scholarly journals The marine sponge Agelas citrina as a source of the new pyrrole–imidazole alkaloids citrinamines A–D and N-methylagelongine

2015 ◽  
Vol 11 ◽  
pp. 2029-2037 ◽  
Author(s):  
Christine Cychon ◽  
Ellen Lichte ◽  
Matthias Köck
Keyword(s):  
Marine Sponge ◽  
Major Metabolite ◽  
Chemical Investigation ◽  
Amide Bond ◽  
Methyl Derivative ◽  
Pyridinium Ring ◽  
Ester Linkage ◽  
The Common ◽  
The Caribbean ◽  
Derivatives Of

The chemical investigation of the Caribbean sponge Agelas citrina revealed four new pyrrole–imidazole alkaloids (PIAs), the citrinamines A–D (1–4) and the bromopyrrole alkaloid N-methylagelongine (5). All citrinamines are dimers of hymenidin (6) which was also isolated from this sponge as the major metabolite. Citrinamines A (1) and B (2) are derivatives of the PIA dimer mauritiamine (7), whereas citrinamine C (3) is derived from the PIA dimer nagelamide B (8). Citrinamine D (4) shows an uncommon linkage between the imidazole rings of both monomeric units as it is only observed in the benzocyclobutane ring moiety of benzosceptrins A–C (9–11). Compound 5 is the N-methyl derivative of agelongine (12) which consist of a pyridinium ring and an ester linkage instead of the aminoimidazole moiety and the common amide bond in PIAs.

Hindered rotation around the amide bond in a series of derivatives of 2-acetamidothiophenes

1991 ◽  
Vol 88 ◽  
pp. 689-707 ◽  
Author(s):  
P Andriamadio ◽  
D Nicole ◽  
A Cartier ◽  
M Wierzbicki ◽  
G Kirsch
Keyword(s):  
Amide Bond ◽  
Hindered Rotation ◽  
Derivatives Of

scholarly journals Anthroponyms of Jewish Women in the 16th Century Grand Duchy of Lithuania

2012 ◽  
Vol 21 (26) ◽  
pp. 200-207
Author(s):  
Jūratė Čirūnaitė
Keyword(s):  
Average Length ◽  
Family Members ◽  
16Th Century ◽  
Canonical Forms ◽  
Family Status ◽  
Social Origin ◽  
Jewish Women ◽  
The Common ◽  
Grand Duchy Of Lithuania ◽  
Derivatives Of

The most popular names among Jewish women in 16th century Lithuania were Simcha, Marjam, Anna, Debora. The names were most frequently recorded as diminutives (63.3%), with only 36.4% appearing in canonical forms. The smallest group comprises names formed using only anthroponyms that were derived from those of (male) family members (29.6%). 35.2% of the namings are recorded as mixed type. The same number of women are recorded using only names in the documents.Personal names are included in 70.4% of recorded women’s namings. Andronyms (anthroponyms formed from the spouse’s name) were found in 64.8% of all the records. 9.3% of women’s namings include anthroponyms formed using the spouse’s patronymic. Only 1.9% of namings had a female patronymic (the derivative of the suffix -owna/-ewna).One-member female namings prevail (59.3%). Two-member namings comprise 33.3%. Three members are found in 5.6% of the namings, while four-membered ones comprise 1.9%. The average length of the namings is 1.5 times that of the anthroponyms.Common words explaining anthroponyms were found in 68.5% of the namings. Common words related to religion prevail (51.4%). 29.7% of the common words characterize relationships or family status, and only 10.8% describe occupation, post or trade (vocation). Common words describing descent (social origin) comprise only 8.1% of all the women’s namings.Namings consisting only of anthroponyms of family members can be subdivided into the following subgroups: 1) derivatives of the suffix -owaja/-ewaja; 2) derivatives of the suffix ‑owaja/-ewaja; 3) derivatives of the suffix -owaja/-ewaja + the genitive of a male patronymic; 4) derivatives of the suffix -owaja/-ewaja + a male patronymic + the genitive of a male patronymic. Namings without anthroponyms consisting of family members included names and names with common words. Mixed namings consisted of: 1) a name + a derivative of the suffix -owaja/-ewaja; 2) a derivative of the suffix -owaja/-ewaja + the genitive of a male patronymic + a name; 3) a derivative of the suffix -owaja/-ewaja + the genitive of a male patronymic + a name + a female patronymic.The most popular type of naming is a recorded name.

