The role of staphyloxanthin in the regulation of membrane biophysical properties in Staphylococcus aureus.

Staphylococcus aureus is an opportunistic pathogen that is considered a global health threat. This microorganism can adapt to hostile conditions by regulating membrane lipid composition in response to external stress factors such as changes in pH and ionic strength. S. aureus synthesizes and incorporates in its membrane staphyloxanthin, a carotenoid providing protection against oxidative damage and antimicrobial agents. Staphyloxanthin is known to modulate the physical properties of the bacterial membranes due to the rigid diaponeurosporenoic group it contains. In this work, preparative thin layer chromatography and liquid chromatography mass spectrometry were used to purify staphyloxanthin from S. aureus and characterize its structure, identifying C15, C17 and C19 as the main fatty acids in this carotenoid. Changes in the biophysical properties of models of S. aureus membranes containing phosphatidylglycerol, cardiolipin, and staphyloxanthin were evaluated. Infrared spectroscopy shows that staphyloxanthin reduces the liquid-crystalline to gel phase transition temperature in the evaluated model systems. Interestingly, these shifts are not accompanied by strong changes in trans/gauche isomerization, indicating that chain conformation in the liquid-crystalline phase is not altered by staphyloxanthin. In contrast, headgroup spacing, measured by Laurdan GP fluorescence spectroscopy, and lipid core dynamics, measured by DPH fluorescence anisotropy, show significant shifts in the presence of staphyloxanthin. The combined results show that staphyloxanthin reduces lipid core dynamics and headgroup spacing without altering acyl chain conformations, therefore decoupling these normally correlated effects. We propose that the rigid diaponeurosporenoic group in staphyloxanthin and its positioning in the membrane is likely responsible for the results observed.

Mechanochemical Degradation of Caffeine and Diclofenac Using Biochar of Fique Bagasse in the Presence of Al: Monitoring by Mass Spectrometry.

Much research has been carried out to remove emerging contaminants using diverse materials. Furthermore, studies related to pollutant degradation have increased over the past decade. Mechanochemical degradation can successfully decompose molecules that are persistent in the environment. In this study, the biochar of fique bagasse with mixtures SiO2, Al, Al2O3, and Al-Al2O3 was treated with a mechanochemical technique using a planetary ball mill to investigate the degradation of caffeine and diclofenac. These tests resulted in the transformation of caffeine and diclofenac due to the use of Al employing mechanochemistry. In fact, through the use of liquid chromatography coupled with mass spectrometry, eight and six subproducts were identified for caffeine and diclofenac, respectively. Additionally, analysis of the molecules proposed for caffeine and diclofenac transformation suggested hydroxylation, demethylation, decarboxylation, oxidation reactions, and cleavage of the C-C and C-N bonds in the pollutants studied. The formation of these transformation products could be possible by reductant oxygen species generated from the molecular oxygen in the presence of aluminum and the energy delivered for ball milling. The results obtained show the potential application in the environmental management of mechanochemical treatment in the elimination of emerging contaminants caffeine and diclofenac.

Staphylococcus aureus Modulates Carotenoid and Phospholipid Content in Response to Oxygen-Restricted Growth Conditions, Triggering Changes in Membrane Biophysical Properties.

Staphylococcus aureus membranes contain carotenoids formed during the biosynthesis of staphyloxanthin. These carotenoids are considered virulence factors due to their activity as scavengers of reactive oxygen species and as inhibitors of antimicrobial peptides. Here, we show that the growth of S. aureus under oxygen-restricting conditions downregulates carotenoid biosynthesis and modifies phospholipid content in biofilms and planktonic cells analyzed using LC-MS. At oxygen-restrictive levels, the staphyloxanthin precursor 4,4-diapophytofluene accumulates, indicating that the dehydrogenation reaction catalyzed by 4,4'-diapophytoene desaturases (CrtN) is inhibited. An increase in lysyl-phosphatidylglycerol is observed under oxygen-restrictive conditions in planktonic cells, and high levels of cardiolipin are detected in biofilms compared to planktonic cells. Under oxygen-restriction conditions, the biophysical parameters of S. aureus membranes show an increase in lipid headgroup spacing, as measured with Laurdan GP, and decreased bilayer core order, as measured with DPH anisotropy. An increase in the liquid-crystalline to gel phase melting temperature, as measured with FTIR, is also observed. S. aureus membranes are therefore less condensed under oxygen-restriction conditions at 37 °C. However, the lack of carotenoids leads to a highly ordered gel phase at low temperatures, around 15 °C. Carotenoids are therefore likely to be low in S. aureus found in tissues with low oxygen levels, such as abscesses, leading to altered membrane biophysical properties.

