Expanding the Diversity of the Cyanobacterial Dialkylresorcinol Bartoloside Family

The cyanobacterial dialkylresorcinol bartolosides were initially reported to feature glycosylated and halogenated moieties. Later, biosynthetic and in vitro studies showed that the chlorinated alkyl chains are utilized for a nucleophilic substitution with free fatty acid carboxylates from primary metabolism, generating bartoloside esters. Here, we applied a workflow based on PCR screening coupled to LC-HRESIMS and molecular network analysis with the aim of discovering additional bartoloside diversity. We report the annotation of 27 bartoloside and bartoloside ester derivatives, including the characterization of two new bartolosides, underlining the breadth of structures generated by bartoloside biosynthetic pathways. Some of the herein reported bartolosides feature hydroxylation in their side chains, a modification that has not been associated with this metabolite family.