Publications by authors named "William Aalbersberg"

38 Publications

Marinocyanins, cytotoxic bromo-phenazinone meroterpenoids from a marine bacterium from the streptomycete clade MAR4.

Tetrahedron 2017 Apr 6;73(16):2234-2241. Epub 2017 Mar 6.

Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, 92093-0204, USA.

Six cytotoxic and antimicrobial metabolites of a new bromo-phenazinone class, the marinocyanins A-F (-), were isolated together with the known bacterial metabolites 2-bromo-1-hydroxyphenazine (), lavanducyanin ( WS-9659A) and its chlorinated analog WS-9659B (). These metabolites were purified by bioassay-guided fractionation of the extracts of our MAR4 marine actinomycete strains CNS-284 and CNY-960. The structures of the new compounds were determined by detailed spectroscopic methods and marinocyanin A () was confirmed by crystallographic methods. The marinocyanins represent the first bromo-phenazinones with an -isoprenoid substituent in the skeleton. Marinocyanins A-F show strong to weak cytotoxicity against HCT-116 human colon carcinoma and possess modest antimicrobial activities against and amphotericin-resistant .
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http://dx.doi.org/10.1016/j.tet.2017.03.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5555602PMC
April 2017

Bioavailability of Fe and Zn in selected legumes, cereals, meat and milk products consumed in Fiji.

Food Chem 2016 Sep 10;207:125-31. Epub 2016 Mar 10.

Institute of Applied Sciences, The University of the South Pacific, Private Mail Bag, Suva, Fiji.

The present study reports contents and the bioavailability of Fe and Zn from 25 selected raw and cooked food samples. The results showed highest variation of Fe content in raw food samples ranging from 2.19 ± 0.04 to 0.93 ± 0.03 mg/100g in legumes. The raw black eye bean, cheese and fish showed high Zn content up to 8.85 ± 0.01, 12.93 ± 0.26 and 172.03 ± 5.09 mg/100g, respectively. Pulses and cereals showed high level of ionizable Fe. Zn bioavailability was quite low in cereals as compared to pulses; 4.02% in yellow split to 17.40% in Bengal gram. Zn bioavailability of 17.40% is in cheese. Fe bioavailability is high in cooked rice 160.60%, white bread 428.30% and milk powder 241.67% showing that Fe bioavailability increased after cooking whereas the lowest in fish 0.84%. The multivariate and cluster analysis categorized studied foods into two main groups.
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http://dx.doi.org/10.1016/j.foodchem.2016.03.029DOI Listing
September 2016

The Wound Healing and Antibacterial Activity of Five Ethnomedical Calophyllum inophyllum Oils: An Alternative Therapeutic Strategy to Treat Infected Wounds.

PLoS One 2015 25;10(9):e0138602. Epub 2015 Sep 25.

Laboratoire Chimie-Toxicologie Analytique et Cellulaire-UMR CNRS COMETE 8638, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France.

Background: Calophyllum inophyllum L. (Calophyllaceae) is an evergreen tree ethno-medically used along the seashores and islands of the Indian and Pacific Oceans, especially in Polynesia. Oil extracted from the seeds is traditionally used topically to treat a wide range of skin injuries from burn, scar and infected wounds to skin diseases such as dermatosis, urticaria and eczema. However, very few scientific studies reported and quantified the therapeutic properties of Calophyllum inophyllum oil (CIO). In this work, five CIO from Indonesia (CIO1), Tahiti (CIO2, 3), Fiji islands (CIO4) and New Caledonia (CIO5) were studied and their cytotoxic, wound healing, and antibacterial properties were presented in order to provide a scientific support to their traditional use and verify their safety.

Methods: The safety of the five CIO was ascertained using the Alamar blue assay on human keratinocyte cells. CIO wound healing properties were determined using the scratch test assay on human keratinocyte cells. CIO-stimulated antibacterial innate immune response was evaluated using ELISA by measuring β defensin-2 release in human derivative macrophage cells. CIO antibacterial activity was tested using oilogramme against twenty aerobic Gram- bacteria species, twenty aerobic Gram+ bacteria species, including a multi-drug resistant Staphylococcus aureus strain and two anaerobic Gram+ bacteria species e.g. Propionibacterium acnes and Propionibacterium granulosum. To detect polarity profile of the components responsible of the antibacterial activity, we performed bioautography against a Staphylococcus aureus strain.

Results: Based on Alamar Blue assay, we showed that CIO can be safely used on keratinocyte cells between 2.7% and 11.2% depending on CIO origin. Concerning the healing activity, all the CIO tested accelerated in vitro wound closure, the healing factor being 1.3 to 2.1 higher compared to control when keratinocytes were incubated after scratch with CIO at 0.1%. Furthermore, our results showed that CIO exhibit two distinct antibacterial effects: one against Gram+ bacteria by direct inhibition of mitotic growth and another potent effect against Gram- bacteria due to increased release of β-defensin 2 peptide by macrophages. Interestingly, the needed concentrations of CIO to inhibit bacteria growth and to promote wound healing are lower than concentrations exhibiting cytotoxic effects on keratinocyte cells. Finally, we performed bioautography assay against Staphylococcus aureus to determine polarity profile of the components responsible for CIO antibacterial activity. Our results showed for the five tested CIO that components responsible of the bacterial growth inhibition are the more polar one on the TLC chromatographic profile and are contained in the resinous fraction of the oil.

