(±)-Usphenethylones A–C, three pairs of heterodimeric polyketide enantiomers from Aspergillus ustus 3.3904. Issue 3 (6th January 2022) - Peng, Xiaogang
Abstract : Usphenethylones A–B (1–2 ) feature a 2, 6, 18-trioxa-tetracyclo-[8.8.0.0 3, 8 .0 11, 16 ]octadecane core and usphenethylone C (3 ) possesses a special 2-phenyl-3, 4-dihydro-pyrano[4, 3- b ]pyran-5-one scaffold. Abstract : Three pairs of new heterodimeric polyketide enantiomers, (±)-usphenethylones A–C (1–3 ), were isolated from the culture extract of Aspergillus ustus 3.3904. Compounds 1–3 present two heterodimerization patterns by a phenylethyl unit connected to an α-pyrone moiety, of which usphenethylones A–B (1–2 ) feature a 2, 6, 18-trioxa-tetracyclo-[8.8.0.0 3, 8 .0 11, 16 ]octadecane core and usphenethylone C (3 ) possesses a 2-phenyl-3, 4-dihydro-pyrano[4, 3- b ]pyran-5-one scaffold. The structures of (±)-1–3 were elucidated based on spectroscopic data analyses, and their absolute configurations were determined by single-crystal X-ray diffraction analysis and ECD calculation. Plausible biosynthetic pathways for 1–3 were proposed. Compounds (+)-3 and (−)-3 exhibited moderate inhibitory effects against ConA-induced T cell and LPS-induced B cell proliferation.