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Eichner A, Lewis LA, Leonard B, Wagoner RMV, Eichner D, Fedoruk MN. Generic Pharmaceuticals as a Source of Diuretic Contamination in Athletes Subject to Sport Drug Testing. Front Sports Act Living 2021; 3:692244. [PMID: 34870192 PMCID: PMC8635962 DOI: 10.3389/fspor.2021.692244] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
This paper describes nine instances of positive anti-doping tests that could be accounted for by the use of permitted generic prescription drugs contaminated with diuretics, which are prohibited in sport at all times under the WADA Prohibited List. The contamination levels found in the medications are reported and were below FDA limits for manufacturers that are based primarily on safety considerations. These cases demonstrate that great care must be taken to identify the source of low-level anti-doping positives for diuretics reported by WADA-accredited laboratories, and possibly other prohibited substances as well, in order to avoid sanctioning innocent athletes. An evaluation of the cases in this paper supports an approach which establishes a laboratory minimum reporting level (MRL) for diuretics found most commonly in medications. A global consensus after extensive review of similar anti-doping cases has resulted in implementation of a recently announced solution regarding potential diuretic contamination cases.
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Affiliation(s)
- Amy Eichner
- United States Anti-Doping Agency, Colorado Springs, CO, United States
| | - Laura A Lewis
- United States Anti-Doping Agency, Colorado Springs, CO, United States
| | - Bridget Leonard
- United States Anti-Doping Agency, Colorado Springs, CO, United States
| | - Ryan M Van Wagoner
- Sports Medicine and Research Testing Laboratory, Salt Lake City, UT, United States
| | - Daniel Eichner
- Sports Medicine and Research Testing Laboratory, Salt Lake City, UT, United States
| | - Matthew N Fedoruk
- United States Anti-Doping Agency, Colorado Springs, CO, United States
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2
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Miller GD, Van Wagoner RM, Bruno BJ, Husk JD, Fedoruk MN, Eichner D. Investigating oral fluid and exhaled breath as alternative matrices for anti-doping testing: Analysis of 521 matched samples. J Pharm Biomed Anal 2019; 176:112810. [DOI: 10.1016/j.jpba.2019.112810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 08/08/2019] [Accepted: 08/10/2019] [Indexed: 01/20/2023]
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3
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Stewart AK, Ravindra R, Van Wagoner RM, Wright JLC. Metabolomics-Guided Discovery of Microginin Peptides from Cultures of the Cyanobacterium Microcystis aeruginosa. J Nat Prod 2018; 81:349-355. [PMID: 29405714 DOI: 10.1021/acs.jnatprod.7b00829] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report a mass-spectrometry-based metabolomics study of a laboratory-cultured strain of Microcystis aeruginosa (UTEX LB2385), which has led to the discovery of five peptides (1-5) belonging to the microginin class of linear cyanopeptides. The structures and configurations of these peptides were determined by spectroscopic analyses and chemical derivitization. The microginin peptides described herein are the first reported derivatives containing N-methyl methionine (1, 5) and N-methyl methionine sulfoxide (2-4). The two tripeptide microginin analogues (4, 5) identified represent the smallest members of this peptide family. Their angiotensin-converting enzyme (ACE) inhibitory activity was also investigated. Microginin 527 (4) was the most potent of the group, with an IC50 of 31 μM.
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Affiliation(s)
- Allison K Stewart
- Center for Marine Science, Department of Chemistry and Biochemistry, University of North Carolina Wilmington , 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409, United States
| | - Rudravajhala Ravindra
- Center for Marine Science, Department of Chemistry and Biochemistry, University of North Carolina Wilmington , 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409, United States
| | - Ryan M Van Wagoner
- Center for Marine Science, Department of Chemistry and Biochemistry, University of North Carolina Wilmington , 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409, United States
| | - Jeffrey L C Wright
- Center for Marine Science, Department of Chemistry and Biochemistry, University of North Carolina Wilmington , 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409, United States
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Van Wagoner RM, Eichner A, Bhasin S, Deuster PA, Eichner D. Chemical Composition and Labeling of Substances Marketed as Selective Androgen Receptor Modulators and Sold via the Internet. JAMA 2017; 318:2004-2010. [PMID: 29183075 PMCID: PMC5820696 DOI: 10.1001/jama.2017.17069] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Recent reports have described the increasing use of nonsteroidal selective androgen receptor modulators, which have not been approved by the US Food and Drug Administration (FDA), to enhance appearance and performance. The composition and purity of such products is not known. OBJECTIVE To determine the chemical identity and the amounts of ingredients in dietary supplements and products marketed and sold through the internet as selective androgen receptor modulators and compare the analyzed contents with product labels. DESIGN AND SETTING Web-based searches were performed from February 18, 2016, to March 25, 2016, using the Google search engine on the Chrome and Internet Explorer web browsers to identify suppliers selling selective androgen receptor modulators. The products were purchased and the identities of the compounds and their amounts were determined from April to August 2016 using chain-of-custody and World Anti-Doping Association-approved analytical procedures. Analytical findings were compared against the label information. EXPOSURES Products marketed and sold as selective androgen receptor modulators. MAIN OUTCOMES AND MEASURES Chemical identities and the amount of ingredients in each product marketed and sold as selective androgen receptor modulators. RESULTS Among 44 products marketed and sold as selective androgen receptor modulators, only 23 (52%) contained 1 or more selective androgen receptor modulators (Ostarine, LGD-4033, or Andarine). An additional 17 products (39%) contained another unapproved drug, including the growth hormone secretagogue ibutamoren, the peroxisome proliferator-activated receptor-δ agonist GW501516, and the Rev-ErbA agonist SR9009. Of the 44 tested products, no active compound was detected in 4 (9%) and substances not listed on the label were contained in 11 (25%). In only 18 of the 44 products (41%), the amount of active compound in the product matched that listed on the label. The amount of the compounds listed on the label differed substantially from that found by analysis in 26 of 44 products (59%). CONCLUSIONS AND RELEVANCE In this limited investigation involving chemical analyses of 44 products marketed as selective androgen receptor modulators and sold via the internet, most products contained unapproved drugs and substances. Only 52% contained selective androgen receptor modulators and many were inaccurately labeled.
