- Komesuamide and odopenicillatamide, two linear lipopeptides from the marine cyanobacterium Caldora penicillata
-
The linear lipopeptides komesuamide (1) and odopenicillatamide (2) were isolated from Caldora penicillata a marine cyanobacterium collected in Okinawa. The structures of these compounds were established by spectroscopic analyses, and the absolute configurations were determined by HPLC analyses of the acid hydrolysates. Both compounds showed glucose uptake activity at 40 μM in cultured L6 myotubes.
- Ozaki, Kaori,Jinno, Atsuhide,Natsume, Noriyuki,Sumimoto, Shimpei,Iwasaki, Arihiro,Suenaga, Kiyotake,Teruya, Toshiaki
-
-
- Exploration of Transaminase Diversity for the Oxidative Conversion of Natural Amino Acids into 2-Ketoacids and High-Value Chemicals
-
The use of 2-ketoacids is very common in feeds, food additives, and pharmaceuticals, and 2-ketoacids are valuable precursors for a plethora of chemically diverse compounds. Biocatalytic synthesis of 2-ketoacids starting from l-amino acids would be highly desirable because the substrates are readily available from biomass feedstock. Here, we report bioinformatic exploration of a series of aminotransferases (ATs) to achieve the desired conversion. Thermodynamic control was achieved by coupling an l-glutamate oxidation reaction in the cascade for the recycling of the amine acceptor. These enzymes were able to convert a majority of proteinogenic amino acids into the corresponding 2-ketoacids with high conversion (up to 99percent) and atom-efficiency. Furthermore, this enzyme cascade was extendable, and one-pot two-step processes were established for the synthesis of d-amino acids and N-methylated amino acids, achieving great overall conversion (up to 99percent) and high ee values (>99percent). These developed enzymatic methodologies offer convenient routes for utilizing amino acids as synthetic reagents.
- Chen, Yanchun,Cui, Xuexian,Cui, Yinglu,Li, Chuijian,Li, Ruifeng,Li, Tao,Sun, Jinyuan,Wu, Bian,Zhu, Tong
-
p. 7950 - 7957
(2020/08/21)
-
- Isolation and Total Synthesis of Mabuniamide, a Lipopeptide from an Okeania sp. Marine Cyanobacterium
-
The bioassay-guided fractionation of an Okeania sp. marine cyanobacterium collected in Okinawa led to the isolation of the lipopeptide mabuniamide (1). The gross structure of 1 was determined by spectroscopic analyses, and its absolute configuration was determined using Marfey's analysis of the acid hydrolysate of 1. The absolute configuration of 1 was confirmed by total synthesis. Mabuniamide (1) stimulated glucose uptake in cultured rat L6 myotubes. In addition, mabuniamide (1) and its stereoisomer (2) exhibited moderate antimalarial activity.
- Ozaki, Kaori,Iwasaki, Arihiro,Sezawa, Dai,Fujimura, Haruka,Nozaki, Tomoyoshi,Saito-Nakano, Yumiko,Suenaga, Kiyotake,Teruya, Toshiaki
-
p. 2907 - 2915
(2019/10/16)
-
- Activation of the NLRP3 Inflammasome by Hyaboron, a New Asymmetric Boron-Containing Macrodiolide from the Myxobacterium Hyalangium minutum
-
A Natural Compound Library containing myxobacterial secondary metabolites was screened in murine macrophages for novel activators of IL-1β maturation and secretion. The most potent of three hits in total was a so far undescribed metabolite, which was identified from the myxobacterium Hyalangium minutum strain Hym3. While the planar structure of 1 was elucidated by high resolution mass spectrometry and NMR data yielding an asymmetric boron containing a macrodiolide core structure, its relative stereochemistry of all 20 stereocenters of the 42-membered ring was assigned by rotating frame Overhause effect spectroscopy correlations, 1H,1H, and 1H,13C coupling constants, and by comparison of 13C chemical shifts to those of the structurally related metabolites tartrolon B-D. The absolute stereochemistry was subsequently assigned by Mosher's and Marfey's methods. Further functional studies revealed that hyaboron and other boronated natural compounds resulted in NLRP3 inflammasome dependent IL-1β maturation, which is most likely due to their ability to act as potassium ionophores. Moreover, besides its inflammasome-stimulatory activity in human and mouse cells, hyaboron (1) showed additional diverse biological activities, including antibacterial and antiparasitic effects.
- Surup, Frank,Chauhan, Dhruv,Niggemann, Jutta,Bartok, Eva,Herrmann, Jennifer,Keck, Matthias,Zander, Wiebke,Stadler, Marc,Hornung, Veit,Müller, Rolf
-
p. 2981 - 2988
(2018/09/27)
-
- Biocatalytic Synthesis of Chiral N-Functionalized Amino Acids
-
N-Functionalized amino acids are important building blocks for the preparation of diverse bioactive molecules, including peptides. The development of sustainable manufacturing routes to chiral N-alkylated amino acids remains a significant challenge in the pharmaceutical and fine-chemical industries. Herein we report the discovery of a structurally diverse panel of biocatalysts which catalyze the asymmetric synthesis of N-alkyl amino acids through the reductive coupling of ketones and amines. Reactions have been performed on a gram scale to yield optically pure N-alkyl-functionalized products in high yields.