Obtention of fatty acids and phenolic compounds from Colombian cashew (Anacardium occidentale) nut shells using pyrolysis: towards a sustainable biodiesel production.

Sustainable management of non-edible agricultural residues of cashew nut production is a concern in Colombia. Therefore, this study aimed to study the fatty acid content of a pyrolytic liquid obtained from cashew nut shells (CNSs) from the Vichada region in Colombia. Transesterification of pyrolytic liquid was conducted to obtain biodiesel at the micro-scale as the first approach for this valorization route. Proximal analysis of samples was carried out using advanced analytical techniques (UHPLC-MS and CG-MS) whereas phenolic content and antioxidant activity were determined. The production yield of pyrolytic liquid was 69.15 ± 5.07% weight (wt.), at 550 °C and 2h of pyrolysis and the liquid was rich in fatty acids (∼70% wt.) and long-chain phenols (∼18% wt.). Among the phenolic compounds in liquid, mainly unsaturated C15:4 cardanol was identified (82.1 ± 5.5 mg/g), whereas the antioxidant activity of pyrolytic liquid was 0.714 ± 0.030 TE/g. Moreover, the biodiesel yield was 81% using catalyst sodium methoxide (12% v), and 50 °C and 26 min for the reaction. The obtained biodiesel in the hexane fraction was rich in methyl trans-8-octadecanoate (20.9 % wt.) and methyl palmitate (14.3 % wt.), being the representative compounds in the biodiesel. Therefore, the results indicated that thermal conversion of CNSs for obtaining biodiesel on a one-step process is a suitable strategy for the management of toxic and non-edible cashew residues. Finally, this is the first work of its kind that propose in detail the composition of pyrolytic liquid obtained from Colombian cashew nut residues under the proximate analysis approach and using advanced analytical techniques.

Eco-Metabolomics Applied to the Chemical Ecology of Poison Frogs (Dendrobatoidea).

Amphibians are one of the most remarkable sources of unique natural products. Biogenic amines, peptides, bufodienolides, alkaloids, and volatile organic compounds have been characterized in different species. The superfamily Dendrobatoidea represents one of the most enigmatic cases of study in chemical ecology because their skin secretome is composed by a complex mixture (i.e. cocktail) of highly lethal and noxious unique alkaloid structures. While chemical defences from dendrobatoids (families Dendrobatidae and Aromobatidae) have been investigated employing ecological, behavioral, phylogenetic and evolutionary perspectives, studies about the analytical techniques needed to perform the chemical characterization have been neglected for many years. Therefore, our aim is to summarize the current methods applied for the characterization of chemical profiles in dendrobatoids and to illustrate innovative Eco-metabolomics strategies that could be translated to this study model. This approach could be extended to natural products other than alkaloids and implemented for the chemical analysis of different species of dendrobatoids employing both low- and high-resolution mass spectrometers. Here, we overview important biological features to be considered, procedures that could be applied to perform the chemical characterization, steps and tools to perform an Eco-metabolomic analysis, and a final discussion about future perspectives.

Why Do These Yeasts Smell So Good? Volatile Organic Compounds (VOCs) Produced by Malassezia Species in the Exponential and Stationary Growth Phases.

