147-85-3Relevant articles and documents
Optical resolution, characterization, and X-ray crystal structures of diastereomeric salts of chiral amino acids with (S)-(-)-1-phenylethanesulfonic acid
Yoshioka,Ohtsuki,Da-Te,Okamura,Senuma
, p. 3012 - 3020 (1994)
Ten DL-Amino acids (AA), including neutral, and basic amino acids, and an imino acid, were optically resolved, without derivatization into their covalent compounds, by means of fractional crystallization of their diastereomeric salts with (-)-1-phenylethanesulfonic acid (PES) in various solvents. Several pairs of the diastereomeric crystalline salts formed during the resolutions were analyzed by DSC and spectroscopy, which showed that the successful resolutions were attributable to differences in various physicochemical properties between the more-soluble D-AA · (-)-PES and less-soluble L-AA · (-)-PES. Chiral recognition of the most successfully resolved species, DL-p-hydroxyphenylglycine (HPG) salt, was explored by comparing the X-ray crystal structures of D- and L-HPG · (-)-PES. The two crystal structures differed obviously in their hydrogen-bonding networks: the less-soluble L-HPG · (-)-PES only had strong hydrogen-bonded infinite chains of HPG in a 'head-to-tail' arrangement through the p-hydroxyl group, the structure of which was more geometrically stable than that of the more-soluble D-HPG · (-)-PES. The differences in the two crystal structures related to striking differences in their solubilities and thermal properties.
The relative catalytic efficiency of β-lactamase catalyzed acyl and phosphyl transfer
Slater, Martin J.,Laws, Andrew P.,Page, Michael I.
, p. 77 - 95 (2001)
Phosphonamidates which bear a simple resemblance to penicillin type structures have been synthesised as potential inhibitors of β-lactamases: -ethyl N-(benzyloxycarbonyl) amidomethyl phosphonyl amides, PhCH2OCONHCH2P(O)(OEt)NR2, the amines HNR2 being L-proline, D-proline, L-thiazolidine, and o-anthranilic acid. The proline derivatives completely and irreversibly inactivated the class C β-lactamase from Enterobacter cloacae P99, in a time-dependent manner, indicative of covalent inhibition. The inactivation was found to be exclusive to the class C enzyme and no significant inhibition was observed with any other class of β-lactamase. The anthranilic acid derivative exhibited no appreciable inactivation of the β-lactamases. The phosphonyl proline and phosphonyl thioproline derivatives were separated into their diastereoisomers and their individual second order rate constants for inhibition were found to be 7.72 ± 0.37 and 8.3 × 10-2 ± 0.004 M-1 s-1 for the L-proline derivatives, at pH 7.0. The products of the inhibition reaction of each individual diastereoisomer, analyzed by electrospray mass spectroscopy, indicate that the more reactive diastereoisomers phosphonylate the enzyme by P-N bond fission with the elimination of proline. Conversely, gas chromatographic detection of ethanol release by the less reactive proline diastereoisomer suggests phosphonylation occurs by P-O bond fission. The enzyme enhances the rate of phosphonylation with P-N fission by at least 106 compared with that effected by hydroxide-ion. The pH dependence of the rate of inhibition of the β-lactamase by the more reactive diasteroisomer is consistent with the reaction of the diprotonated form of the enzyme, EH2, with the inhibitor, I (or its kinetic equivalents EH with IH). This pH dependence and the rate enhancement indicate that the enzyme appears to use the same catalytic apparatus for phosphonylation as that used for hydrolysis of β-lactams. The stereochemical consequences of nucleophilic displacement at the phosphonyl centre are discussed.
Viridamides A and B, lipodepsipeptides with antiprotozoal activity from the marine cyanobacterium Oscillatoria nigro-viridis
Simmons, T. Luke,Engene, Niclas,Urena, Luis David,Romero, Luz I.,Ortega-Barria, Eduardo,Gerwick, Lena,Gerwick, William H.
