TY - JOUR A1 - Cheng, Cheng A1 - Othman, Eman M. A1 - Stopper, Helga A1 - Edrada-Ebel, RuAngelie A1 - Hentschel, Ute A1 - Abdelmohsen, Usama Ramadan T1 - Isolation of petrocidin A, a new cytotoxic cyclic dipeptide from the marine sponge-derived bacterium \(Streptomyces\) sp. SBT348 JF - Marine Drugs N2 - A new cyclic dipeptide, petrocidin A (\(\textbf{1}\)), along with three known compounds—2,3-dihydroxybenzoic acid (\(\textbf{2}\)), 2,3-dihydroxybenzamide (\(\textbf{3}\)), and maltol (\(\textbf{4}\))—were isolated from the solid culture of \(Streptomyces\) sp. SBT348. The strain \(Streptomyces\) sp. SBT348 had been prioritized in a strain collection of 64 sponge-associated actinomycetes based on its distinct metabolomic profile using liquid chromatography/high-resolution mass spectrometry (LC-HRMS) and nuclear magnetic resonance (NMR). The absolute configuration of all α-amino acids was determined by HPLC analysis after derivatization with Marfey’s reagent and comparison with commercially available reference amino acids. Structure elucidation was pursued in the presented study by mass spectrometry and NMR spectral data. Petrocidin A (\(\textbf{1}\)) and 2,3-dihydroxybenzamide (\(\textbf{3}\)) exhibited significant cytotoxicity towards the human promyelocytic HL-60 and the human colon adenocarcinoma HT-29 cell lines. These results demonstrated the potential of sponge-associated actinomycetes for the discovery of novel and pharmacologically active natural products. KW - biology KW - sponges KW - actinomycetes KW - streptomyces KW - cyclic dipeptide KW - cytotoxic Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-172644 VL - 15 IS - 12 ER - TY - JOUR A1 - Balasubramanian, Srikkanth A1 - Othman, Eman M. A1 - Kampik, Daniel A1 - Stopper, Helga A1 - Hentschel, Ute A1 - Ziebuhr, Wilma A1 - Oelschlaeger, Tobias A. A1 - Abdelmohsen, Usama R. T1 - Marine sponge-derived Streptomyces sp SBT343 extract inhibits staphylococcal biofilm formation JF - Frontiers in Microbiology N2 - Staphylococcus epidermidis and Staphylococcus aureus are opportunistic pathogens that cause nosocomial and chronic biofilm-associated infections. Indwelling medical devices and contact lenses are ideal ecological niches for formation of staphylococcal biofilms. Bacteria within biofilms are known to display reduced susceptibilities to antimicrobials and are protected from the host immune system. High rates of acquired antibiotic resistances in staphylococci and other biofilm-forming bacteria further hamper treatment options and highlight the need for new anti-biofilm strategies. Here, we aimed to evaluate the potential of marine sponge-derived actinomycetes in inhibiting biofilm formation of several strains of S. epidermidis, S. aureus, and Pseudomonas aeruginosa. Results from in vitro biofilm-formation assays, as well as scanning electron and confocal microscopy, revealed that an organic extract derived from the marine sponge-associated bacterium Streptomyces sp. SBT343 significantly inhibited staphylococcal biofilm formation on polystyrene, glass and contact lens surfaces, without affecting bacterial growth. The extract also displayed similar antagonistic effects towards the biofilm formation of other S. epidermidis and S. aureus strains tested but had no inhibitory effects towards Pseudomonas biofilms. Interestingly the extract, at lower effective concentrations, did not exhibit cytotoxic effects on mouse fibroblast, macrophage and human corneal epithelial cell lines. Chemical analysis by High Resolution Fourier Transform Mass Spectrometry (HRMS) of the Streptomyces sp. SBT343 extract proportion revealed its chemical richness and complexity. Preliminary physico-chemical characterization of the extract highlighted the heat-stable and non-proteinaceous nature of the active component(s). The combined data suggest that the Streptomyces sp. SBT343 extract selectively inhibits staphylococcal biofilm formation without interfering with bacterial cell viability. Due to absence of cell toxicity, the extract might represent a good starting material to develop a future remedy to block staphylococcal biofilm formation on contact lenses and thereby