scholarly journals Absolute Configuration and Body Part Distribution of the Alkaloid 6-epi-Monanchorin from the Marine Polychaete Chaetopterus variopedatus

2016 ◽  
Vol 11 (9) ◽  
pp. 1934578X1601100 ◽  
Author(s):  
Larisa K. Shubina ◽  
Tatyana N. Makarieva ◽  
Vladimir A. Denisenko ◽  
Pavel S. Dmitrenok ◽  
Sergey A. Dyshlovoy ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Secondary Metabolites ◽  
Absolute Configuration ◽  
Biosynthetic Pathway ◽  
Secondary Alcohol ◽  
Body Part ◽  
Green Microalgae ◽  
Chemical Methods ◽  
Chaetopterus Variopedatus ◽  
Marine Polychaete

As a result of the first study on secondary metabolites from the cosmopolitan bioluminescent marine tube polychaete Chaetopterus variopedatus, a new bicyclic guanidine alkaloid, 6- epi-monanchorin (1), along with the previously known monanchorin (2) were isolated. The structure of 1 was elucidated by spectroscopic and chemical methods, including a cleavage of the C1–O7 bond to obtain a secondary alcohol (3), which was used to determine the absolute configurations by Mosher's method. It was found that 1 and 2 were mainly accumulated in a secreted mucus special organ of the worm (food net), where green and blue-green microalgae were detected. A biosynthetic pathway to 6- epi-monanchorin and monanchorin from dietary polyenic fatty acid precursors was proposed.

Modification of fatty acid profile and biosynthetic pathway in symbiotic corals under eutrophication

2021 ◽  
Vol 771 ◽  
pp. 145336
Author(s):  
Taihun Kim ◽  
Jetty C.Y. Lee ◽  
Do-Hyung Kang ◽  
Nicolas N. Duprey ◽  
Kin Sum Leung ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Profile ◽  
Biosynthetic Pathway

Chromatographic Determination of the Absolute Configuration of an Acyclic Secondary Alcohol Using Difluorodinitrobenzene

2000 ◽  
Vol 72 (17) ◽  
pp. 4142-4147 ◽  
Author(s):  
Ken-ichi Harada ◽  
Youhei Shimizu ◽  
Atsuko Kawakami ◽  
Makiko Norimoto ◽  
Kiyonaga Fujii
Keyword(s):  
Absolute Configuration ◽  
Secondary Alcohol ◽  
Chromatographic Determination ◽  
The Absolute

scholarly journals Identification and Characterization of a New Enoyl Coenzyme A Hydratase Involved in Biosynthesis of Medium-Chain-Length Polyhydroxyalkanoates in Recombinant Escherichia coli

2003 ◽  
Vol 185 (18) ◽  
pp. 5391-5397 ◽  
Author(s):  
Si Jae Park ◽  
Sang Yup Lee
Keyword(s):  
Escherichia Coli ◽  
Fatty Acid ◽  
Chain Length ◽  
Biosynthetic Pathway ◽  
Pha Synthase ◽  
Enzymatic Analysis ◽  
E Coli ◽  
Medium Chain ◽  
Medium Chain Length ◽  
Enoyl Coa Hydratase

ABSTRACT The biosynthetic pathway of medium-chain-length (MCL) polyhydroxyalkanoates (PHAs) from fatty acids has been established in fadB mutant Escherichia coli strain by expressing the MCL-PHA synthase gene. However, the enzymes that are responsible for the generation of (R)-3-hydroxyacyl coenzyme A (R3HA-CoAs), the substrates for PHA synthase, have not been thoroughly elucidated. Escherichia coli MaoC, which is homologous to Pseudomonas aeruginosa (R)-specific enoyl-CoA hydratase (PhaJ1), was identified and found to be important for PHA biosynthesis in a fadB mutant E. coli strain. When the MCL-PHA synthase gene was introduced, the fadB maoC double-mutant E. coli WB108, which is a derivative of E. coli W3110, accumulated 43% less amount of MCL-PHA from fatty acid compared with the fadB mutant E. coli WB101. The PHA biosynthetic capacity could be restored by plasmid-based expression of the maoCEc gene in E. coli WB108. Also, E. coli W3110 possessing fully functional β-oxidation pathway could produce MCL-PHA from fatty acid by the coexpression of the maoCEc gene and the MCL-PHA synthase gene. For the enzymatic analysis, MaoC fused with His6-Tag at its C-terminal was expressed in E. coli and purified. Enzymatic analysis of tagged MaoC showed that MaoC has enoyl-CoA hydratase activity toward crotonyl-CoA. These results suggest that MaoC is a new enoyl-CoA hydratase involved in supplying (R)-3-hydroxyacyl-CoA from the β-oxidation pathway to PHA biosynthetic pathway in the fadB mutant E. coli strain.

