Nangallenes A and B, halogenated nonterpenoid C15-acetogenins from the Bornean red alga Laurencia nangii

Two new halogenated nonterpenoids C-15-acetogenins, nangallenes A-B (1-2), together with two known halogenated compounds itomanallene A (3) and 2,10-dibromo-3-chloro-alpha-chamigrene (4), were isolated and identified from the organic extract of the marine red alga Laurencia nangii Masuda collected from the coastal waters in Semporna, Borneo. Their structures were established by means of spectroscopic analysis including IR, high-resolution electrospray ionization mass spectrometry (HRESI-MS), and 1D and 2D NMR techniques. All these metabolites were submitted for the antifungal assay against four species of selected marine fungi. Compounds 1-4 showed potent activity against Haliphthoros sabahensis and Lagenidium thermophilum.