Prenylemestrins A and B: Two Unexpected Epipolythiodioxopiperazines with a Thioethanothio Bridge from Emericella sp. Isolated by Genomic Analysis

Cytotoxic hexadepsipeptides and anti-coronaviral 4-hydroxy-2-pyridones from an endophytic Fusarium sp

Three new hexadepsipeptides (1-3), along with beauvericin (4), beauvericin D (5), and four 4-hydroxy-2-pyridone derivatives (6-9) were isolated from the endophytic fungus Fusarium sp. CPCC 400857 that derived from the stem of tea plant. Their structures were determined by extensive 1D and 2D NMR, and HRESIMS analyses. The absolute configuration of hexadepsipeptides were elucidated by the advanced Marfey's method and chiral HPLC analysis. Compounds 4, and 7-9 displayed the cytotoxicity against human pancreatic cancer cell line, AsPC-1 with IC₅₀ values ranging from 3.45 to 29.69 μM, and 7 and 8 also showed the antiviral activity against the coronavirus (HCoV-OC43) with IC₅₀ values of 13.33 and 6.65 μM, respectively.

Asperemestrins A-D, Emestrin Hybrid Polymers with Bridged Skeletons from the Endophytic Fungus Aspergillus nidulans

Four emestrin hybrid polymers, asperemestrins A-D (1-4, respectively), were isolated from the fungus Aspergillus nidulans. Asperemestrins A-C are the first examples of emestrin-sterigmatocystin heterodimers bearing a 7/5/6/6/5/5/6/6/6 nonacyclic system with a 2,5-diazabicyclo[2.2.2]octane-3,6-dione core, while asperemestrin D features an unprecedented 2,15-dithia-17,19-diazabicyclo[14.2.2]icosa-4,8-diene-12,18,20-trione core skeleton. Their structures were determined by extensive spectroscopic data, electronic circular dichroism calculations, and single-crystal X-ray diffraction. Asperemestrin B showed moderate cytotoxicity against cancer cell lines, including SU-DHL-2, HEPG2, and HL-60.

Hot off the Press

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as hyjapone A from Hypericum japonicum.