, p. 1544 - 1550 (2008)
Parallel chemical and phylogenetic investigation of a marine cyanobacterium from Panama led to the isolation of two new PKS-NRPS-derived compounds, viridamides A and B. Their structures were determined by NMR and mass spectroscopic methods, and the absolute configurations assigned by Marfey's method and chiral HPLC analysis. In addition to six standard, N-methylated amino and hydroxy acids, these metabolites contained the structurally novel 5-methoxydec-9-ynoic acid moiety and an unusual proline methyl ester terminus. Morphologically, this cyanobacterium was identified as Oscillatoria nigro-viridis, and its 16S rDNA sequence is reported here for the first time. Phylogenetic analysis of these sequence data has identified O. nigro-viridis strain OSC3L to be closely related to two other marine cyanobacterial genera, Trichodesmium and Blennothrix. Viridamide A showed antitrypanosomal activity with an IC50 of 1.1 μM and antileishmanial activity with an IC50 of 1.5 μM.
Structures and solution conformational dynamics of stylissamides G and H from the Bahamian Sponge Stylissa caribica
Wang, Xiao,Morinaka, Brandon I.,Molinski, Tadeusz F.
, p. 625 - 630 (2014)
Two new peptides, stylissamides G and H, were isolated from extracts of a sample of Stylissa caribica collected in deep waters of the Caribbean Sea. A single sample of S. caribica among a collection of 10 samples that were examined by LC-MS appeared to be a different chemotype from the others in that it lacked the familiar pyrrole-2-aminoimidazole alkaloids, stevensine and oroidin, and contained peptides of the stylissamide class. The structures of the title compounds were solved by integrated analysis of the MS and NMR spectra and chemical degradation. The solution conformation of stylissamide G was briefly examined by electronic circular dichroism and temperature-dependent 1H NMR chemical shifts of amide NH signals, which supported a conformationally rigid macrocycle.
Heterogeneous Asymmetric Hydrogenation of a Chiral Tripeptide containing Dehydroalanine and α,β-Dehydrobutyrine Residues
Takasaki, Michiaki,Harada, Kaoru
, p. 571 - 573 (1987)
The heterogeneous asymmetric hydrogenation of a linear tripeptide containing dehydroalanine and α,β-dehydrobutyrine has been carried out, giving asymmetric yields of alanine and butyrine of 94 and 54percent, respectively.
New diketopiperazine derivatives isolated from sea urchin-derived Bacillus sp.
Yonezawa, Ken,Yamada, Koji,Kouno, Isao
, p. 106 - 108 (2011)
Two new diketopiperazine derivatives, bacillusamides A (1) and B (2), have been isolated from the EtOAc extract of the sea urchin-derived Bacillus sp. along with the known cyclo(-L-pro-L-val-) (3), cyclo(-L-pro-L-tyr-) (4), cyclo(-L-pro-L-phe-) (5). These structures were elucidated by extensive spectroscopic methods. Furthermore, the absolute configurations of the amino acid residues were determined using Marfey's method. Compound 1 displayed weak antifungal activity against Aspergillus niger.
Cipralphelin, a new anti-oxidative N-cinnamoyl tripeptide produced by the deep sea-derived fungal strain Penicillium brevicompactum FKJ-0123
Matsuo, Hirotaka,Mokudai, Takayuki,Higo, Mayuka,Nonaka, Kenichi,Nagano, Yuriko,Nagahama, Takahiko,Niwano, Yoshimi,Takahashi, Yōko,ōmura, Satoshi,Nakashima, Takuji
, p. 775 - 778 (2019)
A new N-cinnamoyl tripeptide, designated cipralphelin (1), was isolated from a cultured broth of Penicillium brevicompactum FKJ-0123 by physicochemical (PC) screening. Compound 1 was purified by silica gel and ODS column chromatography followed by preparative HPLC. The structure of 1 was determined as N-cinnamoyl-prolyl-alanyl-phenylalanine methyl ester by nuclear magnetic resonance and mass spectrometry analyses. The absolute configurations of three amino acids were determined by an advanced Marfey’s method applied to the hydrolysate of 1. Compound 1 was evaluated for its cytotoxicity, anti-microbial activity, and ability to scavenge or quench reactive oxygen species (ROS) such as superoxide anion radicals, hydroxy radicals, and singlet oxygen. Compound 1 exhibited potent scavenging activity against hydroxy radicals.
