Naphthalene derivatives and halogenate quinoline from the coral-derived fungus Trichoderma harzianum (XS-20090075) through OSMAC approach.

OSMAC approach was performed on the soft coral-derived fungus Trichoderma harzianum (XS-20090075) leading to the significant changes of its secondary metabolites by using two different cultures. A new naphthalene derivative, trichoharzin B (1) and a new natural product, methyl-trichoharzin (2) were isolated by using rice medium. Whereas, a new natural product, ethyl 2-bromo-4-chloroquinoline-3-carboxylate (9) was obtained by using Czapek's medium. Their structures were established by extensive spectroscopic investigation. The absolute configuration of 5 was determined by single-crystal X-ray diffraction. Compound 9 was the first halogenate quinoline derivative isolated from the genus of Trichoderma.

Terpenoids From the Coral-Derived Fungus Trichoderma harzianum (XS-20090075) Induced by Chemical Epigenetic Manipulation.

The soft coral-derived fungus Trichoderma harzianum (XS-20090075) was found to be a potential strain to produce substantial new compounds in our previous study. In order to explore its potential to produce more metabolites, chemical epigenetic manipulation was used on this fungus to wake its sleeping genes, leading to the significant changes of its secondary metabolites by using a histone deacetylase (HDAC) inhibitor. The most obvious difference was the original main products harziane diterpenoids were changed into cyclonerane sesquiterpenoids. Three new terpenoids were isolated from the fungal culture treated with 10 µM sodium butyrate, including cleistanthane diterpenoid, harzianolic acid A (1), harziane diterpenoid, harzianone E (2), and cyclonerane sesquiterpenoid, 3,7,11-trihydroxy-cycloneran (3), together with 11 known sesquiterpenoids (4-14). The absolute configurations of 1-3 were determined by single-crystal X-ray diffraction, ECD and OR calculations, and biogenetic considerations. This was the first time to obtain cleistanthane diterpenoid and africane sesquiterpenoid from genus Trichoderma, and this was the first chlorinated cleistanthane diterpenoid. These results demonstrated that the chemical epigenetic manipulation should be an efficient technique for the discovery of new secondary metabolites from marine-derived fungi.

Co-cultivation With 5-Azacytidine Induced New Metabolites From the Zoanthid-Derived Fungus Cochliobolus lunatus.

The zoanthid-derived fungus Cochliobolus lunatus (TA26-46) has been proven to be a source of bioactive 14-membered resorcylic acid lactones (RALs). In the present study, chemical epigenetic manipulation was applied to this fungal strain with a DNA methyltransferase inhibitor resulting in the significant changes of the secondary metabolites. Cultivation of C. lunatus (TA26-46) with 10 µM 5-azacytidine in Czapek-Dox liquid medium led to the isolation of new types of metabolites, including two α-pyrones, cochliobopyrones A (1) and B (2), along with three isocoumarins (3-5) and one chromone (6). The planar structures of the new compounds (1-2) were elucidated by comprehensive analyses of NMR and HRESIMS data. Their challenging relative configurations were established by a combination of acetonide reaction, coupling constants and NOESY correlations analysis, and DP4+ probability calculation. Their absolute configurations were determined by comparing with the ECD calculation data of the fragment molecules, 6-(1,2-dihydroxypropyl)-4-methoxy-2H-pyran-2-ones. It is the first time to obtain α-pyrone compounds with the epoxy ring or bromine atom on the seven-numbered side chain. It could be concluded that chemical epigenetic agents could induce C. lunatus to produce new types of secondary metabolites differing from its original products (RALs).

Harzianumnones A and B: two hydroxyanthraquinones from the coral-derived fungus Trichoderma harzianum.

Two new hydroxyanthraquinones, harzianumnones A (1) and B (2), together with seven known analogs (3-9), were isolated from the soft coral-derived fungus Trichoderma harzianum (XS-20090075). Their chemical structures were elucidated by extensive spectroscopic investigation. The absolute configurations of 1 and 2 were determined by ECD calculation and single-crystal X-ray diffraction. Compounds 1 and 2 were identified as a pair of epimers, which are the first example of hydroanthraquinones from T. harzianum. Compounds 7 and 8 exhibited cytotoxicity against hepatoma cell line HepG2 with IC50 values of 2.10 and 9.39 µM, respectively. Compound 7 was still found to show cytotoxicity against cervical cancer cell line HeLa with an IC50 value of 8.59 µM.