Natural resorcylic lactones derived from alternariol

• Joachim Podlech

Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187

• Joachim Podlech Karlsruhe Institute of Technology (KIT), Institute of Organic Chemistry, Kaiserstraße 12, 76131 Karlsruhe, Germany 10.3762/bjoc.20.187 Abstract In this overview, naturally occurring resorcylic lactones biosynthetically derived from alternariol and almost exclusively produced by

• fungi, are discussed with view on their isolation, structure, biological activities, biosynthesis, and total syntheses. This class of compounds consists until now of 127 naturally occurring compounds, with very divers structural motifs. Although only a handful of these toxins (i.e., alternariol and its

• interesting biological activities. Keywords: biosynthesis; fungal metabolites; polyketides; resorcylic lactones; total synthesis; Introduction Alternariol and some of its derivatives are ubiquitous as fungal metabolites present in infested plants and in food and feed, but similarly in soil, in wallpapers

Secondary metabolites of Diaporthe cameroonensis, isolated from the Cameroonian medicinal plant Trema guineensis

• Bel Youssouf G. Mountessou,
• Élodie Gisèle M. Anoumedem,
• Blondelle M. Kemkuignou,
• Yasmina Marin-Felix,
• Frank Surup,
• Marc Stadler and
• Simeon F. Kouam

Beilstein J. Org. Chem. 2023, 19, 1555–1561, doi:10.3762/bjoc.19.112

• polyketide 1, and an acetylated alternariol 2 were isolated, along with fifteen known secondary metabolites. Their structures were established by extensive NMR spectroscopy and mass spectrometry analyses, as well as by comparison with literature data of their analogs. Keywords: alternariol; Diaporthe

• elucidation of a new polyketide 1 and a new acetylated alternariol derivative 2 as well as fifteen known compounds including three alternariol derivatives 3–5, one chromone 6, one biphenyl 7, seven cytochalasins 8–14, two cytosporones 15 and 16, and one macrolide 17 from the endophytic fungus, Diaporthe

• in the (+)-HRESIMS spectrum (Figure S8 in Supporting Information File 1). Its 1H NMR spectrum (Figure S9, Supporting Information File 1) allowed the deduction of an alternariol scaffold [13] with signals of a chelated hydroxy proton at δH 10.33, two pairs of meta-coupled protons at δH 6.68 and 6.55

Biosynthesis of α-pyrones

• Till F. Schäberle

Beilstein J. Org. Chem. 2016, 12, 571–588, doi:10.3762/bjoc.12.56

• that they are mainly distributed in the Alternaria species and mycobionts. Especially endophytic fungi can be regarded as source organisms. Alternariol (17), altenuene (18), and alternariol 9-methyl ether (19) have been described from Alternaria sp. [17], botrallin (20) from Hyalodendriella sp. [18

• temperature. Alternaria spp. had also been linked to a poultry disease outbreak called poultry hemorrhagic syndrome. However, the main toxic effects seem to be linked to other toxins produced, e.g., the non pyrone metabolite tenuazonic acid [20]. Nevertheless, alternariol (17) and altenuene (18) were studied

• for 18 [22]. Further, alternariol (17) and derivatives were tested against L5178Y mouse lymphoma cells. Here 17 was the most active compound with an EC50 value of 1.7 μg/mL [23]. In another in vitro assay, this time a biochemical assay using protein kinase, the IC50 values were determined, and 17