Synthetic studies toward shellfish toxins containing spiroacetal units

2007 ◽  
Vol 79 (2) ◽  
pp. 153-162 ◽  
Author(s):  
Margaret A. Brimble ◽  
Rosliana Halim
Keyword(s):  
Oxidative Cyclization ◽  
Shellfish Toxins ◽  
Synthetic Strategy ◽  
Marine Biotoxins ◽  
Synthetic Studies

The synthesis of the ABC spiroacetal-containing fragment of the marine biotoxins, the pectenotoxins (PTXs), is described. The synthetic strategy involves appendage of the highly substituted tetrahydofuran C ring to the AB spiroacetal unit via stereocontrolled cyclization of a γ-hydroxyepoxide. The bis-spiroacetal moiety of the spirolide family of shellfish toxins is also described, making use of an iterative radical oxidative cyclization strategy.

scholarly journals First Total Synthesis and Investigation of the X-ray Crystal Structure of the Pyrano[3,2-a]carbazole Alkaloid Clausenalansine A

Synthesis ◽  
2020 ◽  
Vol 53 (02) ◽  
pp. 359-364
Author(s):  
Hans-Joachim Knölker ◽  
Valerie Lösle ◽  
Olga Kataeva
Keyword(s):  
Crystal Structure ◽  
Total Synthesis ◽  
Lewis Acid ◽  
Oxidative Cyclization ◽  
Formyl Group ◽  
Pyran Ring ◽  
X Ray ◽  
Synthetic Strategy

AbstractWe describe the first total synthesis of the recently discovered pyrano[3,2-a]carbazole alkaloid clausenalansine A. The synthetic strategy for the construction of this formylpyrano[3,2-a]carbazole is based on a sequence of Buchwald–Hartwig coupling, palladium(II)-catalyzed oxidative cyclization, Lewis acid promoted annulation of the pyran ring, and chemoselective oxidation of a methyl to a formyl group.

scholarly journals Unified Total Synthesis of the Brevianamide Alkaloids Enabled by Chemical Investigations into their Biosynthesis.

2021 ◽  
Author(s):  
Robert C. Godfrey ◽  
Helen E. Jones ◽  
Nicholas J. Green ◽  
Andrew L. Lawrence
Keyword(s):  
Natural Products ◽  
Chemical Synthesis ◽  
Total Synthesis ◽  
Scientific Community ◽  
Biological Activities ◽  
Focus Of Attention ◽  
Complex Structures ◽  
Biosynthetic Pathways ◽  
Synthetic Strategy ◽  
Synthetic Studies

The bicyclo[2.2.2]diazaoctane alkaloids are a vast group of natural products which have been the focus of attention from the scientific community for several decades. This interest stems from their broad range of biological activities, their diverse biosynthetic origins, and their topologically complex structures, which combined make them enticing targets for chemical synthesis. In this article, full details of our synthetic studies into the chemical feasibility of a proposed network of biosynthetic pathways towards the brevianamide family of bicyclo[2.2.2]diazaoctane alkaloids are disclosed. Insights into issues of reactivity and selectivity in the biosynthesis of these structures have aided the development of a unified biomimetic synthetic strategy, which has resulted in the total synthesis of all known bicyclo[2.2.2]diazaoctane brevianamides and the anticipation of an as-yet-undiscovered congener.

scholarly journals Indole Diterpene Synthetic Studies: Development of a Second-Generation Synthetic Strategy for (+)-Nodulisporic Acids A and B.

ChemInform ◽  
2007 ◽  
Vol 38 (43) ◽  
Author(s):  
Amos B. III Smith ◽  
Laszlo Kuerti ◽  
Akin H. Davulcu ◽  
Young Shin Cho ◽  
Kazuyuki Ohmoto
Keyword(s):  
Second Generation ◽  
Synthetic Strategy ◽  
Synthetic Studies ◽  
Nodulisporic Acids

scholarly journals Paralytic and Amnesic Shellfish Toxins Impacts on Seabirds, Analyses and Management

Toxins ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 454
Author(s):  
Begoña Ben-Gigirey ◽  
Lucía Soliño ◽  
Isabel Bravo ◽  
Francisco Rodríguez ◽  
María V. M. Casero
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Ecological Impact ◽  
Clinical Signs ◽  
Analytical Techniques ◽  
Special Focus ◽  
Seabird Species ◽  
Shellfish Toxins ◽  
Marine Biotoxins ◽  
The Impact

