Academic literature on the topic 'Australian marine sponge derived fungi'

Marine organisms are a source of natural products and produce compounds with a molecular structure that is unique and useful. Thousands of new compounds have biological activitity for anticancer, antiviral, and antimicrobial. This compounds isolated from various marine organism, including from marine-derived fungi. Investigation of chemical compounds from marine-derived fungi isolated from sponge has increased steadily, indicating the important role of marine-derived fungi in the discovery of drug compounds. The sponge has produced various kinds of fungi, which have reported to provide a variety of pharmacologically active metabolites and structurally diverse. Study literature showed that many fungal genera isolated from the marine sponge dominated the genus Acremonium, Aspergillus, Penicillium, Phoma, and Fusarium. The high proportion of genera and new compounds showed that the fungi isolated from the sponge could develop.

This review article presents our group's recent research findings with regard to bioactive natural products from marine sponges and tunicates, as well as from sponge derived fungi. The organisms discussed originate in the Indopacific region, which has an exceptionally rich marine biodiversity. Major topics that are covered in our review include the chemical ecology of sponges, focusing on defense against fishes, as well as the isolation and identification of new bioactive constituents from sponges and tunicates. Sponge derived fungi are introduced as an emerging source for new bioactive metabolites, reflecting the currently growing interest in natural products from marine microorganisms.

BACKGROUND: The coral reef on Mandeh Island, West Sumatra, Indonesia, consists of an abundant source of sponge and soft coral. Secondary metabolites of marine-derived fungi isolated from the sponge and soft coral possess numerous biological activities. AIM: This study collected, identified, and screened marine-derived fungi isolated from marine invertebrates for antibacterial and cytotoxic bioactivities. MATERIALS AND METHODS: The marine invertebrates used are sponges; Xestospongia testudinaria and Placortis communis) and soft corals (Sarcophyton elegan and Subergorgia suberosa). The EtOAc extracts were analyzed for antimicrobial and cytotoxic activities using the diffusion agar method and brine shrimps lethality test. RESULTS: After cultivating on rice medium, the EtOAc extracts of 22 isolated fungi showed potent antimicrobial activity with an inhibitory zone of 15.9 mm against Staphylococcus aureus (XT2 extract), and Pseudomonas aeruginosa of 26.7 mm (XT6 extract), and Candida albicans of 29 mm (SE5 extract). XT6 extract showed the potential cytotoxic activity with an LC50 value of 100 μg/ml. CONCLUSION: The ability of the marine-derived fungi to produce bioactive compounds is promising potential as a source of antimicrobial and cytotoxic compounds.

Introduction. Marine sponges have established symbiotic interactions with a large number of microorganisms including fungi. Most of the studies so far have focussed on the characterization of sponge-associated bacteria and archaea with only a few reports on sponge-associated fungi. During the isolation and characterization of bacteria from marine sponges of South Australia, we observed multiple types of fungi. One isolate in particular was selected for further investigation due to its unusually large size and being chromogenic. Here, we report on the investigations on the physical, morphological, chemical, and genotypic properties of this yeast-like fungus. Methods and Materials. Sponge samples were collected from South Australian marine environments, and microbes were isolated using different isolation media under various incubation conditions. Microbial isolates were identified on the basis of morphology, staining characteristics, and their 16S rRNA or ITS/28S rRNA gene sequences. Results. Twelve types of yeast and fungal isolates were detected together with other bacteria and one of these fungi measured up to 35 μm in diameter with a unique chromogen compared to other fungi. Depending on the medium type, this unique fungal isolate appeared as yeast-like fungi with different morphological forms. The isolate can ferment and assimilate nearly all of the tested carbohydrates. Furthermore, it tolerated a high concentration of salt (up to 25%) and a range of pH and temperature. ITS and 28S rRNA gene sequencing revealed a sequence similarity of 93% and 98%, respectively, with the closest genera of Eupenidiella, Hortaea, and Stenella. Conclusions. On the basis of its peculiar morphology, size, and genetic data, this yeast-like fungus possibly constitutes a new genus and the name Magnuscella marinae, gen nov., sp. nov., is proposed. This study is the first of its kind for the complete characterization of a yeast-like fungus from marine sponges. This novel isolate developed a symbiotic interaction with living hosts, which was not observed with other reported closest genera (they exist in a saprophytic relationship). The observed unique size and morphology may favour this new isolate to establish symbiotic interactions with living hosts.

