Exploring the chemodiversity of antimicrobial minalemines from Didemnum granulatum by neutral loss graph

In this study, we report on the identification of the active antimicrobial principles from the tunicate Didemnum granulatum. Two new natural products, minalemines G (1) and H (2), were isolated and their structures were elucidated. Both compounds showed potent antibacterial activity, with compound 1 showing sub-microgram inhibition against Staphylococcus aureus. Moreover, we also report a new mass spectrometry-based approach, named neutral loss graph, developed to explore minor metabolites from complex mixtures. This approach was applied here to reveal twelve additional minalemine analogues in the organic extract of D. granulatum.