New bioactive chlorinated cyclopentene derivatives from the marine-derived Fungus Phoma sp

The new halogenated metabolites cryptophomic acid (1), cryptodiol (2), and cryptotriol (3) and the known dihydro-isocoumarin derivative 4, were isolated from the marine-derived fungus Phoma sp.135. The structural elucidation of these compounds was achieved by extensive analysis of spectroscopic data including 1D- and 2D-NMR, HRMS, optical rotation, UV, and IR. The absolute configuration of cryptophomic acid (1) was determined by using circular dichroism and TD-DFT ECD calculations of the solution conformers. The relative configurations of cryptodiol (2) and cryptotriol (3) were elucidated by a detailed analysis of the spectroscopic data and quantum mechanical calculation of NMR chemical shifts, based also on the newly reported + approach. The dihydro-isocoumarin derivative 4 was also produced by the same fungus and its structure was established as (R)-8-hydroxy-6-methoxy-3-methy-3,4-dihydro-isocoumarin (4), often referred to 6-methoxymellein and its chemical structure and absolute configuration were further confirmed through X-ray diffraction analysis. We report here the new compounds 1–3 and the crystallographic data of compound 4 for the first time. Additionally, we report significant antimicrobial activity of compounds 1–3 against Escherichia coli, Bacillus subtilis, Mycobacterium phlei, and Staphylococcus aureus and they showed no lethality against brine shrimp.