Tetramic acid derivatives are an important class of nitrogen heterocycles with a pyrrolidine-2,4-dione core as a key structural motif. From the sponge-derived fungus Beauveria bassiana, a new equisetin-like tetramic acid derivative, beauversetin (1), was isolated. The sea weed-derived fungus Microdiplodia sp. produced the tetramic acid derivative 2 (Sch210972) which was shown to inhibit human leucocyte elastase (HLE) with an IC50 of 1.04 μg mL−1.

Two new bromotyrosine-derived secondary metabolites, aplysamine-1 (5) and aplysamine-2 (6), were isolated from an Australian marine sponge, Aplysina sp. The structures were assigned on the basis of detailed spectroscopic analysis, and the tertiary amine salt character was revealed by conversion into the corresponding free tertiary amines. Cooccurring with (5) and (6) were the known antibiotic compounds (+)-aeroplysinin (1) and (3′,5′-dibromo-4′-ethoxy-1′-hydroxy-4′-methoxycyclohexa-2′,5′-dienyl)acetamide (2).

The misuse and overuse of antibiotics have led to the emergence of multidrug-resistant microorganisms, which decreases the chance of treating those infected with existing antibiotics. This resistance calls for the search of new antimicrobials from prolific producers of novel natural products including marine sponges. Many of the novel active compounds reported from sponges have originated from their microbial symbionts. Therefore, this study aims to screen for bioactive metabolites from bacteria isolated from sponges. Twelve sponge samples were collected from South Australian marine environments and grown on seven isolation media under four incubation conditions; a total of 1234 bacterial isolates were obtained. Of these, 169 bacteria were tested in media optimized for production of antimicrobial metabolites and screened against eleven human pathogens. Seventy bacteria were found to be active against at least one test bacterial or fungal pathogen, while 37% of the tested bacteria showed activity against Staphylococcus aureus including methicillin-resistant strains and antifungal activity was produced by 21% the isolates. A potential novel active compound was purified possessing inhibitory activity against S. aureus. Using 16S rRNA, the strain was identified as Streptomyces sp. Our study highlights that the marine sponges of South Australia are a rich source of abundant and diverse bacteria producing metabolites with antimicrobial activities against human pathogenic bacteria and fungi.

In our natural product screening program from marine fungi, two new aromatic polyketides karimunones A (1) and B (2) and five known compounds (3–7) were isolated from sponge-associated Fusarium sp. KJMT.FP.4.3 which was collected from an Indonesian sponge Xestospongia sp. The structures of these compounds were determined by the analysis of NMR and MS spectroscopic data. The NMR assignment of 1 was assisted by DFT-based theoretical chemical shift calculation. Compound 2 showed antibacterial activity against multidrug resistant Salmonella enterica ser. Typhi with a MIC of 125 µg/mL while 1 was not active.

