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Find video protocols related to scientific articles indexed in Pubmed.
Wollamides: antimycobacterial cyclic hexapeptides from an Australian soil Streptomyces.
Org. Lett.
PUBLISHED: 09-17-2014
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A soil Streptomyces nov. sp. (MST-115088) isolated from semiarid terrain near Wollogorang Station, Queensland, returned two known and two new examples of a rare class of cyclic hexapeptide, desotamides A and B (1 and 2) and E and F (3 and 4), respectively, together with two new d-Orn homologues, wollamides A and B (5 and 6). Structures were assigned by detailed spectroscopic and C3 Marfey's analysis. The desotamides/wollamides exhibit growth inhibitory activity against Gram-positive bacteria (IC50 0.6-7 ?M) and are noncytotoxic to mammalian cells (IC50 >30 ?M). The wollamides exhibit antimycobacterial activity (IC50 2.8 and 3.1 ?M), including reduction in the intracellular mycobacterial survival in murine bone marrow-derived macrophages.
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Shornephine A: structure, chemical stability, and P-glycoprotein inhibitory properties of a rare diketomorpholine from an Australian marine-derived Aspergillus sp.
J. Org. Chem.
PUBLISHED: 09-02-2014
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Chemical analysis of an Australian marine sediment-derived Aspergillus sp. (CMB-M081F) yielded the new diketomorpholine (DKM) shornephine A (1) together with two known and one new diketopiperazine (DKP), 15b-?-hydroxy-5-N-acetyladreemin (2), 5-N-acetyladreemin (3), and 15b-?-methoxy-5-N-acetyladreemin (4), respectively. Structure elucidation of 1-4 was achieved by detailed spectroscopic analysis, supported by chemical degradation and derivatization, and biosynthetic considerations. The DKM (1) underwent a facile (auto) acid-mediated methanolysis to yield seco-shornephine A methyl ester (1a). Our mechanistic explanation of this transformation prompted us to demonstrate that the acid-labile and solvolytically unstable DKM scaffold can be stabilized by N-alkylation. Furthermore, we demonstrate that at 20 ?M shornephine A (1) is a noncytotoxic inhibitor of P-glycoprotein-mediated drug efflux in multidrug-resistant human colon cancer cells.
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Levofloxacin and Indolicidinfor Combination Antimicrobial Therapy.
Curr Drug Deliv
PUBLISHED: 05-14-2014
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Despite the increasing need for antibiotics to fight infectious diseases, fewer new antibiotics are available on the market. Unfortunately, developing a new class of antibiotics is associated with high commercial risk. Therefore, modification or combination of existing antibiotics to improve their efficacy is a promising strategy. Herein, we conjugated the antibiotic, levofloxacin, with two peptides, i.e. an antimicrobial peptide indolicidin and a cell penetrating peptide (TAT). Glycolic acid and glycine linkers were used between levofloxacin and peptides. We developed an optimized condition for coupling of levofloxacin via its carboxylic group to glycolic acidusing solid phase peptide synthesis (SPPS). Antibacterial and haemolytic assays were carried out on the conjugates andonly the levofloxacin-indolicidinconjugate demonstrated moderate antibacterial activity. Interestingly, physical mixture of levofloxacinand indolicidin showed improvement in the activity against Gram-positive bacteria.
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Lipopolysaccharide (LPS) stimulation of fungal secondary metabolism.
