Three pairs of new isopentenyl dibenzo[b,e]oxepinone enantiomers, (+)-(5S, and a new isopentenyl dibenzo [b,e]oxepinone, arugosin N (4), were isolated from a wetland soil-derived fungus Talaromyces flavus, along with two known biosyntheticallyrelated compounds 5 and 6. Among them, arugosin N (4) and 1,6,10-trihydroxy-8-methyl-2-(3-methyl-2-butenyl)-dibenz[b,e]oxepin-11(6H)-one (CAS: 160585-91-1, 5) were obtained as the tautomeric mixtures. The structures of isolated compounds were determined by detailed spectroscopic analysis. In addition, the absolute configurations of these three pairs of new enantiomers were determined by quantum chemical ECD calculations.

Two new coumarins, talacoumarins A (1) and B (2), were isolated from the ethyl acetate extract of the wetland soil-derived fungus Talaromyces flavus BYD07-13. Their structures were elucidated by spectroscopic data (NMR, MS) analyses. The absolute configuration of C-12 in 1 was assigned using the modified Mosher's method, whereas that of C-12 in 2 was deduced via the circular dichroism data of its corresponding [Rh2(OCOCF3)4] complex. Compounds 1 and 2 were evaluated for their anti-Aβ42 aggregation, cytotoxic, and antimicrobial activities. The results showed that the two compounds had moderate anti-Aβ42 aggregation activity, and this is the first report on the Aβ42 inhibitory aggregation activity of coumarins.

Talaflavuterpenoid A (1), a new nardosinane-type sesquiterpene, was isolated from the wetland soil-derived fungus Talaromyces flavus BYD07-13, and its structure was elucidated on the basis of HR-MS, NMR, and X-ray diffraction analysis. The absolute configuration of 1 was established by comparing the experimental electronic circular dichroism (ECD) spectrum with the calculated ECD spectra. Its cytotoxic effects on five human tumor cell lines (HL-60, SMMC-7721, A-549, MCF-7, and SW480), and antimicrobial activity against Escherichia coli, Staphylococcus aureus, Candida albicans, and Aspergillus niger were evaluated. This is the first report of the presence of nardosinane-type sesquiterpene in Talaromyces sp.