title: A practical strategy to discover new antitumor compounds by activating silent metabolite production in fungi by diethyl sulphate mutagenesis.
abstract: Many fungal biosynthetic pathways are silent in standard culture conditions, and activation of the silent pathways may enable access to new metabolites with antitumor activities. The aim of the present study was to develop a practical strategy for microbial chemists to access silent metabolites in fungi. We demonstrated this strategy using a marine-derived fungus Penicillium purpurogenum G59 and a modified diethyl sulphate mutagenesis procedure. Using this strategy, we discovered four new antitumor compounds named penicimutanolone (1), penicimutanin A (2), penicimutanin B (3), and penicimutatin (4). Structures of the new compounds were elucidated by spectroscopic methods, especially extensive 2D NMR analysis. Antitumor activities were assayed by the MTT method using human cancer cell lines. Bioassays and HPLC-photodiode array detector (PDAD)-UV and HPLC-electron spray ionization (ESI)-MS analyses were used to estimate the activated secondary metabolite production. Compounds 2 and 3 had novel structures, and 1 was a new compound belonging to a class of very rare natural products from which only four members are so far known. Compounds 1-3 inhibited several human cancer cell lines with IC₅₀ values lower than 20 μM, and 4 inhibited the cell lines to some extent. These results demonstrated the effectiveness of this strategy to discover new compounds by activating silent fungal metabolic pathways. These discoveries provide rationale for the increased use of chemical mutagenesis strategies in silent fungal metabolite studies.
authors.affiliation: Key Laboratory of Structure-Based Drug Design & Discovery of Ministry of Education, School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang 110016, China. sdrlcw@126.com.
authors.forename: Shi-Ming
authors.initials: SM
authors.lastname: Fang
authors.affiliation: Key Laboratory of Structure-Based Drug Design & Discovery of Ministry of Education, School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang 110016, China. sdrlcw@126.com.
authors.forename: Chang-Jing
authors.initials: CJ
authors.lastname: Wu
authors.affiliation: Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China. sdrlcw@126.com.
authors.forename: Chang-Wei
authors.initials: CW
authors.lastname: Li
authors.affiliation: Key Laboratory of Structure-Based Drug Design & Discovery of Ministry of Education, School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang 110016, China. cuicb@sohu.com.
authors.forename: Cheng-Bin
authors.initials: CB
authors.lastname: Cui
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D001688:Biological Products / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006801:Humans; D020128:Inhibitory Concentration 50; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D016296:Mutagenesis; D009369:Neoplasms / Q000188:drug therapy* / Q000473:pathology; D010407:Penicillium / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013463:Sulfuric Acid Esters / Q000737:chemistry
chemical_list: D000970:Antineoplastic Agents; D001688:Biological Products; D013463:Sulfuric Acid Esters; C011612:diethyl sulfate