scholarly journals Les catastrophes naturelles dans les romans caribéens d’expression française

Il Tolomeo ◽  
2020 ◽  
Author(s):  
Alessia Vignoli
Keyword(s):  
Native Americans ◽  
Natural Hazards ◽  
Caribbean Literature ◽  
Common Origin ◽  
Caribbean Region ◽  
Common Features ◽  
African Slaves ◽  
European Colonization ◽  
The Common ◽  
The Caribbean

The notion of ‘disaster’ pervades the Caribbean thought. The common origin of the Caribbean region, the European colonization, caused two disasters: the extermination of Native Americans and the deportation of African slaves. The union between nature and the oppressed people against the oppressor resulted in the creation of an environmental conscience that the Caribbean literature has often expressed. This essay will investigate the common points shared by some Haitian, Martinican and Guadeloupean authors in the writing of natural hazards. It will show that, despite the diversity that marks the Caribbean, there is a repetition of common features that proves its geopoetic unity.

scholarly journals New class of sensitive and selective fluorogenic substrates for serine proteinases. Amino acid and dipeptide derivatives of rhodamine

1983 ◽  
Vol 215 (2) ◽  
pp. 253-260 ◽  
Author(s):  
S P Leytus ◽  
W L Patterson ◽  
W F Mangel
Keyword(s):  
Amino Acid ◽  
Kinetic Constants ◽  
Amide Bond ◽  
Single Amino Acid ◽  
Amino Acid Derivative ◽  
Specific Substrate ◽  
Serine Proteinases ◽  
Bovine Trypsin ◽  
Human Thrombin ◽  
Derivatives Of

A series of dipeptide derivatives of Rhodamine, each containing an arginine residue in the P1 position and one of ten representative benzyloxycarbonyl (Cbz)-blocked amino acids in the P2 position, has been synthesized, purified and characterized as substrates for serine proteinases. These substrates are easily prepared with high yields. Cleavage of a single amide bond converts the non-fluorescent bisamide substrate into a highly fluorescent monoamide product. Macroscopic kinetic constants for the interaction of these substrates with bovine trypsin, human and dog plasmin, and human thrombin are reported. Certain of these substrates exhibit extremely large specificity constants. For example, the kcat./Km for bovine trypsin with bis-(N-benzyloxycarbonylglycyl-argininamido)-Rhodamine [(Cbz-Gly-Arg-NH)2-Rhodamine] is 1 670 000 M-1 X S-1. Certain of these substrates are also highly selective. For example, the most specific substrate for human plasmin, (Cbz-Phe-Arg-NH2)-Rhodamine, is not hydrolysed by human thrombin, and the most specific substrate for human thrombin, (Cbz-Pro-Arg-NH)2-Rhodamine, is one of the least specific substrates for human plasmin. Comparison of the kinetic constants for hydrolysis of the dipeptide substrates with that of the single amino acid derivative, (Cbz-Arg-NH)2-Rhodamine, indicates that selection of the proper amino acid residue in the P2 position can effect large increases in substrate specificity. This occurs primarily as a result of an increase in kcat. as opposed to a decrease in Km and, in certain cases, is accompanied by a large increase in selectivity. Because of their high degree of sensitivity and selectivity, these Rhodamine-based dipeptide compounds should be extremely useful substrates for studying serine proteinases.

Synthesis of new cyclopeptide analogues of the miuraenamides

2021 ◽  
Vol 18 ◽  
Author(s):  
Sarah Kappler ◽  
Andreas Siebert ◽  
Uli Kazmaier
Keyword(s):  
Natural Products ◽  
Biological Properties ◽  
Amide Bond ◽  
Side Chain ◽  
Aromatic Side Chain ◽  
Highly Active ◽  
C Terminus ◽  
Terminal Amino ◽  
High Cytotoxicity ◽  
Derivatives Of