Conclusions: This study was conducted to evaluate cytotoxicity, wound healing and antibacterial properties of five CIO traditionally used to treat infected wounds. Using cell and bacteria cultures, we confirmed the pharmacological effects of CIO as wound healing and antimicrobial agent. Moreover, we showed that concentration of CIO needed to exhibit therapeutic effects are lower than concentrations exhibiting cytotoxic effects in vitro. For the first time, this study provides support for traditional uses of CIO. These wound healing and antibiotic properties make CIO a valuable candidate to treat infected wounds especially in tropical areas.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0138602PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4583440PMC
May 2016

Characterization of organochlorine pesticides, brominated flame retardants and dioxin-like compounds in shellfish and eel from Fiji.

Sci Total Environ 2014 Sep 23;491-492:200-4. Epub 2014 Feb 23.

Institute of Applied Sciences, The University of the South Pacific, Laucala Campus, Suva, Fiji.

This article gives an overview of a range of persistent organic pollutant chemical levels in shellfish (Batissa violacea and Anadara antiquata) species and eel (Gymnothorax flavimarginatus) from Fiji. As there is limited data in published literature to date, this paper reports first data on a range of persistent organic pollutants and highlights the more prominent POP chemicals present in marine biota in Fiji. A significant number of POP chemicals were detected (e.g. 17 PCDD/PCDF, 12dl-PCBs, organochlorine pesticides and brominated flame retardants), the concentrations found were generally low (e.g. parts per billion level). The low levels of contamination are indicative of a low input from long range and short-range transport as well as few local point sources. Also concentrations of POPs in eel and shellfish from Fiji are low in comparison to wild species in other regions and are within acceptable limits for POP chemicals in fish and fishery products set by the European Union. It describes also results of early studies on basic POPs levels in shellfish in several Pacific Island Countries, which generally show relatively low levels.
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http://dx.doi.org/10.1016/j.scitotenv.2014.01.125DOI Listing
September 2014

Culturable rare Actinomycetes: diversity, isolation and marine natural product discovery.

Appl Microbiol Biotechnol 2013 Nov 22;97(21):9291-321. Epub 2013 Sep 22.

Centre for Drug Discovery and Conservation, Institute of Applied Sciences, The University of the South Pacific, Laucala Campus, Suva, Fiji Islands,

Rare Actinomycetes from underexplored marine environments are targeted in drug discovery studies due to the Actinomycetes' potentially huge resource of structurally diverse natural products with unusual biological activity. Of all marine bacteria, 10 % are Actinomycetes, which have proven an outstanding and fascinating resource for new and potent bioactive molecules. Past and present efforts in the isolation of rare Actinomycetes from underexplored diverse natural habitats have resulted in the isolation of about 220 rare Actinomycete genera of which more than 50 taxa have been reported to be the producers of 2,500 bioactive compounds. That amount represents greater than 25 % of the total Actinomycetes metabolites, demonstrating that selective isolation methods are being developed and extensively applied. Due to the high rediscovery rate of known compounds from Actinomycetes, a renewed interest in the development of new antimicrobial agents from rare and novel Actinomycetes is urgently required to combat the increasing number of multidrug-resistant human pathogens. To facilitate that discovery, this review updates all selective isolation media including pretreatment and enrichment methods for the isolation of marine rare Actinomycetes. In addition, this review demonstrates that discovering new compounds with novel scaffolds can be increased by intensive efforts in isolating and screening rare marine genera of Actinomycetes. Between 2007 and mid-2013, 80 new rare Actinomycete species were reported from marine habitats. They belong to 23 rare families, of which three are novel, and 20 novel genera. Of them, the family Micromonosporaceae is dominant as a producer of promising chemical diversity.
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http://dx.doi.org/10.1007/s00253-013-5229-7DOI Listing
November 2013

Detection and diversity of pathogenic Vibrio from Fiji.

Environ Microbiol Rep 2012 Aug 12;4(4):403-11. Epub 2012 Apr 12.

School of Biological and Chemical Sciences Institute of Applied Sciences, University of the South Pacific, Suva, Fiji Institute of Molecular BioSciences, Massey University, Private Mailbag 11222, Palmerston North, New Zealand Institute of Translational Medicine, University of Liverpool, L69 3GL Liverpool, UK Institute of Fundamental Sciences Massey Genome Service, Massey University, Private Mailbag 11222, Palmerston North, New Zealand Department of Marine Biology, Microbiology & Biochemistry, Cochin University of Science & Technology, Kerala, India Department of Biological Sciences, Marshall University, Huntington, WV 25755, USA.