Mycology
PUBLISHED: 04-23-2014
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We report on a preliminary investigation of the use the Gram-negative bacterial cell wall constituent lipopolysaccharide (LPS) as a natural chemical cue to stimulate and alter the expression of fungal secondary metabolism. Integrated high-throughput micro-cultivation and micro-analysis methods determined that 6 of 40 (15%) of fungi tested responded to an optimal exposure to LPS (0.6 ng/mL) by activating, enhancing or accelerating secondary metabolite production. To explore the possible mechanisms behind this effect, we employed light and fluorescent microscopy in conjunction with a nitric oxide (NO)-sensitive fluorescent dye and an NO scavenger to provide evidence that LPS stimulation of fungal secondary metabolism coincided with LPS activation of NO. Several case studies demonstrated that LPS stimulation can be scaled from single microplate well (1.5 mL) to preparative (>400 mL) scale cultures. For example, LPS treatment of Penicillium sp. (ACM-4616) enhanced pseurotin A and activated pseurotin A1 and pseurotin A2 biosynthesis, whereas LPS treatment of Aspergillus sp. (CMB-M81F) substantially accelerated and enhanced the biosynthesis of shornephine A and a series of biosynthetically related ardeemins and activated production of neoasterriquinone. As an indication of broader potential, we provide evidence that cultures of Penicillium sp. (CMB-TF0411), Aspergillus niger (ACM-4993F), Rhizopus oryzae (ACM-165F) and Thanatephorus cucumeris (ACM-194F) were responsive to LPS stimulation, the latter two examples being particular noteworthy as neither are known to produce secondary metabolites. Our results encourage the view that LPS stimulation can be used as a valuable tool to expand the molecular discovery potential of fungal strains that either have been exhaustively studied by or are unresponsive to traditional culture methodology.
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Mollemycin A: an antimalarial and antibacterial glyco-hexadepsipeptide-polyketide from an Australian marine-derived Streptomyces sp. (CMB-M0244).
Org. Lett.
PUBLISHED: 03-11-2014
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A marine-derived Streptomyces sp. (CMB-M0244) isolated from a sediment collected off South Molle Island, Queensland, produced mollemycin A (1) as a new first in class glyco-hexadepsipeptide-polyketide. The structure of 1 was assigned by detailed spectroscopic analysis, supported by chemical derivatization and degradation, and C3 Marfey's analysis. Mollemycin A (1) exhibits exceptionally potent and selective growth inhibitory activity against Gram-positive and Gram-negative bacteria (IC50 10-50 nM) and drug-sensitive (3D7; IC50 7 nM) and multidrug-resistant (Dd2; IC50 9 nM) clones of the malaria parasite Plasmodium falciparum.
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Callyspongisines A-D: bromopyrrole alkaloids from an Australian marine sponge, Callyspongia sp.
Org. Biomol. Chem.
PUBLISHED: 01-25-2014
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An extract of the Great Australian Bight marine sponge Callyspongia sp. (CMB-01152) displayed inhibitory activity against the neurodegenerative disease kinase targets casein kinase 1 (CK1), cyclin-dependent kinase 5 (CDK5) and glycogen synthase kinase 3 (GSK3?). Chemical investigation, employing HPLC-DAD-MS single ion extraction protocols, facilitated identification of the new bromopyrrole alkaloids, callyspongisines A-D (1-4), and two known co-metabolites, hymenialdisine (5) and 2-bromoaldisine (6). Structure elucidation of 1-6 was supported by detailed spectroscopic analysis and chemical interconversion, as well as biosynthetic and synthetic considerations. Callyspongisine A (1) is only the second reported example of a natural imino-oxazoline, and the first to feature a spiro heterocyclic framework, while callyspongisines B-D (2-4) were speculated to be storage and handling artefacts of 1. The kinase inhibitory activity detected in Callyspongia sp. (CMB-01152) was attributed to 5.
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Heronapyrrole D: A case of co-inspiration of natural product biosynthesis, total synthesis and biodiscovery.
Beilstein J Org Chem
PUBLISHED: 01-01-2014
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The heronapyrroles A-C have first been isolated from a marine-derived Streptomyces sp. (CMB-0423) in 2010. Structurally, these natural products feature an unusual nitropyrrole system to which a partially oxidized farnesyl chain is attached. The varying degree of oxidation of the sesquiterpenyl subunit in heronapyrroles A-C provoked the hypothesis that there might exist other hitherto unidentified metabolites. On biosynthetic grounds a mono-tetrahydrofuran-diol named heronapyrrole D appeared a possible candidate. We here describe a short asymmetric synthesis of heronapyrrole D, its detection in cultivations of CMB-0423 and finally the evaluation of its antibacterial activity. We thus demonstrate that biosynthetic considerations and the joint effort of synthetic and natural product chemists can result in the identification of new members of a rare class of natural products.