to prevent intractable contact lens-mediated ocular infections. KW - medicine KW - marine sponges KW - actinomycetes KW - Streptomyces KW - staphilococci KW - biofilms KW - contact lens Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-171844 VL - 8 ER - TY - JOUR A1 - Abdelmohsen, Usama Ramadan A1 - Yang, Chen A1 - Horn, Hannes A1 - Hajjar, Dina A1 - Ravasi, Timothy A1 - Hentschel, Ute T1 - Actinomycetes from Red Sea Sponges: Sources for Chemical and Phylogenetic Diversity N2 - The diversity of actinomycetes associated with marine sponges collected off Fsar Reef (Saudi Arabia) was investigated in the present study. Forty-seven actinomycetes were cultivated and phylogenetically identified based on 16S rRNA gene sequencing and were assigned to 10 different actinomycete genera. Eight putatively novel species belonging to genera Kocuria, Mycobacterium, Nocardia, and Rhodococcus were identified based on sequence similarity values below 98.2% to other 16S rRNA gene sequences available in the NCBI database. PCR-based screening for biosynthetic genes including type I and type II polyketide synthases (PKS-I, PKS-II) as well as nonribosomal peptide synthetases (NRPS) showed that 20 actinomycete isolates encoded each at least one type of biosynthetic gene. The organic extracts of nine isolates displayed bioactivity against at least one of the test pathogens, which were Gram-positive and Gram-negative bacteria, fungi, human parasites, as well as in a West Nile Virus protease enzymatic assay. These results emphasize that marine sponges are a prolific resource for novel bioactive actinomycetes with potential for drug discovery. KW - PKS I KW - Meeresschwämme KW - PKS II KW - NRPS KW - Red sea KW - sponges KW - actinomycetes KW - bioactivity Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-112882 ER - TY - JOUR A1 - Abdelmohsen, Usama Ramadan A1 - Szesny, Matthias A1 - Othman, Eman Maher A1 - Schirmeister, Tanja A1 - Grond, Stepanie A1 - Stopper, Helga A1 - Hentschel, Ute T1 - Antioxidant and Anti-Protease Activities of Diazepinomicin from the Sponge-Associated Micromonospora Strain RV115 N2 - Diazepinomicin is a dibenzodiazepine alkaloid with an unusual structure among the known microbial metabolites discovered so far. Diazepinomicin was isolated from the marine sponge-associated strain Micromonospora sp. RV115 and was identified by spectroscopic analysis and by comparison to literature data. In addition to its interesting preclinical broad-spectrum antitumor potential, we report here new antioxidant and anti-protease activities for this compound. Using the ferric reducing antioxidant power (FRAP) assay, a strong antioxidant potential of diazepinomicin was demonstrated. Moreover, diazepinomicin showed a significant antioxidant and protective capacity from genomic damage induced by the reactive oxygen species hydrogen peroxide in human kidney (HK-2) and human promyelocytic (HL-60) cell lines. Additionally, diazepinomicin inhibited the proteases rhodesain and cathepsin L at an IC50 of 70–90 μM. It also showed antiparasitic activity against trypomastigote forms of Trypanosoma brucei with an IC50 of 13.5 μM. These results showed unprecedented antioxidant and anti-protease activities of diazepinomicin, thus further highlighting its potential as a future drug candidate. KW - Biologie KW - diazepinomicin KW - anti-protease KW - antioxidant KW - actinomycetes KW - Micromonospora Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-76279 ER - TY - JOUR A1 - Abdelmohsen, Usama Ramadan A1 - Pimentel-Elardo, Sheila M. A1 - Hanora, Amro A1 - Radwan, Mona A1 - Abou-El-Ela, Soad H. A1 - Ahmed, Safwat A1 - Hentschel, Ute T1 - Isolation, Phylogenetic Analysis and Anti-infective Activity Screening of Marine Sponge-Associated Actinomycetes N2 - Terrestrial actinomycetes are noteworthy producers of a multitude of antibiotics, however the marine representatives are much less studied in this regard. In this study, 90 actinomycetes were isolated from 11 different species of marine sponges that had been collected from offshore Ras Mohamed (Egypt) and from Rovinj (Croatia). Phylogenetic characterization of the isolates based on 16S rRNA