scholarly journals Identification of Novel Gymnodimines and Spirolides from the Marine Dinoflagellate Alexandrium ostenfeldii

Marine Drugs ◽  
2018 ◽  
Vol 16 (11) ◽  
pp. 446 ◽  
Author(s):  
Christian Zurhelle ◽  
Joyce Nieva ◽  
Urban Tillmann ◽  
Tilmann Harder ◽  
Bernd Krock ◽  
...  
Keyword(s):  
Chemical Diversity ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Alexandrium Ostenfeldii ◽  
Exocyclic Methylene ◽  
Polyketide Chain ◽  
Marine Dinoflagellates ◽  
Toxin Class ◽  
Derivatives Of

Cyclic imine toxins are neurotoxic, macrocyclic compounds produced by marine dinoflagellates. Mass spectrometric screenings of extracts from natural plankton assemblages revealed a high chemical diversity among this toxin class, yet only few toxins are structurally known. Here we report the structural characterization of four novel cyclic-imine toxins (two gymnodimines (GYMs) and two spirolides (SPXs)) from cultures of Alexandrium ostenfeldii. A GYM with m/z 510 (1) was identified as 16-desmethylGYM D. A GYM with m/z 526 was identified as the hydroxylated degradation product of (1) with an exocyclic methylene at C-17 and an allylic hydroxyl group at C-18. This compound was named GYM E (2). We further identified a SPX with m/z 694 as 20-hydroxy-13,19-didesmethylSPX C (10) and a SPX with m/z 696 as 20-hydroxy-13,19-didesmethylSPX D (11). This is the first report of GYMs without a methyl group at ring D and SPXs with hydroxyl groups at position C-20. These compounds can be conceived as derivatives of the same nascent polyketide chain, supporting the hypothesis that GYMs and SPXs are produced through common biosynthetic genes. Both novel GYMs 1 and 2 were detected in significant amounts in extracts from natural plankton assemblages (1: 447 pg; 2: 1250 pg; 11: 40 pg per mL filtered seawater respectively).

scholarly journals Synthesis and Characterizations of Dipeptide Derivative of Gentamicin

2019 ◽  
Vol 28 (2) ◽  
pp. 73-82
Author(s):  
Oun D. Khudair ◽  
Diar A. Fatih
Keyword(s):  
Acid Chloride ◽  
Solution Method ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Free Hydroxyl ◽  
Ester Linkage ◽  
Amine Groups ◽  
Conventional Solution ◽  
Dipeptide Derivative

Abstract       The target derivative are gentamicin linked with L-Val- L-Ala by an ester linkage. These were synthesized by esterification method, which included the reaction of -OH hydroxyl group on (carbon No.5) of gentamicin with the acid chloride of the corresponding dipeptide, The preparation of new derivative of gentamicin involved protected the primary & secondary amine groups of Gentamicin, by Ethylchloroformate (ECF) to give N-carbomethoxy Gentamicin which was used for further chemical synthesis involving the free hydroxyl groups. Then prepared dipeptide (L-Val- L-Ala) by conventional solution method in present DCC & HoBt then reacted with thionyl chloride to prepared acid chloride of dipeptides, then after, linked by ester linkage to N-protection gentamicin in present pyridine as base, finally deportation the amino group of synthesized compound by using TFAA in present anisole. The characterization of the titled compounds were performed utilizing FTIR spectroscopy, CHNS elemental analysis, and by measurements of their physical properties.  

scholarly journals Chemical and biochemical studies on 18-hydroxyoestrone

1974 ◽  
Vol 137 (2) ◽  
pp. 263-272 ◽  
Author(s):  
John K. Findlay ◽  
Lothar Siekmann ◽  
Heinz Breuer
Keyword(s):  
Mass Spectra ◽  
Strong Acid ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
No Formation ◽  
Polar Metabolites ◽  
Characteristic Fragmentation ◽  
Liquid Chromatographic

