Plants of the Allium genus produce sulphur compounds that give them a characteristic (alliaceous) flavour and mediate for their medicinal use. In this study, the chemical composition and antimicrobial properties of Allium cepa red cv. and A. sativum in the context of three different drying processes were assessed using metabolomics. Bulbs were dried using either microwave, air drying, or freeze drying and further subjected to chemical analysis of their composition of volatile and non-volatile metabolites. Volatiles were collected using solid phase micro-extraction (SPME) coupled to gas chromatography–mass spectrometry (GC/MS) with 42 identified volatiles including 30 sulphur compounds, four nitriles, three aromatics, and three esters. Profiling of the polar non-volatile metabolites via ultra-performance liquid chromatography coupled to high resolution MS (UPLC/MS) annotated 51 metabolites including dipeptides, flavonoids, phenolic acids, and fatty acids. Major peaks in GC/MS or UPLC/MS contributing to the discrimination between A. sativum and A. cepa red cv. were assigned to sulphur compounds and flavonoids. Whereas sulphur conjugates amounted to the major forms in A. sativum, flavonoids predominated in the chemical composition of A. cepa red cv. With regard to drying impact on Allium metabolites, notable and clear separations among specimens were revealed using principal component analysis (PCA). The PCA scores plot of the UPLC/MS dataset showed closer metabolite composition of microwave dried specimens to freeze dried ones, and distant from air dried bulbs, observed in both A. cepa and A. sativum. Compared to GC/MS, the UPLC/MS derived PCA model was more consistent and better in assessing the impact of drying on Allium metabolism. A phthalate derivative was found exclusively in a commercial garlic preparation via GC/MS, of yet unknown origin. The freeze dried samples of both Allium species exhibited stronger antimicrobial activities compared to dried specimens with A. sativum being in general more active than A. cepa red cv.

A new multicomponent methodology for the solution- and solid-phase macrocyclization of peptides is described. The approach comprises the utilization of the Ugi-Smiles reaction for the cyclization of 3-nitrotyrosine-containing peptides either by the N-terminus or the lysine side-chain amino groups. Both the on-resin and solution cyclizations took place with good to excellent efficiency in the presence of an aldehyde and a lipidic isocyanide, while the use of paraformaldehyde required an aminocatalysis-mediated imine formation prior to the on-resin Ugi-Smiles ring closure. The introduction of a turn motif in the peptide sequence facilitated the cyclization step, shortened the reaction time, and delivered crude products with >90% purity. This powerful method provided a variety of structurally novel N-aryl-bridged cyclic lipopeptides occurring as single atropisomers.

A multicomponent macrocyclization strategy towards cyclic lipopeptides is described. The approach relies on the utilization of the Ugi and Passerini multicomponent reactions for the cyclization of peptides and oxo-peptides, and here it is employed for the construction of a small library of analogues of the natural products mycosubtilin and surfactin A. A key feature of this method is the simultaneous incorporation of either one or two exocyclic lipid tails along with the macrocyclic ring closure, which is only possible due to the multicomponent nature of the macrocyclization step. The evaluation of the anticancer activity of the lipopeptide library showed that the installation of a second lipid moiety in the surfactin scaffold leads to a more potent cytotoxicity in cancer cells. This is a new example of the multicomponent reaction potential in rapidly producing natural product analogues for biological screening.

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.

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.