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Affiliation(s)
| | - Amy Eichner
- US Anti-Doping Agency, Colorado Springs, Colorado
| | - Shalender Bhasin
- Research Program in Men’s Health: Aging and Metabolism, Harvard Medical School, Brigham and Women’s Hospital, Boston, Massachusetts
| | - Patricia A. Deuster
- Consortium for Health and Military Performance, Uniformed Services University, Bethesda, Maryland
| | - Daniel Eichner
- Sports Medicine Research and Testing Laboratory, Salt Lake City, Utah
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Eichner D, Van Wagoner RM, Brenner M, Chou J, Leigh S, Wright LR, Flippin LA, Martinelli M, Krug O, Schänzer W, Thevis M. lmplementation of the prolyl hydroxylase inhibitor Roxadustat (FG‐4592) and its main metabolites into routine doping controls. Drug Test Anal 2017; 9:1768-1778. [DOI: 10.1002/dta.2202] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 03/31/2017] [Accepted: 03/31/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Daniel Eichner
- Sports Medicine Research and Testing Laboratory 560 Arapeen Drive Suite 150A Salt Lake City UT 84108 USA
| | - Ryan M. Van Wagoner
- Sports Medicine Research and Testing Laboratory 560 Arapeen Drive Suite 150A Salt Lake City UT 84108 USA
| | - Mitch Brenner
- FibroGen, Inc. 409 Illinois Street San Francisco CA 94158 USA
| | - James Chou
- FibroGen, Inc. 409 Illinois Street San Francisco CA 94158 USA
| | - Scott Leigh
- FibroGen, Inc. 409 Illinois Street San Francisco CA 94158 USA
| | - Lee R. Wright
- FibroGen, Inc. 409 Illinois Street San Francisco CA 94158 USA
| | - Lee A. Flippin
- FibroGen, Inc. 409 Illinois Street San Francisco CA 94158 USA
| | | | - Oliver Krug
- Institute of Biochemistry ‐ Centre for Preventive Doping ResearchGerman Sport University Cologne Am Sportpark Müngersdorf 6 50933 Cologne Germany
- European Monitoring Center for Emerging Doping Agents Cologne/Bonn Germany
| | - Wilhelm Schänzer
- Institute of Biochemistry ‐ Centre for Preventive Doping ResearchGerman Sport University Cologne Am Sportpark Müngersdorf 6 50933 Cologne Germany
| | - Mario Thevis
- Institute of Biochemistry ‐ Centre for Preventive Doping ResearchGerman Sport University Cologne Am Sportpark Müngersdorf 6 50933 Cologne Germany
- European Monitoring Center for Emerging Doping Agents Cologne/Bonn Germany
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Thorson MK, Van Wagoner RM, Harper MK, Ireland CM, Majtan T, Kraus JP, Barrios AM. Marine natural products as inhibitors of cystathionine beta-synthase activity. Bioorg Med Chem Lett 2015; 25:1064-6. [PMID: 25666819 DOI: 10.1016/j.bmcl.2015.01.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 01/05/2015] [Accepted: 01/07/2015] [Indexed: 10/24/2022]
Abstract
A library consisting of characterized marine natural products as well as synthetic derivatives was screened for compounds capable of inhibiting the production of hydrogen sulfide (H2S) by cystathionine beta-synthase (CBS). Eight hits were validated and shown to inhibit CBS activity with IC50 values ranging from 83 to 187μM. The majority of hits came from a series of synthetic polyandrocarpamine derivatives. In addition, a modified fluorogenic probe for H2S detection with improved solubility in aqueous solutions is reported.
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Affiliation(s)
- Megan K Thorson
- Department of Medicinal Chemistry, University of Utah, 30 South 2000 East, Salt Lake City, UT 84112, USA
| | - Ryan M Van Wagoner
- Department of Medicinal Chemistry, University of Utah, 30 South 2000 East, Salt Lake City, UT 84112, USA
| | - Mary Kay Harper
- Department of Medicinal Chemistry, University of Utah, 30 South 2000 East, Salt Lake City, UT 84112, USA
| | - Chris M Ireland
- Department of Medicinal Chemistry, University of Utah, 30 South 2000 East, Salt Lake City, UT 84112, USA
| | - Tomas Majtan
- Department of Pediatrics, University of Colorado, Aurora, CO 80045, USA
| | - Jan P Kraus
- Department of Pediatrics, University of Colorado, Aurora, CO 80045, USA
| | - Amy M Barrios
- Department of Medicinal Chemistry, University of Utah, 30 South 2000 East, Salt Lake City, UT 84112, USA.
