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- Do bioactive carotenoids contribute to the color of edible mushrooms?Publication . Ribeiro, Bárbara; Pinho, Paula Guedes de; Andrade, Paula B.; Oliveira, Carla; Ferreira, António César Silva; Baptista, Paula; Valentão, PatríciaCarotenoids are biologically active phytochemicals present as micro-components in fruits and vegetables, being responsible for their yellow, orange and red colors. The chromatographic behavior and the UV absorption spectrum provided by HPLC-DAD analysis constitute the clues for their identification. Mushrooms are of increasing importance in modern nutrition and medicine, due to the presence of metabolites with pharmacological potential. In this work, samples of wild and commercial mushroom species (Agaricus bisporus, Amanita caesarea, Amanita rubescens, Boletus edulis, Cantharellus cibarius, Fistulina hepatica, Hydnum rufescens, Hygrophorus agathosmus, Pholiota nameko, Pleurotus ostreatus, Russula cyanoxantha, Suillus bellini, Suillus bovinus, Suillus granulatus, Suillus luteus, Tricholoma equestre and Tricholoma portentosum) were screened by HPLC-DAD for the presence of carotenoids. By applying this methodology to 22 samples, comprising either lyophilized or fresh materials, only β-carotene was found and just in C. cibarius species. The occurrence of this pigment in other three of the analyzed species previously described raises some questions about the methodology used.
- Volatile biomarkers for wild mushrooms species discriminationPublication . Malheiro, Ricardo; Pinho, Paula Guedes de; Soares, Sandra; Ferreira, António César Silva; Baptista, PaulaSecondary metabolites present in the volatile fraction of six wild mushroom species (Clitocybe odora, Clitocybe fragrans, Hebeloma crustuliniforme, Lepista nuda, Tricholoma fracticum and Tricholoma terreum) were studied, as an attempt to identify compounds capable to distinguish mushroom species for taxonomic and authentication purposes. Volatiles were assessed by headspace solid phase microextraction (HS-SPME) and by gas chromatography/ion-trap mass-spectrometry (GC/IT-MS). By using target analysis, 46 volatiles were grouped in 5 chemical classes: alcohols, aldehydes, ketones, sesquiterpene-like compounds and terpenes. Each species revealed a unique volatile profile, with changes in the dominant chemical class. Aliphatic compounds with eight carbon atoms, such as 3-octanol, 1-octanol and 3-octanone were the most abundant. The non-target approach application, using all HS-SPME-GC-MS data (raw chromatograms) aims to detect a large number of compounds to get a fingerprint of each sample. This procedure, involving previous data treatments as chromatogram data alignments, sample data fingerprints, and multivariate analysis, represents a powerful tool to execute an initial screening of the analytical results, enabling a faster interpretability of the results without time-consuming through identifications and quantifications. Unsupervised signal decomposition techniques such as principal component analysis (PCA) applied both to targeted and non-targeted approaches revealed 11 volatile compounds (3-octanol, 3-octanone, linalool, 1-octanol, 1-pentanol, (E)-2-octen-1-ol, hexanol, hexanal, (E)-2-octenal, rho-anisaldehyde and sesquiterpene-like compound) in common with an important discriminating power, suggesting that those compounds can play a crucial biomarker role in the characterization of the six wild species of mushrooms.
- Non-targeted and targeted analysis of wild toxic and edible mushrooms using gas chromatography–ion trap mass spectrometryPublication . Carvalho, Luís Miguel; Carvalho, Félix; Bastos, Maria de Lourdes; Baptista, Paula; Moreira, Nathalie; Monforte, Ana Rita; Silva, Ferreira António César; Pinho, Paula Guedes deMushrooms are known all over the world both due to the remarkable gastronomic value of some species and for severe intoxications mediated by other species that are frequently difficult to distinguish from the edible ones, by the common user. Therefore, it is important to develop strategies to discover molecules that can identify mushroom species. In the present work, two GC-MS methodologies were applied in the chemical characterization of 22 mushroom species (12 edible, 3 toxic and 7 potentially toxic) - a multi-target procedure to simultaneously determine amino acids (AA), fatty acids (FA) and sterols by previous derivatization procedure with MSTFA, and a Head Space-Solid Phase Microextraction method to determine volatiles. For both methods, two approaches to data analysis were used: (I) targeted analysis, to identify and quantify AA, FA sterols and volatiles; (II) untargeted analysis, including Principal Component Analysis and Partial Least Square Discriminant Analysis, in order to identify metabolites/metabolite pattern with potential species identification and/or differentiation. Multi-target experiment allowed the identification and quantification of twenty one primary metabolites (9 AA, 11 FA and 1 sterol). Furthermore, through untargeted data analysis, it was possible to identify a 5-carbon sugar alcohol structure molecule, which was tentatively identified as xylitol or adonitol, with potential to be a species-marker of the edible Suillus bovinus mushrooms. Volatile profiling studies resulted in the identification of the main volatiles in mushrooms. Untargeted analysis allowed the identification of 6 molecules that can be species- or genus-specific: one secondary metabolite specific to the edible species Lycoperdon perlatum, an ester of hexanoic acid, tentatively identified as allyl or vinyl caproate; and five other secondary metabolites, whose identification was not achieved, which were only detected in Lactarius aurantiacus specimens (edibility/toxicity unknown).