Maria Michela Salvatore

Secondary Metabolites of Mangrove-Associated Strains of Talaromyces

Boosted by the general aim of exploiting the biotechnological potential of the microbial component of biodiversity, research on the secondary metabolite production of endophytic fungi has remarkably increased in the past few decades. Novel compounds and bioactivities have resulted from this work, which has stimulated a more thorough consideration of various natural ecosystems as conducive contexts for the discovery of new drugs. Thriving at the frontier between land and sea, mangrove forests represent one of the most valuable areas in this respect. The present paper offers a review of the research on the characterization and biological activities of secondary metabolites from manglicolous strains of species belonging to the genus Talaromyces. Aspects concerning the opportunity for a more reliable identification of this biological material in the light of recent taxonomic revisions are also discussed.

Talarodiolide, a New 12-Membered Macrodiolide, and GC/MS Investigation of Culture Filtrate and Mycelial Extracts of Talaromyces pinophilus

Talarodiolide, a new 12-membered macrodiolide, was isolated and characterized from the culture filtrate of strain LT6 of Talaromyces pinophilus. The structure of (Z)-4,10-dimethyl-1,7-dioxa-cyclododeca-3,9-diene-2,8-dione was assigned essentially based on NMR and MS data. Furthermore, several known compounds were isolated and identified in the crude extract of the culture filtrate and mycelium of this strain. EI mass spectrum at 70 eV of all isolated metabolites was acquired and compiled in a custom GC/MS library to be employed to detect metabolites in the crude extracts.

Inhibitory effect of trichodermanone C, a sorbicillinoid produced by Trichoderma citrinoviride associated to the green alga Cladophora sp., on nitrite production in LPS-stimulated macrophages

Abstract From the green alga Cladophora sp. collected in Italy, the marine fungal strain A12 of Trichoderma citrinoviride was isolated, identified and characterized. LC-MS qTOF analysis was applied to perform a metabolic profile of the fungal culture. Chromatographic techniques and spectroscopic methods were used to isolate and characterize the major secondary metabolites produced by this strain in liquid culture. In particular, four known sorbicillinoids (trichodermanone C, spirosorbicillinol A, vertinolide and sorbicillin) were purified and identified, together with 2-phenylethanol and tyrosol. Moreover, metabolomic analysis allowed to detect small amounts of trichodimerol, rezishanone A, 2′,3′-dihydrosorbicillin and bisvertinol. For the first time a significant inhibitory effect on nitrite levels has been shown for trichodermanone C in lipopolysaccharide-stimulated J774A.1 macrophages.

Production of toxic metabolites by two strains of Lasiodiplodia theobromae, isolated from a coconut tree and a human patient

ABSTRACT Lasiodiplodia theobromae is a phytopathogenic fungus that causes diseases not only in a broad number of plant hosts but also occasionally in humans. The capacity of L. theobromae to produce bioactive metabolites at 25 C (environmental mean temperature) and at 37 C (body mean temperature) was investigated. Two strains, CAA019 and CBS339.90, isolated respectively from a coconut tree and a human patient were characterized. The phytotoxicity and cytotoxicity (on mammalian cells) of the secretomes of both strains of L. theobromae were investigated. Also, phytotoxicity and cytotoxicity of pure compounds were evaluated. The phytotoxicity of the secretome of strain CAA019 was higher than the phytotoxicity of the secretome of strain CBS339.90 at 25 C. However, the phytotoxicity for both strains decreased when they were grown at 37 C. Only the secretome of strain CBS339.90 grown at 37 C induced up to 90% Vero and 3T3 cell mortality. This supports the presence of different metabolites in the secretome of strains CAA019 and CBS339.90. Metabolites typical of L. theobromae were isolated and identified from organic extracts of the secretome of both strains (e.g., 3-indolecarboxylic acid, jasmonic acid, lasiodiplodin, four substituted 2-dihydrofuranones, two melleins, and cyclo-(Trp-Ala)). Also, metabolites such as scytalone, not previously reported for this species, were isolated and identified. Metabolite production is affected by strain and temperature. In fact, some metabolites are strain specific (e.g., lasiodiplodin) and some metabolites are temperature specific (e.g., jasmonic acid). Although more strains should be characterized, it may be anticipated that temperature tuning of secondary-metabolite production emerges as a putative contributing factor in the modulation of L. theobromae pathogenicity towards plants, and also towards mammalian cells.