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8
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Jadulco RC, Pond CD, Van Wagoner RM, Koch M, Gideon OG, Matainaho TK, Piskaut P, Barrows LR. 4-Quinolone alkaloids from Melochia odorata. J Nat Prod 2014; 77:183-187. [PMID: 24392742 PMCID: PMC3931125 DOI: 10.1021/np400847t] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The methanol extract of Melochia odorata yielded three 4-quinolone alkaloids including waltherione A (1) and two new alkaloids, waltherione C (2) and waltherione D (3). Waltheriones A and C showed significant activities in an in vitro anti-HIV cytoprotection assay at concentrations of 56.2 and 0.84 μM and inhibition of HIV P24 formation of more than 50% at 1.7 and 0.95 μM, respectively. The structures of the alkaloids were established by spectroscopic data interpretation.
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Affiliation(s)
- Raquel C. Jadulco
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
| | - Christopher D. Pond
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
| | - Ryan M. Van Wagoner
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, USA
| | - Michael Koch
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
| | - Osia G. Gideon
- School of Natural and Physical Sciences, University of Papua New Guinea, Boroko, NCD, Papua New Guinea
| | - Teatulohi K. Matainaho
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
- School of Medicine and Health Sciences, University of Papua New Guinea, Boroko, NCD, Papua New Guinea
| | - Pius Piskaut
- School of Natural and Physical Sciences, University of Papua New Guinea, Boroko, NCD, Papua New Guinea
| | - Louis R. Barrows
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
- School of Medicine and Health Sciences, University of Papua New Guinea, Boroko, NCD, Papua New Guinea
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9
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Sandoval IT, Manos EJ, Van Wagoner RM, Delacruz RGC, Edes K, Winge DR, Ireland CM, Jones DA. Juxtaposition of chemical and mutation-induced developmental defects in zebrafish reveal a copper-chelating activity for kalihinol F. ACTA ACUST UNITED AC 2014; 20:753-63. [PMID: 23790486 DOI: 10.1016/j.chembiol.2013.05.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 05/10/2013] [Accepted: 05/13/2013] [Indexed: 12/17/2022]
Abstract
A major hurdle in using complex systems for drug screening is the difficulty of defining the mechanistic targets of small molecules. The zebrafish provides an excellent model system for juxtaposing developmental phenotypes with mechanism discovery using organism genetics. We carried out a phenotype-based screen of uncharacterized small molecules in zebrafish that produced a variety of chemically induced phenotypes with potential genetic parallels. Specifically, kalihinol F caused an undulated notochord, defects in pigment formation, hematopoiesis, and neural development. These phenotypes were strikingly similar to the zebrafish mutant, calamity, an established model of copper deficiency. Further studies into the mechanism of action of kalihinol F revealed a copper-chelating activity. Our data support this mechanism of action for kalihinol F and the utility of zebrafish as an effective system for identifying therapeutic and target pathways.
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Affiliation(s)
- Imelda T Sandoval
- Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112, USA
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10
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Lu Z, Van Wagoner RM, Pond CD, Pole AR, Jensen JB, Blankenship D, Grimberg BT, Kiapranis R, Matainaho TK, Barrows LR, Ireland CM. Myristicyclins A and B: antimalarial procyanidins from Horsfieldia spicata from Papua New Guinea. Org Lett 2013; 16:346-9. [PMID: 24350818 DOI: 10.1021/ol4022639] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
An antimalarial screen for plants collected from Papua New Guinea identified an extract of Horsfieldia spicata as having activity. Isolation of the active constituents led to the identification of two new compounds: myristicyclins A (1) and B (2). Both compounds are procyanidin-like congeners of myristinins lacking a pendant aromatic ring. Myristicyclin A was found to inhibit the ring, trophozoite, and schizont stages of Plasmodium falciparum at similar concentrations in the mid-μM range.
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Affiliation(s)
- Zhenyu Lu
- Departments of Medicinal Chemistry and ‡Pharmacology and Toxicology, College of Pharmacy and L. S. Skaggs Pharmacy Institute, University of Utah , 30 S 2000 E, Salt Lake City, Utah 84112, United States
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11
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Lu Z, Koch M, Harper MK, Matainaho TK, Barrows LR, Van Wagoner RM, Ireland CM. Plakinamine M, a steroidal alkaloid from the marine sponge Corticium sp. J Nat Prod 2013; 76:2150-2. [PMID: 24195491 PMCID: PMC3883566 DOI: 10.1021/np400649e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
By means of bioassay-guided fractionation, a new steroidal alkaloid, plakinamine M (1), and the known compound, plakinamine L (2), with a unique acyclic side chain, were isolated from the marine sponge Corticium sp. collected from New Britain, Papua New Guinea. The structures were determined on the basis of extensive 1D and 2D NMR and HRESIMS. The two compounds showed inhibition of Mycobacterium tuberculosis with MIC values of 15.8 and 3.6 μg/mL, respectively.