Introduction: Miuraenamides belong to marine natural compounds with interesting biological properties. Materials and Methods: They initiate polymerization of monomeric actin and therefore show high cytotoxicity by influencing the cytoskeleton. New derivatives of the miuraenamides have been synthesized containing a N-methylated amide bond instead of the more easily hydrolysable ester in the natural products. Results: Incorporation of an aromatic side chain onto the C-terminal amino acid of the tripeptide fragment also led to highly active new miuraenamides. Conclusion: We could show that the ester bond of the natural product miuraenamide can be replaced by an N-methyl amide. The yields in the cyclization step are high and generally much better that with the corresponding esters. On the other hand, the biological activity of the new amide analogs are lower compared to the natural products, but the activity can significantly be increased by incorporation of a p-nitrophenyl group at the C-terminus of the peptide fragment.

scholarly journals Saturated Ceramides from the Sponge Dysidea Robusta

2009 ◽  
Vol 4 (7) ◽  
pp. 1934578X0900400
Author(s):  
Suzi O. Marques ◽  
Katyuscya Veloso ◽  
Antonio G. Ferreira ◽  
Eduardo Hajdu ◽  
Solange Peixinho ◽  
...  
Keyword(s):  
Marine Sponge ◽  
Crude Extract ◽  
Spectroscopic Data ◽  
Chemical Investigation ◽  
Ms Analysis

Chemical investigation of the crude extract of a marine sponge Dysidea robusta led to the isolation of an inseparable mixture of saturated ceramides. These were identified from spectroscopic data as well as by hydrolysis followed by LC-MS analysis of the sphingosine moieties.

scholarly journals Three New Spongian Diterpenes from the Fijian Marine Sponge Spongia sp

2009 ◽  
Vol 4 (3) ◽  
pp. 1934578X0900400 ◽  
Author(s):  
Harald Gross ◽  
Anthony D. Wright ◽  
Uwe Reinscheid ◽  
Gabriele M. König
Keyword(s):  
Molecular Modeling ◽  
Marine Sponge ◽  
Spectroscopic Data ◽  
Chemical Investigation ◽  
Complete Analysis ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Fiji Islands ◽  
Combined Strategy ◽  
Spongian Diterpene

Chemical investigation of the marine sponge Spongia sp., collected from the Fiji Islands resulted in the isolation of three new furanoditerpenoids 1-3, along with the known compounds epispongiatriol (4) and 17,19-dihydroxyspongia-13(16),14-dien-2,3-dione (5) While 1 is a new spongian diterpene with a modified oxidation pattern, compounds 2 and 3 represent two new ring A-contracted spongians, displaying a novel and unprecedented nor-spongian carbon skeleton. Despite their labile nature the structures could be established through a combined strategy including complete analysis of spectroscopic data (NMR, MS), molecular modeling and quantum-mechanical calculations.

scholarly journals Facile synthesis of 1-alkoxy-1H-benzo- and 7-azabenzotriazoles from peptide coupling agents, mechanistic studies, and synthetic applications

2014 ◽  
Vol 10 ◽  
pp. 1919-1932 ◽  
Author(s):  
Mahesh K Lakshman ◽  
Manish K Singh ◽  
Mukesh Kumar ◽  
Raghu Ram Chamala ◽  
Vijayender R Yedulla ◽  
...  
Keyword(s):  
Amide Bond ◽  
Coupling Agents ◽  
Cyclic Ketones ◽  
Substitution Reactions ◽  
Facile Synthesis ◽  
Reaction Conditions ◽  
Peptide Coupling ◽  
Acyclic Nucleoside ◽  
Derivatives Of