Malassezia synthesizes and releases volatile organic compounds (VOCs), small molecules that allow them to carry out interaction processes. These lipid-dependent yeasts belong to the human skin mycobiota and are related to dermatological diseases. However, knowledge about VOC production and its function is lacking. This study aimed to determine the volatile profiles of Malassezia globosa, Malassezia restricta, and Malassezia sympodialis in the exponential and stationary growth phases. The compounds were separated and characterized in each growth phase through headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). We found a total of 54 compounds, 40 annotated. Most of the compounds identified belong to alcohols and polyols, fatty alcohols, alkanes, and unsaturated aliphatic hydrocarbons. Unsupervised and supervised statistical multivariate analyses demonstrated that the volatile profiles of Malassezia differed between species and growth phases, with M. globosa being the species with the highest quantity of VOCs. Some Malassezia volatiles, such as butan-1-ol, 2-methylbutan-1-ol, 3-methylbutan-1-ol, and 2-methylpropan-1-ol, associated with biological interactions were also detected. All three species show at least one unique compound, suggesting a unique metabolism. The ecological functions of the compounds detected in each species and growth phase remain to be studied. They could interact with other microorganisms or be an important clue in understanding the pathogenic role of these yeasts.

Bacterial Carotenoids: Extraction, Characterization, and Applications.

Natural carotenoids are secondary metabolites that exhibit antioxidant, anti-inflammatory, and anti-cancer properties. These types of compounds are highly demanded by pharmaceutical, cosmetic, nutraceutical, and food industries, leading to the search for new natural sources of carotenoids. In recent years, the production of carotenoids from bacteria has become of great interest for industrial applications. In addition to carotenoids with C40-skeletons, some bacteria have the ability to synthesize characteristic carotenoids with C30-skeletons. In this regard, a great variety of methodologies for the extraction and identification of bacterial carotenoids has been reported and this is the first review that condenses most of this information. To understand the diversity of carotenoids from bacteria, we present their biosynthetic origin in order to focus on the methodologies employed in their extraction and characterization. Special emphasis has been made on high-performance liquid chromatography-mass spectrometry (HPLC-MS) for the analysis and identification of bacterial carotenoids. We end up this review showing their potential commercial use. This review is proposed as a guide for the identification of these metabolites, which are frequently reported in new bacteria strains.

Chemical composition and bioactive compounds of cashew (Anacardium occidentale) apple juice and bagasse from Colombian varieties.

Cashew nut production generates large amounts of cashew apple as residue. In Colombia, cashew cultivation is increasing together with the concerns on residue management. The objective of this study was to provide the first chemical, physical and thermal decomposition characterization of cashew apple from Colombian varieties harvested in Vichada, Colombia. This characterization was focused to identify the important bioactive and natural compounds that can be further valorized in the formulation of food, nutraceuticals, and pharmacological products. The results obtained in this study are helpful to portray the cashew apple as a potential by-product due to its renewable nature and valuable composition, instead of seeing it just as an agricultural residue. For that, cashew apples of Regional 8315 and Mapiria varieties were studied. The natural juice (cashew apple juice) that was extracted from the cashew apples and the remanent solids (cashew apple bagasse) were separately analyzed. The HPLC analytical technique was used to determine the concentration of bioactive compounds, structural carbohydrates, and soluble sugars that constitute this biomass. Spectrophotometric techniques were used to determine the concentration of tannins, carotenoids, and total polyphenols. Mineral content and antioxidant activity (DPPH and ABTS assays) were determined in the biomass. Also, the thermal decomposition under an inert atmosphere or pyrolysis was performed on cashew apple bagasse. The varieties of cashew apple studied in this work showed similar content of bioactive compounds, total phenolic content, and structural carbohydrates. However, the Mapiria variety showed values slightly higher than the Regional 8315. Regarding cashew apple juice, it is rich in tannins and ascorbic acid with values of 191 mg/100 mL and 70 mg/100 mL, respectively, for Mapiria variety. Additionally, the principal reservoir of bioactive compounds and constitutive carbohydrates was the cashew apple bagasse. About 50 wt.% of it was composed of cellulose and hemicellulose. Also, in the bagasse, the ascorbic acid content was in a range of 180-200 mg/100 g, which is higher than other fruits and vegetables. Moreover, alkaloids were identified in cashew apples. The maximum value of antioxidant activity (DPPH assay: 405 TEs/g) was observed in the bagasse of Mapiria variety. The bagasse thermal decomposition started around 150 °C when the structural carbohydrates and other constitutive substances started to degrade. After thermogravimetric analysis, a remanent of 20% of the initial weight suggested the formation of a rich-carbon solid, which could correspond to biochar. Therefore, the cashew apple harvested in Vichada is a valuable reservoir of a wide range of biomolecules that potentially could be valorized into energy, foods, and pharmacologic applications. Nevertheless, future work is necessary to describe the complex compounds of this residual biomass that are still unknown.

