Antibacterial Sterigmatocystin Derivatives From <i>Humicola</i> sp. MN006389.1 Associated With <i>Gardenia Jasminoides</i>

The bioactive metabolites produced by the fungal strain Humicola sp. MN006389.1, isolated from fresh Gardenia jasminoides blossoms, were investigated. This study led to the identification of a novel sterigmatocystin derivative named 4-methoxysterigmatocystin (1), along with two known analogues: sterigmatocystin (2) and acyl-hemiacetal sterigmatocystin (3). Structure elucidation of the isolated compounds was achieved with nuclear magnetic resonance (NMR) spectroscopy, high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), and X-ray crystallographic data. Notably, compound 1 demonstrated significant antibacterial activity against B. subtilis and S. aureus (MIC values of 4 µg/mL), while compound 3 displayed antibacterial activity against E. coli and B. subtilis with MIC values of 4 and 16 µg/mL, respectively.