Sporothriolide derivatives as chemotaxonomic markers for Hypoxylon monticulosum

Three new furanones from endophytic fungus Hypoxylon vinosopulvinatum DYR-1-7 from Cinnamomum cassia with their antifungal activity

Hypoxylon vinosopulvinatum DYR-1-7 is a endophytic fungus isolated from the Cinnamomum cassia Presl and has an inhibitory effect on Lasiodiplodia pseudotheobromae. Three new furanones, hypoxylonone A-C (1-3), as well as three known compounds (4-6), were isolated from an EtOAc extract of H. vinosopulvinatum DYR-1-7. The structures were determined by spectroscopic data analysis using UV, IR, 1D-, 2D-NMR and HR-ESI-MS. The absolute configurations of 1-3 were elucidated by electronic circular dichroism (ECD) analyses. In the antifungal bioassay, Hypoxylonone B and C exhibited strong inhibitory effects on L. pseudotheobromae with IC50 value at the concentration of 1.01 and 2.40 μg/mL, respectively. Compound 6 showed medium antifungal activity with IC50 value at the concentration of 10.67 μg/mL on Fusarium oxysporum. Compounds 3 and 4 displayed medium antifungul effects on Candida albicans.

Sporothioethers: deactivated alkyl citrates from the fungus Hypomontagnella monticulosa

Submerged cultivation of Hypomontagnella monticulosa MUCL 54604 resulted in formation of a stereoisomeric mixture of new sulfur-containing sporothriolide derivatives named sporothioethers A and B. The presence of the 2-hydroxy-3-mercaptopropanoic acid moiety attenuates the antimicrobial activity in comparison to the precursor sporothriolide suggesting a detoxification mechanism. However, moderate effects on biofilms of Candida albicans and Staphylococcus aureus were observed for sporothriolide and sporothioethers A and B at concentrations below their MICs.

Cytotoxic tetronic acid derivatives from the mangrove endophytic fungus Hypomontagnella monticulosa YX702

Three new tetronic acid derivatives, nodulisporacid A ethyl ester (3), isosporothric acid methyl ester (4), and (R)-3-(methoxycarbonyl)-2-methyleneundecanoic acid (5) were isolated from mangrove endophytic fungus Hypomontagnella monticulosa YX702, together with three known analogues nodulisporacid A (1), nodulisporacid A methyl ester (2), and dihydrosporothriolide (6). The structures of these new compounds were elucidated by analysis of NMR and HR-ESI-MS spectroscopic data. In addition, the absolute configuration of nodulisporacid A (1) was confirmed by single-crystal X-ray diffraction for the first time. Subsequently, the absolute configuration of compounds 2 and 3 were determined by chemical derivatization of nodulisporacid A (1). The absolute configuration of compound 4 and 5 were established by TDDFT ECD calculations. Compounds 1 and 2 exhibited cytotoxic activities against A549 and Hela cancer cell lines with the IC50 values between 5.64 and 8.14 μM.

Secondary Metabolites from Annulohypoxylon sp. and Structural Revision of Emericellins A and B

Seven previously undescribed compounds were isolated from the endophytic fungus Annulohypoxylon sp. KYG-19 (family Xylariaceae), including three gymnomitrane-type sesquiterpenes xylariacinols A, B, and D (1, 2, and 4), one bisabolane-type sesquiterpene annulnol F (6), one phenol derivative lariacinol G (7), and two polyhydroxy compounds hypoxylonols H and I (8 and 9), together with two known gymnomitrane-type sesquiterpenes emericellin A (3) and 3-gymnomitren-15-ol (5). The assignments of their structures was determined by extensive spectroscopic and spectrometric analysis, acetonide analysis, Mosher's method, and X-ray crystallography. In addition, the structures of emericellins A and B, which were reported to possess an unprecedented tricyclo[4, 4, 2, 1]hendecane scaffold, were revised by comparing their spectroscopic data with those of 1 and 3. Compounds 1 and 4 exhibited antibacterial activity against Escherichia coli with minimum inhibitory concentrations of 4 and 2 μg/mL, respectively.

