Verruculosins A–B, New Oligophenalenone Dimers from the Soft Coral-Derived Fungus Talaromyces verruculosus

Abstract

In an effort to discover new bioactive anti-tumor lead compounds, a specific tyrosine phosphatase CDC25B and an Erb family receptor EGFR were selected as drug screening targets. This work led to the investigation of the soft coral-derived fungus <i>Talaromyces verruculosus</i> and identification of two new oligophenalenone dimers, verruculosins A-B (<b>1</b>-<b>2</b>), along with three known analogues, bacillisporin F (<b>3</b>), duclauxin (<b>4</b>), and xenoclauxin (<b>5</b>). Compound <b>1</b> was the first structure of the oligophenalenone dimer possessing a unique octacyclic skeleton. The detailed structures and absolute configurations of the new compounds were elucidated on the basis of spectroscopic data, X-ray crystallography, optical rotation, Electronic Circular Dichroism (ECD) analysis, and nuclear magnetic resonance (NMR) calculations. Among which, compounds <b>1</b>, <b>3</b>, and <b>5</b> exhibited modest inhibitory activity against CDC25B with IC₅₀ values of 0.38 ± 0.03, 0.40 ± 0.02, and 0.26 ± 0.06 µM, respectively.