A Chemical Investigation Approach of Paraconiothyrium sp. FKR-0637 Fungal Strain Enables the Isolation of New Chlorinated Chromone, Nohocumone

The discovery of novel natural products (NPs) from diverse microorganisms is essential for advancing drug discovery. In this study, a chemical investigation approach was employed for NP exploration using the genus Paraconiothyrium sp. isolated from the root soil of Ficus microcarpa on Noho Island, Okinawa. Consequently, we isolated five compounds, including a new chromone, nohocumone (1), as well as four known compounds, known chromone (2), 10-norparvulenone (3), sclerotinin A (4), and calbistrin A (5), from the culture broth of Paraconiothyrium sp. FKR-0637. The planar structure of 1 was elucidated using 1D and 2D NMR analyses, HR-ESIMS, and chemical derivatization. Chlorinated chromone 1 is a novel compound that was not previously isolated from Paraconiothyrium sp. These results expand the structural diversity and collection of NPs obtained from the culture broth of Paraconiothyrium sp.