Multi-Gene Phylogeny and Taxonomy of Hypoxylon (Hypoxylaceae, Ascomycota) from China

The Hypoxylon species play an important ecological role in tropical rainforest as wood-decomposers, and some might have benefical effects on their hosts as endophytes. The present work concerns a survey of the genus Hypoxylon from Hainan Tropical Rainforest National Park of China. Four new species: H. wuzhishanense, H. hainanense, H.chrysalidosporum, and H.cyclobalanopsidis, were discovered based on a combination of morphological characteristics and molecular data. Hypoxylon wuzhishanense is characterized by Rust pulvinate stromata, amyloid apical apparatus and brown ascospores, with most of the perispore being indehiscent in 10% KOH. Hypoxylon hainanense has effused–pulvinate and Violet stromata, amyloid apical apparatus, light-brown to brown ascospores with straight germ slit and dehiscent perispore. Hypoxylonchrysalidosporum is distinguished by glomerate to pulvinate stromata, highly reduced or absent inamyloid apical apparatus, and light-brown to brown ascospores with very conspicuous coil-like ornamentation. Hypoxyloncyclobalanopsidis has Livid Purple pulvinate stromata, highly reduced amyloid apical apparatus, faint bluing, brown ascospores and dehiscent perispore, and it grows on dead branches of Cyclobalanopsis. Detailed descriptions, illustrations, and contrasts with morphologically similar species are provided. Phylogenetic analyses inferred from ITS, RPB2, LSU, and β-tubulin sequences confirmed that the four new species are distinct within the genus Hypoxylon.

The integrative taxonomy of Beauveria asiatica and B. bassiana species complexes with whole-genome sequencing, morphometric and chemical analyses

Fungi are rich in complexes of cryptic species that need a combination of different approaches to be delimited, including genomic information. Beauveria (Cordycipitaceae, Hypocreales) is a well-known genus of entomopathogenic fungi, used as a biocontrol agent. In this study we present a polyphasic taxonomy regarding two widely distributed complexes of Beauveria: B. asiatica and B. bassiana s.lat. Some of the genetic groups as previously detected within both taxa were either confirmed or fused using population genomics. High levels of divergence were found between two clades in B. asiatica and among three clades in B. bassiana, supporting their subdivision as distinct species. Morphological examination focusing on the width and the length of phialides and conidia showed no difference among the clades within B. bassiana while conidial length was significantly different among clades within B. asiatica. The secondary metabolite profiles obtained by liquid chromatography-mass spectrometry (LC-MS) allowed a distinction between B. asiatica and B. bassiana, but not between the clades therein. Based on these genomic, morphological, chemical data, we proposed a clade of B. asiatica as a new species, named B. thailandica, and two clades of B. bassiana to respectively represent B. namnaoensis and B. neobassiana spp. nov. Such closely related but divergent species with different host ranges have potential to elucidate the evolution of host specificity, with potential biocontrol application. Citation: Kobmoo N, Arnamnart N, Pootakham W, et al. 2021. The integrative taxonomy of Beauveria asiatica and B. bassiana species complexes with whole-genome sequencing, morphometric and chemical analyses. Persoonia 47: 136-150. https://doi.org/10.3767/persoonia.2021.47.04.

Seven-Step Total Synthesis of Sporothriolide

An enantioselective total synthesis of sporothriolide, a bioactive furofurandione-type fungal metabolite, has been achieved in a 21% overall yield from a commercially available β,γ-unsaturated carboxylic acid via seven steps. The key steps of this synthesis include a highly diastereoselective Michael addition of a chiral oxazolidinone derivative to a nitro olefin, the exploitation of an aromatic ring as a masked carboxylic acid functionality, and the base-promoted elimination of nitrous acid to install the α-methylene lactone unit of sporothriolide in the final step.

The integrative taxonomy of Beauveria asiatica and B. bassiana species complexes with whole-genome sequencing, morphometric and chemical analyses