Dudawalamides A-D, Antiparasitic Cyclic Depsipeptides from the Marine Cyanobacterium Moorea producens
Almaliti, Jehad,Malloy, Karla L.,Glukhov, Evgenia,Spadafora, Carmenza,Gutiérrez, Marcelino,Gerwick, William H.
, p. 1827 - 1836 (2017)
A family of 2,2-dimethyl-3-hydroxy-7-octynoic acid (Dhoya)-containing cyclic depsipeptides, named dudawalamides A-D (1-4), was isolated from a Papua New Guinean field collection of the cyanobacterium Moorea producens using bioassay-guided and spectroscopic approaches. The planar structures of dudawalamides A-D were determined by a combination of 1D and 2D NMR experiments and MS analysis, whereas the absolute configurations were determined by X-ray crystallography, modified Marfey's analysis, chiral-phase GCMS, and chiral-phase HPLC. Dudawalamides A-D possess a broad spectrum of antiparasitic activity with minimal mammalian cell cytotoxicity. Comparative analysis of the Dhoya-containing class of lipopeptides reveals intriguing structure-activity relationship features of these NRPS-PKS-derived metabolites and their derivatives.
Synergie effect of two metal centers in catalytic hydrolysis of methionine-containing peptides promoted by dinuclear palladium(II) hexaazacyclooctadecane complex
Yang, Gaosheng,Miao, Ren,Li, Yizhi,Hong, Jing,Zhao, Chuenmei,Guo, Zijian,Zhu, Longgen
, p. 1613 - 1619 (2005)
The species obtained by the reaction of [Pd2([18]aneN 6)Cl2](ClO4)2 (where [18]aneN 6 is 1,4,7,10,13,16-hexaazacyclooctadecane) with AgBF4 have been determined by electrospray ionization mass spectrometry (ESI-MS) to be an equilibrium mixture of three major types of dinuclear Pd(II) complex cations, [Pd2(-O)([18]aneN6)]2+, [Pd 2(μ-OH)-([18]aneN6)]3+ and [Pd 2(H2O)(OH)([18]aneN6)]3+, in aqueous solution. The hydroxo-group-bridged one, [Pd2(μ-OH)-([18] aneN6)]3+, is a dominant species, whose crystal structure has been obtained. The crystal structure of [Pd2(μ-OH)-([18] aneN6)](ClO4)3 shows that each Pd(II) ion in the dinuclear complex is tetra-coordinated by three nitrogen atoms and one hydroxo group bridge in a distorted square configuration. The two Pd(II) ions are 3.09 A apart from each other. The dinuclear Pd(II) complex cations [Pd2(μ-OH)([18]aneN6)]3+ and [Pd 2(H2O)(OH)([18]aneN6)]3+ can efficiently catalyze hydrolysis of the amide bond involving the carbonyl group of methionine in methionine-containing peptides with turnover number of larger than 20. In these hydrolytic reactions, the two Pd(II) ions are synergic; one Pd(II) ion anchors to the side chain of methionine and the other one delivers hydroxo group or aqua ligand to carbonyl carbon of methionine, or acts as a Lewis acid to activate the carbonyl group of methionine, resulting in cleavage of Met-X bond. The binding constant of dinuclear Pd(II) complex cations with AcMet-Gly and AcMet were determined by 1H NMR titration to be 282±2 M-1 and 366±4 M-1, respectively. The relatively low binding constants enable the catalytic cycle and the possible catalytic mechanism is proposed. This is the first artificial mimic of metallopeptidases with two metal active centers. The Royal Society of Chemistry 2005.
Isolation and synthesis of falcitidin, a novel myxobacterial-derived acyltetrapeptide with activity against the malaria target falcipain-2
Somanadhan, Brinda,Kotturi, Santosh R.,Yan Leong, Chung,Glover, Robert P.,Huang, Yicun,Flotow, Horst,Buss, Antony D.,Lear, Martin J.,Butler, Mark S.