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Oxygen tension assessment: an overlooked tool for prediction of delayed healing in a clinical setting.
Int Wound J
PUBLISHED: 09-15-2011
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Successful wound healing requires adequate transcutaneous oxygen tension (tcpO(2) ). TcpO(2) may not commonly be incorporated in clinical assessments because of variable measurement response at different sensory temperatures. This study aims to assess the relationship between changes in tcpO(2) , measured under basal (39°C) and stimulated (44°C) conditions and healing rate of chronic wounds over 4 weeks, to determine whether tcpO(2) measurement can predict delayed wound healing. TcpO(2) (Radiometer TCM400) measurements at sensor temperatures 39 and 44°C were recorded (twice, 4 weeks apart) adjacent to the ulcer site, and at a mirror image site on the contralateral leg. Ulcer outline was traced on clear acetate and perimeter and area measured (Visitrak™, Smith and Nephew). TcpO(2) measured at 44 and 39°C adjacent to all 13 wounds were lower compared to the contralateral site, significant at 44°C (P = 0·008). Significant correlation (r(2) = 0·8) occurred between wound healing rate and increased tcpO(2) at 44°C over 4 weeks. Importantly, the ratio of 39/44°C tcpO(2) , measured at the initial appointment, appeared to predict normal or delayed healing rate. TcpO(2) may provide clinicians with information regarding anticipated healing ability of wounds at the initial appointment, and hence identify wounds requiring early implementation of adjuvant therapies to accelerate healing.
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Reveromycins revealed: new polyketide spiroketals from Australian marine-derived and terrestrial Streptomyces spp. A case of natural products vs. artifacts.
Org. Biomol. Chem.
PUBLISHED: 12-14-2010
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Chemical analysis of fermentation products from two Australian Streptomyces isolates yielded all four known and twelve new examples of the rare reveromycin class of polyketide spiroketals, including hemi-succinates, hemi-fumarates and hemi-furanoates. Reveromycins were identified with the aid of HPLC-DAD-MS and HPLC-DAD-SPE-NMR methodology, and structures were assigned by detailed spectroscopic analysis. The structural and mechanistic requirements for an unprecedented hemi-succinate?:?ketal-succinyl equilibrium were defined and provided a basis for proposing that reveromycin 4-methyl esters and 5,6-spiroketals were artifacts. A plausible reveromycin polyketide biosynthesis is proposed, requiring a 2-methylsuccinyl-CoA starter unit, with flexible incorporation of a C(6-8) polyketide chain extension and diacid esterification units. Structure activity relationship investigations by co-metabolites were used to assess the anticancer, antibacterial and antifungal properties of reveromycins.
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Heronapyrroles A-C: farnesylated 2-nitropyrroles from an Australian marine-derived Streptomyces sp.
Org. Lett.
PUBLISHED: 10-15-2010
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Chemical analysis of a marine-derived Streptomyces sp. (CMB-M0423) isolated from beach sand off Heron Island, Australia, yielded three new members of the rare pyrroloterpene biosynthetic structure class. Identified by detailed spectroscopic analysis as the first reported examples of naturally occurring 2-nitropyrroles, heronapyrroles A-C (1-3) displayed promising biological activity-with low to submicromolar IC(50) activity against Gram-positive bacteria but no cytotoxicity toward mammalian cell lines.
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Heterofibrins: inhibitors of lipid droplet formation from a deep-water southern Australian marine sponge, Spongia (Heterofibria) sp.
Org. Biomol. Chem.