Here we investigate the diversity of pathogenic Vibrio species in marine environments close to Suva, Fiji. We use four distinct yet complementary analyses - biochemical testing, phylogenetic analyses, metagenomic analyses and molecular typing - to provide some preliminary insights into the diversity of vibrios in this region. Taken together our analyses confirmed the presence of nine Vibrio species, including three of the most important disease-causing vibrios (i.e. V. cholerae, V. parahaemolyticus and V. vulnificus), in Fijian marine environments. Furthermore, since toxigenic V. parahaemolyticus are present on fish for consumption we suggest these bacteria represent a potential public health risk. Our results from Illumina short read sequencing are encouraging in the context of microbial profiling and biomonitoring. They suggest this approach may offer an efficient and cost-effective method for studying the dynamics of microbial diversity in marine environments over time.
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http://dx.doi.org/10.1111/j.1758-2229.2012.00344.xDOI Listing
August 2012

Cytotoxic and antibacterial substances against multi-drug resistant pathogens from marine sponge symbiont: Citrinin, a secondary metabolite of Penicillium sp.

Asian Pac J Trop Biomed 2013 Apr;3(4):291-6

Centre for Drug Discovery and Conservation, Institute of Applied Sciences, The University of the South Pacific, Laucala Campus, Suva, Fiji Islands.

Objective: To Isolate, purify, characterize, and evaluate the bioactive compounds from the sponge-derived fungus Penicillium sp. FF001 and to elucidate its structure.

Methods: The fungal strain FF001 with an interesting bioactivity profile was isolated from a marine Fijian sponge Melophlus sp. Based on conidiophores aggregation, conidia development and mycelia morphological characteristics, the isolate FF001 was classically identified as a Penicillium sp. The bioactive compound was identified using various spectral analysis of UV, high resolution electrospray ionization mass spectra, 1H and 13C NMR spectral data. Further minimum inhibitory concentrations (MICs) assay and brine shrimp cytotoxicity assay were also carried out to evaluate the biological properties of the purified compound.

Results: Bioassay guided fractionation of the EtOAc extract of a static culture of this Penicillium sp. by different chromatographic methods led the isolation of an antibacterial, anticryptococcal and cytotoxic active compound, which was identified as citrinin (1). Further, citrinin (1) is reported for its potent antibacterial activity against methicillin-resistant Staphylococcus aureus (S. aureus), rifampicin-resistant S. aureus, wild type S. aureus and vancomycin-resistant Enterococcus faecium showed MICs of 3.90, 0.97, 1.95 and 7.81 µg/mL, respectively. Further citrinin (1) displayed significant activity against the pathogenic yeast Cryptococcus neoformans (MIC 3.90 µg/mL), and exhibited cytotoxicity against brine shrimp larvae LD50 of 96 µg/mL.

Conclusions: Citrinin (1) is reported from sponge associated Penicillium sp. from this study and for its strong antibacterial activity against multi-drug resistant human pathogens including cytotoxicity against brine shrimp larvae, which indicated that sponge associated Penicillium spp. are promising sources of natural bioactive metabolites.
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http://dx.doi.org/10.1016/S2221-1691(13)60065-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3634926PMC
April 2013

Investigations of the marine flora and fauna of the Fiji Islands.

Nat Prod Rep 2012 Dec 14;29(12):1424-62. Epub 2012 Sep 14.

Centre for Drug Discovery and Conservation, Institute of Applied Sciences, The University of the South Pacific, Suva, Fiji.

Over the past 30 years, approximately 140 papers have been published on marine natural products chemistry and related research from the Fiji Islands. These came about from studies starting in the early 1980s by the research groups of Crews at the University of California Santa Cruz, Ireland at the University of Utah, Gerwick from the Scripps Institution of Oceanography, the University of California at San Diego and the more recent groups of Hay at the Georgia Institute of Technology (GIT) and Jaspars from the University of Aberdeen. This review covers both known and novel marine-derived natural products and their biological activities. The marine organisms reviewed include invertebrates, plants and microorganisms, highlighting the vast structural diversity of compounds isolated from these organisms. Increasingly during this period, natural products chemists at the University of the South Pacific have been partners in this research, leading in 2006 to the development of a Centre for Drug Discovery and Conservation (CDDC).
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http://dx.doi.org/10.1039/c2np20055dDOI Listing
December 2012

Three bioactive sesquiterpene quinones from the Fijian marine sponge of the genus Hippospongia.

Nat Prod Res 2013 10;27(16):1488-91. Epub 2012 Sep 10.

a Centre for Drug Discovery and Conservation, Institute of Applied Sciences, The University of the South Pacific , Suva , Fiji Islands.