Heterogeneous fitness landscape cues, pknG low expression, and phthiocerol dimycocerosate low production of Mycobacterium tuberculosis ATCC25618 rpoB S450L in enriched broth.

Multidrug-resistant tuberculosis (isoniazid/rifampin[RIF]-resistant TB) ravages developing countries. Fitness is critical in clinical outcomes. Previous studies on RIF-resistant TB (RR-TB) showed competitive fitness gains and losses, with rpoB-S450L as the most isolated/fit mutation. This study measured virulence/resistance genes, phthiocerol dimycocerosate (PDIM) levels and their relationship with rpoB S450L ATCC25618 RR-TB strain fitness. After obtaining 10 different RR-TB GenoType MTBDRplus 2.0-genotyped isolates (with nontyped, S441, H445 and S450 positions), only one S450L isolate (R9, rpoB-S450L ATCC 25618, RR 1 µg/mL) was observed, with H445Y being the most common. A competitive fitness in vitro assay with wild-type (wt) ATCC 25618: R9 1:1 in 50 mL Middlebrook 7H9/OADC was performed, and generation time (G) in vitro and relative fitness were obtained. mRNA and PDIM were extracted on log and stationary phases. Fitness decreased in rpoB S450L and H445Y strains, with heterogeneous fitness cues in three biological replicas of rpoB-S450L: one high and two low fitness replicas. S450L strain had significant pknG increase. Compared with S450L, wt-rpoB showed increased polyketide synthase ppsA expression and high PDIM peak measured by HPLC-MS in log phase compared to S450L. This contrasts with previously increased PDIM in other RR-TB isolates.

First characterization of toxic alkaloids and volatile organic compounds (VOCs) in the cryptic dendrobatid Silverstoneia punctiventris.

BACKGROUND: Poison frogs are known for the outstanding diversity of alkaloid-based chemical defences with promising therapeutic applications. However, current knowledge about chemical defences in Dendrobatoidea superfamily has two sources of bias. First, cryptic, brown-colored species have been neglected in comparison to those conspicuously colored, and second, there has been little interest in characterizing metabolites other than alkaloids mediating defensive functions. In an effort to contribute to fill the gap of knowledge about cryptic species and broadening the spectrum of compounds analyzed we have applied head-space solid phase microextraction coupled to gas chromatography and mass spectrometry (HS-SPME/GC-MS) for extracting amphibian alkaloids and volatile organic compounds (VOCs) from Silverstoneia punctiventris. RESULTS: Using the skin from 8 specimens in 4 biological replicates we have found 33 different compounds. Twenty of them were classified as VOCs into 15 chemical classes including alkanes, alcohols, carbonyl compounds, methylpyridines, benzothiazoles, N-alkylpyrrolidines, pyrazines, and sesquiterpenoids, some of which were previously reported as repellents, defence compounds or defence pheromones in other organisms, and as sex pheromones in a treefrog. Interestingly, six of the remaining compounds were identified as alkaloids previously reported in other toxic/unpalatable dendrobatid frogs. CONCLUSIONS: This is the first report of alkaloids and VOCs found in the Silverstoneia genus, which has been assumed for decades as non-chemically defended. This study establishes HS-SPME/GC-MS as a new application for a simultaneous approach to amphibian alkaloids and VOCs in poison frogs while opens up new research questions to assess the co-occurrence of both type of compounds and to investigate the evolutionary significance of a defence gradient that includes olfactory avoidance, unpalatability, and toxicity in dendrobatids. In addition, our results show that amphibian alkaloids could have a dual function (olfactory at distance, taste by contact) never explored before neither in Silverstonaeia nor in any other dendrobatid species.

