Chemical Profiling (HPLC-NMR HPLC-MS) Isolation and Identification of Bioactive Meroditerpenoids from the Southern Australian Marine Brown Alga Sargassum paradoxum

摘要

A phytochemical investigation of a southern Australian marine brown alga, Sargassum paradoxum, resulted in the isolation and identification of four new (>5, >9, >10, and >15) and nine previously reported (>1, >2, >6–>8, and >11–>14) bioactive meroditerpenoids. HPLC-NMR and HPLC-MS were central to the identification of a new unstable compound, sargahydroquinal (>9), and pivotal in the deconvolution of eight (>1, >2, >5–>7, and >10–>12) other meroditerpenoids. In particular, the complete characterization and identification of the two main constituents (>1 and >2) in the crude dichloromethane extract was achieved using stop-flow HPLC-NMR and HPLC-MS. This study resulted in the first acquisition of gHMBCAD NMR spectra in the stop-flow HPLC-NMR mode for a system solely equipped with a 60 μL HPLC-NMR flow cell without the use of a cold probe, microcoil, or any pre-concentration.