ABSTRACT Symbiotic microbes play a variety of fundamental roles in the health and habitat ranges of their hosts. While prokaryotes in marine sponges have been broadly characterized, the diversity of sponge-inhabiting fungi has barely been explored using molecular approaches. Fungi are an important component of many marine and terrestrial ecosystems, and they may be an ecologically significant group in sponge-microbe interactions. This study tested the feasibility of using existing fungal primers for molecular analysis of sponge-associated fungal communities. None of the eight selected primer pairs yielded satisfactory results in fungal rRNA gene or internal transcribed spacer (ITS) clone library constructions. However, 3 of 10 denaturing gradient gel electrophoresis (DGGE) primer sets, which were designed to preferentially amplify fungal rRNA gene or ITS regions from terrestrial environmental samples, were successfully amplified from fungal targets in marine sponges. DGGE analysis indicated that fungal communities differ among different sponge species (Suberites zeteki and Mycale armata) and also vary between sponges and seawater. Sequence analysis of DGGE bands identified 23 and 21 fungal species from each of the two sponge species S. zeteki and M. armata, respectively. These species were representatives of 11 taxonomic orders and belonged to the phyla of Ascomycota (seven orders) and Basidiomycota (four orders). Five of these taxonomic orders (Malasseziales, Corticiales, Polyporales, Agaricales, and Dothideomycetes et Chaetothyriomcetes incertae sedis) have now been identified for the first time in marine sponges. Seven and six fungal species from S. zeteki and M. armata, respectively, are potentially new species because of their low sequence identity (≤98%) with their references in GenBank. Phylogenetic analysis indicated sponge-derived sequences were clustered into “marine fungus clades” with those from other marine habitats. This is the first report of molecular analysis of fungal communities in marine sponges, adding depth and dimension to our understanding of sponge-associated microbial communities.

This thesis described the chemical investigations of natural products from Australian marine sponge-derived fungi. Sponge samples were collected from the Great Barrier Reef, Queensland, Australia, by Queensland Museum. The thesis is divided into eight chapters and can be devided into two major parts. The first three chapters comprised the first part of the thesis: Chapter 1 outlined the research background, literature review of marine fungal secondary metabolites; Chapter 2 introduced fungal culture and storage background knowledge, and the list of isolated marine fungal strains. Chapter 3 introduced the background of the thrombin inhibition assay and assay results. The second part (Chapter 4 to 7) of this thesis is focused on chemical isolation and structure elucidation of secondary metabolites from isolated fungal strains, mostly active strains against thrombin. An unidentified fungal strain, FS-G315858 (T)-Y, isolated from the frozen sponge sample Dysidea sp.1400 produced five peptide compounds (chapter 4, 16-20). Compound 16 is a polypeptide which features the same relative configuration with a known compound unguisine A, and compounds 17-20 are diketopiperazines. Active fungal strains FS-G315695 (T)-Y and FDPS-61732-YB were isolated from different sponge samples. However, they were identified to be the identical fungal strain Eurotium rubrum; the chemical isolation of FS-G315695 (T)-Y from its mycelia EtOAc extract resulted in three compounds (chapter 5, 17-19). Compounds 18 and 19 were identified to be flavoglaucin and iso-dihydroauroglaucin. Compound 17 was identified to have the same relative configuration with a known compound neo-echinulin A. The chemical isolation of FDPS-61732-YB from its broth EtOAc extract resulted in several diketopiperazines (chapter 5, 27-29). Another active fungal strain FS-G315695 (T)-WY was identified as Aspergillus ochraceous, the chemical isolation of its mycelia EtOAc extract resulted in one benzodiazepine compound (chapter 6, 18), together with two fatty acids (chapter 6, 16-17). The structure of compound 18 was elucidated and identified to have same relative configuration with the known compound circumdatin E. Media comparison for active fungal strain FS-G315695 (T)-Y was conducted and this work resulted in producing several neo-echinulin analogues (chapter 7, 1-3). The isolation and structure elucidation of these compounds were reported in chapter 7.

