Penicisteckins A–F, Isochroman-Derived Atropisomeric Dimers from <i>Penicillium steckii</i> HNNU-5B18
Xiaozhen Wu, Wen‐Jun Huang, Wei Liu, Attila Mándi, Qingbo Zhang, Liping Zhang, Wenjun Zhang, Tibor Kurtán, Chengshan Yuan, Changsheng Zhang
Abstract
Penicisteckins A–D ( 1 – 4 ), two pairs of atropodiastereomeric biaryl-type hetero- and homodimeric bis-isochromans with 7,5′- and 7,7′-linkages and a pair of atropodiastereomeric 2-(isochroman-5-yl)-1,4-benzoquinone derivatives [penicisteckins E ( 5 ) and F ( 6 )], were isolated from the Penicillium steckii HNNU-5B18. Their structures including the absolute configuration were determined by extensive spectroscopic and single-crystal X-ray diffraction analysis and TDDFT-ECD calculations. Both the bis-isochromans and the isochroman/1,4-benzoquinone conjugates represent novel biaryl scaffolds containing both central and axial chirality elements. The monomer anserinone B ( 8 ) exhibited potent antibacterial activities against Staphylococcus aureus ATCC 29213 and methicillin-resistant Staphylococcus aureus with minimal inhibition concentration values ranging from 2 to 8 μg mL –1 . Plausible biosynthetic pathways of 1 – 6 are proposed, which suggest how the absolute configurations of the isolates were established during the biosynthetic scheme.