Fungi are rich in complexes of cryptic species that need a combination of different approaches to be delimited, including genomic information. Beauveria (Cordycipitaceae, Hypocreales) is a well-known genus of entomopathogenic fungi, used as a biocontrol agent. In this study we present a polyphasic taxonomy regarding two widely distributed complexes of Beauveria: B. asiatica and B. bassiana s.lat. Some of the genetic groups as previously detected within both taxa were either confirmed or fused using population genomics. High levels of divergence were found between two clades in B. asiatica and among three clades in B. bassiana, supporting their subdivision as distinct species. Morphological examination focusing on the width and the length of phialides and conidia showed no difference among the clades within B. bassiana while conidial length was significantly different among clades within B. asiatica. The secondary metabolite profiles obtained by liquid chromatography-mass spectrometry (LC-MS) allowed a distinction between B. asiatica and B. bassiana, but not between the clades therein. Based on these genomic, morphological, chemical data, we proposed a clade of B. asiatica as a new species, named B. thailandica, and two clades of B. bassiana to respectively represent B. namnaoensis and B. neobassiana spp. nov. Such closely related but divergent species with different host ranges have potential to elucidate the evolution of host specificity, with potential biocontrol application. Citation: Kobmoo N, Arnamnart N, Pootakham W, et al. 2021. The integrative taxonomy of Beauveria asiatica and B. bassiana species complexes with whole-genome sequencing, morphometric and chemical analyses. Persoonia 47: 136-150. https://doi.org/10.3767/persoonia.2021.47.04.

New Diterpenoids and Isocoumarin Derivatives from the Mangrove-Derived Fungus Hypoxylon sp

Two new diterpenoids, hypoxyterpoids A (1) and B (2), and four new isocoumarin derivatives, hypoxymarins A–D (4–7), together, with seven known metabolites (3 and 8–13) were obtained from the crude extract of the mangrove-derived fungus Hypoxylon sp. The structures of the new compounds were elucidated on the basis of 1- and 2-dimensional (1D/2D) nuclear magnetic resonance (NMR) spectroscopic and mass spectrometric analysis. The absolute configurations of compounds 1, 2, 4, 5, and 7 were determined by comparison of experimental and calculated electronic circular dichroism (ECD) spectra, and the absolute configurations of C-4′ in 6 and C-9 in 7 were determined by [Rh₂(OCOCF₃)₄]-induced ECD spectra. Compound 1 showed moderate α-glucosidase inhibitory activities with IC₅₀ values of 741.5 ± 2.83 μM. Compounds 6 and 11 exhibited DPPH scavenging activities with IC₅₀ values of 15.36 ± 0.24 and 3.69 ± 0.07 μM, respectively.

Secondary metabolite biosynthetic diversity in the fungal family Hypoxylaceae and Xylaria hypoxylon

To date little is known about the genetic background that drives the production and diversification of secondary metabolites in the Hypoxylaceae. With the recent availability of high-quality genome sequences for 13 representative species and one relative (Xylaria hypoxylon) we attempted to survey the diversity of biosynthetic pathways in these organisms to investigate their true potential as secondary metabolite producers. Manual search strategies based on the accumulated knowledge on biosynthesis in fungi enabled us to identify 783 biosynthetic pathways across 14 studied species, the majority of which were arranged in biosynthetic gene clusters (BGC). The similarity of BGCs was analysed with the BiG-SCAPE engine which organised the BGCs into 375 gene cluster families (GCF). Only ten GCFs were conserved across all of these fungi indicating that speciation is accompanied by changes in secondary metabolism. From the known compounds produced by the family members some can be directly correlated with identified BGCs which is highlighted herein by the azaphilone, dihydroxynaphthalene, tropolone, cytochalasan, terrequinone, terphenyl and brasilane pathways giving insights into the evolution and diversification of those compound classes. Vice versa, products of various BGCs can be predicted through homology analysis with known pathways from other fungi as shown for the identified ergot alkaloid, trigazaphilone, curvupallide, viridicatumtoxin and swainsonine BGCs. However, the majority of BGCs had no obvious links to known products from the Hypoxylaceae or other well-studied biosynthetic pathways from fungi. These findings highlight that the number of known compounds strongly underrepresents the biosynthetic potential in these fungi and that a tremendous number of unidentified secondary metabolites is still hidden. Moreover, with increasing numbers of genomes for further Hypoxylaceae species becoming available, the likelihood of revealing new biosynthetic pathways that encode new, potentially useful compounds will significantly improve. Reaching a better understanding of the biology of these producers, and further development of genetic methods for their manipulation, will be crucial to access their treasures.