This thesis described the chemical investigations of natural products from Australian marine sponge-derived fungi. Sponge samples were collected from the Great Barrier Reef, Queensland, Australia, by Queensland Museum. The thesis is divided into eight chapters and can be devided into two major parts. The first three chapters comprised the first part of the thesis: Chapter 1 outlined the research background, literature review of marine fungal secondary metabolites; Chapter 2 introduced fungal culture and storage background knowledge, and the list of isolated marine fungal strains. Chapter 3 introduced the background of the thrombin inhibition assay and assay results. The second part (Chapter 4 to 7) of this thesis is focused on chemical isolation and structure elucidation of secondary metabolites from isolated fungal strains, mostly active strains against thrombin. An unidentified fungal strain, FS-G315858 (T)-Y, isolated from the frozen sponge sample Dysidea sp.1400 produced five peptide compounds (chapter 4, 16-20). Compound 16 is a polypeptide which features the same relative configuration with a known compound unguisine A, and compounds 17-20 are diketopiperazines. Active fungal strains FS-G315695 (T)-Y and FDPS-61732-YB were isolated from different sponge samples. However, they were identified to be the identical fungal strain Eurotium rubrum; the chemical isolation of FS-G315695 (T)-Y from its mycelia EtOAc extract resulted in three compounds (chapter 5, 17-19). Compounds 18 and 19 were identified to be flavoglaucin and iso-dihydroauroglaucin. Compound 17 was identified to have the same relative configuration with a known compound neo-echinulin A. The chemical isolation of FDPS-61732-YB from its broth EtOAc extract resulted in several diketopiperazines (chapter 5, 27-29). Another active fungal strain FS-G315695 (T)-WY was identified as Aspergillus ochraceous, the chemical isolation of its mycelia EtOAc extract resulted in one benzodiazepine compound (chapter 6, 18), together with two fatty acids (chapter 6, 16-17). The structure of compound 18 was elucidated and identified to have same relative configuration with the known compound circumdatin E. Media comparison for active fungal strain FS-G315695 (T)-Y was conducted and this work resulted in producing several neo-echinulin analogues (chapter 7, 1-3). The isolation and structure elucidation of these compounds were reported in chapter 7.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Eskitis Institute for Cell and Molecular Therapies
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Low-molecular mass natural products from bacteria, fungi, plants and marine organisms exhibit unique structural diversity which are of interest for the identification of new lead structures for medicinals and agrochemicals. In the search for bioactive compounds from marine sponges and sponge-associated fungi, this research work resulted to the isolation of twenty-six compounds, eight of which are new metabolites. The sponges were collected from the Indo-pacific regions, particularly those from Indonesian and Philippine waters, as well as those from the Mediterranean Sea near the island of Elba in Italy. A combination of the chemically- and biologically-driven approach for drug discovery was employed, wherein extracts were screened for antibacterial, antifungal and cytotoxic activities. In addition to the bioassay-guided approach to purify the compounds responsible for the activity of the extract, TLC, UV and MS were also used to isolate the chemically most interesting substances. Hence, purified compounds which are not responsible for the initial bioscreening activity may have a chance to be evaluated for other bioactivities. Enumerated below are the compounds which have been isolated and structurally elucidated and whose bioactivities have been further characterized. 1. The extract of the fungus Cladosporium herbarum associated with the sponge Callyspongia aerizusa afforded seven structurally related polyketides, including two new twelve-membered macrolides: pandangolide 3 and 4, and a new acetyl congener of the previously isolated 5-hydroxymethyl-2-furoic acid. The two furoic acid analogues isolated were found to be responsible for the antimicrobial activity of the extract. The isolation of the known phytotoxin Cladospolide B from Cladosporium herbarum, which was originally known from Cladosporium cladosporioides and C. tenuissimum, indicates the possibility that Cladospolide B may be a chemotaxonomic marker of particular Cladosporium species. 2. The extract of the fungus Curvularia lunata associated with the Indonesian sponge Niphates olemda yielded three compounds, namely the new antimicrobially-active anthraquinone lunatin, the known bisanthraquinone cytoskyrin A, and the known plant hormone abscisic acid. The co-occurrence of the two structurally-related anthraquinones suggests that the monomeric lunatin may be a precursor in the biosynthesis of the bisanthraquinone cytoskyrin A. 3. The fungus Penicillium spp. associated with the Mediterranean sponge Axinella verrucosa yielded six compounds, namely the known antifungal griseofulvin and its less active dechloro analogue; the known toxin oxaline; and the known cytotoxic metabolite communesin B and its two new congeners communesin C and D. The new communesins were less active than communesin B in the brine-shrimp lethality test. 4. An unidentified fungus which was also isolated from the same Mediterranean sponge Axinella verrucosa as Penicillium spp. yielded the known compound monocerin which has been reported to possess phytotoxic and insecticidal activities. 