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Affiliation(s)
- Zhenyu Lu
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84112
| | - Michael Koch
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, 84112
| | - Mary Kay Harper
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84112
| | - Teatulohi K. Matainaho
- Discipline of Pharmacology, School of Medicine and Health Sciences, University of Papua New Guinea, National Capital District, Papua New Guinea
| | - Louis R. Barrows
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, 84112
| | - Ryan M. Van Wagoner
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84112
| | - Chris M. Ireland
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84112
- To whom correspondence should be addressed. Tel: (801) 581-8305. Fax: (801) 581-3716.
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Lu Z, Harper MK, Pond CD, Barrows LR, Ireland CM, Wagoner RMV. Thiazoline peptides and a tris-phenethyl urea from Didemnum molle with anti-HIV activity. J Nat Prod 2012; 75:1436-40. [PMID: 22845329 PMCID: PMC4176947 DOI: 10.1021/np300270p] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
As part of our screening for anti-HIV agents from marine invertebrates, the MeOH extract of Didemnum molle was tested and showed moderate in vitro anti-HIV activity. Bioassay-guided fractionation of a large-scale extract allowed the identification of two new cyclopeptides, mollamides E and F (1 and 2), and one new tris-phenethyl urea, molleurea A (3). The absolute configurations were established using the advanced Marfey's method. The three compounds were evaluated for anti-HIV activity in both an HIV integrase inhibition assay and a cytoprotective cell-based assay. Compound 2 was active in both assays with IC(50) values of 39 and 78 μM, respectively. Compound 3 was active only in the cytoprotective cell-based assay, with an IC(50) value of 60 μM.
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Affiliation(s)
- Zhenyu Lu
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Mary Kay Harper
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Christopher D. Pond
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Louis R. Barrows
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Chris M. Ireland
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Ryan M. Van Wagoner
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84112, USA
- To whom correspondence should be addressed. Tel: (801) 581-4932. Fax: (801) 585-6208.
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Abstract
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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Affiliation(s)
- Pritesh Prasad
- Institute of Applied Science, Faculty of Science, Technology and Environment, The University of the South Pacific, Laucala Campus, Suva, Fiji Islands
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Sasaki S, Tozawa T, Van Wagoner RM, Ireland CM, Harper MK, Satoh T. Strongylophorine-8, a pro-electrophilic compound from the marine sponge Petrosia (Strongylophora) corticata, provides neuroprotection through Nrf2/ARE pathway. Biochem Biophys Res Commun 2011; 415:6-10. [PMID: 21982768 DOI: 10.1016/j.bbrc.2011.09.114] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2011] [Accepted: 09/23/2011] [Indexed: 11/17/2022]
Abstract
Green plant-origin electrophilic compounds are a newly-recognized class of neuroprotective compounds that provide neuroprotection through activation of the Nrf2/ARE pathway. Electrophilic hydroquinones are of particular interest due to their ability to become electrophilic quinones upon auto-oxidation. Although marine organisms frequently produce a variety of electrophilic compounds, the detailed mechanisms of action of these compounds remain unknown. Here, we focused on the neuroprotective effects of strongylophorine-8 (STR8), a para-hydroquinone-type pro-electrophilic compound from the sponge Petrosia (Strongylophora) corticata. STR8 activated the Nrf2/ARE pathway, induced phase 2 enzymes, and increased glutathione, thus protecting neuronal cells from oxidative stress. Microarray analysis indicated that STR8 induced a large number of phase 2 genes, the regulation of which is controlled by the Nrf2/ARE pathway. STR8 is the first example of a neuroprotective pro-electrophilic compound from marine organisms.
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Affiliation(s)
- Shunsuke Sasaki
- Department of Welfare Engineering, Faculty of Engineering, Iwate University, Morioka, Iwate 020-8551, Japan
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Jadulco RC, Koch M, Van Wagoner RM, Pond C, Gideon OG, Matainaho T, Piskaut P, Barrows LR. New antimycobacterial triterpenoids from Rhus taitensis. Planta Med 2011; 77:1651-1654. [PMID: 21544777 DOI: 10.1055/s-0030-1271027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Two new triterpenoids were isolated from the leaves and twigs of Rhus taitensis. Their structures were elucidated by 1D and 2D NMR spectroscopic studies as 1,10,24,25,30-pentahydroxysqualene and dammar-20(22),24-diene-3 β,26,27-triol. Both compounds exhibited moderate antimycobacterial activities with an MIC of 45 µg/mL.
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Affiliation(s)
- Raquel C Jadulco
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
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Lu Z, Ding Y, Li XC, Djigbenou DR, Grimberg BT, Ferreira D, Ireland CM, Van Wagoner RM. 3-bromohomofascaplysin A, a fascaplysin analogue from a Fijian Didemnum sp. ascidian. Bioorg Med Chem 2011; 19:6604-7. [PMID: 21696970 DOI: 10.1016/j.bmc.2011.05.046] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 04/29/2011] [Accepted: 05/23/2011] [Indexed: 11/20/2022]
Abstract
A new fascaplysin analogue, 3-bromohomofascaplysin A (1), along with two known analogues, homofascaplysin A (2) and fascaplysin (3), were isolated from a Fijian Didemnum sp. ascidian. The absolute configurations of 3-bromohomofascaplysin A (1) and homofascaplysin A (2) were determined via experimental and theoretically calculated ECD spectra. The differential activities of 1-3 against different blood-borne life stages of the malaria pathogen Plasmodium falciparum were assessed. Homofascaplysin A (2) displayed an IC(50) of 0.55±0.11 nM against ring stage parasites and 105±38 nM against all live parasites. Given the stronger resistance of ring stage parasites against most current antimalarials relative to the other blood stages, homofascaplysin A (2) represents a promising agent for treatment of drug resistant malaria.
