RESUMO
Coffee is a popular beverage owing to its unique flavor and diverse health benefits. The current study aimed at investigating the antioxidant activity, in relation to the phytochemical composition, of authenticated Brazilian green and roasted Coffea arabica and C. robusta, along with 15 commercial specimens collected from the Middle East. Ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-ESI-HRMS) and UV spectrometry were employed for profiling and fingerprinting, respectively. With the aid of global natural product social molecular networking (GNPS), a total of 88 peaks were annotated as belonging to different chemical classes, of which 11 metabolites are reported for the first time in coffee seeds. Moreover, chemometric tools showed comparable results between both platforms, with more advantages for UV in the annotation of roasting products, suggesting that UV can serve as a discriminative tool. Additionally, antioxidant assays coupled with the UHPLC-ESI-HRMS dataset using partial least-squares discriminant analysis (PLS-DA) demonstrated that caffeoylquinic acid and caffeine were potential antioxidant markers in unroasted coffee versus dicaffeoyl quinolactone and melanoidins in roasted coffee. The study presents a multiplex metabolomics approach to the quality control of coffee, one of the most consumed beverages.
RESUMO
High-performance thin-layer chromatography (HPTLC) coupled with negative ion desorption electrospray ionization high-resolution mass spectrometry (DESI-HRMS) was used for the analysis of anthraquinones in complex crude extracts of Chilean dermocyboid Cortinarii. For this proof-of-concept study, the known anthraquinones emodin, physcion, endocrocin, dermolutein, hypericin, and skyrin were identified by their elemental composition. HRMS also allowed the differentiation of the investigated anthraquinones from accompanying compounds with the same nominal mass in the crude extracts. An investigation of the characteristic fragmentation pattern of skyrin in comparison with a reference compound showed, exemplarily, the feasibility of the method for the determination of these coloring, bioactive and chemotaxonomically important marker compounds. Accordingly, we demonstrate that the coupling of HPTLC with DESI-HRMS represents an advanced and efficient technique for the detection of anthraquinones in complex matrices. This analytical approach may be applied in the field of anthraquinone-containing food and plants such as Rheum spp. (rhubarb), Aloe spp., Morinda spp., Cassia spp. and others. Furthermore, the described method can be suitable for the analysis of anthraquinone-based colorants and dyes, which are used in the food, cosmetic, and pharmaceutical industry.
RESUMO
The Chilean Sepedonium aff. chalcipori strain KSH 883, isolated from the endemic Boletus loyo Philippi, was studied in a polythetic approach based on chemical, molecular, and biological data. A taxonomic study of the strain using molecular data of the ITS, EF1-α, and RPB2 barcoding genes confirmed the position of the isolated strain within the S. chalcipori clade, but also suggested the separation of this clade into three different species. Two new linear 15-residue peptaibols, named chilenopeptins A (1) and B (2), together with the known peptaibols tylopeptins A (3) and B (4) were isolated from the semisolid culture of strain KSH 883. The structures of 1 and 2 were elucidated on the basis of HRESIMS(n) experiments in conjunction with comprehensive 1D and 2D NMR analysis. Thus, the sequence of chilenopeptin A (1) was identified as Ac-Aib(1)-Ser(2)-Trp(3)-Aib(4)-Pro(5)-Leu(6)-Aib(7)-Aib(8)-Gln(9)-Aib(10)-Aib(11)-Gln(12)-Aib(13)-Leu(14)-Pheol(15), while chilenopeptin B (2) differs from 1 by the replacement of Trp(3) by Phe(3). Additionally, the total synthesis of 1 and 2 was accomplished by a solid-phase approach, confirming the absolute configuration of all chiral amino acids as l. Both the chilenopeptins (1 and 2) and tylopeptins (3 and 4) were evaluated for their potential to inhibit the growth of phytopathogenic organisms.