Carotenogenesis of Staphylococcus aureus: New insights and impact on membrane biophysical properties.

Staphyloxanthin (STX) is a saccharolipid derived from a carotenoid in Staphylococcus aureus involved in oxidative-stress tolerance and antimicrobial peptide resistance. STX influences the biophysical properties of the bacterial membrane and has been associated to the formation of lipid domains in the regulation of methicillin-resistance. In this work, a targeted metabolomics and biophysical characterization study was carried out to investigate the biosynthetic pathways of carotenoids, and their impact on the membrane biophysical properties. Five different S. aureus strains were investigated, including three wild-type strains containing the crtM gene related to STX biosynthesis, a crtM-deletion mutant, and a crtMN plasmid-complemented variant. LC-DAD-MS/MS analysis of extracts allowed the identification of 34 metabolites related to carotenogenesis in S. aureus at different growth phases (8, 24 and 48 h), showing the progression of these metabolites as the bacteria advances into the stationary phase. For the first time, 22 members of a large family of carotenoids were identified, including STX and STX-homologues, as well as Dehydro-STX and Dehydro-STX-homologues. Moreover, thermotropic behavior of the CH2 stretch of lipid acyl chains in live cells by FTIR, show that the presence of STX increases acyl chain order at the bacterial growth temperature. Indeed, the cooperative melting event of the bacterial membrane, which occurs around 15 °C in the native strains, shifts with increased carotenoid content. These results show the diversity biosynthetic of carotenoids in S. aureus, and their influence on membrane biophysical properties.

Learning about microbial language: possible interactions mediated by microbial volatile organic compounds (VOCs) and relevance to understanding Malassezia spp. metabolism.

BACKGROUND: Microorganisms synthesize and release a large diversity of small molecules like volatile compounds, which allow them to relate and interact with their environment. Volatile organic compounds (VOCs) are carbon-based compounds with low molecular weight and generally, high vapor pressure; because of their nature, they spread easily in the environment. Little is known about the role of VOCs in the interaction processes, and less is known about VOCs produced by Malassezia, a genus of yeasts that belongs to the human skin mycobiota. These yeasts have been associated with several dermatological diseases and currently, they are considered as emerging opportunistic yeasts. Research about secondary metabolites of these yeasts is limited. The pathogenic role and the molecular mechanisms involved in the infection processes of this genus are yet to be clarified. VOCs produced by Malassezia yeasts could play an important function in their metabolism; in addition, they might be involved in either beneficial or pathogenic host-interaction processes. Since these yeasts present differences in their nutritional requirements, like lipids to grow, it is possible that these variations of growth requirements also define differences in the volatile organic compounds produced in Malassezia species. AIM OF REVIEW: We present a mini review about VOCs produced by microorganisms and Malassezia species, and hypothesize about their role in its metabolism, which would reveal clues about host-pathogen interaction. KEY SCIENTIFIC CONCEPTS OF REVIEW: Since living organisms inhabit a similar environment, the interaction processes occur naturally; as a result, a signal and a response from participants of these processes become important in understanding several biological behaviors. The efforts to elucidate how living organisms interact has been studied from several perspectives. An important issue is that VOCs released by the microbiota plays a key role in the setup of relationships between living micro and macro organisms. The challenge is to determine what is the role of these VOCs produced by human microbiota in commensal/pathogenic scenarios, and how these allow understanding the species metabolism. Malassezia is part of the human mycobiota, and it is implicated in commensal and pathogenic processes. It is possible that their VOCs are involved in these behavioral changes, but the knowledge about this remains overlocked. For this reason, VOCs produced by microorganisms and Malassezia spp. and their role in several biological processes are the main topic in this review.

Auto-deconvolution and molecular networking of gas chromatography-mass spectrometry data.