gene sequencing supported their assignment to 18 different actinomycete genera representing seven different suborders. Fourteen putatively novel species were identified based on sequence similarity values below 98.2% to other strains in the NCBI database. A putative new genus related to Rubrobacter was isolated on M1 agar that had been amended with sponge extract, thus highlighting the need for innovative cultivation protocols. Testing for anti-infective activities was performed against clinically relevant, Gram-positive (Enterococcus faecalis, Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria, fungi (Candida albicans) and human parasites (Leishmania major, Trypanosoma brucei). Bioactivities against these pathogens were documented for 10 actinomycete isolates. These results show a high diversity of actinomycetes associated with marine sponges as well as highlight their potential to produce anti-infective agents. KW - Biologie KW - actinomycetes KW - marine sponges KW - anti-infective KW - anti-parasitic KW - phylogenetic Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68307 ER - TY - THES A1 - Pimentel Elardo, Sheila Marie T1 - Novel anti-infective secondary metabolites and biosynthetic gene clusters from actinomycetes associated with marine sponges T1 - Neue anti-infektive Sekundärmetabolite und biosynthetische Gencluster aus mit marinen Schwämmen assoziierten Actinomyceten N2 - Marine sponges (Porifera) harbor diverse microbial communities within their mesohyl, among them representatives of the phylum Actinobacteria, commonly known as actinomycetes. Actinomycetes are prolific producers of pharmacologically important compounds and are responsible for producing the majority of antibiotics. The main aim of this Ph.D. study was to investigate the metabolic potential of the sponge-associated actinomycetes to produce novel anti-infective agents. The first aim was to cultivate actinomycetes derived from different marine sponges. 16S rDNA sequencing revealed that the strains belonged to diverse actinomycete genera such as Gordonia, Isoptericola, Micromonospora, Nocardiopsis, Saccharopolyspora and Streptomyces. Phylogenetic analyses and polyphasic characterization further revealed that two of these strains represent new species, namely Saccharopolyspora cebuensis strain SPE 10-1T (Pimentel-Elardo et al. 2008a) and Streptomyces axinellae strain Pol001T (Pimentel-Elardo et al. 2008b). Furthermore, secondary metabolite production of the actinomycete strains was investigated. The metabolites were isolated using a bioassay-guided purification scheme followed by structure elucidation using spectroscopic methods and subjected to an elaborate anti-infective screening panel. Several interesting compounds were isolated namely, the novel polyketides cebulactam A1 and A2 (Pimentel-Elardo et al. 2008c), a family of tetromycin compounds including novel derivatives, cyclodepsipeptide valinomycin, indolocarbazole staurosporine, diketopiperazine cycloisoleucylprolyl and butenolide. These compounds exhibited significant anti-parasitic as well as protease inhibitory activities. The third aim of this Ph.D. study was to identify biosynthetic gene clusters encoding for nonribosomal peptide synthetases (NRPS) and polyketide synthases (PKS) present in the actinomycete strains. Genomic library construction and sequencing revealed insights into the metabolic potential and biosynthetic pathways of selected strains. An interesting NRPS system detected in Streptomyces sp. strain Aer003 was found to be widely distributed in several sponge species, in an ascidian and in seawater and is postulated to encode for a large peptide molecule. Sequencing of the PKS gene cluster of Saccharopolyspora cebuensis strain SPE 10-1T allowed the prediction of the cebulactam biosynthetic pathway which utilizes 3-amino-5-hydroxybenzoic acid as the starter unit followed by successive condensation steps involving methylmalonyl extender units and auxiliary domains responsible for the polyketide assembly. In conclusion, this Ph.D. study has shown that diverse actinomycete genera are associated with marine sponges. The strains, two of them novel