The diphenyl ether pestheic acid was isolated from the endophytic fungus Pestalotiopsis fici, which is proposed to be the biosynthetic precursor of the unique chloropupukeananes. The pestheic acid biosynthetic gene (pta) cluster was identified in the fungus through genome scanning. Sequence analysis revealed that this gene cluster encodes a nonreducing polyketide synthase, a number of modification enzymes, and three regulators. Gene disruption and intermediate analysis demonstrated that the biosynthesis proceeded through formation of the polyketide backbone, cyclization of a polyketo acid to a benzophenone, chlorination, and formation of the diphenyl ether skeleton through oxidation and hydrolyzation. A dihydrogeodin oxidase gene, ptaE, was essential for diphenyl ether formation, and ptaM encoded a flavin-dependent halogenase catalyzing chlorination in the biosynthesis. Identification of the pta cluster laid the foundation to decipher the genetic and biochemical mechanisms involved in the pathway.

Two new α-pyrones (=2H-pyran-2-ones), ficipyrones A and B (1 and 2, resp.), and two new α-furanones (=2H-furan-2-ones), ficifuranones A and B (3 and 4, resp.), together with three known metabolites, antibiotic F 0368 (5), hydroxyseiridin (6), and hydroxyisoseiridin (7), were isolated from solid cultures of the plant endophytic fungus Pestalotiopsis fici. Their structures were elucidated primarily by NMR spectroscopy, and the absolute configuration of 1 was deduced from the circular-dichroism (CD) data. Compound 1 showed antifungal activity against the plant pathogen Gibberella zeae (CGMCC 3.2873) with an IC₅₀ value of 15.9 μM.

Three new α-pyrones, scirpyrones A–C (1–3), and four new pyranes, scirpyranes A–D (4–7), were isolated from solid cultures of the plant pathogen Pestalotiopsis scirpina. Their structures were elucidated primarily by NMR experiments. The absolute configurations of C-7 and C-2′ in 1, C-7 in 2, and C-6 and C-7 in 3 were deduced on the basis of circular dichroism (CD) data, whereas those of the secondary alcohols in 4–7 were determined by a modification of Mosher's method. Compound 1 is the first described 6-(5-oxotetrahydrofuran-2-yl)-2H-pyran-2-one. Compounds 4–6 showed significant cytotoxicity towards MCF-7 cells.

Chloropupukeanolides C–E (8–10), three highly functionalized secondary metabolites featuring a novel spiroketal skeleton derived from the chlorinated tricyclo-[4.3.1.0^3, 7]-decane (pupukeanane) and the 2,6-dihydroxy-4-methylbenzoic acid moieties, were isolated from the scale-up fermentation extract of the plant endophytic fungus Pestalotiopsis fici. The constitutions of compounds 8–10 were elucidated primarily by NMR experiments. Their relative configurations were deduced by analogy to metabolites 4–6, which were previously isolated from the same fungus. The absolute configuration of 8 was assigned by X-ray crystallography and those of 9 and 10 by quantum-chemical CD calculations. Biogenetically, chloropupukeanolides C–E (8–10) are presumably derived from the same oxidation-induced Diels–Alder reaction pathway as compounds 1 and 4–7, via the putative biosynthetic precursors 2 and 3. The opposite configurations of the complete “Southern parts” of 8 and 9 suggests that this Diels–Alder reaction is stereochemically not very selective. Compounds 8–10 showed significant cytotoxicity against a small panel of human tumor cell lines and weak activities against the pathogens of tropical diseases.

New tricyclic sesquiterpenoids brasilamides A–D (1–4) and the known pinthunamide (5) have been isolated from cultures of the plant endophytic fungus Paraconiothyrium brasiliense Verkley. Their structures were elucidated primarily by NMR spectroscopy, and the structure of 1 was further confirmed by X-ray crystallography. The absolute configuration of the C-5 tertiary alcohol in 2 was assigned by analogy to 1 and confirmed by observing the circular dichroism of in situ generated [Rh₂(OCOCF₃)₄] complex. Compounds 2–4 showed modest inhibitory effects on HIV-1 replication in C8166 cells. Compounds 1 and 2 possess an unprecedented4-oxatricyclo-[3.3.1.0^2,7]nonane skeleton.

Trichocladinols A–C (1–3), three new metabolites, and the known massarigenin A (4), have been isolated from cultures of a Cordyceps-colonizing ascomycete Trichocladium opacum. Their structures were elucidated by NMR spectroscopy and X-ray crystallography. The absolute configuration of 1 was assigned by using the modified Mosher method and that of 3 was determined by X-ray crystallographic analysis of its (S)-MTPA ester. Compounds 1–3 showed modest cytotoxic effects against the human tumor cell lines HeLa and MCF-7. Structurally, compounds 1 and 2 possess a previously undescribed 2,9-dioxatricyclo[5.2.1.0^3,8]dec-4-ene skeleton.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)