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Affiliation(s)
- Zhenyu Lu
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, UT 84112, USA
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Wei X, Henriksen NM, Skalicky JJ, Harper MK, Cheatham TE, Ireland CM, Van Wagoner RM. Araiosamines A-D: tris-bromoindole cyclic guanidine alkaloids from the marine sponge Clathria (Thalysias) araiosa. J Org Chem 2011; 76:5515-23. [PMID: 21462976 DOI: 10.1021/jo200327d] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Four new tris-bromoindole cyclic guanidine alkaloids, araiosamines A-D, were isolated from the methanol extract of a marine sponge, Clathria (Thalysias) araiosa, collected from Vanuatu. Their carbon skeletons delineate a new class of indole alkaloids apparently derived from a linear polymerization process involving a carbon-carbon bond formation. Comparison of the structures including the relative configurations suggests a common intermediate containing a dihydroaminopyrimidine moiety capable of undergoing various modalities of conjugate addition to yield unprecedented ring systems.
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Affiliation(s)
- Xiaomei Wei
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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Lu Z, Van Wagoner RM, Harper MK, Baker HL, Hooper JNA, Bewley CA, Ireland CM. Mirabamides E-H, HIV-inhibitory depsipeptides from the sponge Stelletta clavosa. J Nat Prod 2011; 74:185-93. [PMID: 21280591 PMCID: PMC3072293 DOI: 10.1021/np100613p] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Four new depsipeptides, mirabamides E-H (1-4), and the known depsipeptide mirabamide C (5) have been isolated from the sponge Stelletta clavosa, collected from the Torres Strait. The planar structures were determined on the basis of extensive 1D and 2D NMR and HRESIMS. The absolute configurations were established by the advanced Marfey's method, NMR, and GC-MS. The four new compounds all showed strong inhibition of HIV-1 in a neutralization assay with IC(50) values of 121, 62, 68, and 41 nM, respectively.
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Affiliation(s)
| | | | | | | | | | | | - Chris M. Ireland
- To whom correspondence should be addressed. Tel: (801) 581-8305. Fax: (801) 585-6208.
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19
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Abstract
Two ring-A-aromatized bile acids, 1 and 2, were isolated from the sponge Sollasella moretonensis, collected from the seabed of northern Queensland. Structures were assigned on the basis of extensive 1D and 2D NMR studies, as well as analysis by HRESIMS. Compound 2 has previously been produced synthetically, though this marks its first isolation from a natural source.
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Affiliation(s)
- Zhenyu Lu
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Ryan M. Van Wagoner
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Mary Kay Harper
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84112, USA
| | - John N. A. Hooper
- Biodiversity Program, Queensland Museum, South Brisbane, Queensland, 4101, Australia
| | - Chris M. Ireland
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah, 84112, USA
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20
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Lu Z, Van Wagoner RM, Harper MK, Hooper JNA, Ireland CM. Two ring-A-aromatized bile acids from the marine sponge Sollasella moretonensis. Nat Prod Commun 2010; 5:1571-1574. [PMID: 21121250 PMCID: PMC3050653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023] Open
Abstract
Two ring-A-aromatized bile acids, 1 and 2, were isolated from the sponge Sollasella moretonensis, collected from the seabed of northern Queensland. Structures were assigned on the basis of extensive 1D and 2D NMR studies, as well as analysis by HRESIMS. Compound 2 has previously been produced synthetically, though this marks its first isolation from a natural source.
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Affiliation(s)
- Zhenyu Lu
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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21
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Van Wagoner RM, Deeds JR, Tatters AO, Place AR, Tomas CR, Wright JLC. Structure and relative potency of several karlotoxins from Karlodinium veneficum. J Nat Prod 2010; 73:1360-5. [PMID: 20795740 PMCID: PMC2929920 DOI: 10.1021/np100158r] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The karlotoxins are a family of amphidinol-like compounds that play roles in avoiding predation and in prey capture for the toxic dinoflagellate Karlodinium veneficum. The first member of the toxin group to be reported was KmTx 1 (1), and here we report an additional five new members of this family (3-7) from the same strain. Of these additional compounds, KmTx 3 (3) differs from KmTx 1 (1) in having one less methylene group in the saturated portion of its lipophilic arm. In addition, 64-E-chloro-KmTx 3 (4) and 10-O-sulfo-KmTx 3 (5) were identified. Likewise, 65-E-chloro-KmTx 1 (6) and 10-O-sulfo-KmTx 1 (7) were also isolated. Comparison of the hemolytic activities of the newly isolated compounds to that of KmTx 1 shows that potency correlates positively with the length of the lipophilic arm and is disrupted by sulfonation of the polyol arm.