5. The fungus Aspergillus flavus associated with the Philippine sponge Hyrtios aff. reticulatus yielded the known toxin a-cyclopiazonic acid. 6. The Indonesian sponge Agelas nakamurai yielded four bromopyrrole alkaloids namely the new compound 4-bromo-pyrrole-2-carboxylic acid, and the known compounds: 4-bromo-pyrrole-2-carboxamide, mukanadin B and mukanadin C. All of the four compounds except mukanadin B were found to be antimicrobially-active. Bromopyrrole alkaloids are well-known metabolites of the genus Agelas and are proven to play an important role in the chemical defense of the sponge against predation from fishes. 7. The Indonesian sponge Jaspis splendens yielded three known substances which are known for their antiproliferative activities, namely the depsipeptides jaspamide (jasplakinolide), and its derivatives jaspamide B and jaspamide C
Niedermolekulare Naturstoffe aus Bakterien, Pilzen, Pflanzen und marinen Organismen weisen eine einzigartige strukturelle Diversität auf, die für die Identifizierung neuer Leitstrukturen für die Entwicklung von Arzneistoffen und Pflanzenschutzmitteln von großer Bedeutung ist. Im Rahmen der Suche nach bioaktiven Verbindungen aus marinen Schwämmen und mit diesen Schwämmen assoziierten Pilzen wurden in dieser Arbeit insgesamt 26 Sekundärstoffe isoliert, wobei es sich bei acht Substanzen um neue Verbindungen handelt. Die Schwämme wurden im indo-pazifischen Gebiet gesammelt, insbesondere aus Indonesien und den Philippinen, so wie aus dem Mittelmeer in der Nähe der Insel Elba in Italien. Für die Entdeckung neuer bioaktiver Substanzen wurde eine Kombination von chemischen und biologischen Methoden angewendet, wodurch Extrakte mit verschiedenen Screening-Methoden auf Bioaktivität getestet worden sind. Zum Einsatz kamen dabei Versuche mit Raupen des polyphagen Nachtfalters Spodoptera littoralis (Noctuidae; Lepidoptera) im Hinblick auf potentielle insektizide Wirkungen, antimikrobielle Untersuchungen mit gram-negativen und gram-positiven Bakterien und dem Pilz Candida albicans, Zytotoxizitätstests gegenüber menschlichen Krebszellen und Toxizitätstests mit dem Krebs Artemia salina. Zusätzlich zur bioaktivitäts-geleiteten Isolierung von Substanzen aus aktiven Extrakten wurden daneben auch DC, UV und MS als Kriterien herangezogen, um die aus chemischer Sicht interessantesten Verbindungen zu isolieren. Damit konnten auch solche Substanzen, die nicht für die Aktivität der Extrakte im Bioscreening verantwortlich waren, weiteren Biotests unterzogen werden. Im einzelnen wurden die folgenden Verbindungen isoliert, ihre Struktur aufgeklärt, und ihre biologische Aktivität näher charakterisiert: 1. Der antimikrobiell aktive Extrakt aus dem Pilz Cladosporium herbarum, der mit dem indonesischen Schwamm Callyspongia aerizusa assoziiert ist, ergab sieben Polyketide, die strukturell ähnlich sind, einschließlich der beiden neuen zwölf-gliedrigen Makrolide Pandangolid 3 und Pandangolid 4, sowie ein neues acetyliertes Derivat des bereits bekannten Naturstoffs 5-Hyroxymethyl-2-furancarbonsäure. Beide Furancarbonsäuren zeigten antimikrobielle Aktivität und dürften deshalb hauptsächlich für die antimikrobielle Aktivität des Extrakts verantwortlich sein. Daß Cladospolid B, ein bekanntes Phytotoxin, das bereits für die Arten Cladosporium cladosporoiodes und C. tenuissimum beschrieben wurde, ebenfalls aus C. herbarum isoliert wurde, deutet darauf hin, daß Cladospolid B als ein chemotaxonomischer Marker für bestimmte Cladosporium-Arten angesehen werden könnte. 2. Der antimikrobiell aktive Extrakt aus dem Pilz Curvularia lunata, der mit dem indonesischen Schwamm Niphates olemda assoziiert ist, ergab drei Substanzen, nämlich das neue antimikrobiell aktive Anthrachinon Lunatin sowie das bereits bekannte Bisanthrachinon Cytoskyrin A, und das bekannte Pflanzenhormon Abscisinsäure. Das gemeinsame Vorkommen der beiden strukturell verwandten Anthranoide könnte ein Indiz dafür sein, daß das Monomer Lunatin eine biogenetische Vorstufe des Bisanthrachinons Cytoskyrin A darstellt. 3. Ein mit dem im Mittelmeer gesammelten Schwamm Axinella verrucosa assoziierter Pilz der Gattung Penicillium ergab insgesamt sechs Substanzen, im einzelnen das bekannte Antimykotikum Griseofulvin und dessen weniger aktives Dechlor-Derivat, das bekannte Toxin Oxalin, sowie die als zytotoxisch beschriebene Verbindung Communesin B und deren neue Derivate Communesin C und Communesin D. Im Vergleich zu Communesin B erwiesen sich die neuen Communesin-Derivate als weniger aktiv gegenüber dem Krebs A. salina. 4. Ein bisher unidentifizierter Pilz aus dem gleichen Schwamm Axinella verrucosa lieferte die bekannte Substanz Monocerin, über deren phytotoxische und insektizide Eigenschaften bereits berichtet wurde. 5. Der mit dem philippinischen Schwamm Hyrtios aff. reticulatus assoziierte Pilz Aspergillus flavus ergab das bereits bekannte Toxin a-Cyclopiazonsäure. 6. Der indonesische Schwamm Agelas nakamurai lieferte vier bromierte Pyrrol-Alkaloide, nämlich die neue Substanz 4-Brompyrrol-2-carbonsäure sowie die bereits bekannten Verbindungen 4-Brompyrrol-2-carboxamid, Mukanadin B und Mukanadin C. Alle vier Substanzen außer Mukanadin B zeigten antimikrobielle Aktivität. Bromierte Pyrrol-Alkaloide wurden in vielen Untersuchungen als typische Sekundärstoffe der Schwammgattung Agelas beschrieben, die bei der chemischen Verteidigung der Schwämme gegen Fische eine wichtige Rolle spielen. 7. Der indonesiche Schwamm Jaspis splendens ergab drei bekannte Substanzen, die für ihre antiproliferative Aktivität bekannt sind, nämlich die Depsipeptide Jaspamid (Jasplakinolid) und dessen Derivate Jaspamid B und Jaspamid C

