Recent trends in the structural revision of natural products

The dearomatizing oxidative annulation of 2-alkenylphenols with alkynes and enynes proceeds with high yields and regioselectivities under Rh(III) catalysis. These reactions are successful using Cu(OAc)2 or air as the stoichiometric oxidant, and provide spirocyclic enones, the basic ring system of which appears in several natural products. Application of this process to the preparation of a highly functionalized tetracycle is also demonstrated.

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Synthesis of Spirocyclic Enones by Rhodium‐Catalyzed Dearomatizing Oxidative Annulation of 2‐Alkenylphenols with Alkynes and Enynes

The genus Cordyceps: An extensive review of its traditional uses, phytochemistry and pharmacology

Fumagillin (1), a meroterpenoid from Aspergillus fumigatus, is known for its antiangiogenic activity due to binding to human methionine aminopeptidase 2. 1 has a highly oxygenated structure containing a penta-substituted cyclohexane that is generated by oxidative cleavage of the bicyclic sesquiterpene β-trans-bergamotene. The chemical nature, order, and biochemical mechanism of all the oxygenative tailoring reactions has remained enigmatic despite the identification of the biosynthetic gene cluster and the use of targeted-gene deletion experiments. Here, we report the identification and characterization of three oxygenases from the fumagillin biosynthetic pathway, including a multifunctional cytochrome P450 monooxygenase, a hydroxylating nonheme-iron-dependent dioxygenase, and an ABM family monooxygenase for oxidative cleavage of the polyketide moiety. Most significantly, the P450 monooxygenase is shown to catalyze successive hydroxylation, bicyclic ring-opening, and two epoxidations that generate the sesquiterpenoid core skeleton of 1. We also characterized a truncated polyketide synthase with a ketoreductase function that controls the configuration at C-5 of hydroxylated intermediates.

http://pubs.acs.org/doi/pdf/10.1021/ja500881e

Generation of complexity in fungal terpene biosynthesis: Discovery of a multifunctional cytochrome P450 in the fumagillin pathway

Secondary metabolites of higher fungi (mushrooms) are an underexplored resource compared to plant-derived secondary metabolites. An increasing interest in mushroom natural products has been noted in recent years. This chapter gives a comprehensive overview of the secondary metabolites from higher fungi, with 765 references highlighting the isolation, structure elucidation, biological activities, chemical syntheses, and biosynthesis of pigments, nitrogen-containing compounds, and terpenoids from mushrooms. Mushroom toxins are also included in each section.

Secondary Metabolites from Higher Fungi

Investigation of the cultured mycelia of Cordyceps ophioglossoides resulted in the isolation and characterization of three new unusual spiro[4.5]decane sesquiterpenes, cordycepol A (1), cordycepol B (2), and cordycepol C (3), and a new fumagillol analogue, cordycol (4). Their structures were established by spectroscopic means. The cytotoxic activities were also evaluated, compounds 3 and 4 showing their IC50 values in the range of 1233 mu g/ml against HeLa and HepG2 (Table 3). In addition, 3 and 4 were not obviously harmful towards normal liver cell lines LO2, showing IC50 values above 80 mu g/ml.

Qiangsheng Feng

Papers

Unusual Spirodecane Sesquiterpenes and a Fumagillol Analogue from Cordyceps ophioglossoides