(1H-Benzo[d][1,2,3]triazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP), 1H-benzo[d][1,2,3]triazol-1-yl 4-methylbenzenesulfonate (Bt-OTs), and 3H-[1,2,3]triazolo[4,5-b]pyridine-3-yl 4-methylbenzenesulfonate (At-OTs) are classically utilized in peptide synthesis for amide-bond formation. However, a previously undescribed reaction of these compounds with alcohols in the presence of a base, leads to 1-alkoxy-1H-benzo- (Bt-OR) and 7-azabenzotriazoles (At-OR). Although BOP undergoes reactions with alcohols to furnish 1-alkoxy-1H-benzotriazoles, Bt-OTs proved to be superior. Both, primary and secondary alcohols undergo reaction under generally mild reaction conditions. Correspondingly, 1-alkoxy-1H-7-azabenzotriazoles were synthesized from At-OTs. Mechanistically, there are three pathways by which these peptide-coupling agents can react with alcohols. From 31P{1H}, [18O]-labeling, and other chemical experiments, phosphonium and tosylate derivatives of alcohols seem to be intermediates. These then react with BtO− and AtO− produced in situ. In order to demonstrate broader utility, this novel reaction has been used to prepare a series of acyclic nucleoside-like compounds. Because BtO− is a nucleofuge, several Bt-OCH2Ar substrates have been evaluated in nucleophilic substitution reactions. Finally, the possible formation of Pd π–allyl complexes by departure of BtO− has been queried. Thus, alpha-allylation of three cyclic ketones was evaluated with 1-(cinnamyloxy)-1H-benzo[d][1,2,3]triazole, via in situ formation of pyrrolidine enamines and Pd catalysis.

Molecular Aspects of Herbicide Action on Protoporphyrinogen Oxidase

1993 ◽  
Vol 48 (3-4) ◽  
pp. 326-333 ◽  
Author(s):  
Beate Nicolaus ◽  
Gerhard Sandmann ◽  
Peter Böger
Keyword(s):  
Diphenyl Ether ◽  
Protoporphyrin Ix ◽  
Protoporphyrinogen Oxidase ◽  
Relative Specificity ◽  
Oxidase Inhibition ◽  
Dilution Experiments ◽  
Membrane Bound ◽  
The Common ◽  
Molecular Aspects ◽  
Derivatives Of

Abstract Protoporphyrinogen oxidase, the last enzyme of the common tetrapyrrole biosynthetic pathway, is inhibited by several peroxidizing compounds resulting in accumulation of photodynamic tetrapyrroles, mainly protoporphyrin IX. The inhibition characteristics of two chemi­cally unrelated compounds were studied using membrane bound protoporphyrinogen oxidase from corn etioplasts. As shown by Lineweaver-Burk-analysis, the inhibition of enzyme activity by the diphenyl ether oxyfluorfen and the cyclic imide MCI 15 are competitive with respect to the substrate. The competitive interaction of protoporphyrinogen and the two chemically un­related inhibitors indicate a relative specificity of the binding site. The reversibility of oxyfluorfen inhibition was evaluated by dilution experiments and was shown to be independent of the presence of DTT. The analysis of structure-activity-relationship on protoporphyrinogen oxidase inhibition was investigated with para-substituted derivatives of phenyl-3,4,5,6-tetrahydro-phthalimides. The results obtained by QSAR -calculation yielded a good correlation of the inhibitory activity determined by the lipophilicity of the para-substituent. These data point to one binding region of the inhibitors within a lipophilic environment associated with the active center of the enzyme.

“Loop-at-a-Time” Design of Dynamic Surface Controllers for Nonlinear Systems

1998 ◽  
Vol 124 (1) ◽  
pp. 104-110 ◽  
Author(s):  
J. Christian Gerdes ◽  
J. Karl Hedrick
Keyword(s):  
Robust Control ◽  
Nonlinear Systems ◽  
Engine Speed ◽  
Design Procedure ◽  
Sequential Design ◽  
Bounded Region ◽  
Dynamic Surface ◽  
Mismatched Uncertainties ◽  
The Common ◽  
Derivatives Of

The use of multiple surface sliding controllers for robust control of nonlinear systems with mismatched uncertainties has produced a number of impressive applications, but also raised a few theoretical questions. Among the latter are the use of numerical differencing to obtain derivatives of desired trajectories, robustness to uncertainties in the gain terms and the common practice of filtering desired trajectories for implementation. This paper seeks to address these issues through the concept of a Dynamic Surface Controller, in which filters form an integral part of the structure. This filtering removes the need for numerical differencing and guarantees a certain smoothness, enabling other assumptions of smoothness to be relaxed. In this paper, the Dynamic Surface Controller is coupled with a sequential design procedure that carves a system workspace out of the state space. Within this bounded region, bounded tracking performance can be rigorously guaranteed in the presence of uncertainties and constraints such as rate limits and saturation can be systematically avoided. The design of a Dynamic Surface Controller and the advantages of the workspace concept are demonstrated in the context of engine speed control.

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