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Affiliation(s)
| | | | | | | | | | - Jeffrey L. C. Wright
- Author to whom correspondence should be addressed. Phone: 910 962 2397 Fax: 910 962 2410
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22
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Van Wagoner RM, Satake M, Bourdelais AJ, Baden DG, Wright JLC. Absolute configuration of brevisamide and brevisin: confirmation of a universal biosynthetic process for Karenia brevis polyethers. J Nat Prod 2010; 73:1177-9. [PMID: 20527743 PMCID: PMC2925417 DOI: 10.1021/np100159j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The discovery of brevisin, the first example of an "interrupted" polycyclic ether, obtained from the dinoflagellate Karenia brevis, posed some important questions regarding the mechanism of the cyclization process. Consequently, we have established absolute configurations of brevisin and its related metabolite brevisamide using a modified Mosher's esterification method. For brevisin, analysis was carried out on both the 31-monokis- and the 10,31-bis-MTPA esters. The results suggest that both metabolites, like other polyethers from K. brevis, result from polyepoxide precursors with uniform (S, S) configurations for all epoxides and provide further support for a universal stereochemical model for dinoflagellate polyether formation.
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Affiliation(s)
| | | | | | | | - Jeffrey L. C. Wright
- Author to whom correspondence should be addressed: Phone: 910 962 2397 Fax: 910 962 2410
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23
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Wei X, Bugni TS, Harper MK, Sandoval IT, Manos EJ, Swift J, Van Wagoner RM, Jones DA, Ireland CM. Evaluation of pyridoacridine alkaloids in a zebrafish phenotypic assay. Mar Drugs 2010; 8:1769-78. [PMID: 20631869 PMCID: PMC2901824 DOI: 10.3390/md8061769] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 05/20/2010] [Accepted: 05/25/2010] [Indexed: 11/16/2022] Open
Abstract
Three new minor components, the pyridoacridine alkaloids 1-hydroxy-deoxyamphimedine (1), 3-hydroxy-deoxyamphimedine (2), debromopetrosamine (3), and three known compounds, amphimedine (4), neoamphimedine (5) and deoxyamphimedine (6), have been isolated from the sponge Xestospongia cf. carbonaria, collected in Palau. Structures were assigned on the basis of extensive 1D and 2D NMR studies as well as analysis by HRESIMS. Compounds 1–6 were evaluated in a zebrafish phenotype-based assay. Amphimedine (4) was the only compound that caused a phenotype in zebrafish embryos at 30 μM. No phenotype other than death was observed for compounds 1–3, 5, 6.
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Affiliation(s)
- Xiaomei Wei
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, UT84112, USA; E-Mails: (X.M.W.); (M.K.H.); (R.M.V.W.)
| | - Tim S. Bugni
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, UT84112, USA; E-Mails: (X.M.W.); (M.K.H.); (R.M.V.W.)
| | - Mary Kay Harper
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, UT84112, USA; E-Mails: (X.M.W.); (M.K.H.); (R.M.V.W.)
| | - Imelda T. Sandoval
- Department of Oncological Sciences, Huntsman Cancer Institute, 2000 Circle of Hope, Salt Lake City, UT84112, USA ; E-Mails: (I.T.S.); (E.J.M.); (J.S.) ; (D.A.J.)
| | - Elizabeth J. Manos
- Department of Oncological Sciences, Huntsman Cancer Institute, 2000 Circle of Hope, Salt Lake City, UT84112, USA ; E-Mails: (I.T.S.); (E.J.M.); (J.S.) ; (D.A.J.)
| | - Jennifer Swift
- Department of Oncological Sciences, Huntsman Cancer Institute, 2000 Circle of Hope, Salt Lake City, UT84112, USA ; E-Mails: (I.T.S.); (E.J.M.); (J.S.) ; (D.A.J.)
| | - Ryan M. Van Wagoner
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, UT84112, USA; E-Mails: (X.M.W.); (M.K.H.); (R.M.V.W.)
| | - David A. Jones
- Department of Oncological Sciences, Huntsman Cancer Institute, 2000 Circle of Hope, Salt Lake City, UT84112, USA ; E-Mails: (I.T.S.); (E.J.M.); (J.S.) ; (D.A.J.)
| | - Chris M. Ireland
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, UT84112, USA; E-Mails: (X.M.W.); (M.K.H.); (R.M.V.W.)
- *Author to whom correspondence should be addressed; E-Mail: ; Tel.: +01-801-581-8305; Fax: +01-801-585-6208
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Meng Y, Van Wagoner RM, Misner I, Tomas C, Wright JLC. Structure and biosynthesis of amphidinol 17, a hemolytic compound from Amphidinium carterae. J Nat Prod 2010; 73:409-415. [PMID: 20108948 DOI: 10.1021/np900616q] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Amphidinol 17 (AM17; 1), a novel amphidinol, has been isolated from a Bahamas strain of Amphidinium carterae. This new congener contains the signature hairpin region and a Delta(6) polyene arm, whereas the polyol arm is distinct from those of other amphidinols. The pattern of acetate incorporation in 1 was directly determined by feeding a single labeled substrate, [2-(13)C]acetate. While the highly conserved regions within the amphidinol family of AM17 have exhibited identical occurrences of cleaved acetates to other amphidinols for which the biosynthesis has been explored, the polyol arm for AM17 displays a higher degree of nascent chain processing that shows similarities to amphidinolide biosynthesis. AM17 exhibited an EC(50) of 4.9 microM in a hemolytic assay using human red blood cells but displayed no detectable antifungal activity.
