A Chemical Investigation Approach of the Paraconiothyrium sp. FKR-0637 Fungal Strain Enables the Isolation of the 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 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 were elucidated using 1D and 2D NMR analyses, HR-ESI-MS, and chemical derivatization. Chlorinated chromone 1 is a novel compound that was not previously isolated from Paraconiothyrium sp. These results contribute to expanding the structural diversity and collection of NPs that can be obtained from the culture broths of Paraconiothyrium sp.