Chemical analysis and anticancer activity of sesterterpenoid from an endophytic fungus Hypomontagnella monticulosa Zg15SU and its host Zingiber griffithii Baker

Zingiber griffithii Baker is one of the native Zingiberaceous species in a tropical forest of North Sumatra, Indonesia. Zingiberaceous species have been intensively studied and reported as herbal ingredients in ethnomedicine and currently their endophytic fungal associates were studied for pharmacological importance. Fifteen endophytic fungi were isolated from Zingiber griffithii following morphological and molecular characterization. All isolates exhibited antibacterial properties to at least one of the tested pathogenic bacteria Staphylococcus aureus, Escherichia coli, Methicilin-resistant S. aureus (MRSA), and Enteropathogenic E. coli (EPEC). The isolate, identified as Hypomontagnella monticulosa strain Zg15SU (syn. Hypoxylon monticulosum Mont.) based on its rDNA/ITS sequence, displayed antibacterial activities to all tested pathogens. The EtOAc extract of the H. monticulosum Zg15SU showed the highest activity for gram-negative bacteria, the E. coli and EPEC, while the extract of Z. griffithii rhizome displayed activity only for E. coli. The gas chromatography-mass spectrometry analysis (GC-MS) indicated a major portion of similar compounds found in both the endophytic fungus and plant extract, revealing the compounds of oleic acid, cyclononasiloxane, octadecamethyl, and eicosanoic acid Furthermore, purification and structural elucidation on the EtOAc extract of both Z. griffithii rhizome and H. monticulosa Zg15SU yielded two bioactive compounds: a novel compound, griffithiiene, a terpenoid-alkaloid bearing the skeleton of a scalarane (1) and scalaradial (2) which were confirmed by ¹H- (500 MHz) and ¹³C-NMR (125 MHz) spectroscopy. Importantly, the elucidated compounds showed a cytotoxicity activity against cancer cell lines, the Panc-1, NBT-T2, and HCT116 based on in vitro MTT proliferation assay. This is the first report of Z. griffithii harboring an endophytic fungus, H. monticulosa, which produced potential antibacterial and anticancer metabolites along with its host to be utilized for future prospects.

The sporothriolides. A new biosynthetic family of fungal secondary metabolites

The biosynthetic gene cluster of the antifungal metabolite sporothriolide 1 was identified from three producing ascomycetes: Hypomontagnella monticulosa MUCL 54604, H. spongiphila CLL 205 and H. submonticulosa DAOMC 242471. A transformation protocol was established, and genes encoding a fatty acid synthase subunit and a citrate synthase were simultaneously knocked out which led to loss of sporothriolide and sporochartine production. In vitro reactions showed that the sporochartines are derived from non-enzymatic Diels-Alder cycloaddition of 1 and trienylfuranol A 7 during the fermentation and extraction process. Heterologous expression of the spo genes in Aspergillus oryzae then led to the production of intermediates and shunts and delineation of a new fungal biosynthetic pathway originating in fatty acid biosynthesis. Finally, a hydrolase was revealed by in vitro studies likely contributing towards self-resistance of the producer organism.

Seven New Cytotoxic and Antimicrobial Xanthoquinodins from Jugulospora vestita

During the course of a screening for novel biologically active secondary metabolites produced by the Sordariomycetes (Ascomycota, Fungi), the ex-type strain of Jugulospora vestita was found to produce seven novel xanthone-anthraquinone heterodimers, xanthoquinodin A11 (1) and xanthoquinodins B10–15 (2–7), together with the already known compound xanthoquinodin B4 (8). The structures of the xanthoquinodins were determined by analysis of the nuclear magnetic resonance (NMR) spectroscopic and mass spectrometric data. Moreover, the absolute configurations of these metabolites were established by analysis of the ¹H−¹H coupling constants, nuclear Overhauser effect spectroscopy (NOESY) correlations, and Electronic Circular Dichroism (ECD) spectroscopic data. Antifungal and antibacterial activities as well as cytotoxicity of all compounds were tested. Xanthoquinodin B11 showed fungicidal activities against Mucor hiemalis [minimum inhibitory concentration (MIC) 2.1 µg/mL], Rhodotorula glutinis (MIC 2.1 µg/mL), and Pichia anomala (MIC 8.3 µg/mL). All the compounds 1–8 displayed anti-Gram-positive bacteria activity (MIC 0.2–8.3 µg/mL). In addition, all these eight compounds showed cytotoxicity against KB 3.1, L929, A549, SK-OV-3, PC-3, A431, and MCF-7 mammalian cell lines. The six novel compounds (1–3, 5–7), together with xanthoquinodin B4, were also found in the screening of other strains belonging to Jugulospora rotula, revealing the potential chemotaxonomic significance of the compound class for the genus.