- Hyslop, Julia F.,Lovelock, Sarah L.,Sutton, Peter W.,Brown, Kristin K.,Watson, Allan J. B.,Roiban, Gheorghe-Doru
-
supporting information
p. 13821 - 13824
(2018/09/27)
-
- Biseokeaniamides A, B, and C, Sterol O-Acyltransferase Inhibitors from an Okeania sp. Marine Cyanobacterium
-
Biseokeaniamides A, B, and C (1-3), structurally novel sterol O-acyltransferase (SOAT) inhibitors, were isolated from an Okeania sp. marine cyanobacterium. Their structures were elucidated by spectroscopic analyses and degradation reactions. Biseokeaniamide B (2) exhibited moderate cytotoxicity against human HeLa cancer cells, and compounds 1-3 inhibited both SOAT1 and SOAT2, not only at an enzyme level but also at a cellular level. Biseokeaniamides (1-3) are the first linear lipopeptides that have been shown to exhibit SOAT-inhibitory activity.
- Iwasaki, Arihiro,Tadenuma, Takato,Sumimoto, Shimpei,Ohshiro, Taichi,Ozaki, Kaori,Kobayashi, Keisuke,Teruya, Toshiaki,Tomoda, Hiroshi,Suenaga, Kiyotake
-
p. 1161 - 1166
(2017/05/05)
-
- Anti-Cryptococcus Phenalenones and Cyclic Tetrapeptides from Auxarthron pseudauxarthron
-
Auxarthrones A-E (1-5), five new phenalenones, and two new naturally occurring cyclic tetrapeptides, auxarthrides A (7) and B (8), were obtained from three different solvent extracts of cultures of the coprophilous fungus Auxarthron pseudauxarthron. Auxarthrones C (3) and E (5) possess an unusual 7a,8-dihydrocyclopenta[a]phenalene-7,9-dione ring system that has not been previously observed in natural products. Formation of 1-5 was found to be dependent on the solvent used for culture extraction. The structures of these new compounds were elucidated primarily by analysis of NMR and MS data. Auxarthrone A (1) was obtained as a mixture of chromatographically inseparable racemic diastereomers (1a and 1b) that cocrystallized, enabling confirmation of their structures by X-ray crystallography. The absolute configurations of 7 and 8 were assigned by analysis of their acid hydrolysates using Marfey's method. Compound 1 displayed moderate antifungal activity against Cryptococcus neoformans and Candida albicans, but did not affect human cancer cell lines.
- Li, Yan,Yue, Qun,Jayanetti, Dinith R.,Swenson, Dale C.,Bartholomeusz, Geoffrey A.,An, Zhiqiang,Gloer, James B.,Bills, Gerald F.
-
supporting information
p. 2101 - 2109
(2017/08/04)
-
- Dudawalamides A-D, Antiparasitic Cyclic Depsipeptides from the Marine Cyanobacterium Moorea producens
-
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.
- Almaliti, Jehad,Malloy, Karla L.,Glukhov, Evgenia,Spadafora, Carmenza,Gutiérrez, Marcelino,Gerwick, William H.
-
p. 1827 - 1836
(2017/06/28)
-
- Identification of Cyclic Depsipeptides and Their Dedicated Synthetase from Hapsidospora irregularis
-
Seven cyclic depsipeptides were isolated from Hapsidospora irregularis and structurally characterized as the calcium channel blocker leualacin and six new analogues based on the NMR and HRESIMS data. These new compounds were named leualacins B-G. The absolute configurations of the amino acids and 2-hydroxyisocaproic acids were determined by recording the optical rotation values. Biological studies showed that calcium influx elicited by leualacin F in primary human lobar bronchial epithelial cells involves the TRPA1 channel. Through genome sequencing and targeted gene disruption, a noniterative nonribosomal peptide synthetase was found to be involved in the biosynthesis of leualacin. A comparison of the structures of leualacin and its analogues indicated that the A2 and A4 domains of the leualacin synthetase are substrate specific, while A1, A3, and A5 can accept alternative precursors to yield new molecules.
- Zhang, Shuwei,Qiu, Yixing,Kakule, Thomas B.,Lu, Zhenyu,Xu, Fuchao,Lamb, John G.,Reilly, Christopher A.,Zheng, Yong,Sham, Shing Wo Simon,Wang, Wei,Xuan, Lijiang,Schmidt, Eric W.,Zhan, Jixun
-
p. 363 - 370
(2017/03/08)
-
- Peptide Tyrosinase Activators
-
Peptides that increase melanin synthesis are provided. These peptides include pentapeptides YSSWY, YRSRK, and their variants. The peptides may activate the enzymatic activity of tyrosinase to increase melanin synthesis. The pharmaceutical, cosmetic, and other compositions including the peptides are also provided. The methods of increasing melanin production in epidermis of a subject are provided where the methods include administering compositions comprising an amount of one or more peptides effective to increase the melanin production. The methods also include treating vitiligo or other hypopigmentation disorders with compositions including one or more peptides.