Parkinson’s disease (PD) is the second most common neurodegenerative disease, affecting over five million patients worldwide. Like Alzheimer’s disease (AD), it mostly affects the elderly and causes considerable disability and suffering. Unfortunately, the molecular mechanism of PD is still poorly understood, and there are no drugs available to treat the disease. Our overall aim was to identify natural products to probe PD by phenotypic assay using human olfactory neurosphere-derived (hONS) cells from PD patients. The research presented in this thesis exemplifies the importance of natural products as chemical probes for further investigation of PD as well as lead compounds for future PD-drug development. The thesis begins with an introduction of PD and the chemotherapeutics for PD. It also covers a review on the natural origin anti-PD compounds and the analysis of their physicochemical properties using Lipinski’s rule of five. As part of a research program aiming to identify anti-PD chemical probes, a high throughput screening assay was developed to screen 4224 fractions. Twenty fractions were confirmed to display neuroprotective effects of the PD cells against rotenone. Seven prioritized fractions, representing one Australian marine sponge Jaspis splendens (subject 1) and two Australian terrestrial plants Gloriosa superba (subject 2) and Alangium villosum (subject 3), were selected for large scale extraction and isolation. The results were presented in Chapter 2 to 5.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Natural Sciences
Science, Environment, Engineering and Technology
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