Discovery and Bioactivity Evaluation of Citrinin Derivatives from the Mangrove Sediment‐Derived Fungus Talaromyces sp. SCSIO 41428

Abstract A dimeric citrinin derivative with a unique spiro[chroman‐2,3′‐isochroman] skeleton, xerucitrinic acid C ( 1 ), and a new citrinin derivative, cladosporin E ( 6 ), along with ten known polyketides ( 2 – 5 and 7 – 12 ), were isolated from the mangrove sediment‐derived fungus Talaromyces sp. SCSIO 41428. Their structures were elucidated through comprehensive spectral data analysis. The absolute configurations of 1 and 6 were determined by quantum chemical calculations. Compound 1 exhibited significant inhibitory effects on Staphylococcus aureus and Streptococcus suis , with the MIC of 25 μ g/mL for both bacterial strains. Xerucitrinin C ( 3 ) exhibited significant radical scavenging activity against DPPH, with an IC 50 value of 25.4 μ M, and also demonstrated inhibitory activity against phosphodiesterase‐4 (PDE4). Moreover, cladosporin C ( 7 ) notably inhibited prostate cancer cells PC‐3 and 22Rv1, with IC 50 values of 6.10 and 9.25 μ M, respectively.