Determination of Egg Number Added to Special Pasta by Means of Cholesterol Contained in Extracted Fat Using GC-FID

Pasta with eggs added (generally termed “special pasta” for Italian legislation) is made by adding no less than 4 eggs without shells (or no less than 200 g of liquid or lyophilized egg product) per kilogram of semolina, as provided by law. In this work, to determine the final content of eggs added to dough, an analytical procedure was developed for the rapid analysis of the cholesterol content in the finished pastas. The proposed procedure was simpler, faster, and more accurate than that of official methods of analysis based on the gravimetric determination of sterols. Moreover, the determination of the quality of fat content in the special pasta (egg pasta in this case) allowed the evaluation of its origin, avoiding possible fraud resulting from the addition of foreign fat as an alternative to fat derived from eggs. In this new gas chromatographic procedure, the internal standard squalene for the quantification of cholesterol was used because a more polar GC capillary column was used (RTX 65 TG-HT) for the separation of sterols, rather than 5% phenyl methylsilicone. The ratio between cholesterol and squalene allowed for the determination of the number of eggs added, while from analysis of the same gas chromatogram, it was also possible to evaluate the composition of triglycerides in the fat contained in the pasta, allowing discrimination of foreign fats with respect to fats contained in eggs and therefore avoiding adulteration of pasta. The same analytical procedure was applied to the determination of cholesterol content in lyophilized yolk.

Do You Know What the Buffer Capacity of Your pH Buffer Is

This paper develops the item of buffer capacity of pH buffers and targets chemists, biologists, physiologists or anyone who may be interested to become familiar with and develop a quantitative perception of factors controlling buffer capacity of aqueous solutions (which can be complex mixtures of acids and/or bases and/or ionic salts, as are commercial pH buffers in use in a variety of applications which require control of pH, or most biological fluids, e.g., blood). The fundamental idea of representing a pH buffer or a buffered biological fluid with a matrix constitutes the leitmotif of the suggested approach through which the boring complexity of a quantitative mathematical treatment of buffer capacity has been overcome. It is shown how the matrix representing a given pH buffer or biological fluid (from which a quantitative evaluation of pH and buffer capacity can be performed) can be built in a matter of minutes (regardless of their complexity) in a MS Excel sheet by employing an Excel library of custom functions which is made available as associated material to this paper. Furthermore, from the matrix representing the pH buffer or biological fluid a plot can be derived which is used as a graphical support for enlightening the chemical significance of the matrix and to connect the buffer capacity to the Acid-Base chemistry which takes place in the represented pH buffer or biological fluid.

Riboflavin (Vitamin B2) Assay by Adsorptive Cathodic Stripping Voltammetry (Adcsv) at the Hanging Mercury Drop Electrode (HMDE)

In this study the interactions of Riboflavin (Vitamin B2) with a mercury surface are investigated. Firstly, by using Cyclic Voltammetry, it is demonstrated that Riboflavin can be efficiently accumulated, by adsorption from buffered solutions containing an excess of NaClO4, onto the mercury drop of a HMDE. Secondly, it is shown that the adsorbed Riboflavin can be reduced through an electrochemical reaction whose stoichiometry is extricated by confronting simulated with experimental CV voltammograms acquired in a range of pH between about four and nine. Finally, the cathodic current, sustained by the surface reduction of Riboflavin, is exploited for assaying Riboflavin via Differential Pulse Adsorption Cathodic Stripping Voltammetry (DP AdCSV) within the frame of the standard additions calibration procedure. By applying the suggested DP AdCSV procedure with standard voltammetric equipment, typical DP settings and pre-electrolysis time of about 10 s, a linear response is maintained if Riboflavin concentration in the electrolysed solution does not exceed about 2 mg/l. On the other side, a limit of detection (expressed as the concentration of Riboflavin in the electrolysed solution) of 7 μg/l has been achieved with a pre-electrolysis time of 68 s.