Antimicrobial Isochroman‐Derived Atropo‐Diastereomeric Dimers from Penicillium Steckii SCISO 41228

Abstract A pair of unidentified atropo‐diastereomeric dimers, penicisteckins G ( 1 ) and H ( 2 ), and twelve known compounds ( 3 – 16 ) were isolated from the marine coral‐derived fungus Penicillium steckii SCISO 41228. Their structures including the absolute configuration were determined by HR‐ESI‐MS, ECD, 1D‐, and 2D‐NMR spectra. Compounds 1 and 2 exhibited moderate antibacterial activity against most tested pathogenic strains, especially for methicillin‐resistant Staphyloccocus aureus (MASA) and Micrococcus luteus , with MIC values of 4.0 μ g mL −1 . In addition, compounds 2 and 3 exhibit potent radical scavenging activity against 2,2‐diphenyl‐1‐picrylhydrazylhydrate (DPPH), with IC 50 values of 10.76 and 8.66 μ g mL −1 , respectively.