New Citrinin and Coumarin Derivatives from a Marine-Derived Penicillium sp. RCDB006

One new citrinin derivative (1) and four new coumarins (2–5), along with seven known compounds, were isolated from a deep-sea-derived fungus Penicillium sp. RCDB006 in the sediments of the Diamantina Fracture Zone, the second deepest trench in the Indian Ocean. Comprehensive spectroscopic analyses (NMR and HRESIMS) established the planar structures. Furthermore, the absolute configurations of compounds 1–5 were assigned by comparing experimental and calculated ECD data, alongside X-ray crystallographic analysis. These compounds were evaluated for antibacterial and antiproliferative activities against a panel of Gram-positive and Gram-negative bacteria, as well as two cancer cell lines. Compound 9 exhibited modest bactericidal activity and also inhibited the growth of human acute myeloid leukemia (MV4–11) and colorectal cancer (SW620) cells with IC50 values of 34.36 and 36.50 μM, respectively.