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Affiliation(s)
- Yanhui Meng
- Center for Marine Science, University of North Carolina Wilmington, Wilmington, North Carolina 28409, USA
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25
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Rochfort SJ, Moore S, Craft C, Martin NH, Van Wagoner RM, Wright JLC. Further studies on the chemistry of the flustra alkaloids from the bryozoan Flustra foliacea. J Nat Prod 2009; 72:1773-1781. [PMID: 19785389 DOI: 10.1021/np900282j] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Since 1980, over a dozen novel brominated alkaloids, named flustramines, have been isolated from Scandinavian and Canadian collections of the marine bryozoan Flustra foliacea. This paper describes the reisolation of the known compound dihydroflustramine C (1) and the isolation of 11 new flustramines (2-4, 6-13), including two dimers (12, 13) that may be isolation artifacts. Together these compounds, some with an unexpected aryl substitution pattern, reveal an intricate network of metabolites present in the extracts of the bryozoan. The structures of these metabolites were solved using a variety of spectroscopic techniques and chemical derivatization and modification. This work also led to the recognition of an unusual rearrangement reaction that occurred slowly over a number of years.
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Affiliation(s)
- Simone J Rochfort
- Institute for Marine Biosciences, National Research Council of Canada, 1411 Oxford Street, Halifax, NS, Canada B3H 3Z1
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26
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Satake M, Campbell A, Van Wagoner RM, Bourdelais AJ, Jacocks H, Baden DG, Wright JLC. Brevisin: an aberrant polycyclic ether structure from the dinoflagellate Karenia brevis and its implications for polyether assembly. J Org Chem 2009; 74:989-94. [PMID: 19123836 DOI: 10.1021/jo802183n] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Brevisin is an unprecedented polycyclic ether isolated from the dinoflagellate Karenia brevis, an organism well-known to produce complex polycyclic ethers. The structure of brevisin was determined by detailed analyses of MS and 2D NMR spectra and is remarkable in that it consists of two separate fused polyether ring assemblies linked by a methylene group. One of the polycyclic moieties contains a conjugated aldehyde side chain similar to that recently observed in other K. brevis metabolites, though the "interrupted" polyether structure of brevisin is novel and provides further insight into the biogenesis of such fused-ring polyether systems. On the basis of the unusual structure of brevisin, principles underlying the initiation of polyether assemblies are proposed. Brevisin was found to inhibit the binding of [(3)H]-PbTx-3 to its binding site on the voltage-sensitive sodium channels in rat brain synaptosomes.
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Affiliation(s)
- Masayuki Satake
- Center for Marine Science, University of North Carolina Wilmington, 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409, USA
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27
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Van Wagoner RM, Deeds JR, Satake M, Ribeiro AA, Place AR, Wright JLC. Isolation and characterization of karlotoxin 1, a new amphipathic toxin from Karlodinium veneficum. Tetrahedron Lett 2008; 49:6457-6461. [PMID: 20798789 DOI: 10.1016/j.tetlet.2008.08.103] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The karlotoxins (KmTxs) are a family of compounds produced by the dinoflagellate Karlodinium veneficum that cause membrane permeabilization. The structure of KmTx 1, determined using extensive 2D NMR spectroscopy, is very similar to the amphidinols and related compounds, though KmTx 1 features unique structural modifications of the conserved core region. The structure of KmTx 1 differs from that reported for KmTx 2, the only other reported karlotoxin to date, in lacking chlorination at its terminal alkene and possessing a hydrophobic arm that is two carbons longer.
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Affiliation(s)
- Ryan M Van Wagoner
- Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin K Moss Lane, Wilmington, NC 28409, USA
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28
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Satake M, Bourdelais AJ, Van Wagoner RM, Baden DG, Wright JLC. Brevisamide: an unprecedented monocyclic ether alkaloid from the dinoflagellate Karenia brevis that provides a potential model for ladder-frame initiation. Org Lett 2008; 10:3465-8. [PMID: 18646771 DOI: 10.1021/ol801243n] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dinoflagellate Karenia brevis is known for the production of brevetoxins, a family of polycyclic ether toxins, as well as their antagonist brevenal. Further examination of organic extracts of K. brevis has uncovered yet another unprecedented cyclic ether alkaloid named brevisamide. This report describes the structure elucidation of brevisamide based on detailed MS and NMR spectral analysis, and the importance of this new compound in shedding light on the biogenesis of fused polyethers is discussed.