1. 18-Hydroxyoestrone was reduced by NaBH4 in methanol, giving 18-hydroxyoestradiol-17α and 18-hydroxyoestradiol-17β in the ratio 3:7. 2. Treatment of 18-hydroxyoestrone with a strong alkali yielded 18-noroestrone; however, the 18-hydroxyoestradiols did not undergo transformation to their respective 18-nor derivatives. 3. All the 18-hydroxylated oestrogens were stable under acid conditions. They formed Kober chromogens: the chromogenicity of 18-hydroxyoestrone was only one-third that of the 18-hydroxyoestradiols and oestriol. 4. Paper-, thin-layer- and gas–liquid-chromatographic systems for the characterization of these compounds are described. 5. An examination of the mass spectra revealed peaks characteristic of the substituted carbon atoms. Definite assignment of the 17α- and 17β-hydroxyl groups of the epimeric 18-hydroxyoestrogens was possible by characteristic fragmentation of the free steroids. Further, the configuration of 18-hydroxyoestradiol-17β was confirmed by the formation of the dimethylsildioxy derivative of the 3-methylether of the steroid. 6. Both rat and rabbit liver slices reduced 18-hydroxyoestrone to 18-hydroxyoestradiol-17β and some other labile, polar metabolites with properties similar to 2-hydroxylated oestrogens. No formation of 18-hydroxyoestradiol-17α in vitro was observed. 7. The results are discussed with respect to the possible influence of the 18-hydroxyl group on reactions at C-17, as well as the reactions of 18-hydroxylated oestrogens with strong acid (Kober reactions) and alkali.

scholarly journals SYNTHESIS OF 1,2;3,4-DI-O-ISOPROPYLIDENE-6- O-[4-(1H-AZOL-1-YLMETHYL) PHENYL]- ¯-D-GALACTOPYRANOSE AND 1,2,3,4-TETRA-O-ACETYL-6- O-[4-(1H-AZOL-1- YLMETHYL)PHENYL]-¯-D-GLUCOPYRANOSE

2017 ◽  
Vol 17 (5) ◽  
pp. 122-128
Author(s):  
Z.P. Belousova ◽  
P.P. Purygin ◽  
A.P. Tyurin
Keyword(s):  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Secondary Hydroxyl ◽  
Primary Hydroxyl ◽  
Derivatives Of

Derivatives of D-galactose and D-glucose substituted for the primary hydroxyl group, which contain an aglycone azolylmethylphenyl fragments (for imidazole, 1,2,4-triazole, benzimidazole and benzotriazole) has been synthesized. Toprotect the secondary hydroxyl groups of monosaccharides acetyl and isopropylidene groups were used.

scholarly journals Antioxidant activity of some coumarins / Antioxidačná activita niektorých kumarínov

2015 ◽  
Vol 62 (s9) ◽  
pp. 41-45 ◽  
Author(s):  
F. Šeršeň ◽  
M. Lácová
Keyword(s):  
Antioxidant Activity ◽  
Acetic Acid ◽  
Superoxide Anion ◽  
The Other ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Coumarin Derivatives ◽  
Antioxidant Effectiveness ◽  
Derivatives Of ◽  
Superoxide Anion Radicals

AbstractNineteen derivatives of coumarin were tested on the scavenging of 2,2-diphenyl-1-picrylhydrazyl, hydroxyl and superoxide anion radicals. It was found that antioxidant activity exhibits only such coumarins that contain hydroxyl groups. The derivatives without hydroxyl group showed very low antioxidant effectiveness or they were ineffective. On the other hand, the greatest antioxidant effectiveness was exhibited by coumarin derivatives that contained hydroxyl groups in 6 or 8 position, whereas the effectiveness of derivatives with one hydroxyl group in 4, 5 or 7 position was very low. Based on scavenging of the above-mentioned radicals, it was found that the most effective scavengers were 7,8-dihydroxy-4-methylcoumarin (i.e. compound that contains two hydroxyl groups in 7 and 8 positions), (7,8-dihydroxy-2-oxo-2H-chromen-4-yl)acetic acid (this compound contains in addition to two hydroxyl groups in 7 and 8 positions also one hydroxyl group in the acidic residue), esculetin (6,7-dihydroxycoumarin) and 6,7-dihydroxy-4-methylcoumarin.