We engineered a machine learning approach, MSHub, to enable auto-deconvolution of gas chromatography-mass spectrometry (GC-MS) data. We then designed workflows to enable the community to store, process, share, annotate, compare and perform molecular networking of GC-MS data within the Global Natural Product Social (GNPS) Molecular Networking analysis platform. MSHub/GNPS performs auto-deconvolution of compound fragmentation patterns via unsupervised non-negative matrix factorization and quantifies the reproducibility of fragmentation patterns across samples.

Hydrophilic Interaction Liquid Chromatography Coupled to Mass Spectrometry and Multivariate Analysis of the De Novo Pyrimidine Pathway Metabolites.

In this study, we describe the optimization of a Hydrophilic Interaction Liquid Chromatography coupled to mass spectrometry (HILIC-MS) method for the evaluation of 14 metabolites related to the de novo synthesis of pyrimidines (dnSP) while using multivariate analysis, which is the metabolic pathway for pyrimidine nucleotide production. A multivariate design was used to set the conditions of the column temperature, flow of the mobile phase, additive concentration, gradient rate, and pH of the mobile phase in order to attain higher peak resolution and ionization efficiency in shorter analysis times. The optimization process was carried out while using factorial fractional designs, Box-Behnken design and central composite design while using two zwitterionic columns, ZIC-p-HILIC and ZIC-HILIC, polymeric, and silica-based columns, respectively. The factors were evaluated while using resolution (R), retention factor (k), efficiency of the column (N), and peak height (h) as the response variables. The best optimized conditions were found with the ZIC-p-HILIC column: elution gradient rate 2 min., pH 7.0, temperature 45 °C, mobile phase flow of 0.35 mL min-1, and additive (ammonium acetate) concentration of 6 mM. The total analysis time was 28 min. The ZIC-p-HILIC LC-MS method yielded satisfactory results for linearity of calibration curves, limit of detection (LOD), and limit of quantification (LOQ). The method has been shown to be appropriate for the analysis of dnSP on samples of tomato plants that were infected with Phytophthora infestans.

Yeast Smell Like What They Eat: Analysis of Volatile Organic Compounds of Malassezia furfur in Growth Media Supplemented with Different Lipids.

Malassezia furfur is part of the human skin microbiota. Its volatile organic compounds (VOCs) possibly contribute to the characteristic odour in humans, as well as to microbiota interaction. The aim of this study was to investigate how the lipid composition of the liquid medium influences the production of VOCs. Growth was performed in four media: (1) mDixon, (2) oleic acid (OA), (3) oleic acid + palmitic acid (OA+PA), and (4) palmitic acid (PA). The profiles of the VOCs were characterized by HS-SPME/GC-MS in the exponential and stationary phases. A total number of 61 VOCs was found in M. furfur, among which alkanes, alcohols, ketones, and furanic compounds were the most abundant. Some compounds previously reported for Malassezia (γ-dodecalactone, 3-methylbutan-1-ol, and hexan-1-ol) were also found. Through our experiments, using univariate and multivariate unsupervised (Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA)) and supervised (Projection to Latent Structures Discriminant Analysis (PLS-DA)) statistical techniques, we have proven that each tested growth medium stimulates the production of a different volatiles profile in M. furfur. Carbon dioxide, hexan-1-ol, pentyl acetate, isomer5 of methyldecane, dimethyl sulphide, undec-5-ene, isomer2 of methylundecane, isomer1 of methyldecane, and 2-methyltetrahydrofuran were established as differentiating compounds among treatments by all the techniques. The significance of our findings deserves future research to investigate if certain volatile profiles could be related to the beneficial or pathogenic role of this yeast.

Metabolomics of Solanum lycopersicum Infected with Phytophthora infestans Leads to Early Detection of Late Blight in Asymptomatic Plants.