A sesquiterpenoid quinone, epi-ilimaquinone (1), and two sesquiterpene amino quinones, smenospongine (2) and glycinylilimaquinone (3), were isolated from the Fijian marine sponge Hippospongia sp. The structures of these compounds were determined by spectroscopic analysis. Compounds 1 and 3 were reported for the first time in this study from the sponge of the genus Hippospongia. Compound 1 displayed potent cytotoxic activity and showed antibacterial activity against methicillin-resistant Staphylococcus aureus, wild type S. aureus and vancomycin-resistant Enterococcus faecium and displayed antifungal activity against amphotericin-resistant Candida albicans while compounds 2 and 3 showed moderate cytotoxic activity. However, compound 1 did not show appreciable antifungal activity against wild type C. albicans, Cryptococcus neoformans, Aspergillus niger, Penicillium sp., Rhizopus sporangia or Sordaria sp.
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http://dx.doi.org/10.1080/14786419.2012.722086DOI Listing
March 2014

Bromophycoic acids: bioactive natural products from a Fijian red alga Callophycus sp.

J Org Chem 2012 Sep 5;77(18):8000-6. Epub 2012 Sep 5.

School of Biology, Aquatic Chemical Ecology Center, Institute of Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.

Bioassay-guided fractionation of extracts from a Fijian red alga in the genus Callophycus resulted in the isolation of five new compounds of the diterpene-benzoate class. Bromophycoic acids A-E (1-5) were characterized by NMR and mass spectroscopic analyses and represent two novel carbon skeletons, one with an unusual proposed biosynthesis. These compounds display a range of activities against human tumor cell lines, malarial parasites, and bacterial pathogens including low micromolar suppression of MRSA and VREF.
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http://dx.doi.org/10.1021/jo301246xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3474338PMC
September 2012

New antiplasmodial bromotyrosine derivatives from Suberea ianthelliformis Lendenfeld, 1888.

Chem Biodivers 2012 Aug;9(8):1436-51

UMR 152, IRD, 118, route de Narbonne, FR-31062 Toulouse cedex 9, France.

Four samples of Suberea ianthelliformis were investigated and furnished five new and 13 known brominated tyrosine-derived compounds. Two of the new compounds were identified as araplysillin N20-formamide and its N-oxide derivative. Three other new compounds, araplysillins IV, V, and VI, were isolated and identified as analogs of araplysillin II. Most of these compounds exhibit moderate inhibitory activities against chloroquine-resistant and -sensitive strains of Plasmodium falciparum, and were investigated for their PFTase inhibitory properties. The chemical content of the investigated sponges is correlated with their molecular phylogeny.
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http://dx.doi.org/10.1002/cbdv.201100309DOI Listing
August 2012

Marine actinomycetes: an ongoing source of novel bioactive metabolites.

Microbiol Res 2012 Dec 15;167(10):571-80. Epub 2012 Jul 15.

Centre for Drug Discovery and Conservation, Institute of Applied Sciences, The University of the South Pacific, Laucala Campus, Suva, Fiji.

Actinomycetes are virtually unlimited sources of novel compounds with many therapeutic applications and hold a prominent position due to their diversity and proven ability to produce novel bioactive compounds. There are more than 22,000 known microbial secondary metabolites, 70% of which are produced by actinomycetes, 20% from fungi, 7% from Bacillus spp. and 1-2% by other bacteria. Among the actinomycetes, streptomycetes group are considered economically important because out of the approximately more than 10,000 known antibiotics, 50-55% are produced by this genus. The ecological role of actinomycetes in the marine ecosystem is largely neglected and various assumptions meant there was little incentive to isolate marine strains for search and discovery of new drugs. The search for and discovery of rare and new actinomycetes is of significant interest to drug discovery due to a growing need for the development of new and potent therapeutic agents. Modern molecular technologies are adding strength to the target-directed search for detection and isolation of bioactive actinomycetes, and continued development of improved cultivation methods and molecular technologies for accessing the marine environment promises to provide access to this significant new source of chemical diversity with novel/rare actinomycetes including new species of previously reported actinomycetes.
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http://dx.doi.org/10.1016/j.micres.2012.06.005DOI Listing
December 2012

Aurantoside K, a new antifungal tetramic acid glycoside from a Fijian marine sponge of the genus Melophlus.

Mar Drugs 2012 Jan 18;10(1):200-8. Epub 2012 Jan 18.

Centre for Drug Discovery and Conservation, Institute of Applied Sciences, The University of the South Pacific, Suva, Fiji Islands.

A new tetramic acid glycoside, aurantoside K, was isolated from a marine sponge belonging to the genus Melophlus. The structure of the compound was elucidated on the basis of spectroscopic analysis (¹H NMR, ¹H-¹H COSY, HSQC, and HMBC, as well as high-resolution ESILCMS). Aurantoside K did not show any significant activity in antimalarial, antibacterial, or HCT-116 cytotoxicity assays, but exhibited a wide spectrum of antifungal activity against wild type Candida albicans, amphotericin-resistant C. albicans, Cryptococcus neoformans, Aspergillus niger, Penicillium sp., Rhizopus sporangia and Sordaria sp.
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http://dx.doi.org/10.3390/md10010200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3280539PMC
January 2012

High content live cell imaging for the discovery of new antimalarial marine natural products.

BMC Infect Dis 2012 Jan 3;12. Epub 2012 Jan 3.

