Structural Diversity of New C₁₃-Polyketides Produced by <i>Chaetomium mollipilium</i> Cultivated in the Presence of a NAD⁺‑Dependent Histone Deacetylase Inhibitor

Cultivation of Chaetomium mollipilium with nicotinamide, a NAD+-dependent HDAC inhibitor, stimulated its secondary metabolism, leading to the isolation of structurally diverse new C13-polyketides, mollipilin A–E (1–5) as well as two known compounds (6 and 7). Spectroscopic methods, X-ray single crystal diffraction analysis, and VCD elucidated the absolute configurations of structures 1–6, and plausible biosynthetic pathways for 1–7 were proposed based on structural relationships. Mollipilins A (1) and B (2) exhibited moderate growth inhibitory effects on HCT-116 cells.