A Cellular Assay for Inhibitors of the Fatty Acid Biosynthetic Pathway Using Scintillating Microplates

2015 ◽  
Vol 13 (5) ◽  
pp. 285-292 ◽  
Author(s):  
Thao Ung ◽  
Jennifer L. Mason ◽  
Ron G. Robinson ◽  
Chrysanthe M. Spais ◽  
Mark A. Ator ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Biosynthetic Pathway ◽  
Cellular Assay ◽  
Fatty Acid Biosynthetic Pathway

scholarly journals The fungal gene cluster for biosynthesis of the antibacterial agent viriditoxin

2019 ◽  
Author(s):  
Andrew S. Urquhart ◽  
Jinyu Hu ◽  
Yit-Heng Chooi ◽  
Alexander Idnurm
Keyword(s):  
Secondary Metabolites ◽  
Gene Cluster ◽  
Gene Disruption ◽  
Biosynthetic Pathway ◽  
Fluorescent Protein ◽  
Model Species ◽  
Paecilomyces Variotii ◽  
Bioinformatic Approaches ◽  
Green Fluorescent ◽  
Fungal Gene

AbstractBackgroundViriditoxin is one of the ‘classical’ secondary metabolites produced by fungi and that has antibacterial and other activities; however, the mechanism of its biosynthesis has remained unknown.ResultsHere, a gene cluster responsible for its synthesis was identified, using bioinformatic approaches from two species that produce viriditoxin and then through gene disruption and metabolite profiling. All eight genes in the cluster inPaecilomyces variotiiwere mutated, revealing their roles in the synthesis of this molecule and establishing its biosynthetic pathway which includes an interesting Baeyer-Villiger monooxygenase catalyzed reaction. Additionally, a candidate catalytically-inactive hydrolase was identified as being required for the stereoselective biosynthesis of (M)-viriditoxin. The localization of two proteins were assessed by fusing these proteins to green fluorescent protein, revealing that at least two intracellular structures are involved in the compartmentalization of the synthesis steps of this metabolite.ConclusionsThe full pathway for synthesis of viriditoxin was established by a combination of genomics, bioinformatics, gene disruption and chemical analysis processes. Hence, this work reveals the basis for the synthesis of an understudied class of fungal secondary metabolites and provides a new model species for understanding the synthesis of biaryl compounds with a chiral axis.

The Rychnovsky Synthesis of Leucascandrolide A

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Vinyl Ether ◽  
Absolute Configuration ◽  
Secondary Alcohol ◽  
Primary Alcohol ◽  
Addition Product ◽  
Cyclic Ether ◽  
Acid Activation ◽  
Leucascandrolide A ◽  
Stereogenic Centers ◽  
Bromide Ion

The macrolactone leucascandrolide A 4, isolated from the calcareous sponge L. caveolata, has both cytotoxic and antifungal activity. The key step in the synthesis of 4 reported (J. Org. Chem. 2007, 72, 5784) by Scott D. Rychnovsky of the University of California, Irvine, was the stereoselective condensation of the aldehyde 1 with the allyl vinyl ether 2 to give 3. The cyclic ether of 1 was assembled from the crotyl addition product 5. Tandem Ru-catalyzed metathesis/hydrogenation converted 5 to the lactone 6. Reduction of 6 to the lactol followed by activation as the acetate gave 7, axial-selective condensation of which with the enol ether 8 delivered the enone 9. Diastereoselective Itsuno-Corey reduction of 9 followed by protecting group exchange and oxidation then gave 1, containing four of the eight stereogenic centers of leucascandrolide A 4. The vinyl ether 2 was readily prepared from the corresponding homoallylic alcohol. Condensation of 1 with 2 involved Lewis acid activation of the aldehyde, addition of the resulting carbocation to the vinyl ether, and cyclization with trapping by bromide ion. In this process, the other four of the eight stereogenic centers were assembled. Three of those centers were formed in the course of the reaction. While stereocontrol was not perfect, the route is pleasingly succinct, so practical quantities of diastereomerically pure 3 could be prepared. To complete the synthesis, the secondary alcohol of 3 was methylated. Selective desilyation of the primary alcohol followed by oxidation and desilylation then set the stage for the Mitsunobu macrolactonization. The intermediates in the Mitsunobu reaction are such that the lactonization can proceed with either inversion of absolute configuration at the secondary center, or retention. While the usually-employed Ph3P gave the lactone with retention of absolute configuration, Bu3P led to clean inversion. The last challenge was the establishment of the (Z) alkene of the side chain. This was accomplished using the Toru protocol. Coupling of the secondary bromide with the Cs salt 12 proceeded with inversion of absolute configuration, to give 13.

