Antifungal activity of selected Malassezia indolic compounds detected in culture

Background: Malassezia yeasts produce bioactive indolic substances when grown on L‐tryptophan agar. A panel of these substances was tested against commensal and opportunistic fungi, the Minimum Inhibitory Concentration (MIC) was determined and the potential for in loco antifungal activity on the skin was assessed. Materials and Methods: Eight indoles were included (malassezin, pityriacitrin, indirubin, indolo[3,2‐b]carbazole, 6‐formylindolo[3,2‐b]carbazole, tryptanthrin, 6‐hydroxymethylindolo[3,2‐b]carbazole and 6‐methylindolo[3,2‐b]carbazole) and were tested against 40 fungal strains [yeasts: Malassezia spp.(N = 9); Cryptococcus spp.(N = 10); Candida spp.(N = 7); Yarrowia lipolytica(N = 1); Exophialla dermatitidis (N = 2); moulds: Aspergillus spp.(N = 7); Fusarium spp.(N = 2); Rhizopus oryzae(N = 2)]. The concentration of 5/8 of the tested indoles on diseased skin was calculated from published data. Kruskal‐Wallis and Mann‐Whitney U tests were employed for group susceptibility evaluation in 33 strains. Results: The MIC range was 0.125‐32 μg/mL, and the median log2MIC was four. Indirubin was the most potent antifungal agent and differed significantly from the others. The highest median MIC was found for FICZ. Malassezia with Candida strains were more susceptible compared to Cryptococcus and Aspergillus, and this inhibitory activity was predicted to be valid also on human skin. Conclusions: Malassezia yeasts produce indolic species that inhibit an array of clinically significant yeasts and moulds

Kemijski sastav endemske biljke Centaurea austro-anatolica i ispitivanje antimikrobnog djelovanja protiv multi-rezistentnih bakterija

Hexane, chloroform, ethyl acetate and ethanolic extracts of the aerial parts of C. austro-anatolica Hub.-Mor. (Asteraceae) were evaluated against microorganisms, including multi-resistant bacteria, using a paper disc diffusion method. The chloroform extract exhibited significant antibacterial activity toward all bacteria tested. The chemical composition of the chloroform extract was determined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The major compounds of the extract were caryophyllene oxide (21.32 %), spathulenol (10.86 %), n-tricosanol (9.58 %) and geranyl isovalerate (8.71 %).Heksanski, kloroformski, etil-acetatni i etanolni ekstrakti vršnih dijelova biljke C. austro-anatolica Hub.-Mor. (Asteraceae) ispitivani su na antimikrobno djelovanje protiv multi-rezistentnih bakterija, koristeći difuzijsku metodu na papirnom disku. Kloroformski ekstrakt pokazao je značajno antibakterijsko djelovanje protiv svih testiranih bakterija. Kemijski sastav tog ekstrakta određivan je plinskom kromatografijom (GC) i plinskom kromatografijom-spektrometrijom masa (GC-MS). Najvažniji sastojci ekstrakta bili su kariofilen oksid (21,32 %), spatulenol (10,86 %), n-trikozanol (9,58 %) i geranil izovalerat (8,71 %)

Isolation of megaritolactones and other bioactive metabolites from 'Megaritiki' table olives and debittering water

'Megaritiki' is an olive cultivar widely used in Greece for the production of low polyphenol olive oil and table olives. To investigate possible metabolic differentiation in comparison with other varieties, the composition of 'Megaritiki' olive fruits and wastewaters from the debittering procedure was studied. Moreover, the recovery of bioactive metabolites from wastewater using adsorption resin was studied to exploit this byproduct. Metabolites in fruits and wastewaters were monitored using NMR spectroscopy. The major constituents of wastewater were hydroxytyrosol-4-O-glucoside, 11-methyl-oleoside, hydroxytyrosol, and tyrosol but not oleuropein. Furthermore, wastewater afforded rengyoxide and rengyoside B, which are for the first time isolated from olives. The final edible olives, besides hydroxytyrosol and tyrosol, contained rengyoxide and cleroindicin C, which are the first isolated from the species, haleridone for the first time isolated from edible olives, and four metabolites, which are the first reported as natural products, megaritodilactone, megaritolactonic acid, methyl ester of megaritolactonic acid B, and megaritolactonol. © 2014 American Chemical Society

Identification and quantitation of benzoxazinoids in wheat malt beer by qNMR and GC-MS

Based on a previous identification of benzoxazinoids in wheat malt beer we performed a more in depth screening of beers that led to the identification and isolation of 6-methoxy-2-(3. H)-benzoxazolone (6MBOA) as a new beer ingredient. In addition, a new methodology for the quantitative measurement of this compound in beer extracts was developed using quantitative Nuclear Magnetic Resonance (qNMR). Ten commercial samples of wheat beers were studied and 6MBOA was found in concentrations ranging from 0.4 to 3.6 mg/L. The same compound was not detected in seventeen samples of commercial beers (lager, ale) that were produced using barley malt. Similar concentrations (1.6-7.3 mg/L) of a relative compound, 2-(3. H)-benzoxazolone, was found only in beers made with wheat malt. This is the first report of 6MBOA in beer and the first quantitation of benzoxazinoids in beer. © 2015 Elsevier Ltd

Measuring protection of aromatic wine thiols from oxidation by competitive reactions vs wine preservatives with ortho-quinones