Department of Cell Biology and Neuroscience, University of California Riverside, Riverside, CA 92521, USA.

Background: The human malaria parasite remains a burden in developing nations. It is responsible for up to one million deaths a year, a number that could rise due to increasing multi-drug resistance to all antimalarial drugs currently available. Therefore, there is an urgent need for the discovery of new drug therapies. Recently, our laboratory developed a simple one-step fluorescence-based live cell-imaging assay to integrate the complex biology of the human malaria parasite into drug discovery. Here we used our newly developed live cell-imaging platform to discover novel marine natural products and their cellular phenotypic effects against the most lethal malaria parasite, Plasmodium falciparum.

Methods: A high content live cell imaging platform was used to screen marine extracts effects on malaria. Parasites were grown in vitro in the presence of extracts, stained with RNA sensitive dye, and imaged at timed intervals with the BD Pathway HT automated confocal microscope.

Results: Image analysis validated our new methodology at a larger scale level and revealed potential antimalarial activity of selected extracts with a minimal cytotoxic effect on host red blood cells. To further validate our assay, we investigated parasite's phenotypes when incubated with the purified bioactive natural product bromophycolide A. We show that bromophycolide A has a strong and specific morphological effect on parasites, similar to the ones observed from the initial extracts.

Conclusion: Collectively, our results show that high-content live cell-imaging (HCLCI) can be used to screen chemical libraries and identify parasite specific inhibitors with limited host cytotoxic effects. All together we provide new leads for the discovery of novel antimalarials.
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http://dx.doi.org/10.1186/1471-2334-12-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3268092PMC
January 2012

Papuamides E and F, Cytotoxic Depsipeptides from the Marine Sponge Melophlus sp.

Tetrahedron 2011 Nov;67(44):8529-8531

Institute of Applied Science, Faculty of Science, Technology and Environment, The University of the South Pacific, Laucala Campus, Suva, Fiji Islands.

Two known papuamides C (1) and D (2) together with two new depsipeptides, papuamides E (3) and F (4), were isolated from an undescribed sponge of the genus Melophlus collected in the Solomon Islands. The planar structures of the compounds were elucidated on the basis of spectroscopic studies. Papuamides C-F (1-4) showed cytotoxicity against brine shrimp with LD(50) values between 92 and 106 μg/mL.
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http://dx.doi.org/10.1016/j.tet.2011.08.100DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3192506PMC
November 2011

Rapid identification of triterpenoid sulfates and hydroxy fatty acids including two new constituents from Tydemania expeditionis by liquid chromatography-mass spectrometry.

J Mass Spectrom 2011 Sep;46(9):908-16

Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou, China.

Tydemania expeditionis Weber-van Bosse (Udoteaceae) is a weakly calcified green alga. In the present paper, liquid chromatography coupled with photodiode array detection and electrospray mass spectrometry was developed to identify the fingerprint components. A total of four triterpenoid sulfates and three hydroxy fatty acids in the ethyl acetate fraction of the crude extract were structurally characterized on the basis of retention time, online UV spectrum, and mass fragmentation pattern. Furthermore, a detailed liquid chromatography-mass spectrometry analysis revealed two new hydroxy fatty acids, which were then prepared and characterized by extensive nuclear magnetic resonance (NMR) analyses. The proposed method provides a scientific and technical platform for the rapid identification of triterpenoid sulfates and hydroxy fatty acids in similar marine algae and terrestrial plants.
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http://dx.doi.org/10.1002/jms.1969DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3205076PMC
September 2011

Fijimycins A-C, three antibacterial etamycin-class depsipeptides from a marine-derived Streptomyces sp.

Bioorg Med Chem 2011 Nov 26;19(22):6557-62. Epub 2011 Jun 26.

Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093-0204, USA.

Three new depsipeptides, fijimycins A-C (1-3), together with the known etamycin A (4), were isolated and identified from the fermentation broth of strain CNS-575, a Streptomyces sp. cultured from a marine sediment sample collected off Nasese, Fiji. The planar structures of the new fijimycins were assigned by combined interpretation of NMR and MS/MS spectroscopic data. These assignments were complicated by the fact that 1-3 occurred as complex amide conformational mixtures. The absolute configurations of the component amino acids were established using the Marfey's method. Fijimycins A-C, and etamycin A, were shown to possess significant in vitro antibacterial activity against three methicillin-resistant Staphylococcus aureus (MRSA) strains with MIC(100) values between 4 and 16 μg mL(-1).
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http://dx.doi.org/10.1016/j.bmc.2011.06.053DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3205191PMC
November 2011

Structure and biological evaluation of novel cytotoxic sterol glycosides from the marine red alga Peyssonnelia sp.

Bioorg Med Chem 2010 Dec 28;18(23):8264-9. Epub 2010 Oct 28.

Georgia Institute of Technology, Atlanta, 30332, USA.