Tomato crops suffer attacks of various pathogens that cause large production losses. Late blight caused by Phytophthora infestans is a devastating disease in tomatoes because of its difficultly to control. Here, we applied metabolomics based on liquid chromatography⁻mass spectrometry (LC-MS) and metabolic profiling by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) in combination with multivariate data analysis in the early detection of late blight on asymptomatic tomato plants and to discriminate infection times of 4, 12, 24, 36, 48, 60, 72 and 96 h after inoculation (hpi). MALDI-MS and LC-MS profiles of metabolites combined with multivariate data analysis are able to detect early-late blight-infected tomato plants, and metabolomics based on LC-MS discriminates infection times in asymptomatic plants. We found the metabolite tomatidine as an important biomarker of infection, saponins as early infection metabolite markers and isocoumarin as early and late asymptomatic infection marker along the post infection time. MALDI-MS and LC-MS analysis can therefore be used as a rapid and effective method for the early detection of late blight-infected tomato plants, offering a suitable tool to guide the correct management and application of sanitary defense approaches. LC-MS analysis also appears to be a suitable tool for identifying major metabolites of asymptomatic late blight-infected tomato plants.

Behavioral responses of Rhodnius prolixus to volatile organic compounds released in vitro by bacteria isolated from human facial skin.

BACKGROUND: Previous studies have demonstrated the role of volatile organic compounds (VOCs) produced by skin microbiota in the attraction of mosquitoes to humans. Recently, behavioral experiments confirmed the importance of VOCs released by skin microbiota in the attraction of Rhodnius prolixus (Hemiptera: Triatominae), a vector of Chagas disease. METHODS/FINDINGS: In this study, we screened for VOCs released in vitro by bacteria isolated from human facial skin that were able to elicit behavioral responses in R. prolixus. The VOCs released in vitro by eight bacterial species during two growth phases were tested with adult Rhodnius prolixus insects using a dual-choice "T"-shaped olfactometer. In addition, the VOCs released by the bacteria were analyzed with headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). The VOCs produced by Staphylococcus capitis 11C, Staphylococcus warneri and Staphylococcus epidermidis 1 were attractive to R. prolixus, while the VOCs released by Citrobacter koseri 6P, Brevibacterium epidermidis and Micrococcus luteus 23 were non-attractive. CONCLUSIONS: The results shown here indicate that VOCs released by bacteria isolated from human facial skin have a potential for biotechnological uses as a strategy to prevent the vectorial transmission of Chagas disease mediated by Rhodnius prolixus.

Identification of organic acids in Cichorium intybus inhibiting virulence-related properties of oral pathogenic bacteria.

The low molecular mass (LMM) extract of Cichorium intybus var. silvestre (red chicory) has been shown to inhibit virulence-linked properties of oral pathogens including Streptococcus mutans, Actinomyces naeslundii and Prevotella intermedia. In the present study HPLC-DAD-ESI/MS(2) was used to investigate the compounds contained in this extract for their anti-virulence activity. The extract contained a number of components, including oxalic, succinic, shikimic and quinic acids, which interfere with the growth and virulence traits (i.e., biofilm formation, adherence to epithelial cells and hydroxyapatite) of oral pathogens involved in gingivitis and tooth decay. Succinic and quinic acid seem to be the most potent, mainly by interfering with the ability of oral pathogens to form biofilms (either through inhibition of their development or promotion of their disruption). Our findings suggest that one or more of these compounds may modulate plaque formation in vivo, which is a prerequisite for the development of both caries and gingivitis.

Identification of phenolic constituents in red chicory salads (Cichorium intybus) by high-performance liquid chromatography with diode array detection and electrospray ionisation tandem mass spectrometry.

Phenolic acids and flavonoids extracted from several types of Cichorium intybus var. silvestre salads ("Chioggia", "Treviso", "Treviso tardivo", and "Verona") were characterised by high-performance liquid chromatography-electrospray ionisation/mass spectrometry. Among the 64 compounds detected, several hydroxycinnamic acid derivatives including 8 mono- and dicaffeoylquinic acids, 3 tartaric acid derivatives, 31 flavonol and 2 flavone glycosides, as well as 10 anthocyanins were characterised based on UV spectra and MS(n) fragmentation patterns. Furthermore, several isomers of caffeic acid derivatives were distinguished for the first time by their specific mass spectral data. This is the first study reporting the glycosylation type and position of mono- and diglycosylated flavonoids in red salads.