RESUMEN
Molecular networking (MN) can efficiently dereplicate extracts and pure compounds. Red algae of the genus Laurencia are rich in halogenated secondary metabolites, mainly sesquiterpenes and C15-acetogenins. Brown algae of the genus Dictyopteris produce mainly C11-hydrocarbons, sesquiterpenes and sulfur-containing compounds, while Dictyota and Canistrocarpus are reported to contain mainly diterpenes. This study performs an exploratory MN analysis of 14 extracts from algae collected in Brazil (including the oceanic islands) and characterizes the secondary metabolites from the analyzed species. The extracts and some isolated metabolites were analyzed by LC-MS using the FastDDA algorithm, and the MS/MS spectra were submitted to GNPS and displayed in Cytoscape 3.5.1. The GNPS platform generated 68 individual nodes and nine family networks. The MN exploratory analysis indicated chemical differences among species, and also in sampling sites for the same species. For some extracts, it was possible to identify mass values that could correspond to terpenoids and C15-acetogenins that have already been isolated from those or related species. An interesting chemodiversity was highlighted between Laurencia catarinensis from two nearby islands, and this was revealed and was also suggested by the family networks. Many nodes in the MN could not be characterized, and these metabolites can be used as targets for isolation in future works.
RESUMEN
Abstract Acetogenins are secondary metabolites derived from the polyketide pathway and their potential role as chemotaxonomical markers for red algae belonging to the Laurencia complex has been long pointed out. C15 acetogenins from algae are quite different from plant acetogenins: they are usually halogenated, and have an enyne or a bromoallene terminal group. Since they were first reported, laurencin and other algal acetogenins have inspired great curiosity among natural product chemists and also those working with synthesis. This paper reviews the literature about C15 acetogenins, focusing on their distribution, chemical and biological aspects, including their reported biological activities.