Bioactivity-guided fractionation of the extract from a Fijian red alga Peyssonnelia sp. led to the isolation of two novel sterol glycosides 19-O-β-d-glucopyranosyl-19-hydroxy-cholest-4-en-3-one (1) and 19-O-β-d-N-acetyl-2-aminoglucopyranosyl-19-hydroxy-cholest-4-en-3-one (2), and two known alkaloids indole-3-carboxaldehyde (3) and 3-(hydroxyacetyl)indole (4). Their structures were characterized by 1D and 2D NMR and mass spectral analysis. The sterol glycosides inhibited cancer cell growth with mean IC₅₀ values (for 11 human cancer cell lines) of 1.63 and 1.41μM for 1 and 2, respectively. The most sensitive cancer cell lines were MDA-MB-468 (breast) and A549 (lung), with IC₅₀'s in of 0.71-0.97μM for 1 and 2. Modification of the sterol glycoside structures revealed that the α,β-unsaturated ketone at C-3 and oxygenation at C-19 of 1 and 2 are crucial for anticancer activity, whereas the glucosidic group was not essential but contributed to enhanced activity against the most sensitive cell lines.
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http://dx.doi.org/10.1016/j.bmc.2010.10.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2998995PMC
December 2010

Unusual antimalarial meroditerpenes from tropical red macroalgae.

Bioorg Med Chem Lett 2010 Oct 10;20(19):5662-5. Epub 2010 Aug 10.

School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA.

Three antimalarial meroditerpenes have been isolated from two Fijian red macroalgae. The absolute stereochemistry of callophycolide A (1), a unique macrolide from Callophycus serratus, was determined using a combination of Mosher's ester analysis, circular dichroism analysis with a dimolybdenum tetraacetate complex, and conformational analysis using NOEs. In addition, two known tocopherols, β-tocopherylhydroquinone (4) and δ-tocopherylhydroquinone (5), were isolated from Amphiroa crassa. By oxidizing 5 to the corresponding δ-tocopherylquinone (6), antimalarial activity against the human malaria parasite Plasmodium falciparum was increased by more than 20-fold.
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http://dx.doi.org/10.1016/j.bmcl.2010.08.031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2939151PMC
October 2010

Ecological leads for natural product discovery: Novel sesquiterpene hydroquinones from the red macroalga Peyssonnelia sp.

Tetrahedron 2010 Jan;66(2):455-461

School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA.

Pharmacologically-motivated marine natural product investigations have yielded a large variety of structurally unique compounds with interesting biomedical properties, but the natural roles of these molecules often remain unknown. While secondary metabolites may function as antimicrobial chemical defenses, few studies have examined this hypothesis. In the present investigation, chromatographic fractions from 69 collections of Fijian red macroalgae representing at least 43 species were evaluated for growth inhibition of three microbial pathogens and saprophytes of marine macrophytes. At least one microbe was suppressed by fraction(s) of all evaluated algae, suggesting that antimicrobial defenses are common among tropical seaweeds. From these leads, peyssonoic acids A-B (1-2), novel sesquiterpene hydroquinones, were isolated from the crustose red alga Peyssonnelia sp. At ecologically realistic concentrations, both compounds inhibited growth of Pseudoalteromonas bacteriolytica, a bacterial pathogen of marine algae, and Lindra thalassiae, a fungal pathogen of marine algae, and exhibited modest antineoplastic activity against ovarian cancer cells. The peyssonoic acids included one novel carbon skeleton and illustrated the utility of ecological studies in natural product discovery.
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http://dx.doi.org/10.1016/j.tet.2009.11.042DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908918PMC
January 2010

Bioactive bromophycolides R-U from the Fijian red alga Callophycus serratus.

J Nat Prod 2010 Feb;73(2):275-8

School of Biology and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.

Four new bromophycolides, R-U (1-4), were isolated from the Fijian red alga Callophycus serratus and were identified by 1D and 2D NMR and mass spectroscopic analyses. These compounds expand the known structural variety of diterpene-benzoate macrolides and exhibited modest cytotoxicity toward selected human cancer cell lines. Bromophycolide S (2) also showed submicromolar activity against the human malaria parasite Plasmodium falciparum.
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http://dx.doi.org/10.1021/np900686wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3375676PMC
February 2010

Naseseazines A and B: a new dimeric diketopiperazine framework from a marine-derived actinomycete, Streptomyces sp.

Org Lett 2009 Sep;11(17):3862-5

Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia.

Chemical analysis of a Streptomyces sp. (CMB-MQ030) isolated from a Fijian marine sediment yielded two new diketopiperazines, naseseazines A and B (1, 2), featuring a new dimeric framework. Structures were determined by detailed spectroscopic analysis and C(3) Marfey's analysis.
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http://dx.doi.org/10.1021/ol901466rDOI Listing
September 2009

The inhibition of TNF-alpha-induced NF-kappaB activation by marine natural products.

Biochem Pharmacol 2009 Sep 13;78(6):592-606. Epub 2009 May 13.

Department of Chemistry, University of Aberdeen, Old Aberdeen, UK.