Itaconic acid derivatives: structure, function, biosynthesis, and perspectives

Itaconic acid possessing a vinylidene group, which is mainly produced by fungi, is used as a biobased platform chemical and shows distinctive bioactivities. On the other hand, some fungi and lichens produce itaconic acid derivatives possessing itaconic acid skeleton, and the number of the derivatives is currently more than seventy. Based on the molecular structures, they can be categorized into two groups, alkylitaconic acids and α-methylene-γ-butyrolactones. Interestingly, some itaconic acid derivatives show versatile functions such as antimicrobial, anti-inflammatory, antitumor, and plant growth-regulating activities. The vinylidene group of itaconic acid derivatives likely participates in these functions. It is suggested that α-methylene-γ-butyrolactones are biosynthesized from alkylitaconic acids which are first biosynthesized from acyl-CoA and oxaloacetic acid. Some modifying enzymes such as hydroxylase and dehydratase are likely involved in the further modification after biosynthesis of their precursors. This contributes to the diversity of itaconic acid derivatives. In this review, we summarize their structures, functions, and biosynthetic pathways together with a discussion of a strategy for the industrial use. KEY POINTS: • Itaconic acid derivatives can be categorized into alkylitaconic acids and α-methylene-γ-butyrolactones. • The vinylidene group of itaconic acid derivatives likely participates in their versatile function. • It is suggested that α-methylene-γ-butyrolactones are biosynthesized from alkylitaconic acids which are first synthesized from acyl-CoA and oxaloacetic acid.

High quality genome sequences of thirteen Hypoxylaceae (Ascomycota) strengthen the phylogenetic family backbone and enable the discovery of new taxa

The Hypoxylaceae (Xylariales, Ascomycota) is a diverse family of mainly saprotrophic fungi, which commonly occur in angiosperm-dominated forests around the world. Despite their importance in forest and plant ecology as well as a prolific source of secondary metabolites and enzymes, genome sequences of related taxa are scarce and usually derived from environmental isolates. To address this lack of knowledge thirteen taxonomically well-defined representatives of the family and one member of the closely related Xylariaceae were genome sequenced using combinations of Illumina and Oxford nanopore technologies or PacBio sequencing. The workflow leads to high quality draft genome sequences with an average N50 of 3.0 Mbp. A backbone phylogenomic tree was calculated based on the amino acid sequences of 4912 core genes reflecting the current accepted taxonomic concept of the Hypoxylaceae. A Percentage of Conserved Proteins (POCP) analysis revealed that 70% of the proteins are conserved within the family, a value with potential application for the definition of family boundaries within the order Xylariales. Also, Hypomontagnella spongiphila is proposed as a new marine derived lineage of Hypom. monticulosa based on in-depth genomic comparison and morphological differences of the cultures. The results showed that both species share 95% of their genes corresponding to more than 700 strain-specific proteins. This difference is not reflected by standard taxonomic assessments (morphology of sexual and asexual morph, chemotaxonomy, phylogeny), preventing species delimitation based on traditional concepts. Genetic changes are likely to be the result of environmental adaptations and selective pressure, the driving force of speciation. These data provide an important starting point for the establishment of a stable phylogeny of the Xylariales; they enable studies on evolution, ecological behavior and biosynthesis of natural products; and they significantly advance the taxonomy of fungi.

Observations on Texas hypoxylons, including two new Hypoxylon species and widespread environmental isolates of the H. croceum complex identified by a polyphasic approach

Two new species and a new combination of Hypoxylon from Texas were identified and described based on morphological, multigene phylogenetic (ITS [nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2], 28S [5' 1200 bp of nuc 28S rDNA], RPB2 [partial second largest subunit of the DNA-directed RNA polymerase II], TUB2 [partial β-tubulin]), and chemotaxonomic data. Hypoxylon olivaceopigmentum is characterized by its pulvinate to glomerate stromata, olivaceous KOH-extractable pigments, equilateral ascospores, and indehiscent perispore. Hypoxylon texense can be distinguished from morphologically similar species by its rust to dark brick KOH-extractable pigments and the high-performance liquid chromatography (HPLC) profile of its stromatal secondary metabolites. Hypoxylon hinnuleum is proposed as the sexual morph of Nodulisporium hinnuleum, featuring dark vinaceous glomerate stromata with dark brick KOH-extractable pigments composed of cohaerin-type azaphilones and smooth equilateral ascospores with indehiscent perispore. Based on these diagnostic characters, H. hinnuleum forms a complex with H. croceum and H. minicroceum. More than 50 ITS sequences with high identity originating from North American and East Asian environmental isolates formed a well-supported clade with the type of N. hinnuleum, demonstrating the widespread distribution of the species complex. In addition, updated descriptions and comprehensive illustrations with detailed information on the diagnostic features of H. fendleri and H. perforatum are provided. The multilocus phylogenetic reconstruction of Hypoxylon supported the status of the new species and broadened the knowledge about intergeneric relationships.