Marine biotoxins have been frequently implicated in morbidity and mortality events in numerous species of birds worldwide. Nevertheless, their effects on seabirds have often been overlooked and the associated ecological impact has not been extensively studied. On top of that, the number of published studies confirming by analyses the presence of marine biotoxins from harmful algal blooms (HABs) in seabirds, although having increased in recent years, is still quite low. This review compiles information on studies evidencing the impact of HAB toxins on marine birds, with a special focus on the effects of paralytic and amnesic shellfish toxins (PSTs and ASTs). It is mainly centered on studies in which the presence of PSTs and/or ASTs in seabird samples was demonstrated through analyses. The analytical techniques commonly employed, the tissues selected and the adjustments done in protocols for processing seabird matrixes are summarized. Other topics covered include the role of different vectors in the seabird intoxications, information on clinical signs in birds affected by PSTs and ASTs, and multifactorial causes which could aggravate the syndromes. Close collaboration between seabird experts and marine biotoxins researchers is needed to identify and report the potential involvement of HABs and their toxins in the mortality events. Future studies on the PSTs and ASTs pharmacodynamics, together with the establishment of lethal doses in various seabird species, are also necessary. These studies would aid in the selection of the target organs for toxins analyses and in the postmortem intoxication diagnoses.

Indole Diterpene Synthetic Studies:  Development of a Second-Generation Synthetic Strategy for (+)-Nodulisporic Acids A and B

2007 ◽  
Vol 72 (13) ◽  
pp. 4611-4620 ◽  
Author(s):  
Amos B. Smith ◽  
László Kürti ◽  
Akin H. Davulcu ◽  
Young Shin Cho ◽  
Kazuyuki Ohmoto
Keyword(s):  
Second Generation ◽  
Synthetic Strategy ◽  
Synthetic Studies ◽  
Nodulisporic Acids

Facile oxidative cyclization to access C2-quaternary 2-hydroxy-indolin-3-ones: synthetic studies towards matemone

2017 ◽  
Vol 41 (20) ◽  
pp. 11503-11506 ◽  
Author(s):  
Sai-Shuai Wen ◽  
Zhao-Fang Zhou ◽  
Jun-An Xiao ◽  
Jun Li ◽  
Haoyue Xiang ◽  
...  
Keyword(s):  
Oxidative Cyclization ◽  
Synthetic Studies

Synergistic oxidation can do it! The precursor for matemone can be facilely prepared in 21% overall yield in 8 steps. The key step is the oxidative cyclization by utilizing CAN and TEMPO to install the quaternary centre.

A National Survey of Marine Biotoxins in Wild-Caught Abalone in Australia

2014 ◽  
Vol 77 (11) ◽  
pp. 1960-1967 ◽  
Author(s):  
NAVREET MALHI ◽  
ALISON TURNBULL ◽  
JESSICA TAN ◽  
ANDREAS KIERMEIER ◽  
RAMA NIMMAGADDA ◽  
...  
Keyword(s):  
National Survey ◽  
Domoic Acid ◽  
Survey Period ◽  
Shellfish Toxins ◽  
Paralytic Shellfish Toxins ◽  
Marine Biotoxins ◽  
Paralytic Shellfish ◽  
Low Levels ◽  
Seawater Samples ◽  
Diarrhetic Shellfish Toxins

The first national survey of Australian wild-caught abalone was conducted between September 2012 and December 2013. The aim of the survey was to determine the presence of paralytic shellfish toxins (PSTs), amnesic shellfish toxins (ASTs), and diarrhetic shellfish toxins (DSTs) in wild-caught abalone at levels above the current Codex marine biotoxin limits during the 2013 fishing season. Abalone (n = 190) were collected from 68 abalone-fishing blocks for which the combined annual harvest accounts for 80% of Australian production. Concurrent seawater samples were collected and enumerated for potentially toxic phytoplankton. The foot and viscera tissues of each abalone sample were analyzed separately for PSTs, ASTs, and DSTs. No samples (abalone foot or viscera) contained toxins at levels exceeding the marine biotoxin limits stipulated by Codex. The resulting prevalence estimate suggests that less than 1.6% of the commercially caught wild abalone population in Australia were contaminated with marine biotoxins at levels above the regulatory limit during the survey period. ASTs were detected at very low (trace) levels in the foot and viscera tissue of four and three abalone samples, respectively. To our knowledge, this represents the first reported detection of domoic acid in Australian abalone. PSTs also were detected at very low levels in 17 samples of abalone foot tissue and 6 samples of abalone viscera. The association between the low levels of ASTs and PSTs detected in abalone and the presence of potential toxin-producing phytoplankton in seawater samples was weak. DSTs were not detected in any abalone despite the detection of very low levels of DST-producing phytoplankton in a small number (9 of 77) of seawater samples. The results of this survey should be useful for public health risk assessments and provide additional evidence that the prevalence of marine biotoxins in Australian wild-caught abalone is very low.

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