PUBLISHED: 07-14-2010
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A bioassay-guided search for inhibitors of lipid droplet formation in a deep-water southern Australian marine sponge, Spongia (Heterofibria) sp., yielded six new compounds, fatty acids heterofibrins A1 (1) and B1 (4), along with related monolactyl and dilactyl esters, heterofibrins A2 (2), B2 (5), A3 (3) and B3 (6). Heterofibrin structures were assigned on the basis of detailed spectroscopic analysis, with comparison to chiral synthetic model compounds. All heterofibrins possess a diyne-ene moiety, while the monolactyl and dilactyl moiety featured in selected heterofibrins is unprecedented in the natural products literature. SAR by co-metabolite studies on the heterofibrins confirmed them to be non-cytotoxic, with the carboxylic acids 1 and 4 inhibiting lipid droplet formation in A431 fibroblast cell lines. Such inhibitors have potential application in the management of obesity, diabetes and atherosclerosis
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The use of sensory nerve stimulation and compression bandaging to improve sensory nerve function and healing of chronic venous leg ulcers.
Curr Aging Sci
PUBLISHED: 12-22-2009
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Low frequency transcutaneous sensory nerve stimulation (LF-SNS) [International Patent PCT/AU2004/001079: "nerve function and tissue healing" (Khalil, Z.)] improves sensory nerve function and accelerates wound healing of older animals.
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Effect of pH on growth and biochemical responses of Dunaliella bardawil and Chlorella ellipsoidea.
World J. Microbiol. Biotechnol.
PUBLISHED: 10-21-2009
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The goal of the present investigation was to study the effect of pH on growth and biochemical responses of Dunaliella bardawil and Chlorella ellipsoidea when exposed to different pH values. The two tested microalgae could grow in a wide range of pH (4-9 for D. bardawil and 4-10 for C. ellipsoidea). The dry weight gain and the biochemical components of D. bardawil were greatly enhanced at pH 7.5. In contrast, dry weight and carbohydrate content of C. ellipsoidea attained their maximum values at the alkaline pH. On the other hand, the protein content of C. ellipsoidea recorded its highest value at pH 4, while the pigment content of the same alga was highest at pH 4, 6, and 7.5 and decreased at alkaline pH. Both pH 6 and pH 9 stimulated the accumulation of ?-carotene, vitamin E and vitamin C in D. bardawil, with the highest values of the three compounds recorded at pH 9. In the case of C. ellipsoidea, ?-carotene content increased at pH 6 and pH 10 as compared with the control, but the amount of ?-carotene was much higher at pH 6 than at pH 10. Vitamin E content was higher in C. ellipsoidea cells at pH 10 than at pH 6. Both pH 6 and pH 10 caused a significant decline in vitamin C content of C. ellipsoidea.
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Spiralisones A-D: acylphloroglucinol hemiketals from an Australian marine brown alga, Zonaria spiralis.
Org. Biomol. Chem.
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An intertidal sample of the Australian marine brown alga, Zonaria spiralis, exhibited promising kinase inhibitory and antibacterial activity. Chemical analysis returned six phloroglucinol-derived lipids, the new hemiketal spiralisones A-D (1-4) and the known chromones 5-6, and the known norsesquiterpenoid apo-9-fucoxanthinone (7). Structures 1-7 were assigned on the basis of detailed spectroscopic analysis, biosynthetic considerations and total synthesis. Spiralisones undergo facile acid-mediated dehydration to yield the corresponding chromones, revealing for the first time that brown algal chromones may be handling artifacts rather than natural products. Hemiketals 1 and 2, and chromone 6, displayed inhibitory activity against the neurodegenerative disease kinase targets CDK5/p25, CK1? and GSK3?, while hemiketals 1, 3 and 4, and chromone 6, displayed growth inhibitory activity against the Gram-positive bacteria Bacillus subtilis (ATCC 6051 and 6633). The promising kinase inhibitory and antibacterial properties of the Z. spiralis extract were attributed to the cumulative effect of many moderately potent phloroglucinol-derived lipid co-metabolites.
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Kinase inhibitor scaffolds against neurodegenerative diseases from a Southern Australian ascidian, Didemnum sp.
