Structure, Synthesis, and Stereochemistry of (+)-Orthosporin, a Phytotoxic Metabolite of <i>Rhynchosporium Orthosporum</i>

Ichihara, Akitami; Hashimoto, Masaaki; Hirai, Takamasa; Takeda, Ichiro; Sasamura, Yasuaki; Sakamura, Sadao; Sato, Rinzo; Tajimi, Akitoshi

doi:10.1246/cl.1989.1495

Cited by 42 publications

(31 citation statements)

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“…The only secondary metabolite described to date from a Rhynchosporium species is orthosporin, a polyketide from R. orthosporum [77]. This isocoumarin was also isolated from Drechslera siccans , a pathogen of oats ( Avena sativa ), perennial ryegrass ( L. perenne ) and Italian ryegrass ( L. multiflorum ).…”

Section: Resultsmentioning

confidence: 99%

Comparative genomics to explore phylogenetic relationship, cryptic sexual potential and host specificity of Rhynchosporium species on grasses

et al. 2016

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BackgroundThe Rhynchosporium species complex consists of hemibiotrophic fungal pathogens specialized to different sweet grass species including the cereal crops barley and rye. A sexual stage has not been described, but several lines of evidence suggest the occurrence of sexual reproduction. Therefore, a comparative genomics approach was carried out to disclose the evolutionary relationship of the species and to identify genes demonstrating the potential for a sexual cycle. Furthermore, due to the evolutionary very young age of the five species currently known, this genus appears to be well-suited to address the question at the molecular level of how pathogenic fungi adapt to their hosts.ResultsThe genomes of the different Rhynchosporium species were sequenced, assembled and annotated using ab initio gene predictors trained on several fungal genomes as well as on Rhynchosporium expressed sequence tags. Structures of the rDNA regions and genome-wide single nucleotide polymorphisms provided a hypothesis for intra-genus evolution. Homology screening detected core meiotic genes along with most genes crucial for sexual recombination in ascomycete fungi. In addition, a large number of cell wall-degrading enzymes that is characteristic for hemibiotrophic and necrotrophic fungi infecting monocotyledonous hosts were found. Furthermore, the Rhynchosporium genomes carry a repertoire of genes coding for polyketide synthases and non-ribosomal peptide synthetases. Several of these genes are missing from the genome of the closest sequenced relative, the poplar pathogen Marssonina brunnea, and are possibly involved in adaptation to the grass hosts. Most importantly, six species-specific genes coding for protein effectors were identified in R. commune. Their deletion yielded mutants that grew more vigorously in planta than the wild type.ConclusionBoth cryptic sexuality and secondary metabolites may have contributed to host adaptation. Most importantly, however, the growth-retarding activity of the species-specific effectors suggests that host adaptation of R. commune aims at extending the biotrophic stage at the expense of the necrotrophic stage of pathogenesis. Like other apoplastic fungi Rhynchosporium colonizes the intercellular matrix of host leaves relatively slowly without causing symptoms, reminiscent of the development of endophytic fungi. Rhynchosporium may therefore become an object for studying the mutualism-parasitism transition.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3299-5) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Comparative genomics to explore phylogenetic relationship, cryptic sexual potential and host specificity of Rhynchosporium species on grasses

et al. 2016

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“…Thus, the structure of 5 was determined to be a C(12) epimer of citreoisocoumarinol, namely isocitreoisocoumarinol. In addition, the remaining known isocoumarinrelated derivatives were identical to mucorisocoumarin A (8) [13], citreoisocoumarinol (9) [16], mucorisocoumarin B (10) [13], orthosporin (11) [21], diaportinol (12) [19], LL-Z 1640-7 (13) [20], demethylcitreoviranol (14) [22], citreoviranol (15) [22], alternariol (16) [23], alternariol monomethyl ether (17) [23], and alutenusin (18) [24], based on the spectroscopic analyses and comparison of their NMR, MS, and specific rotation data with those reported in literature. Compound 6 was determined to be (+)citreoisocoumarin [16][17] based on the 1D-and 2D-NMR data analyses and the comparable specific rotations of 6 (½a 25 D = +38.6) and that of citreoisocoumarin (½a 25 D = +46.4) in literature [17].…”

Section: Resultsmentioning

confidence: 99%

Isocoumarin Derivatives from the Sponge‐Associated Fungus Peyronellaea glomerata with Antioxidant Activities

Zhao

Liu

Proksch

et al. 2016

Chemistry & Biodiversity

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Chemical examination of the solid culture of the sponge-associated fungus Peyronellaea glomerata led to the isolation of five new isocoumarins, namely peyroisocoumarins A - D (1 - 4) and isocitreoisocoumarinol (5), together with 13 known analogues (6 - 18). Their structures were determined on the basis of extensive spectroscopic analyses, including the modified Mosher's method for the configurational assignments. Peyroisocoumarins A and B were characterized by the presence of Cl-atom at pentane chain, which were unusual in isocoumarin derivatives. The ARE reporter assay revealed that peyroisocoumarins A, B, and D exerted potent ARE activation in HepG2C8 cells, while the preliminary analyses of structure-activity relationship was discussed.

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“…Some well known examples being the 6-methoxymellein [5], diaporthin [6], fusamarin [7], asperentin derivatives [8], agrimonolide [9], canescin A and B [10], sclerotiorin A and B [11], LL-1640-6, 7, 8 [12], feralolide [13], achlisocoumarin [14], dihydroisocoumarins from Ononis natrix [15], and various chlorinated isocoumarins from Swartzia and Periconia spp. [16].…”

Section: Introductionmentioning

confidence: 99%

“…EIMS showed the M + - Isocoumarins related to agrimonolide (5) isolated from Agrimonia pilosa [9] and achlisocoumarin I from Achylis triphylla (6) [14] were prepared in good yields by condensation of homophthalic acid 4 with acid chlorides derived from commercial 4-methoxyphenylpropionic and 3,4-dimethoxycinnamic acid respectively. (Scheme 2).…”

Section: Introductionmentioning

confidence: 99%

An efficient synthesis of 3,5‐dimethoxyhomophthalic acid, a key intermediate for synthesis of natural isocoumarins

Saeed

Rama

Arfan

2003

Journal of Heterocyclic Chem

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Structure, Synthesis, and Stereochemistry of (+)-Orthosporin, a Phytotoxic Metabolite of Rhynchosporium Orthosporum

Abstract: Structure of (+)-orthosporin, a phytotoxic metabolite isolated from Rhynchosporium orthosporum has been elucidated from spectroscopic data and chemical reaction, and the stereochemistry of (+)-orthosporin and (+)-diaporthin has been confirmed by the synthesis.

Cited by 42 publications

References 3 publications

Comparative genomics to explore phylogenetic relationship, cryptic sexual potential and host specificity of Rhynchosporium species on grasses

Comparative genomics to explore phylogenetic relationship, cryptic sexual potential and host specificity of Rhynchosporium species on grasses

Isocoumarin Derivatives from the Sponge‐Associated Fungus Peyronellaea glomerata with Antioxidant Activities

An efficient synthesis of 3,5‐dimethoxyhomophthalic acid, a key intermediate for synthesis of natural isocoumarins

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