Light-Independent Metabolomics of Endophytic Thielavia subthermophila Provides Insight into Microbial Hypericin Biosynthesis

• Published in: Journal of natural products (Washington, D.C.) Vol. 72; no. 10; pp. 1825 - 1835
• Main Authors: Kusari, Souvik, Zühlke, Sebastian, Košuth, Ján, Čellárová, Eva, Spiteller, Michael
• Format: Journal Article
• Language: English
• Published: Northbrook, IL American Chemical Society and American Society of Pharmacognosy 23.10.2009; American Society of Pharmacognosy
• Subjects: Antibiotics, microbial producers, chemotherapic agents, antiseptics, disinfecting agents; Antineoplastic Agents - chemistry; Antineoplastic Agents - isolation & purification; Antineoplastic Agents - pharmacology; Applied microbiology; Base Sequence; Biological and medical sciences; Chemotherapic agents; Drug Screening Assays, Antitumor; Emodin - metabolism; Fundamental and applied biological sciences. Psychology; Humans; Hypericum - microbiology; Hypericum perforatum; Light; Metabolomics; Microbiology; Molecular Structure; Perylene - analogs & derivatives; Perylene - metabolism; Sordariales - chemistry; Sordariales - genetics; Antineoplastic agent; Hypericum perforatum; Metabolomics; Axenic culture; Metabolite; Guttiferae; Leukemia; Cytotoxicity; Biosynthesis; Extract; Medicinal plant; Fungi; Dicotyledones; Angiospermae; Quinonemethide; Anthraquinone(6-methyl 1,3,8-trihydroxy); Tumor cell; Ascomycota; Human; Quinone; In vitro; Biological activity; Cell line; Submerged culture; Endophyte; Spermatophyta; Kinetics; Photosensitizer
• ISSN: 0163-3864; 1520-6025
• DOI: 10.1021/np9002977

The possible microbial mechanism of hypericin (1) and emodin (2) biosynthesis was studied in axenic submerged culture conditions in the endophytic fungus Thielavia subthermophila, isolated from Hypericum perforatum. The growth and secondary metabolite production of the endophyte remained independent of the illumination conditions. This production remained unaltered on spiking the medium with 3 or 5 mM 2, although the biomass accumulation was reduced. Neither emodin anthrone (3) nor protohypericin (4) could be detected at any stage of fermentation, irrespective of either spiking or illumination conditions. The endophytic metabolites exhibited photodynamic cytotoxicity against the human acute monocytic leukemia cell line (THP-1), at 92.7 vs 4.9%, and 91.1 vs 1.0% viability by resazurin and ATPlite assays, in light and in the dark, respectively. In trying to ascertain the presence/expression of the candidate hyp-1 gene in the endophyte, it was revealed that the hyp-1 gene was absent in T. subthermophila, indicating that the biosynthetic pathway in the endophytic fungus might be different and/or governed by a different molecular mechanism than the host plant or host cell suspension cultures. We have discussed the biosynthetic principles and evolutionary implications relating to endophytic T. subthermophila based on the results obtained.