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Orhan I.E.,Gazi University | Orhan I.E.,Eastern Mediterranean University | Ozcelik B.,Gazi University | Konuklugil B.,Ankara University | And 3 more authors.
Records of Natural Products | Year: 2012

The extracts of various marine sponges (Agelas oroides and Axinella damicornis, Axinella cannabina, Ircinia spinulosa, I. fasciculata, and I. variabilis, Dysidea avara, and Sarcotragus spinulosus) collected from different spots of the Turkish cost of the Mediterranean Sea have been evaluated for their antibacterial, antifungal, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, and acetylcholinesterase (AChE) inhibitory activities. Three compounds (oroidin, 4,5-dibromopyrrol-2-carboxylic acid, and 25-hydroxy-24-methylcholesterol) were isolated from A. oroides and tested in the same manner. The sponge extracts showed notable antimicrobial and anti-AChE activity and low DPPH scavenging activity. Oroidin was found to have moderate anti-AChE and strong radical scavenging activities. The results demonstrated that the sponge extracts exerted a variable degree of antibacterial, anti-radical, and anti-AChE activity, whereas they seemed to have similar antifungal effect. Our findings point out to the fact that the collection site has an important influence on bioactivity of the sponges. © 2012 Reproduction is free for scientific studies. Source

Dobretsov S.,Sultan Qaboos University | Al-Wahaibi A.S.M.,Sultan Qaboos University | Lai D.,Institute For Pharmazeutische Biologie Und Biotechnologie | Lai D.,China Agricultural University | And 5 more authors.
International Biodeterioration and Biodegradation | Year: 2015

Six common soft coral species (Sarcophyton sp., Sinularia sp.1 and sp.2, Cladiella sp., Scleronephthya sp. and Dendronephthya sp.) from Bandar Al-Khayran (Sultanate of Oman) had significantly lower bacterial density in comparison with surfaces of empty shells. Methanol: chloroform (1:1) extracts of these species were tested against Gram positive (Micrococcus luteus, Staphlococcus aureus, Bacillus subtilis, Bacillus sp.) and Gram negative (Salmonella enterica, Pseudomonas aeruginosa, Escherichia coli, Cytophaga sp., Pseudomonas sp., Shewanella sp.) marine biofouling and pathogenic bacterial strains. All tested extracts had some activity against human pathogens and the highest antimicrobial activity was observed for extracts of Sinularia sp.1 and Cladiella sp. (inhibited 50% and 60% of the strains, respectively). Only ethyl acetate extracts of Cladiella sp. inhibited growth of biofouling bacteria. The active fraction was purified and identified as a mixture of hexadecyl palmitate and hexadecyl stearate. Pure hexadecyl palmitate inhibited growth (Bacillus sp. and Psychrobacter sp.) and attachment (Bacillus sp., Cytophaga sp., Pseudomonas sp., Psychrobacter sp., Shewanella sp.) of the marine biofouling bacteria. The results of this study suggest that soft corals have developed mechanisms to combat microbial infections and inhibit bacterial fouling. © 2014 Elsevier Ltd. Source

Dobretsov S.,Sultan Qaboos University | Teplitski M.,University of Florida | Bayer M.,Institute For Pharmazeutische Biologie Und Biotechnologie | Gunasekera S.,Smithsonian Marine Station | And 2 more authors.
Biofouling | Year: 2011

Seventy eight natural products from chemical libraries containing compounds from marine organisms (sponges, algae, fungi, tunicates and cyanobacteria) and terrestrial plants, were screened for the inhibition of bacterial quorum sensing (QS) using a reporter strain Chromobacterium violaceum CV017. About half of the natural products did not show any QS inhibition. Twenty four percent of the tested compounds inhibited QS of the reporter without causing toxicity. The QS inhibitory activities of the most potent and abundant compounds were further investigated using the LuxR-based reporter E. coli pSB401 and the LasR-based reporter E. coli pSB1075. Midpacamide and tenuazonic acid were toxic to the tested reporters. QS-dependent luminescence of the LasR-based reporter, which is normally induced by N-3-oxo-dodecanoyl-L-homoserine lactone, was reduced by demethoxy encecalin and hymenialdisin at concentrations >6.6 μM and 15 μM, respectively. Hymenialdisin, demethoxy encecalin, microcolins A and B and kojic acid inhibited responses of the LuxR-based reporter induced by N-3-oxo-hexanoyl-L-homoserine lactone at concentrations >0.2 μM, 2.2 μM, 1.5 μM, 15 μM and 36 μM, respectively. The ability to prevent microfouling by one of the compounds screened in this study (kojic acid; final concentrations 330 μM and 1 μM) was tested in a controlled mesocosm experiment. Kojic acid inhibited formation of microbial communities on glass slides, decreasing the densities of bacteria and diatoms in comparison with the control lacking kojic acid. The study suggests that natural products with QS inhibitory properties can be used for controlling biofouling communities. © 2011 Taylor & Francis. Source

Xie X.,University of Marburg | Wallwey C.,Institute For Pharmazeutische Biologie Und Biotechnologie | Matuschek M.,Institute For Pharmazeutische Biologie Und Biotechnologie | Steinbach K.,University of Marburg | Li S.-M.,Institute For Pharmazeutische Biologie Und Biotechnologie
Magnetic Resonance in Chemistry | Year: 2011

A previous study showed that together with the festuclavine synthase FgaFS, the old yellow enzyme FgaOx3 from Aspergillus fumigatus catalyzed the conversion of chanoclavine-I aldehyde to festuclavine in the biosynthesis of ergot alkaloids. In the absence of FgaFS, a mixture containing two compounds with a ratio of 7:3 was detected in the enzyme assay of FgaOx3. NMR experiments including (DQF)-COSY, HSQC, HMBC and NOESY identified their structures as E/Z isomers of N-methyl-N-[(5R,10R)-10-(2-oxo-propyl)-2,4,5,10-tetrahydrobenzo[cd] indol-5-yl]formamide and proved the migration of the formyl group at C-8 in chanoclavine I-aldehyde to N-6 in the identified products. © 2011 John Wiley & Sons, Ltd. Source

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