The deregulated activation of NF-kappaB is associated with cancer development and inflammatory diseases. With an aim to find new NF-kappaB inhibitors, we purified and characterized compounds from extracts of the Fijian sponge Rhabdastrella globostellata, the crinoid Comanthus parvicirrus, the soft corals Sarcophyton sp. nov. and Sinularia sp., and the gorgonian Subergorgia sp. after an initial screening of 266 extracts from different marine origins. Results obtained show that selected purified compounds had a cytotoxic effect on the human leukaemia cell line K562, inhibited both TNF-alpha-induced NF-kappaB-DNA binding as well as TNF-alpha-induced IkappaBalpha degradation and nuclear translocation of p50/p65. Furthermore, we observed the inhibition of NF-kappaB activation induced by an overexpression of IKKbeta. Interestingly, natural products inhibited IKKbeta kinase as well as the 26S proteasome proteolytic activity.
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http://dx.doi.org/10.1016/j.bcp.2009.05.009DOI Listing
September 2009

Antimalarial bromophycolides J-Q from the Fijian red alga Callophycus serratus.

J Org Chem 2009 Apr;74(7):2736-42

School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.

Bromophycolides J-Q (1-8) were isolated from extracts of the Fijian red alga Callophycus serratus and identified with 1D and 2D NMR spectroscopy and mass spectral analyses. These diterpene-benzoate macrolides represent two novel carbon skeletons and add to the 10 previously reported bromophycolides (9-18) from this alga. Among these 18 bromophycolides, several exhibited activities in the low micromolar range against the human malaria parasite Plasmodium falciparum.
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http://dx.doi.org/10.1021/jo900008wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2707147PMC
April 2009

Isolation and identification of a potent antimalarial and antibacterial polyacetylene from Bidens pilosa.

Planta Med 2009 May 4;75(6):624-8. Epub 2009 Mar 4.

Showa Pharmaceutical University, Higashi-tamagawagakuen, Machida, Tokyo 194-8543, Japan.

Diseases caused by malaria parasites and pathogenic bacteria were thought to be on the brink of eradication in the 1950-1960s, but they have once again become a serious threat to mankind as a result of the appearance of multidrug resistant strains. The spread of these multidrug resistant organisms has prompted a worldwide search for new classes of effective antimalarial and antibacterial drugs. Natural products have been recognized as highly important candidates for this purpose. Our attention has focused on the herbal plant Bidens pilosa, a weed common throughout the world, as one of the target plants in the search for new active compounds, owing to its empirical use in the treatment of infectious diseases and to pharmaco-chemical studies of its crude extract. We report the isolation of two new compounds of B. pilosa, the linear polyacetylenic diol 1 and its glucoside 2 which have previously been isolated from different plants. Compound 1 exhibited highly potent antimalarial and antibacterial properties in vitro as well as potent antimalarial activity by way of intravenous injection in vivo, thereby representing a promising new class of drugs potentially effective in the treatment of malarial and bacterial diseases. We suspect that discovery of these compounds in B. pilosa in appreciable quantity is because the Fijian tradition of using the fresh plant for extraction rather than the Asian tradition of using dried plants (1 is unstable in the dried state) was followed.
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http://dx.doi.org/10.1055/s-0029-1185377DOI Listing
May 2009

Correspondence between human diet, body composition and stable isotopic composition of hair and breath in Fijian villagers.

Isotopes Environ Health Stud 2009 Mar;45(1):1-17

Research Laboratory for Archaeology, University of Oxford, Oxford, UK.

The main aim of this work was to describe the relationship between diet, and hair and breath isotopic composition. From one Fijian rural village, hair and breath samples were procured from 20 women. Physical anthropometrics were made, and hair (13)C/(12)C and (15)N/(14)N and breath (13)C/(12)C were measured. Individual diet diaries were kept for two of the four preceding weeks, and isotopic compositions of items which accounted for most of the diet were measured. Individual average diets were analysed for macronutrient and energy content and conform to reasonable nutritional expectation. Characteristics of the diet are described in terms of protein and energy, their patterning with respect to different clusters of food items and their relationship to individuals' anthropometry. Breath CO(2) is depleted in (13)C by 1-2 per thousand on average with respect to the total diet. Hair was enriched on average by 4.1 per thousand in nitrogen and 4.5 per thousand in carbon with respect to the total diet. There was insufficient population variation in hair isotopic composition to establish individual hair-diet isotopic differences. The definite relationship that we establish in this work, between dietary and tissue isotopic values for a human community, provides a basis for determining and validating dietary regimes more generally within non-industrial, non-global-'supermarket' economies.
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http://dx.doi.org/10.1080/10256010802522010DOI Listing
March 2009

Antibacterial neurymenolides from the Fijian red alga Neurymenia fraxinifolia.

Org Lett 2009 Jan;11(1):225-8

School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, 30332, USA.

