continuous, easy to perform, and adaptable to a bioreactor for industrial purposes. The HTyr concentration is time-predicted, and the yield of reaction can be 100%. The synthesis method reported here is an alternative approach to obtain this compound in an environmentally friendly way.

Phenolic compounds in extra virgin olive oil (EVOO) have been associated with beneficial effects for health. Indeed, these compounds exert strong antiproliferative effects on many pathological processes, which has stimulated chemical characterization of the large quantities of wastes generated during olive oil production. In this investigation, the potential of byproducts generated during storage of EVOO as a natural source of antioxidant compounds has been evaluated using solid-liquid and liquid-liquid extraction processes followed by rapid resolution liquid chromatography (RRLC) coupled to electrospray time-of-flight and ion trap mass spectrometry (TOF/IT-MS). These wastes contain polyphenols belonging to different classes such as phenolic acids and alcohols, secoiridoids, lignans, and flavones. The relationship between phenolic and derived compounds has been tentatively established on the basis of proposed degradation pathways. Finally, qualitative and quantitative characterizations of solid and aqueous wastes suggest that these byproducts can be considered an important natural source of phenolic compounds, mainly hydroxytyrosol, tyrosol, decarboxymethyl oleuropein aglycone, and luteolin, which, after suitable purification, could be used as food antioxidants or as ingredients in nutraceutical products due to their interesting technological and pharmaceutical properties.

Oxidative stress arises from an imbalance between the production of free radicals and antioxidant defences. Several studies have suggested that dietary antioxidants (such as polyphenols and berberine) may counteract oxidative stress through the involvement of the Sirtuin 1/Adenosine Monophosphate-Activated Protein Kinase (SIRT1/AMPK) pathway. The aim of this study was to evaluate the direct and specific antioxidant activity of some natural compounds, as well as their ability to modulate the expression of SIRT1 and the activation of AMPK. Quercetin, tyrosol, ferulic acid, catechin, berberine and curcumin were evaluated for their specific and direct antioxidant activity with TOSC assay. Their ability to modulate SIRT1 and AMPK was assessed by immunoblotting assay, while their cytotoxicity by CellTiter-Blue Cell Viability Assay. No statistically significant decrease (p>> 0.05) in the number of viable cells was found upon challenging with the natural compounds. Quercetin exhibited the highest antioxidant activity against peroxyl radical and peroxinitrate derivates, while curcumin showed the best anti-hydroxyl activity with respect to the other compounds and, most importantly, respect to the reference antioxidants. Finally, all the tested compounds significantly increased the SIRT1 expression and the activation of AMPK. Our results clearly disclose the specific antioxidant activity of these natural compounds and their ability to increase SIRT1 expression and AMPK activation.

The efficient growth of pathogenic bacteria and fungi in the host organism is possible due to the formation of microbial biofilms that cover the host tissues. Biofilms provide optimal local environmental conditions for fungal cell growth and increased their protection against the immune system. A common biofilm-forming fungus-Candida albicans-uses the quorum sensing (QS) mechanism in the cell-to-cell communication, which determines the biofilm development and, in consequence, host colonization. In the presented work, we focused on the ability of neutrophils-the main cells of the host's immune system to recognize quorum sensing molecules (QSMs) produced by C. albicans, especially farnesol (FOH), farnesoic acid (FA), and tyrosol (TR), with emphasis on the neutrophil extracellular traps (NETs) formation in a process called netosis. Our results showed for the first time that only farnesol but not farnesolic acid or tyrosol is capable of activating the NET production. By using selective inhibitors of the NET signaling pathway and analyzing the activity of selected enzymes such as Protein Kinase C (PKC), ERK1/2, and NADPH oxidase, we showed that the Mac-1 and TLR2 receptors are responsible for FOH recognizing and activating the reactive oxygen species (ROS)-dependent netosis pathway.