Diversity of biologically active secondary metabolites from endophytic and saprotrophic fungi of the ascomycete order Xylariales

Covering: up to December 2017 The diversity of secondary metabolites in the fungal order Xylariales is reviewed with special emphasis on correlations between chemical diversity and biodiversity as inferred from recent taxonomic and phylogenetic studies. The Xylariales are arguably among the predominant fungal endophytes, which are the producer organisms of pharmaceutical lead compounds including the antimycotic sordarins and the antiparasitic nodulisporic acids, as well as the marketed drug, emodepside. Many Xylariales are "macromycetes", which form conspicuous fruiting bodies (stromata), and the metabolite profiles that are predominant in the stromata are often complementary to those encountered in corresponding mycelial cultures of a given species. Secondary metabolite profiles have recently been proven highly informative as additional parameters to support classical morphology and molecular phylogenetic approaches in order to reconstruct evolutionary relationships among these fungi. Even the recent taxonomic rearrangement of the Xylariales has been relying on such approaches, since certain groups of metabolites seem to have significance at the species, genus or family level, respectively, while others are only produced in certain taxa and their production is highly dependent on the culture conditions. The vast metabolic diversity that may be encountered in a single species or strain is illustrated based on examples like Daldinia eschscholtzii, Hypoxylon rickii, and Pestalotiopsis fici. In the future, it appears feasible to increase our knowledge of secondary metabolite diversity by embarking on certain genera that have so far been neglected, as well as by studying the volatile secondary metabolites more intensively. Methods of bioinformatics, phylogenomics and transcriptomics, which have been developed to study other fungi, are readily available for use in such scenarios.

New Alkylitaconic Acid Derivatives from Nodulisporium sp. A21 and Their Auxin Herbicidal Activities on Weed Seeds

Five alkylitaconic acid (AA) derivatives, including two novel compounds, epideoxysporothric acid (2) and sporochartine F (5), and three known compounds, deoxysporothric acid (1), deoxyisosporothric acid (3), and 1-undecen-2,3-dicarboxylic acid (4), were obtained from the fermentation culture of the endophytic fungus Nodulisporium sp. A21. The auxin herbicidal activities of compounds 1-4 against weed seeds were investigated under laboratory conditions. In general, the tested compounds displayed radicle growth promoting activity at low doses and inhibitory activity at higher doses. Compounds 1 and 2 could significantly inhibit the radicle growth of dicotyledon weeds, Eclipta prostrata and Veronica persica, at a concentration range from 50 to 200 μg mL^-1, while 3 notably stimulated radicle growth at the same concentration range. The results suggested that these AA derivatives have the potential to be used as the lead scaffold for novel auxin herbicide development. In addition, the biosynthetic pathways of 1-4 were deduced based on ¹³C labeling experiment.

Oryzines A & B, Maleidride Congeners from Aspergillus oryzae and Their Putative Biosynthesis

Aspergillus oryzae is traditionally used in East Asia for the production of food and brewing. In addition, it has been developed into a suitable host for the heterologous expression of natural product biosynthetic genes and gene clusters, enabling the functional analysis of the encoded enzymes. A. oryzae shares a 99.5% genome homology with Aspergillus flavus, but their secondary metabolomes differ significantly and various compounds unique to A. oryzae have been reported. While using A. oryzae as a host for heterologous expression experiments we discovered two new metabolites in extracts of A. oryzae M-2-3 with an unusual maleidride backbone, which were named oryzine A and B. Their structures were elucidated by high resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR) analysis. Their structural relationships with known maleidrides implied involvement of a citrate synthase (CS) and a polyketide (PKS) or fatty acid synthase (FAS) in their biosynthesis. Analysis of the A. oryzae genome revealed a single putative biosynthetic gene cluster (BGC) consistent with the hypothetical biosynthesis of the oryzines. These findings increase knowledge of the chemical potential of A. oryzae and are the first attempt to link a novel product of this fungus with genomic data.

