Related Experiment Video
Updated: Aug 14, 2026

Methods to Inhibit Bacterial Pyomelanin Production and Determine the Corresponding Increase in Sensitivity to Oxidative Stress
Published on: August 31, 2015
Phaeosphaones: Tyrosinase Inhibitory Thiodiketopiperazines from an Endophytic Phaeosphaeria fuckelii
Yi-Jie Zhai1, Guang-Ming Huo2, Qiang Zhang1
1Shaanxi Key Laboratory of Natural Products & Chemical Biology, College of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi 712100, People's Republic of China.
Abstract:
Phaeosphaeria fuckelii, an endophytic fungus associated with the herbal medicine Phlomis umbrosa, produced four new thiodiketopiperazine alkaloids, phaeosphaones A-D (1-4), featuring an unusual β-(oxy)thiotryptophan motif, along with four known analogues, phaeosphaone E (5), chetoseminudin B (6), polanrazine B (7), and leptosin D (8). Their structures were elucidated by extensive spectroscopic data analysis, and their absolute configurations were determined by single-crystal X-ray diffraction and ECD calculations. Compounds 4, 6, and 8 were found to display mushroom tyrosinase inhibitory activity with IC50 values of 33.2 ± 0.2, 31.7 ± 0.2, and 28.4 ± 0.2 μM, respectively, more potent than that of the positive control, kojic acid (IC50 = 40.4 ± 0.1 μM). A molecular-docking study disclosed the π-π stacking interaction between the indole moiety of 8 and the His243 residue of tyrosinase.
Related Concept Videos
Bacterial Phylum Planctomycetes
Bacterial Phylum Tenericutes
Fungal Phylum Ascomycota
Antifungal Agents