, p. 259 - 264 (2013)
A 384-well microtitre plate fluorescence cleavage assay was developed to identify inhibitors of the cysteine protease falcipain-2, an important antimalarial drug target. Bioassay-guided isolation of a MeOH extract from a myxobacterium Chitinophaga sp. Y23 isolated from soil collected in Singapore, led to the identification of a new acyltetrapeptide, falcitidin (1), which displayed an IC 50 value of 6 μM against falcipain-2. The planar structure of 1 was secured by NMR and MS/MS analysis. Attempts to isolate further material for biological testing were hampered by inconsistent production and by a low yield (100 μg l -1). The absolute configuration of 1 was determined by Marfey's analysis and the structure was confirmed through total synthesis as isovaleric acid-D-His-L-Ile-L-Val-L-Pro-NH 2. Falcitidin (1) is the first member of a new class of falcipain-2 inhibitors and, unlike other peptide-based inhibitors, does not contain reactive groups that irreversibly bind to active cysteine sites.
Tunicyclin a, the first plant tricyclic ring cycloheptapeptide from Psammosilene tunicoides
Tian, Jun-Mian,Shen, Yun-Heng,Yang, Xian-Wen,Liang, Shuang,Tang, Jian,Shan, Lei,Zhang, Wei-Dong
, p. 1131 - 1133 (2009)
A novel cycloheptapeptide, tunicyclin A, with a unique tricyclic ring cyclopeptide skeleton, was isolated from Psammosilene tunicoides. Its structure was elucidated by extensive NMR and MS analysis. Biogenetically, tunicyclin A might be derived from cyclo
Specialized metabolites from the aerial parts of Centaurea polyclada DC.
Demir, Serdar,Karaalp, Canan,Bedir, Erdal
, p. 12 - 18 (2017)
The genus Centaurea L. (Asteraceae) is represented by 200 taxa in the flora of Turkey and several Centaurea species are used as herbal remedies against different conditions. Previous phytochemical investigations on this genus generally revealed the isolation of sesquiterpene lactones and flavonoid derivatives. In our continuous search on Centaurea genus, a phytochemical study was performed on Centaurea polyclada DC., an endemic of West Anatolia. Previously undescribed two sesquiterpene-amino acid conjugates, an elemane and an eudesmane derivative were isolated from the aerial parts of Centaurea polyclada, together with eight known compounds; two elemane derivatives, three flavonoids, a lignan, a phenolic glucoside and a phenylpropanoid glucoside. Structural elucidation of the compounds was based on spectroscopic evidence, including 1D and 2D NMR and high-resolution mass spectrometry, chemical degradation results and reference data comparison. Sesquiterpene-amino acid conjugates are representatives of an unusual group of sesquiterpenes, and elemane-amino acid conjugates are herein reported for the first time in nature.
Jahanyne, an apoptosis-inducing lipopeptide from the marine cyanobacterium lyngbya sp.
Iwasaki, Arihiro,Ohno, Osamu,Sumimoto, Shinpei,Ogawa, Hidetoshi,Nguyen, Kim Anh,Suenaga, Kiyotake
, p. 652 - 655 (2015)
An acetylene-containing lipopeptide, jahanyne, was isolated from the marine cyanobacterium Lyngbya sp. Its gross structure was established by spectroscopic analyses, and the absolute configuration was clarified based on a combination of chiral HPLC analyses, spectroscopic analyses, and derivatization reactions. Jahanyne significantly inhibited the growth of human cancer cells and induced apoptosis in HeLa cells.
STRUCTURE OF CYCLOTHIAZOMYCIN, A UNIQUE POLYTHIAZOLE-CONTAINING PEPTIDE WITH RENIN INHIBITORY ACTIVITY. PART 1. CHEMISTRY AND PARTIAL STRUCTURES OF CYCLOTHIAZOMYCIN
Aoki, Masahiro,Ohtsuka, Tatsuo,Itezono, Yoshiko,Yokose, Kazuteru,Furihata, Kazuo,Seto, Haruo
, p. 217 - 220 (1991)
Cyclothiazomycin is a novel renin inhibitor produced by Streptomyces sp.NR 0516 (IC50 1.66μM).Its molecular formular was determined to be C59H64N18O14S7 (MW. 1472) based on high-resolution FAB mass and NMR spectroscopy.Five fragments of cyclothiazomycin containing thiazole, thiazoline, heterocyclic chromophore were clarified by extensive 2D-NMR experiments.