Sporothriolide-Related Compounds from the Fungus Hypoxylon monticulosum CLL-205 Isolated from a Sphaerocladina Sponge from the Tahiti Coast

Two sporothriolide-related compounds were obtained from an extract of the fungus Hypoxylon monticulosum CLL-205, isolated from a Sphaerocladina sponge collected from the Tahiti coast. Compound 2 is a deoxy analogue of sporothric acid (4). Compound 3 is a newly reported unusual scaffold combining sporothriolide (1) and trienylfuranol A (5) moieties, through a Diels-Alderase-type reaction. Various experimental and analytical arguments supported the biocatalytic origin of compound 3. The structures of the isolated compounds were elucidated using 1D and 2D NMR, HRMS, and IR data. The structure and the absolute configuration of 3 were unambiguously confirmed by a single-crystal X-ray diffraction analysis.

Terphenyl derivatives and drimane - Phathalide/isoindolinones from Hypoxylon fendleri BCC32408

The genus Hypoxylon, a member of the family Xylariaceae, has been known to produce significant secondary metabolites in terms of chemical diversity. Moreover, the compounds isolated can also be used as chemotaxonomic characters for differentiation among the two sections, which are sect. Annulata and sect. Hypoxylon. In our continuing chemical screening programme for novel compounds, the crude extracts of H. fendleri BCC32408 gave significant chemical profiles in HPLC analyses. Thus, the chemical investigation of these crude extracts was then carried out. The investigation led to the isolation of ten previously undescribed compounds including three terphenylquinones (fendleryls A - C), one terphenyl (fendleryl D), and six novel drimane - phthalide-type lactone/isoindolinones derivatives (fendlerinines A - F) along with seven known compounds (2-O-methylatromentin, rickenyl E, atromentin, rickenyls C - D, (+)-ramulosin, and O-hydroxyphenyl acetic acid). The chemical structures were determined on the basis of spectroscopic analyses, including 1D, 2D NMR and high-resolution mass spectrometry, as well as chemical transformations. In addition, these isolated compounds were assessed for antimicrobial activity including antimalarial (against Plasmodium falciparum, K-1 strain), antifungal (against Candida albicans), antibacterial (against Bacillus cereus) activities. Cytotoxicity against both cancerous (KB, MCF-7, NCI-H187) and non-cancerous (Vero) cells of these compounds were also evaluated.

Anti-phytopathogenic activity of sporothriolide, a metabolite from endophyte Nodulisporium sp. A21 in Ginkgo biloba

Phytopathogenic fungi such as Rhizoctonia solani and Sclerotinia sclerotiorum caused multiple plant diseases resulting in severe loss of crop production. Increasing documents endorsed that endophytes are a striking resource pool for numerous metabolites with various bioactivities such as anti-fungal. Here we reported the characterization and anti-phytopathogenic activity of sporothriolide, a metabolite produced by Nodulisporium sp. A21-an endophytic fungus in the leaves of Ginkgo biloba. Among the total twenty-five endophytic fungi isolated from the healthy leaves of G. biloba, the fermentation broth (FB) of the strain A21 was found potently inhibitory activity against R. solani and S. sclerotiorum using mycelia growth inhibition method. A21 was then identified as Nodulisporium sp., the asexual stage of Hypoxylon sp., by microscopic examination and ITS rDNA sequence data comparison. Under the bioassay-guided fractionation, sporothriolide was isolated from the petroleum ether extract of the FB of A21, whose structure was established by integrated interpretation of HR-ESI-MS and (1)H- and (13)C-NMR. Furthermore, the crystal structure of sporothriolide was first reported. In addition, sporothriolide was validated to be potently antifungal against R. solani, S. sclerotiorum and inhibit conidium germination of Magnaporthe oryzae in vitro and in vivo, indicating that it could be used as a lead compound for new fungicide development.