Two novel alpha-pyrone macrolides, neurymenolides A (1) and B (2), were isolated from the Fijian red alga Neurymenia fraxinifolia and characterized using a combination of NMR and mass spectral analyses. These molecules represent only the second example of alpha-pyrone macrolides, with 1 existing as interchanging atropisomers due to restricted rotation about the alpha-pyrone ring system. Neurymenolide A (1) displayed moderately potent activities against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VREF).
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http://dx.doi.org/10.1021/ol8024814DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2646105PMC
January 2009

Structures and absolute configurations of sulfate-conjugated triterpenoids including an antifungal chemical defense of the green macroalga Tydemania expeditionis.

J Nat Prod 2008 Sep 3;71(9):1616-9. Epub 2008 Sep 3.

School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.

Cytotoxicity-guided fractionation of the green macroalga Tydemania expeditionis led to isolation of four sulfate-conjugated triterpenoids including one new lanostane-type triterpenoid disulfate, lanosta-8-en-3,29-diol-23-oxo-3,29-disodium sulfate (1), and three known cycloartane-type triterpenoid disulfates, cycloartan-3,29-diol-23-one 3,29-disodium sulfate (2), cycloart-24-en-3,29-diol-23-one 3,29-disodium sulfate (3), and cycloartan-3,23,29-triol 3,29-disodium sulfate (4). Extensive 1D and 2D NMR analyses in combination with X-ray crystallography established the structure and absolute configuration of 1 and allowed determination of the absolute configurations of 2-4 with a revision of previously assigned configuration at C-5. Each natural product was moderately cytotoxic in tumor cell and invertebrate toxicity assays. Of the natural products, only 4 exhibited significant antifungal activity at whole-tissue natural concentrations against the marine pathogen Lindra thalassiae. Comparison of the biological activities of natural products with their desulfated derivatives indicated that sulfation does not appear to confer cytotoxicity or antifungal activity.
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http://dx.doi.org/10.1021/np800307hDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3375682PMC
September 2008

Antineoplastic unsaturated fatty acids from Fijian macroalgae.

Phytochemistry 2008 Oct 29;69(13):2495-500. Epub 2008 Aug 29.

School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA.

Phytochemical analysis of Fijian populations of the green alga Tydemania expeditionis led to the isolation of two unsaturated fatty acids, 3(zeta)-hydroxy-octadeca-4(E),6(Z),15(Z)-trienoic acid (1) and 3(zeta)-hydroxy-hexadeca-4(E),6(Z)-dienoic acid (2), along with the known 3(zeta)-hydroxy-octadeca-4(E),6(Z)-dienoic acid (4). Investigations of the red alga Hydrolithon reinboldii led to identification of a glycolipid, lithonoside (3), and five known compounds, 15-tricosenoic acid, hexacosa-5,9-dienoic methyl ester, beta-sitosterol, 10(S)-hydroxypheophytin A, and 10(R)-hydroxypheophytin A. The structures of 1-3 were elucidated by spectroscopic methods (1D and 2D NMR spectroscopy and ESI-MS). Compounds 1, 2, and 4, containing conjugated double bonds, demonstrated moderate inhibitory activity against a panel of tumor cell lines (including breast, colon, lung, prostate and ovarian cells) with IC(50) values ranging from 1.3 to 14.4 microM. The similar cell selectivity patterns of these three compounds suggest that they might act by a common, but unknown, mechanism of action.
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http://dx.doi.org/10.1016/j.phytochem.2008.07.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2590869PMC
October 2008

The glycemic index (GI) and glycemic load (GL) of five commonly consumed foods of the South Pacific.

Pac Health Dialog 2004 Mar;11(1):47-54

Asia Pacific Health and Nutrition Centre, Monash Asia Institute, Monash University, Clayton 3800, Victoria, Australia.

Glycemic index (GI) has been widely used in the management of blood sugar levels among diabetes however; in the South Pacific very little information regarding the GI of local foods is made available. The objectives of this research were to determine the glycemic index and the glycemic load of 5 South Pacific foods, which have not been studied. The foods tested were plantain (Musa AAB), tannia (Xanthosoma sagittifolium), roti or chappati, homemade pancake and Lees cabin crackers. Glucose powder mixed in 200 mL of water was used as reference food. Eight apparently healthy indigenous Fijian males from the Fiji Military Forces aged 25-36 years old were recruited for this study. Participants were given a 50 g carbohydrate portion of the test foods to ingest after a 10-12 hour fast the night before the test and the standard reference food were administered to participants on different days for comparison. In the morning, capillary blood samples were drawn from the fingers at 0 min, 15, 30, 45, 60, 90 and 120 minutes postprandially and the blood glucose level was determined. The equation of Wolever using computer software was used to calculate the glycemic index and the glycemic load was calculated using the formular provided in the Harvard Health Online. The results showed that individuals respond to foods differently thus affecting the GI average values. The glycemic index has been categorized by Miller as low GI is pounds 55, moderate GI is between 56-69 and high GI is > or = 70. All the five carbohydrate foods understudy have moderate GI values ranging from 59 to 68. The Glycemic Load (GL) for cabin biscuit was the highest.
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March 2004
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