Stylissamides e and F, cyclic heptapeptides from the caribbean sponge stylissa caribica
Cychon, Christine,Koeck, Matthias
, p. 738 - 742 (2010)
In addition to the four known stylissamides, A (1), B (2), C, and D, two new cyclic heptapeptides, stylissamides E (3) and F (4), were isolated from the Caribbean sponge Stylissa caribica. The structures of 3 and 4 were elucidated from a combination of mass spectrometric and NMR spectroscopic data as cyclo-(cis-Pro1-Tyr2-trans-Pro3-Ala 4-Ile5-Gln6-Ile7) for stylissamide E (3) and cyclo-(trans-Pro1-cis-Pro2-Phe 3-Asp4-trans-Pro5-Arg6-Phe 7) for stylissamide F (4).
Ionic Liquids Derived from Proline: Application as Surfactants
Fernández-Stefanuto, Verónica,Corchero, Raquel,Rodríguez-Escontrela, Iria,Soto, Ana,Tojo, Emilia
, p. 2885 - 2893 (2018)
Ionic liquids derived from prolinium esters, previously described as fully green and stable, were found to decompose in the presence of water by ester hydrolysis. To avoid this problem, a new family of these biodegradable salts incorporating an alcohol instead of the ester group is proposed. From this family, two novel ionic liquids that incorporate the prolinolium cation [HOPro] and the [DS] or [DBS] anion were selected (DS=dodecylsulfate; DBS=dodecylbenzenesulfonate). Both salts are liquid at room temperature, a property not usually found in ionic surfactants, and are also chemically and thermally stable. Moreover, they are more effective in reducing the surface tension of water than the corresponding traditional surfactants in the form of sodium salts, being useful for applications related to their aggregation capacity. They were tested for surfactant enhanced oil recovery and an optimal formulation for reservoirs at high salinity and temperature, able to produce ultra-low interfacial tension, was found with [HOPro][DBS].
(-)/(+)-Sparteine induced chirally-active carbon nanoparticles for enantioselective separation of racemic mixtures
Vulugundam, Gururaja,Misra, Santosh K.,Ostadhossein, Fatemeh,Schwartz-Duval, Aaron S.,Daza, Enrique A.,Pan, Dipanjan
, p. 7513 - 7516 (2016)
Chiral carbon nanoparticles (CCNPs) were developed by surface passivation using the chiral ligand (-)-sparteine or (+)-sparteine (denoted (-)-SP/CNP and (+)-SP/CNP, respectively). The chirality of the prepared CCNPs was demonstrated by circular dichroism
An angiogenesis inhibitor isolated from a marine-derived actinomycete, Nocardiopsis sp. 03N67
Shin, Hee Jae,Mondol, M.A. Mojid,Yu, Tae Kyung,Lee, Hyi-Seung,Lee, Yeon-Ju,Jung, Hye Jin,Kim, Jong Hyeon,Kwon, Ho Jeong
, p. 194 - 197 (2010)
Cyclo-(l-Pro-l-Met) was isolated from the fermentation broth of a marine-derived actinomycete Nocardiopsis sp. 03N67 by chromatographic analysis and showed anti-angiogenesis activity against human umbilical vein endothelial cells (HUVECs). The structure and absolute stereochemistry of this compound were determined based on extensive spectroscopic data analysis, and Marfey's method, respectively.