Aminoglycoside antibiotics: The formation and characterization of dihydrooxazine derivatives in the paromomycin series

1978 ◽  
Vol 56 (11) ◽  
pp. 1492-1499 ◽  
Author(s):  
Stephen Hanessian ◽  
Robert Massé ◽  
Goran Ekborg
Keyword(s):  
Chemical Modification ◽  
Zinc Chloride ◽  
Aminoglycoside Antibiotics ◽  
High Yield ◽  
Hydroxyl Groups ◽  
Model Studies ◽  
Derivatives Of ◽  
Excess Zinc ◽  
Chemical Evidence

Treatment of penta-N-benzyloxycarbonylparomomycin with benzaldehyde and excess zinc chloride gives a dibenzylidene derivative in high yield. This consists of the 4′,6′-O-benzylidene 4′′′,6′′′-N,O-benzylidene (dihydrooxazine) derivative of penta-N-benzyloxycarbonylparomomycin. Chemical evidence is presented to support this structure and model studies are reported for the formation of dihydrooxazine and oxazolidine derivatives of benzyloxycarbonylamino sugars containing suitably situated hydroxyl groups. The easily obtained dihydrooxazine derivative of paromomycin constitutes an interesting, preferentially blocked derivative, that is useful for the chemical modification of the parent antibiotic.

scholarly journals New bio-amphiphilic structures of sucrose via amides linkages

2019 ◽  
Vol 10 (4) ◽  
pp. 3143-3154
Author(s):  
Salih Mahdi Salman
Keyword(s):  
Chemical Structure ◽  
13C Nmr Spectroscopy ◽  
Alkyl Halides ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Staudinger Reaction ◽  
Target Structure ◽  
Leaving Group ◽  
Derivatives Of ◽  
Resolution Mass

A series of four new derivatives of sucrose have been synthesized using the straightforward methodology in order to give a mono substituted analogs of sucrose at C-6’ of fructose moiety. The synthesis was started from the reaction of sucrose with tert-butylchlorodiphenylsilane, which is able to react with an only less steric hindrance hydroxyl group at C-6’ due to its bulky structure. The other hydroxyl groups were acetylated by the reaction with acetic anhydride in pyridine. Then free the hydroxyl group at C-6’ again by the treatment with t-butylammonium fluoride in THF. The later was activated by conversion to a good leaving group via tosylation, followed by functionalized via azidation to give the precursor of the target series hepta-O-acetyl-6’-azido- sucrose. The precursor was coupled with four alkyl halides (C12, C8-4, C14, C10-8) via Staudinger reaction to produced the target structure after deacetylating. The purity and chemical structure of the synthesized compound was confirmed by CHN elemental analysis, high-resolution mass and 1H, 13C NMR spectroscopy. 

Glucuronidierung von Hydroxy-testosteron- und Hydroxy-androstendion-Verbindungen durch die mikrosomale UDP-Glucuronyl-Transferase der Rattenleber / Glucuronidation of Hydroxy-compounds of Testosterone and Androstenedione by the Microsomal UDP Glucuronyl Transferase of Rat Liver

1972 ◽  
Vol 27 (1) ◽  
pp. 49-52
Author(s):  
Herbert Schriefers ◽  
Rüdiger Ghraf ◽  
Birgit Lehnen
Keyword(s):  
High Specificity ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Testosterone Metabolism ◽  
Glucuronyl Transferase ◽  
Hydroxy Compounds ◽  
Derivatives Of ◽  
Special Case ◽  
Free Steroid ◽  
Very High

The microsomal UDP glucuronyl transferase exhibits activities against hydroxy derivatives of androstenedione (hydroxyl groups in the positions 2β, 6β or 16α) between 5% and 27% of the extent shown against testosterone. 2β-, 6β· and 16α-hydroxyl groups are much less efficient in accepting the glucuronic acid than the 17β-hydroxyl group.However, the acceptor function of the 17β-hydroxyl group is restricted by other hydroxy substituents in the testosterone molecule to an increasing extent represented by the following sequence: 2α, 6β, 6α, 16α, and 7α. A special case is represented by 2β-hydroxy-testosterone. The transferase displays a higher activity against this compound than against testosterone.Apparently the transferase approaches the steroid molecule from the α-side (with the β-side there is also contact at the C-6 atom) requires the 17β-hydroxyl group and the 3-oxo-4-ene system to display full activity.Thus the very high specificity of the transferase for testosterone explains the selective action of this enzyme on testosterone metabolism in the liver. This action is expressed by the fact, that in liver perfusates the percentage of testosterone in the glucuronide fraction is twice as large as the percentage of testosterone in the free steroid fraction.