species, produced diverse chemical structures with interesting anti-infective properties. Lastly, the presence of biosynthetic gene clusters identified in this study substantiates the biosynthetic potential of actinomycetes to produce exploitable natural products and hopefully provides a sustainable supply of anti-infective compounds. N2 - Zahlreiche marine Schwämme (Phylum: Porifera) beherbergen eine phylogenetisch diverse mikrobielle Gemeinschaft in der Mesohyl-Matrix, darunter auch viele Vertreter des bakteriellen Phylums Actinobacteria, die umgangssprachlich als Actinomyceten bekannt sind. Actinomyceten sind wichtige Produzenten vieler Antibiotika und von weiteren pharmazeutisch relevanten Substanzen. Das Hauptziel dieser Promotionsarbeit war die Untersuchung des Potentials Schwamm-assoziierter Actinomyceten zur Produktion neuer Infektions-hemmender Substanzen. Ein erstes Ziel dieser Doktorarbeit war die Kultivierung von Actinomyceten aus verschiedenen marinen Schwammarten. Die Sequenzierung der respektiven 16S rRNA Gene zeigte eine phylogenetische Zugehörigkeit der Isolate zu verschiedenen Actinomyceten-Familien, wie Gordonia, Isoptericola, Micromonospora, Nocardiopsis, Saccharopolyspora und Streptomyces. Durch phylogenetische Analysen und umfangreiche taxonomische Charakterisierungen konnten zwei neue Actinomyceten-Arten, Saccharopolyspora cebuensis strain SPE 10-1T (Pimentel-Elardo et al. 2008a) und Streptomyces axinellae strain Pol001T (Pimentel-Elardo et al. 2008b) beschrieben werden. Des Weiteren sollten die Actinomyceten-Isolate auf die Produktion von Sekundär-Metaboliten hin untersucht werden. Die Substanzen wurden „bioassay-guided“ aufgereinigt und isoliert sowie deren Struktur mittels spektroskopischer Methoden aufgeklärt. Anschließend wurden die Substanzen ausführlichen Screening-Methoden unterzogen, um sie auf anti-infektive Wirkungen hin zu untersuchen. Zahlreiche interessante Verbindungen konnten so isoliert werden, u. a. die neuen Polyketide Cebulactam A1 und A2 (Pimentel-Elardo et al. 2008c); eine Familie von Tetromycin-Substanzen inklusive neuartiger Derivative; das Cyclodepsipeptid Valinomycin, Indolocarbazole Staurosporine, Diketopiperazine Cycloisoleucylprolyl und Butenolide. Die Verbindungen zeigten signifikante anti-parasitische und Protease-hemmende Aktivitäten. Das dritte Ziel dieser Arbeit war es, die für nicht-ribosomale Peptidsynthetasen (NRPS) und Polyketidsynthasen (PKS) kodierenden, biosynthetischen Gen-Cluster in den Actinomyceten-Isolaten zu identifizieren. Die Konstruktion von Genbanken sowie die Sequenzierung ausgewählter Cosmidklone lieferte erste Einblicke in das Stoffwechsel- und Biosynthesepotential ausgewählter Isolate. Beispielsweise konnte ein interessantes NRPS-System in Streptomyces sp. Stamm Aer003 identifiziert werden, welches in verschiedenen Schwammarten, einer Ascidienart sowie im Meerwasser gefunden wurde. Die Sequenzierung eines PKS-Genclusters aus Saccharopolyspora cebuensis strain SPE 10-1T ermöglicht die Voraussage des Cebulactam-Biosynthesewegs in dem 3-Amino-5-Hydroxybenzoesäure als Ausgangsprodukt dient, welches durch sukzessive Kondensationsschritte sowie Verlängerungen durch Methylmalonyl- und Zusatzdomänen zum endgültigen Polyketid führen. Zusammenfassend konnte in dieser Promotionsarbeit gezeigt werden, dass marine Schwämme mit diversen Vertretern aus verschiedenen Familien der Actinomyceten assoziiert sind. Die Bakterienisolate, von denen zwei neue Arten repräsentieren, produzierten mehrere chemische Substanzen mit interessanten anti-infektiven Eigenschaften. Des Weiteren konnte mit dieser Arbeit durch die Identifizierung von Biosynthese-Genclustern das Potential von Actinomyceten zur Produktion verwertbarer bioaktiver Substanzen bekräftigt und somit ein Beitrag zur Entdeckung neuer anti-infektiver Substanzen erbracht werden. KW - Meeresschwämme KW - Strahlenpilze KW - Sekundärmetabolit KW - Actinomyceten KW - Biosynthese-Genclustern KW - neuer anti-infektiver Substanzen KW - actinomycetes KW - marine sponges KW - anti-infective KW - biosynthetic gene clusters KW - secondary metabolites Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-40463 ER -