Delitpyrones: α-Pyrone Derivatives from a Freshwater Delitschia sp.

In research focused on the discovery of new chemical diversity from freshwater fungi, a peak library was built and evaluated against a prostate cancer cell line, E006AA-hT, which was derived from an African American, as this population is disproportionately affected by prostate cancer. The chemical study of the bioactive sample accessioned as G858 ( sp.) led to the isolation of eight new -pyrone derivatives (1:  - 7: , and 11: ), as well as the new 3,4-7-ethyl-4,8-dihydroxy-3,6-dimethoxy-3,4-dihydronaphthalen-1()-one (15: ). In addition, the known compounds 5-(3--hydroxybutyl)-4-methoxy-6-methyl-2-pyran-2-one (8: ), 5-(3-oxobutyl)-4-methoxy-6-methyl-2-pyran-2-one (9: ), pyrenocine I (10: ), 5-butyl-6-(hydroxymethyl)-4-methoxy-2-pyran-2-one (12: ), sporidesmin A (13: ), 6-ethyl-2,7-dimethoxyjuglone (14: ), artrichitin (16: ), and lipopeptide 15G256 (17: ) were also obtained. The structures of the new compounds were elucidated using a set of spectroscopic (NMR) and spectrometric (HRMS) methods. The absolute configuration of the most abundant member of each subclass of compounds was assigned through a modified Mosher's ester method. For 15: , the relative configuration was assigned based on analysis of values. Compounds 1, 2, 5:  - 14, 16: , and 17: were evaluated against the cancer cell line E006AA-hT under hypoxic conditions, where compound 13: inhibited cell proliferation at a concentration of 2.5 µM.