Planktocyclin, a cyclooctapeptide protease inhibitor produced by the freshwater cyanobacterium Planktothrix rubescens
Baumann, Heike I.,Keller, Simone,Wolter, Falko E.,Nicholson, Graeme J.,Jung, Guenther,Suessmuth, Roderich D.,Juettner, Friedrich
, p. 1611 - 1615 (2007)
The freshwater cyanobacterium Planktothrix rubescens produces the cyclooctapeptide cyclo(Pro-Gly-Leu-Val-Met-Phe-Gly-Val). The chemical structure is new. This homodetic cyclic octapeptide was named planktocyclin (1). It consists solely of proteinogenic L-amino acids and is a strong inhibitor of mammalian trypsin and α-chymotrypsin and a moderately active inhibitor of human recombinant caspase-8. Mass spectrometric and 2D-NMR spectroscopic data allowed the determination of its structure. Synthetic planktocyclin was identical to the natural product.
Aestuaramides, a natural library of cyanobactin cyclic peptides resulting from isoprene-derived Claisen rearrangements
McIntosh, John A.,Lin, Zhenjian,Tianero, Ma. Diarey B.,Schmidt, Eric W.
, p. 877 - 883 (2013)
We report 12 cyanobactin cyclic peptides, the aestuaramides, from the cultivated cyanobacterium Lyngbya aestuarii. We show that aestuaramides are synthesized enzymatically as reverse O-prenylated tyrosine ethers that subsequently undergo a Claisen rearrangement to produce forward C-prenylated tyrosine. These results reveal that a nonenzymatic Claisen rearrangement dictates isoprene regiochemistry in a natural system. They also reveal one of the mechanisms that organisms use to generate structurally diverse compound libraries starting from simple ribosomal peptide pathways (RiPPs).
Chromatographic method for the determination of conditional equilibrium constants for the carbamate formation reaction from amino acids and peptides in aqueous solution
Chen, Jian-Ge,Sandberg, Mats,Weber, Stephen G.
, p. 7343 - 7350 (1993)
A novel and sensitive method has been developed and evaluated for the study of carbamate formation equilibria of amino acids and peptides in aqueous solution. The method is based on reversed-phase liquid chromatography with cetyltrimethylammonium bromide. The reliability of the method was established by comparing the results determined from the present study with the few data in the literature. The relaxation rate of the carbamate reaction was shown to be faster than the chromatographic distribution relaxation rate (seconds). As a result, the retention time of amine solutes is increased in the presence of CO2. Carbamate formation constants and mole fractions of carbamates at physiological pH of eleven L-α-amino acids and peptides were determined. No correlation between the formation constant and the ammonium pKa was found. There is significant dependence of the amount of a particular amino acid or peptide that exists as carbamate at pH 7.4 on the pKa of the ammonium group, however. This is due to mass action rather than reflecting the influence of pKa on the propensity of the amine to react with CO2. It is suggested that amino acids and peptides with ammonium pKa greater than 9.5 do not form significant amounts of carbamates in aqueous solution near neutral pH.
Urumamide, a novel chymotrypsin inhibitor with a β-amino acid from a marine cyanobacterium Okeania sp.
Kanamori, Yuki,Iwasaki, Arihiro,Sumimoto, Shinpei,Suenaga, Kiyotake
, p. 4213 - 4216 (2016)
Urumamide, a novel cyclic depsipeptide that contains a β-amino acid, was isolated from a marine cyanobacterium Okeania sp. Its gross structure was determined by spectroscopic analyses, and the absolute configuration was established based on Marfey's analyses and chiral HPLC analyses of hydrolysis products. Biologically, urumamide inhibited the growth of human cancer cells. In addition, urumamide inhibited chymotrypsin.
Odobromoamide, a terminal alkynyl bromide-containing cyclodepsipeptide from the marine cyanobacterium okeania sp.
Sueyoshi, Kosuke,Kudo, Takafumi,Yamano, Aki,Sumimoto, Shimpei,Iwasaki, Arihiro,Suenaga, Kiyotake,Teruya, Toshiaki
, p. 436 - 440 (2017)
The bioassay-guided fractionation of the Okinawan marine cyanobacterium Okeania sp. led to the isolation of the novel cyclodepsipeptide odobromoamide (1). The gross structure of 1 was determined by spectroscopic analyses, and its absolute stereochemistry was determined using a variety of different methods, including chemical derivatization and degradation followed by HPLC analysis. In addition, odobromoamide (1) exhibited broad-spectrum cytotoxicity against a human cancer cell line panel.
