Meroterpenes from an algicolous strain of Penicillium echinulatum

One new meroterpene, arisugacin K (1), and four known ones, arisugacin J (2), arisugacin G (3), arisugacin C (4), and territrem C (5), were isolated from the culture of Penicillium echinulatum pt‐4, an endophytic fungus isolated from the marine red alga Chondrus ocellatus. The structure and the absolute configuration of 1 were unambiguously elucidated by spectroscopic analyses and quantum chemical calculations, which further resulted in the assignments of absolute configurations for the other arisugacins and territrems. Compound 1 showed inhibitory activity against Escherichia coli with an inhibition diameter 8 mm at 30 µg/disk and 4 exhibited lethality against Artemia salina with an LC50 of 48.6 µg/ml. Copyright © 2014 John Wiley & Sons, Ltd. One new meroterpene (1) along with four known ones (2–5) was isolated from the culture of an alga‐endophytic strain of Penicillium echinulatum and identified by the analysis of 1D and 2D NMR, electronic circular dichroism, and mass spectra.