ChemMedChem
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Screening a library of Southern Australian and Antarctic marine invertebrates and algae for inhibitors of neurodegenerative disease kinase targets casein kinase 1 (CK1?), cyclin-dependent kinase 5 (CDK5) and glycogen synthase kinase 3? (GSK3?) identified a Western Australian Didemnum species (CMB-02127) as a high-priority specimen. Chemical fractionation returned the known aromatic alkaloids ningalins B-D as the major metabolites, together with six minor metabolites, the new ningalins E-G and the known hexacyclic pyrrole alkaloids lamellarins Z, G and A6. All structures were assigned by detailed spectroscopic analysis and literature comparisons, and the structural assignments were supported by biosynthetic considerations. The ningalins showed potent and broad inhibition across the three kinases, while the lamellarins were generally more selective for CDK5. Docking studies using published X-ray crystal structures of CDK5 revealed both scaffolds target the ATP binding pocket.
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Lamellarins as inhibitors of P-glycoprotein-mediated multidrug resistance in a human colon cancer cell line.
Chem Asian J
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Chemical analysis of a Didemnum sp. (CMB-01656) collected during scientific Scuba operations off Wasp Island, New South Wales, yielded five new lamellarins A1 (1), A2 (2), A3 (3), A4 (4) and A5 (5) and eight known lamellarins C (6), E (7), K (8), M (9), S (10), T (11), X (12) and ? (13). Analysis of a second Didemnum sp. (CMB-02127) collected during scientific trawling operations along the Northern Rottnest Shelf, Western Australia, yielded the new lamellarin A6 (14) and two known lamellarins G (15) and Z (16). Structures were assigned to 1-16 on the basis of detailed spectroscopic analysis with comparison to literature data and authentic samples. Access to this unique library of natural lamellarins (1-16) provided a rare opportunity for structure-activity relationship (SAR) investigations, probing interactions between lamellarins and the ABC transporter efflux pump P-glycoprotein (P-gp) with a view to reversing multidrug resistance in a human colon cancer cell line (SW620 Ad300). These SAR studies, which were expanded to include the permethylated lamellarin derivative (17) and a series of lamellarin-inspired synthetic coumarins (19-24) and isoquinolines (25-26), successfully revealed 17 as a promising new non-cytotoxic P-gp inhibitor pharmacophore.
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A search for BACE inhibitors reveals new biosynthetically related pyrrolidones, furanones and pyrroles from a southern Australian marine sponge, Ianthella sp.
Org. Biomol. Chem.
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Fractionation of a southern Australian marine sponge, Ianthella sp., yielded sixteen metabolites including a new class of pyrrolidone, ianthellidones A-F (1-6), a new class of furanone, ianthellidones G-H (7-8), new and known lamellarins, lamellarins O1 (9), O2 (10), O (11) and Q (12), plus the known 4-hydroxybenzaldehyde (13), 4-hydroxybenzoic acid (14), 4-methoxybenzoic acid (15) and ethyl 4-hydroxybenzoate (16). Structures for all Ianthella metabolites were determined by detailed spectroscopic analysis, supported by a plausible biosynthetic relationship. The ianthellidones were non-cytotoxic towards two human colon cancer cell lines (SW620 and SW620 Ad300), as well as Gram +ve and Gram -ve bacteria, and a fungus. Ianthellidone F (6) and lamellarins O2 (10) and O (11) displayed modest BACE inhibitory properties (IC(50) > 10 ?M), while lamellarin O1 (9) was more potent (IC(50) < 10 ?M). Lamellarin O (11) exhibited modest cytotoxicity towards SW620 and SW620 Ad300 cell lines (IC(50) > 22 ?M), was an inhibitor of the multi-drug resistance efflux pump P-glycoprotein, and displayed selective growth inhibitory activity against the Gram +ve bacterium Bacillus subtilis (ATCC 6633) (IC(50) 2.5 ?M).
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.