Porpoisamides A and B, two novel epimeric cyclic depsipeptides from a Florida Keys collection of Lyngbya sp.
Meickle, Theresa,Gunasekera, Sarath P.,Liu, Yanxia,Luesch, Hendrik,Paul, Valerie J.
, p. 6576 - 6580 (2011)
NMR-guided fractionation of a non-polar extract of a Florida Keys collection of Lyngbya sp. resulted in the isolation of two novel epimeric cyclic depsipeptides, porpoisamides A (1) and B (2). The planar structures of these compounds were determined using NMR spectroscopic techniques. The absolute configurations of amino and hydroxy acid subunits were assigned by enantioselective HPLC analysis. These compounds showed weak cytotoxicity towards HCT-116 colorectal carcinoma and U2OS osteosarcoma cells. The porpoisamides are a unique pair of cyclic depsipeptides that are epimeric at C-2 of the β-amino acid, 3-amino-2-methyloctanoic acid.
Selective activation of organocatalysts by specific signals
Maity, Chandan,Trausel, Fanny,Eelkema, Rienk
, p. 5999 - 6005 (2018)
Reminiscent of signal transduction in biological systems, artificial catalysts whose activity can be controlled by physical or chemical signals would be of high interest in the design of chemical systems that can respond to their environment. Self-immolative chemistry offers a generic method for the development of catalysts that can be activated by different signals. To demonstrate the versatility of that concept, we synthesized organocatalysts that can be activated by three different signals and that can be used to control two different reactions. In this way the organocatalyst proline is designed as a pro-catalyst that is activated either by the chemical signal H2O2, by light or by the enzyme penicillin acylase. The pro-catalysts were used to exert temporal control over the rate of an aldol reaction and a Michael reaction.
Squamins C–F, four cyclopeptides from the seeds of Annona globiflora
Sosa-Rueda, Javier,Domínguez-Meléndez, Vanihamin,Ortiz-Celiseo, Araceli,López-Fentanes, Fernando C.,Cuadrado, Cristina,Fernández, José J.,Daranas, Antonio Hernández,Cen-Pacheco, Francisco
, (2021/08/04)
Four cyclic octapeptides, squamins C–F, were isolated from the seeds of Annona globiflora Schltdl. These compounds share part of their amino acid sequence, -Pro-Met(O)-Tyr-Gly-Thr-, with previously reported squamins A and B. Their structures were determined using NMR spectroscopic techniques together with quantum mechanical calculations (QM-NMR), ESI-HRMS data and a modified version of Marfey's chromatographic method. All compounds showed cytotoxic activity against DU-145 (human prostate cancer) and HeLa (human cervical carcinoma) cell lines. Clearly, A. globiflora is an important source of bioactive molecules, which could promote the sustainable exploitation of this undervalued specie.
Isolation, Structure Determination, and Total Synthesis of Hoshinoamide C, an Antiparasitic Lipopeptide from the Marine Cyanobacterium Caldora penicillata
Iwasaki, Arihiro,Ohtomo, Keisuke,Kurisawa, Naoaki,Shiota, Ikuma,Rahmawati, Yulia,Jeelani, Ghulam,Nozaki, Tomoyoshi,Suenaga, Kiyotake
, p. 126 - 135 (2021/01/13)
Hoshinoamide C (1), an antiparasitic lipopeptide, was isolated from the marine cyanobacterium Caldora penicillata. Its planar structure was elucidated by spectral analyses, mainly 2D NMR, and the absolute configurations of the α-amino acid moieties were determined by degradation reactions followed by chiral-phase HPLC analyses. To clarify the absolute configuration of an unusual amino acid moiety, we synthesized two possible diastereomers of hoshinoamide C and determined its absolute configuration based on a comparison of their spectroscopic data with those of the natural compound. Hoshinoamide C (1) did not exhibit any cytotoxicity against HeLa or HL60 cells at 10 μM, but inhibited the growth of the parasites responsible for malaria (IC50 0.96 μM) and African sleeping sickness (IC50 2.9 μM).