Biosynthesis of the allene (–)-marasin in Marasmius ramealis

Abstract

[1-14C]-E-dehydromatricaria methyl ester and dimethyl [1-14C]-deca-4,6,8-triyne-1,10-dioate are incorporated into the allene (-)-marasin in Marasmius ramealis without scrambling of the 14C label. This and the levels of the incorporations (0.8% and 4.9% respectively) strongly suggests that the above esters, or close relatives, can be converted directly into (-)-marasin in M. ramealis, and that the diyne-allene moiety in this latter compound arises by the rearrangement, under enzymic control, of an alkyltriyne moiety.

Biosynthesis and function of polyacetylenes and allied natural products

“…Incorporation levels into polyacetylenic metabolites, such as 3L, when the preferred (14Z)-isomer of dehydrocrepenynate was fed were 30-300X that of the (14E)-isomer in the fungi M. grammopodium, Lepista diemii, C. quadrifidus, and S. lacrymans [59]. In Marasmius ramealis, incorporation of esters 1A and 3M into (-)-marasin 3N (0.8 and 2.0%, respectively) occurred without scrambling of the carboxyl groups [60]. In their analysis of this study, Davies et al clearly stated that the order of four modifications -oxidation of the methyl group of 1A to the carboxyl group and 10-decarboxylation, reduction of the 1-carboxyl group to an alcohol, and hydrogenation -was unresolved, as the substrate specificities are not known for any of the likely activities.…”

Stereochemical Study of Puna’auic Acid, an Allenic Fatty Acid from the Eastern Indo-Pacific Cyanobacterium Pseudanabaena sp

“…Due to their rare occurrence in natural products, the biosynthesis of allenes has not been clearly demonstrated; feeding experiments have only been performed, and the preliminary results suggest enynes as precursors of the allenes in fungal metabolites . Remarkably, some natural allenes have been found, together with their alkyne analogues in two other families of marine fungal metabolites: truncateol from the sponge-associated fungus Truncatella angustata , oxirapentyns from marine-sediment-derived fungus Isaria feline , underpinning this hypothesis .…”

A Reactive Conjugated Allene Involved in the Biosynthesis of Volatile Oxylipins in the Moss Dicranum scoparium

“…A proposed biosynthetic pathway could be initiated by an isomerase acting on 7 (Scheme ). Such isomerase activity was previously postulated by Davies and Hodge for the formation of allenes from acetylenic fatty acids in fungi . The resulting allene 9 could then be transformed by a lipoxygenase and an alcohol dehydrogenase to give 8 and 12 .…”

“…Such isomerase activity was previously postulated by Davies and Hodge for the formation of allenes from acetylenic fatty acids in fungi. 15 The resulting allene 9 could then be transformed by a lipoxygenase and an alcohol dehydrogenase 16 to give 8 and 12. Such a 13-lipoxygenase-mediated transformation of 9 could be supported by the formation of the energetically favored conjugated system.…”