Bicyclic and tetracyclic diterpenes from a Trichoderma symbiont of Taxus baccata

Natural Products with Anti‐Bredt and Bridgehead Double Bonds

“…Shen et al uncovered two further cespitularin-type natural products, cespihypotins C (131) and D (132), from Cespitularia hypotentaculata Roxas (Xeniidae) in Taiwan in 2006 ( Figure 24). [91,92] Their structures were deduced by NMR spectroscopic methods. HMBC correlations between the gemdimethyl protons and the bridgehead sp 2 carbon atom were important in identifying the bridgehead olefin of 131 and 132.…”

“…Like the phomactins, the cespitularin-type structures have shared lineage with the taxane natural products. Indeed, Shen and co-workers postulated that the cespitularins and cespihypotins all arise from verticillene (133; Figure 24), [91,92] a putative structure that has been proposed to be the biogenetic precursor of the taxane natural products. The recently reported compound 134, from Trichoderma atroviridae (UB-LMA), an endophytic fungus isolated from Taxus baccata trees, further supports this biosynthetic hypothesis ( Figure 24).…”

Harzianone Biosynthesis by the Biocontrol Fungus Trichoderma

“…The 1,2 hydride shift Mass spectrum of harzianone with highest deuterium incorporation after feedingofA )(6,6,6-2 H 3 )-10,B)(2,2,6,6,6-2 H 5 )-10,C)(5,5,6,6,6-2 H 5 )-10,a nd D) (4,4,6,6,6-2 H 5 )-10.C olored dots indicatepositionso f 2 Hl abeling. [16] Detection of 4 in all seven analyzed Trichoderma strains investigated in this study indicates a conserved genetic occurrence of ah arziane terpenes ynthase within this genus. Resultsoffeeding experiments.…”

“…The charcoalf ilter was extracted with5 0mLC 6 D 6 every day,a nd the collected extractsw ere directly used for further analysis. [13,16] The terpene cyclization mechanism of 4 was studied by feedingo faseries of synthetic 13 C-labeled mevalonolactones (10). The contento ft he labeled diterpene in the sample was sufficient for recording a 13 C, 13 CCOSY spectrum that suggested the structure of harzianone (4,F igure 2).…”

“…[10] Its absolute configuration was deduced by enantioselective synthesis, [11] and its biosynthesis was addressed by feeding experiments with isotopically labeled precursors. [16] Diketone 5 is as trong antifungal compound that is active against the plant pathogenic fungus Sclerotium rolfsii, [17] whereas ketone 4 lacks such antifungal activity bute xhibits activity against Escherichia coli and Staphylococcus aureus and in ab rine shrimp( Artemia salina)t oxicitya ssay. Notably, 5 and the relatedd iterpenoids 7-9 were recently isolated from a Trichoderma symbiont of the taxane-producing plant Taxus baccata.…”