Acetylcholinesterase inhibitors from a marine fungus Talaromyces sp. strain LF458.

Two new oxaphenalenone dimers, talaromycesone A (1) and talaromycesone B (2), and a new isopentenyl xanthenone, talaroxanthenone (3), together with six known diphenyl ether derivatives, e.g., Δ(1',3'),-1'-dehydroxypenicillide (4), 1',2'-dehydropenicillide (5), vermixocin A (6), vermixocin B (7), 3'-methoxy-1'2'-dehydropenicillide (8), and AS-186c (9), were isolated from the culture broth and mycelia of a marine fungus Talaromyces sp. strain LF458. Compound 2 represents the first example of 1-nor oxaphenalenone dimer carbon skeleton. All isolated compounds were subjected to bioactivity assays. Compounds 1, 2, and 9 exhibited potent antibacterial activities with IC50 3.70, 17.36, and 1.34 µM, respectively, against human pathogenic Staphylococcus strains. Compounds 1, 3, and 9 displayed potent acetylcholinesterase inhibitory activities with IC50 7.49, 1.61, and 2.60 µM, respectively. Interestingly, phosphodiesterase PDE-4B2 was inhibited by compounds 3 (IC50 7.25 µM) and 9 (IC50 2.63 µM).

Spirocyclic drimanes from the marine fungus Stachybotrys sp. strain MF347.

A novel spirocyclic drimane coupled by two drimane fragment building blocks 2 and a new drimane 1 were identified in mycelia and culture broth of Stachybotrys sp. MF347. Their structures were established by spectroscopic means. This is the first example of spirocyclic drimane coupled by a spirodihydrobenzofuranlactam unit and a spirodihydroisobenzofuran unit; and the connecting position being N-C instead of an N and N connecting unit. Strain MF347 produced also the known spirocyclic drimanes stachybocin A (12) and stachybocin B (11) featured by two sesquiterpene-spirobenzofuran structural units connected by a lysine residue; the known spirocyclic drimanes chartarlactam O (5); chartarlactam K (6); F1839A (7); stachybotrylactam (8); stachybotramide (9); and 2α-acetoxystachybotrylactam acetate (10); as well as ilicicolin B (13), a known sesquiterpene. The relative configuration of two known spirobenzofuranlactams (3 and 4) was determined. All compounds were subjected to biological activity tests. The spirocyclic drimane 2, 11, and 12, as well as the sesquiterpene 13, exhibited antibacterial activity against the clinically relevant methicillin-resistant Staphylococcus aureus (MRSA).

Two new antibiotic pyridones produced by a marine fungus, Trichoderma sp. strain MF106.

Two unusual pyridones, trichodin A (1) and trichodin B (2), together with the known compound, pyridoxatin (3), were extracted from mycelia and culture broth of the marine fungus, Trichoderma sp. strain MF106 isolated from the Greenland Seas. The structures of the new compounds were characterized as an intramolecular cyclization of a pyridine basic backbone with a phenyl group. The structure and relative configuration of the new compounds were established by spectroscopic means. The new compound 1 and the known compound 3 showed antibiotic activities against the clinically relevant microorganism, Staphylococcus epidermidis, with IC50 values of 24 µM and 4 µM, respectively.