The Boger Synthesis of (-)-Vindoline

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Absolute Configuration ◽  
Secondary Alcohol ◽  
Ring System ◽  
Simple Solution ◽  
Relative Configuration ◽  
Amine Oxidation ◽  
Formidable Challenge ◽  
Starting Point ◽  
La Jolla ◽  
Stereogenic Center

The periwinkle-derived alkaloids vinblastine 2a and vincristine 2b are still mainstays of cancer chemotherapy. The more complex half of these dimeric alkaloids, vindoline 1, presents a formidable challenge for total synthesis. Building on his previous work (Organic Lett. 2005, 7, 4539), Dale L. Boger of Scripps/La Jolla devised (J. Am. Chem. Soc. 2010, 132, 3685) a strikingly simple solution to this problem based on sequential cycloaddition. The starting point for the synthesis was the ester 3, derived from D-asparagine. This was extended to 4, condensation of which with 5 gave the enol ether 6. On heating, 7 cyclized to 8, which lost N2 to give the zwitterion 9. Addition of the intermediate 9 to the indole then gave 10. In one reaction, the entire ring system of vindoline, appropriately oxygenated, was assembled, with the original stereogenic center from D-asparagine directing the relative and absolute configuration of the final product. To complete the synthesis, the pendant carbon on 11 had to be incorporated into the pentacyclic skeleton. After adjusting the relative configuration of the secondary alcohol, the N was rendered nucleophilic by reduction of the amide to the amine. Oxidation delivered 14, which on activation as the tosylate smoothly rearranged to the ketone 15. Reduction and regioselective dehydration then completed the synthesis of vindoline 1.

scholarly journals Verrucosamide, a Cytotoxic 1,4-Thiazepane-Containing Thiodepsipeptide from a Marine-Derived Actinomycete

Marine Drugs ◽  
2020 ◽  
Vol 18 (11) ◽  
pp. 549
Author(s):  
Vimal Nair ◽  
Min Cheol Kim ◽  
James A. Golen ◽  
Arnold L. Rheingold ◽  
Gabriel A. Castro ◽  
...  
Keyword(s):  
Breast Carcinoma ◽  
Diffraction Study ◽  
Cell Line ◽  
Absolute Configuration ◽  
Spectral Methods ◽  
Biosynthetic Pathway ◽  
Cyclic Peptide ◽  
Colon Adenocarcinoma ◽  
X Ray Diffraction ◽  
X Ray

A new cytotoxic thiodepsipeptide, verrucosamide (1), was isolated along with the known, related cyclic peptide thiocoraline, from the extract of a marine-derived actinomycete, a Verrucosispora sp., our strain CNX-026. The new peptide, which is composed of two rare seven-membered 1,4-thiazepane rings, was elucidated by a combination of spectral methods and the absolute configuration was determined by a single X-ray diffraction study. Verrucosamide (1) showed moderate cytotoxicity and selectivity in the NCI 60 cell line bioassay. The most susceptible cell lines were MDA-MB-468 breast carcinoma with an LD50 of 1.26 µM, and COLO 205 colon adenocarcinoma with an LD50 of 1.4 µM. Also isolated along with verrucosamide were three small 3-hydroxy(alkoxy)-quinaldic acid derivatives that appear to be products of the same biosynthetic pathway.

scholarly journals Absence of Cyanotoxins in Llayta, Edible Nostocaceae Colonies from the Andes Highlands

Toxins ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 382 ◽  
Author(s):  
Alexandra Galetović ◽  
Joana Azevedo ◽  
Raquel Castelo-Branco ◽  
Flavio Oliveira ◽  
Benito Gómez-Silva ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Target Genes ◽  
Food Ingredient ◽  
Chemical Methods ◽  
The Andes ◽  
Mcye Gene ◽  
Safe Food

Edible Llayta are cyanobacterial colonies consumed in the Andes highlands. Llayta and four isolated cyanobacteria strains were tested for cyanotoxins (microcystin, nodularin, cylindrospermopsin, saxitoxin and β-N-methylamino-L-alanine—BMAA) using molecular and chemical methods. All isolates were free of target genes involved in toxin biosynthesis. Only DNA from Llayta amplified the mcyE gene. Presence of microcystin-LR and BMAA in Llayta extracts was discarded by LC/MS analyses. The analysed Llayta colonies have an incomplete microcystin biosynthetic pathway and are a safe food ingredient.

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