Quinones are central intermediates in wine oxidation that can degrade the quality of wine by reactions with varietal thiols, such as 3-sulfanylhexanol, decreasing desirable aroma. Protection by wine preservatives (sulphur dioxide, glutathione, ascorbic acid and model tannin, phloroglucinol) was assessed by competitive sacrificial reactions with 4-methyl-1,2-benzoquinone, quantifying products and ratios by HPLC-UV-MS. Regioselectivity was assessed by product isolation and identification by NMR spectroscopy. Nucleophilic addition reactions compete with two electron reduction of quinones by sulphur dioxide or ascorbic acid, and both routes serve as effective quenching pathways, but minor secondary products from coupled redox reactions between the products and reactants are also observed. The wine preservatives were all highly reactive and thus all very protective against 3-sulfanylhexanol loss to the quinone, but showed only additive antioxidant effects. Confirmation of these reaction rates and pathways in wine is needed to assess the actual protective action of each tested preservative. © 2014 Elsevier Ltd. All rights reserved

High-Throughput 1H-Nuclear Magnetic Resonance-Based Screening for the Identification and Quantification of Heartwood Diterpenic Acids in Four Black Pine (Pinus nigra Arn.) Marginal Provenances in Greece

A high-throughput quantitative Nuclear Magnetic Resonance 1H-NMR method was developed and applied to screen the quantity of the diterpenic resin acids in the heartwood of black pine, due to the renewed scientific interest in their medicinal properties and use in various diseases treatment. The 260 samples were taken from Pinus nigra clones, selected from four provenances of the Peloponnese (Greece), participating in a 35-year-old clonal seed orchard. Total resin acids per dry heartwood weight (dhw) varied greatly, ranging from 30.05 to 424.70 mg/gdhw (average 219.98 mg/gdhw). Abietic was the predominant acid (76.77 mg/gdhw), followed by palustric acid (47.94 mg/gdhw), neoabietic acid (39.34 mg/gdhw), and pimaric acid (22.54 mg/gdhw). Dehydroabietic acid was at moderate levels (11.69 mg/gdhw), while levopimaric, isopimaric, and sandaracopimaric acids were in lower concentrations. The resin acid fraction accounted for 72.33% of the total acetone extractives. Stilbenes were presented in significant quantities (19.70%). The resin acid content was composed mainly of the abietane type resin acids (83.56%). Peloponnesian Pinus nigra heartwood was found to be the richest source of resin acids identified to date and is considered the best natural source for the production of such bioactive extracts. The results indicate a high potential for effective selection and advanced breeding of pharmaceutical and high economic value bioactive substances from Pinus nigra clones. © 2019 by the authors

Direct Analysis of Free and Sulfite-Bound Carbonyl Compounds in Wine by Two-Dimensional Quantitative Proton and Carbon Nuclear Magnetic Resonance Spectroscopy

Recent developments that have accelerated 2D NMR methods and improved quantitation have made these methods accessible analytical procedures, and the large signal dispersion allows for the analysis of complex samples. Few natural samples are as complex as wine, so the application to challenges in wine analysis look promising. The analysis of carbonyl compounds in wine, key oxidation products, is complicated by a multitude of kinetically reversible adducts, such as acetals and sulfonates, so that sample preparation steps can generate complex interferences. These challenges could be overcome if the compounds could be quantified in situ. Here, two-dimensional (1H-1H) homonuclear and heteronuclear (13C-1H) single quantum correlations (correlation spectroscopy, COSY, and heteronuclear single quantum coherence, HSQC) nuclear magnetic resonance spectra of undiluted wine samples were observed at natural abundance. These techniques achieve simultaneous direct identification and quantitation of acetaldehyde, pyruvic acid, acetoin, methylglyoxal, and α-ketoglutaric acid in wine with only a small addition of D2O. It was also possible to observe and sometimes quantify the sulfite, hydrate, and acetal forms of the carbonyl compounds. The accuracy of the method was tested in wine samples by spiking with a mixture of all analytes at different concentrations. The method was applied to 15 wine samples of various vintages and grape varieties. The application of this method could provide a powerful tool to better understand the development, evolution, and perception of wine oxidation and insight into the impact of these sulfite bound carbonyls on antimicrobial and antioxidant action by SO2. © 2015 American Chemical Society

S-(E)-Elenolide: a new constituent of extra virgin olive oil

BACKGROUND: Extra virgin olive oil is a food with a recognized health claim in the EU related to its phenolic content. Based on nuclear magnetic resonance (NMR) analysis, we observed for the first time that most high-phenolic olive oils also contain significant quantities of another potential beneficial ingredient, S-(E)-elenolide, which is a non-phenolic compound related to oleuropein or ligstroside. Elenolide had only been found in olive leaves and fruits as the Z isomer or had been synthesized and had been recognized as an antihypertensive agent. RESULTS: (E)-Elenolide was isolated from olive oil and its structure was elucidated and completely characterized for the first time using 1D and 2D NMR and gas chromatography–mass spectrometry. In addition, we developed a method of quantitative measurement based on qNMR. Investigation of 2120 olive oil samples showed that elenolide was present in the majority of samples, in quantities ranging from 0 to 2821 mg kg−1. Although elenolic acid, which is a hydrated derivative of elenolide, had been reported as an olive oil ingredient, this is the first time that elenolide has proved to be transformed to elenolic acid after reaction with water. Finally, it was found that the quantity of elenolide in olive oil depends on the quantity of water remaining in the olive oil during storage. CONCLUSION: S-(E)-Elenolide is a new important substance of olive oil and could be used as marker of high-quality oils with low water content. © 2019 Society of Chemical Industry. © 2019 Society of Chemical Industr