Proxiphomin und Protophomin, zwei neue Cytochalasane

Abstract

Herrn Prof. Edgar Ledeyer zum 65. Geburtstag gewidmet (2.5. VI. 73) Szcmmary. Two ncw cytochalasans, proxiphomin and protophomin have been isolated from culturcs of a Phoma species (strain S 298). Thcy are shown t o possess the same skeleton as deoxaphomin (4), which has been isolated recently. Thus they represent lower states of oxidation of 4. On thc basis of the spectral data, the structures 16-methyl-l0-phenyl-[13]cytochalasa-6 (7), 13t, Zlt-triene-l,23-dionc (1) 13t, 19t-trien-l,l7-dion) [5] bewiesen werden. Es ist uns nun gelungen, aus Kulturen der genannten Phoma Species zwei weitere, in geringer Menge gebildete Metabolite zu isolieren, die das gleiche carbocyclische Grundgeriist wie Desoxaphomin (4) besitzen, aber weniger Sauerstoff als dieses enthalten. Im folgenden berichten wir uber die im wesentlichen mit spektroskopischen Methoden durchgefiihrte Strukturaufklarung der beiden neuen Cytochalasane, die wir Proxiphomin und Protophomin nennen, sowie fiber ilire mogliche Funktion im Rahmen der Riogenese der 24-0xa-[14]cytochalasane.

Isolation, Structural Analyses and Biological Activity Assays against Chronic Lymphocytic Leukemia of Two Novel Cytochalasins — Sclerotionigrin A and B

“…The formula was used for a query in Antibase2012 [34] with one resulting hit, proxiphomin ( 3 ). NMR data and optical rotation of 3 matched published data [32].…”

“…Here we report the target-guided isolation and structure elucidation based on UV, MS, and NMR data of the two novel cytochalasins sclerotionigrin A ( 1 ) and B ( 2 ). Compounds 1 and 2 were isolated from Aspergillus sclerotioniger (IBT 22905) together with the known cytochalasin proxiphomin ( 3 ) [32]. We have previously reported ochratoxin A, ochratoxin B and pyranonigrin A from this isolate [33].…”

Biosynthetic assembly of cytochalasin backbone

“…2b The structure of 4 suggested that the CcsA reductase (R) domain reductively liberated the putative thioester intermediate appended to the CcsA thiolation (T) domain to give 1. Isolation of proxiphomin 17 and procheatoglobosin I 6 (Fig. 1), non oxidatively modified putative precursors in the corresponding cytochalasan producing fungi, provides the circumstantial evidence that the first free linear intermediate has an enone moiety.…”

Explorations of fungal biosynthesis of reduced polyketides – a personal viewpoint

“…[4][5][6] It also provided a template for their total chemical syntheses. 4,7,8 His prediction of biological Baeyer Villiger reactions 9 to convert initially formed macrocyclic ketones to macrolide lactones and carbonates has also been recently conrmed using an isolated enzyme. 10 A subsequent postdoctoral year with Professor Heinz Floss at Purdue University not only provided further insights into biosynthesis, but also afforded valuable experience working with puried enzymes 11,12 (Fig.…”