Exploitation of Fungal Biodiversity for Discovery of Novel Antibiotics

Fungi were among the first sources for antibiotics. The discovery and development of the penicillin-type and cephalosporin-type β-lactams and their synthetic versions were transformative in emergence of the modern pharmaceutical industry. They remain some of the most important antibiotics, even 70 years after their discovery. Meanwhile, thousands of fungal metabolites have been discovered, yet these metabolites have only contributed a few additional compounds that have entered clinical development. Substantial expansion in fungal biodiversity assessment along with the availability of modern "-OMICS" technology and revolutionary developments in fungal biotechnology have been made in the last 15 years subsequent to the exit of most of the big Pharma companies from the field of novel antibiotics discovery. Therefore, the timing seems opportune to revisit these fascinating chemically rich organisms as a reservoir of small-molecule templates for lead discovery. This review will describe ongoing interdisciplinary scenarios in which specialists in fungal biology collaborate with chemists, pharmacologists and biochemical and process engineers in order to reveal and make new antibiotics. The utility of a pre-selection process based on phylogenetic data and distribution of secondary metabolite encoding gene cluster will be highlighted. Examples of novel bioactive metabolites from fungi derived from special ecological groups and new phylogenetic lineages will also be discussed.

Rickenyls A-E, antioxidative terphenyls from the fungus Hypoxylon rickii (Xylariaceae, Ascomycota)

Our screening efforts for new natural products with interesting bioactivity have revealed the neotropical ascomycete Hypoxylon rickii as a prolific source. We isolated five secondary metabolites with a p-terphenyl backbone from the mycelial extract of a fermentation of this fungus in 70 l scale by using RP-HPLC, which were named rickenyls A-E (1-5). Their structures were elucidated by X-ray crystallography and NMR spectroscopy, complemented by HRESIMS. Two of the compounds contained a quinone core structure in ortho (2) and para-position (5), respectively. We obtained 2 spontaneously and by lead tetraacetate oxidation from 1. All compounds were screened for antimicrobial, antioxidative and cytotoxic activities. Rickenyl A (1) exhibited strong antioxidative effects and moderate cytotoxic activity against various cancer cell lines.

Botryane, noreudesmane and abietane terpenoids from the ascomycete Hypoxylon rickii

In the course of our screening for new bioactive natural products, a culture of Hypoxylon rickii, a xylariaceous ascomycete collected from the Caribbean island Martinique, was identified as extraordinary prolific producer of secondary metabolites. Ten metabolites of terpenoid origin were isolated from submerged cultures of this species by preparative HPLC. Their structures were elucidated using spectral techniques including 2D NMR and HRESIMS. Three of the compounds were elucidated as new botryanes (1-3) along with three known ones, i.e. (3aS)-3a,5,5,8-tetramethyl-3,3a,4,5-tetrahydro-1H-cyclopenta[de]isochromen-1-one (4), (3aS,8R)-3a,5,5,8-tetramethyl-3,3a,4,5,7,8-hexahydro-1H-cyclopenta[de]isochromen-1-one (5) and botryenanol (6). Further three new sesquiterpenoids featured a 14-noreudesmane-type skeleton and were named hypoxylan A-C (7-9); the diterpenoid rickitin A (10) contains an abietane-type backbone. Compounds 1, 2, 3, 7, and 10 showed cytotoxic effects against murine cells.

Silphiperfolene-Type Terpenoids and Other Metabolites from Cultures of the Tropical Ascomycete Hypoxylon rickii (Xylariaceae)

A culture isolated from ascospores of Hypoxylon rickii, a xylariaceous ascomycete collected in Martinique, had yielded botryane, noreremophilane and abietane-type terpenoids in a preceding study, but additional metabolites were detected by extensive HPLC-MS analysis in other fractions. Herein we report the further isolation of four new sesquiterpenoids with a silphiperfol-6-ene skeleton from extracts of H. rickii. The planar structures were elucidated by NMR and HRMS data as 13-hydroxysilphiperfol-6-ene (1), 9-hydroxysilphiperfol-6-en-13-oic acid (2), 2-hydroxysilphiperfol-6-en-13-oic acid (3) and 15-hydroxysilphiperfol-6-en-13-oic acid (4). For compounds 2-4 we propose the trivial names rickinic acids A-C. Their stereochemistry was assigned by ROESY correlations as well as by the specific optical rotation. Additionally, the known compounds, botryenanol, dehydrobotrydienol, cyclo(Phe-Pro), cyclo(Pro-Leu), (+)-ramulosin and α-eleostearic acid were isolated. The antimicrobial and cytotoxic activities of the new compounds are also reported.