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Affiliation(s)
- Masayuki Satake
- Center for Marine Science, University of North Carolina, Wilmington, 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409, USA
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29
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Van Wagoner RM, Mantle PG, Wright JLC. Biosynthesis of scorpinone, a 2-azaanthraquinone from Amorosia littoralis, a fungus from marine sediment. J Nat Prod 2008; 71:426-430. [PMID: 18281953 DOI: 10.1021/np070614i] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The biogenetic origin of the carbon atoms in the 2-azaanthraquinone scorpinone ( 1), produced by the rare fungus Amorosia littoralis isolated from marine sediment, was explored through isotopic enrichment studies utilizing [2- (13)C]-acetate and [1,2- (13)C]-acetate. The labeling results reveal a heptaketide precursor is involved in the biosynthesis of 1, as has been found for the structurally related naphthoquinone dihydrofusarubin. The previously identified naphthoquinone herbarin ( 2) was also isolated and appears to bear the same biogenetic relationship to 1 as the fusarubins do to the fungal 2-azaanthraquinone bostrycoidins.
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30
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Affiliation(s)
- Ryan M Van Wagoner
- Center for Marine Science, University of North Carolina at Wilmington, Wilmington, NC 28409, USA
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31
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Van Wagoner RM, Clardy J. FeeM, an N-acyl amino acid synthase from an uncultured soil microbe: structure, mechanism, and acyl carrier protein binding. Structure 2006; 14:1425-35. [PMID: 16962973 DOI: 10.1016/j.str.2006.07.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Revised: 07/09/2006] [Accepted: 07/16/2006] [Indexed: 11/25/2022]
Abstract
Attempts to access antibiotics by capturing biosynthetic genes and pathways directly from environmental DNA, which is overwhelmingly derived from uncultured bacteria, have revealed a large and previously unknown family of N-acyl amino acid synthases (NASs). The structure of the NAS FeeM reveals structural similarity to the GCN5-related N-acyl transferases and acylhomoserine lactone synthases. The overall structure has a central beta sheet with alpha helices on both sides. A bound product at a cleft in the beta sheet identifies the active site and the structural basis for catalysis, and sequence conservation in this region indicates a bias for recognition over speed. FeeM interacts with an acyl carrier protein (FeeL), and the structure, mutagenesis, and enzymatic measurements reveal that a small hydrophobic pocket in alpha helix 5 dominates binding of FeeM to FeeL. The structural and mechanistic analyses suggest that the products of FeeM could be bacterial signaling agents.
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Affiliation(s)
- Ryan M Van Wagoner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
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32
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Van Wagoner RM, Jacobsen RB, Olivera BM, Ireland CM. Characterization and three-dimensional structure determination of psi-conotoxin Piiif, a novel noncompetitive antagonist of nicotinic acetylcholine receptors. Biochemistry 2003; 42:6353-62. [PMID: 12767216 DOI: 10.1021/bi0272757] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel inhibitor of nicotinic acetylcholine receptors (nAChRs), psi-conotoxin Piiif, was isolated from the venom of Conus purpurascens and found to have the sequence GOOCCLYGSCROFOGCYNALCCRK-NH2. The sequence is highly homologous to that of psi-conotoxin Piiie, a previously identified noncompetitive inhibitor of Torpedo electroplax nAChR, also isolated from C. purpurascens. Both psi-conotoxins block Torpedo and mouse nicotinic acetylcholine receptors (nAChRs), but psi-Piiif is less potent by a factor of 10(1)-10(2). A high-resolution structure of psi-Piiif was determined by NMR and molecular modeling calculations. Psi-Piiif analogues containing [(13)C]-labeled cysteine at selected positions were synthesized to resolve spectral overlap of Cys side chain proton signals. The structures are well-converged, with backbone atom position RMSDs of 0.21 A for the main body of the peptide between residues 4 and 22 and 0.47 A for all residues. The overall backbone conformation is closely similar to psi-Piiie, the main difference being in the degree of conformational disorder at the two termini. Psi-Piiie and psi-Piiif have similar locations of positive charge density, although psi-Piiif has a lower overall charge. One disulfide bridge of psi-Piiif appears to undergo dynamic conformational fluctuations based on both the model and on experimental observation. Chimeras in which the three intercysteine loops were swapped between psi-Piiie and psi-Piiif were tested for inhibitory activity against Torpedo nAChRs. The third loop, which contains no charged residues in either peptide, is the prime determinant of potency in these psi-conotoxins.
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Affiliation(s)
- Ryan M Van Wagoner
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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33
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Abstract
A revised, high-resolution structure of psi-conotoxin Piiie (psi-Piiie), a noncompetitive inhibitor of the nicotinic acetylcholine receptor (nAChR), produced through the use of NMR and molecular modeling calculations is presented. The original structures of psi-Piiie had a relatively high degree of disorder, particularly in the conformation of the disulfide bridges. Our studies utilized (13)C-labeling of selected cysteine residues allowing the resolution of all problems of resonance overlap for the cysteine residues. The improved data were used to produce a new set of structures by a molecular modeling process incorporating relaxation matrix methods for the determination of interproton distance restraints and a combination of distance geometry and simulated annealing for structure generation. The structures produced are very well converged with the RMSD of backbone atom positions of the main body of the peptide improving from 0.73 to 0.13 A. Other indicators of correlation with the experimental data and quality of covalent geometry showed significant improvement in the new structures. The overall conformation of the peptide backbone is similar between the two determinations with the exception of the N-terminus. This difference leads to a significant effect on the predicted distribution of positive charge within psi-Piiie, a property likely to influence interpretation of future mutational studies.
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Affiliation(s)
- Ryan M Van Wagoner
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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