Thirty-two fungal polyketide derivatives, including eleven new compounds, namely (3
R,5′
R)-5-hydroxytalaroflavone (
1), talaroisochromenols A–C (
3,
5, and
11), (8
R,9
R,10a
R)-5-hydroxyaltenuene (
13), (8
R,9
R,10a
S
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Thirty-two fungal polyketide derivatives, including eleven new compounds, namely (3
R,5′
R)-5-hydroxytalaroflavone (
1), talaroisochromenols A–C (
3,
5, and
11), (8
R,9
R,10a
R)-5-hydroxyaltenuene (
13), (8
R,9
R,10a
S)-5-hydroxyaltenuene (
14), (8
R,9
S,10a
R)-5-hydroxyaltenuene (
15), nemanecins D and E (
25 and
26), 2,5-dimethyl-8-iodochromone (
27), and talarofurolactone A (
29), together with one new naturally occurring but previously synthesized metabolite, 6-hydroxy-4-methoxycoumarin (
28), were isolated and identified from the deep-sea cold-seep-derived fungus
Talaromyces sp. CS-258. Among them, racemic ((±)-
11) or epimeric (
13–
15,
25, and
26) mixtures were successfully separated by chiral or gradient elution HPLC. Meanwhile, compound
27 represents a rarely reported naturally occurring iodinated compound. Their planar structures as well as absolute configurations were determined by extensive analysis via NMR, MS, single-crystal X-ray diffraction, Mosher’s method, and ECD or NMR calculation (with DP4
+ probability analysis). Possible biosynthetic routes of some isolated compounds, which are related to chromone or isochromone biosynthetic pathways, were put forward. The biological analysis results revealed that compounds
7,
9, 10, 18–
22,
24,
30, and
31 showed broad-spectrum antibacterial activities against several human and aquatic pathogens with MIC ranges of 0.5–64 μg/mL.
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