Volatiles from the tropical ascomycete Daldinia clavata (Hypoxylaceae, Xylariales)

Abstract

The volatiles from the fungus Daldinia clavata were collected by use of a closed-loop stripping apparatus and analysed by GC-MS. A few compounds were readily identified by comparison of measured to library mass spectra and of retention indices to published data, while for other compounds a synthesis of references was required. For one of the main compounds, 5-hydroxy-4,6-dimethyloctan-3-one, the relative and absolute configuration was determined by synthesis of all eight stereoisomers and gas chromatographic analysis using a homochiral stationary phase. Another identified new natural product is 6-nonyl-2H-pyran-2-one. The antimicrobial and cytotoxic effects of the synthetic volatiles are also reported.135

Recent progress in biodiversity research on the Xylariales and their secondary metabolism

“…Moreover, this study also resulted in the recognition of Muscodor/Induratia and the related genus Emarcea as a unique phylogenetic lineage for which the new family Induratiaceae has been erected [117]. Interestingly, these fungi were never studied for the production of nonvolatile secondary metabolites and even the identity of the compounds that were detected by database aided GC-MS analytics often remains dubious [103,[118][119][120]. The Induratiaceae certainly deserve further studies of their secondary metabolome, including the identification of metabolites that show pronounced production in dual antagonist cultures.…”

Volatiles from the ascomyceteDaldinia cf. childiae(Hypoxylaceae), originating from China

“…The absolute configuration of compound 8 was recently determined for the same compound produced by Daldinia clavata by comparison to all eight synthetic stereoisomers through GC using a chiral stationary phase. 16 Furthermore, the widespread typical mushroom odour oct-1-en-3-ol (9, matsutake alcohol) and traces of cyclohexanol (10) and cyclohexanone (11) were detected.…”

“…While 12-14 are widespread volatiles, compound 15 is rare and has only occasionally been reported as a constituent of plant essential oils [17][18][19] and from bacteria of the genus Collimonas, 20 but never from fungal sources before. Aromatic compounds included the widespread volatiles 2-phenylethanol (18), its isomer 1-phenylethanol (16) and the corresponding ketone acetophenone (17).…”

“…Significantly larger amounts were observed for 6-nonyl-2H-pyran-2-one (28), a compound that we have recently reported from D. clavata. 16 Furthermore, a few terpenes were found including the widespread trisnorsesquiterpene geosmin (29), 1,39 β-bisabolene (30), trans-βbergamotene (31), and cisand trans-linalool oxide (32 and 33). The sesquiterpenes 30 and 31 are biosynthetically linked through the bisabolyl cation A (Scheme 3) and may potentially arise from the same sesquiterpene synthase.…”

Volatiles from the hypoxylaceous fungi Hypoxylon griseobrunneum and Hypoxylon macrocarpum

“…Furthermore, some of the isomers may also have similar retention indices, and therefore it is mandatory for unambiguous structure elucidation to compare analytes that fall into this class to all the possible isomers. A similar problem can apply to the structural assignment of compounds with multiple stereocentres based on GC–MS data, because the various possible diastereomers usually also produce very similar mass spectra [16], a phenomenon that is also reported for E and Z stereoisomers and can lead to wrong structural assignments, if no authentic standards are used for comparison [17]. We have recently reported on two chlorinated aromatic compounds from an endophytic Geniculosporium sp.…”