Xanalterate A, altertoxin VIII and IX, perylenequinone derivatives from antarctica-sponge-derived fungus Alternaria sp. HDN19-690

[Display omitted] •Chemical investigation of a marine-derived fungus Alternaria sp. HDN19-690 led to the isolation of three new perylenequinone derivatives.•Xanalterate A (1) possesses a unique pyran ring at E ring with only 4 cases have been reported so far and altertoxin VIII (2) is a third example of chlorinated perylenequinone derivative.•Compounds 1–4 showed broad antibacterial activity with compound 1 the best (MIC values ranging from 3.13 to 12.5 µM). Three new perylenequinone derivatives, namely xanalterate A (1), altertoxin VIII and IX (2 and 3), together with one known analogue, stemphyperylenol (4), were isolated from the extract of the Antarctic sponge-derived fungus Alternaria sp. HDN19-690. The structures of compounds 1–3, including absolute configurations, were confirmed based on the analysis of MS, NMR and ECD data. Compound 1 exhibited promising antimicrobial activity against the tested strains with MIC values ranging from 3.13 to 12.5 µM.