Continuation of a study into the chemistry of the brown alga Notheia anomala has resulted in the isolation and structure elucidation of six new C21 lipids. These include the first reported occurrence of a secondary metabolite (3), O-acylated by arachidonic acid, along with three new bisepoxy lipids (4)-(6), and two novel trisepoxy lipids (7) and (8). The structures were secured by detailed spectroscopic analysis and chemical degradation.
A chemical profiling/dereplication exercise, involving the use of HPLC-NMR and mass spectrometry in combination with the MarinLit database, was conducted on the crude dichloromethane extract of the southern Australian marine brown alga Cystophora torulosa. This strategy was successful in identifying a total of nine secondary metabolites representing two principle structure classes, including seven resorcinol (1–7) and two polyene derivatives (8 and 9). Validation of this on-line dereplication strategy was supported by the isolation and complete 2D NMR assignment of the major secondary metabolite (1). This methodology was concluded to be suitable for the rapid on-line identification of the resorcinol and polyene structure classes that are frequently encountered in the genus Cystophora.
From the brown alga Dilophus ligulatus a new secondary metabolite with antimicrobial activity, crenuladial 4, has been isolated and its structure determined.
HPLC-NMR Chemical Profiling and Dereplication Studies of the Marine Brown Alga, Cystophora torulosa