scholarly journals Partial characterization of a biologically active steroid glycoside isolated from the starfish Marthasterias glacialis

1970 ◽  
Vol 117 (3) ◽  
pp. 543-550 ◽  
Author(s):  
A. M. Mackie ◽  
A. B. Turner
Keyword(s):  
Steroid Glycoside ◽  
Exchange Chromatography ◽  
Biologically Active ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Molecular Formula ◽  
Buccinum Undatum ◽  
Marthasterias Glacialis ◽  
Olefinic Double Bond

1. A steroid glycoside (M2), which induces avoidance and other reactions in the mollusc Buccinum undatum, has been isolated from extracts of the starfish Marthasterias glacialis by ion-exchange chromatography. 2. The steroid glycoside was homogeneous by t.l.c. and contained glucose, quinovose, fucose and sulphate in the molar proportions 1:2:1:1, in addition to a water-insoluble aglycone. 3. The aglycone was identified as a cholestane derivative containing an unusual Δ24-23-ketone system, two secondary hydroxyl groups and an olefinic double bond, and had the molecular formula C27H42O3. 4. The rates of release of sugars and sulphate suggested that fucose was at the non-reducing end of the oligosaccharide, with glucose glycosidically linked to the steroid. The sulphate group appeared to be linked to the other hydroxyl group of the steroid.

The formation of hex-5-enopyranosides and their selective hydrolysis in methylated polysaccharides

1978 ◽  
Vol 56 (5) ◽  
pp. 680-684 ◽  
Author(s):  
Gerald Oliver Aspinall ◽  
Karl-Gunnar Rosell
Keyword(s):  
Uronic Acid ◽  
Gum Arabic ◽  
Hydroxyl Groups ◽  
Triphenyl Phosphite ◽  
Reaction Sequence ◽  
Selective Hydrolysis ◽  
Acidic Polysaccharides ◽  
Hydrolysis Of ◽  
Derivatives Of

The introduction of hex-5-enopyranoside residues into methylated acidic polysaccharides is effected by reduction of uronic acid residues, followed by reaction with triphenyl phosphite methiodide, and dehydroiodination. The selective hydrolysis of hex-5-enopyranosidic linkages with characterization of the 6-deoxyglycos-5-uloses thus formed and location of the aglyconic hydroxyl groups thus exposed has been demonstrated for methylated derivatives of birch xylan and gum arabic. The reaction sequence provides a new method for linkage analysis of acidic polysaccharides.

Selective Protection Strategies in the Synthesis of TRIS-Fatty Ester Derivatives

2002 ◽  
Vol 55 (10) ◽  
pp. 629 ◽  
Author(s):  
R. Adhikari ◽  
C. L. Francis ◽  
G. W. Simpson ◽  
Q. Yang
Keyword(s):  
Fatty Ester ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Selective Protection ◽  
Palmitoyl Chloride ◽  
Protection Strategies ◽  
Mild Hydrolysis ◽  
Derivatives Of ◽  
Trimethyl Orthoformate ◽  
Acyl Derivatives

A methodology for the selective synthesis of lipophilic acyl derivatives of the glycinamido triol (1) with either one, two, or three fatty ester groups has been established. Peracylation of (1), with palmitoyl chloride gave the triacylated derivative. Conversion of (1) into the acetonide, followed by acylation with either palmitoyl chloride or lauroyl chloride, and acetal hydrolysis provided the monoacylated derivatives. Treatment of (1) with trimethyl orthoacetate gave the orthoacetate derivative. Mild hydrolysis provided the monoacetate/diol. Acylation of the two hydroxyl groups with palmitoyl chloride gave the dipalmitate/acetate. Selective cleavage of the acetate group afforded the dipalmitate of (1). Analogous chemistry with trimethyl orthoformate provided the same dipalmitate via the orthoformate, monoformate/diol, and dipalmitate/formate. A more robust synthesis of the dipalmitate was achieved by converting the hydroxyl group of the acetonide of (1) into a tert-butyldiphenylsilyl ether, followed by acetal hydrolysis, palmitoylation of the liberated hydroxyl groups, and desilylation.

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