- -
-
-
- Two new diketopiperazines and a new glucosyl sesterterpene from Alternaria alternata, an endophytic fungi from Ceratostigma griffithii
-
Two diketopiperazine derivatives, altenarizines A (1) and B (2), and a new glucosyl sesterterpene, 24-α-d-glucosyl-(-)-terpestacin (3), together with two known phytotoxic sesterterpenes, (-)-terpestacin (4) and fusaproliferin (5), were isolated from the fermentation broth of an endophytic fungus Alternaria alternata, which was obtained from the fresh root of Ceratostigma griffithii. Structures of all the isolates were identified by spectroscopic data.
- Guo, Da-Le,Zhao, Min,Xiao, Shi-Ji,Xia, Bing,Wan, Bo,Gu, Yu-Cheng,Ding, Li-Sheng,Zhou, Yan
-
p. 260 - 264
(2015/11/23)
-
- Jahanyne, an apoptosis-inducing lipopeptide from the marine cyanobacterium lyngbya sp.
-
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.
- Iwasaki, Arihiro,Ohno, Osamu,Sumimoto, Shinpei,Ogawa, Hidetoshi,Nguyen, Kim Anh,Suenaga, Kiyotake
-
supporting information
p. 652 - 655
(2015/03/05)
-
- Design, synthesis, and optimization of balanced dual NK1/NK 3 receptor antagonists
-
In connection with a program directed at potent and balanced dual NK 1/NK3 receptor ligands, a focused exploration of an original class of peptidomimetic derivatives was performed. The rational design and molecular hybridization of a novel phenylalanine core series was achieved to maximize the in vitro affinity and antagonism at both human NK1 and NK3 receptors. This study led to the identification of a new potent dual NK1/NK3 antagonist with pKi values of 8.6 and 8.1, respectively.
- Hanessian, Stephen,Jennequin, Thomas,Boyer, Nicolas,Babonneau, Vincent,Soma, Udaykumar,Mannoury La Cour, Clotilde,Millan, Mark J.,De Nanteuil, Guillaume
-
supporting information
p. 550 - 555
(2014/06/09)
-
- Structural revision and absolute configuration of lateritin
-
'Lateritin' (1), a morpholine-2,5-dione (depsipeptide), was reinvestigated for its structure and absolute configuration. On the basis of thorough 1D and 2D NMR and mass spectrometrical analyses, the structure of 1 was revised to be identical with beauvericin (8) and confirmed that beauvericin (8) is the trimeric lactone of 'lateritin' (1). The absolute configuration was determined by acidic hydrolysis, followed by application of Marfey's method, menthyl ester derivatization, and GC-MS analysis. In addition, the specific optical rotation values of the hydrolysis products were compared with those of available standards.
- Ola, Antonius R.B.,Aly, Amal H.,Lin, Wenhan,Wray, Victor,Debbab, Abdessamad
-
supporting information
p. 6184 - 6187
(2014/12/10)
-
- Isolation of ciliatamide D from a marine sponge Stelletta sp. and a reinvestigation of the configuration of ciliatamide A
-
A new lipopeptide, ciliatamide D (1), was isolated from a marine sponge Stelletta sp., collected at Oshimashinsone, together with the known compound ciliatamide A (2). Ciliatamide D (1) is a congener of 2, in which N-Me-Phe is replaced by N-Me-Met(O). Marfey's analysis of the acid hydrolysate of 1 demonstrated that the two constituent amino acids were both in the l-form. This result prompted us to carefully investigate the configuration of 2, resulting in the assignment of the l-form for both residues.
- Imae, Yasufumi,Takada, Kentaro,Okada, Shigeru,Ise, Yuji,Yoshimura, Hiroshi,Morii, Yasuhiro,Matsunaga, Shigeki
-
p. 755 - 758
(2013/06/05)
-
- Pitipeptolides C-F, antimycobacterial cyclodepsipeptides from the marine cyanobacterium Lyngbya majuscula from Guam
-
Pitipeptolides A (1) and B (2) are cyclic depsipeptides isolated from the marine cyanobacterium Lyngbya majuscula from Piti Bomb Holes, Guam. Additional analogues have now been isolated by revisiting larger collections of the same cyanobacterium. The four identified analogues, pitipeptolides C-F (3-6), are the tetrahydro analogue (3), an analogue with a lower degree of methylation (4) as well as two homologues (5 and 6) of pitipeptolide A. Their structures were elucidated using 2D NMR experiments, chiral HPLC analysis and comparison with pitipeptolide A. The identified analogues showed weaker cytotoxic activities compared to the two major parent compounds, pitipeptolides A (1) and B (2), against HT-29 colon adenocarcinoma and MCF7 breast cancer cells. On the other hand, pitipeptolide F (6) was the most potent pitipeptolide in a disc diffusion assay against Mycobacterium tuberculosis. The latter finding suggests that the structure of pitipeptolides could be optimized for selective antibacterial activity.
- Montaser, Rana,Paul, Valerie J.,Luesch, Hendrik
-
experimental part
p. 2068 - 2074
(2012/01/13)
-
- Cyclodepsipeptides, sesquiterpenoids, and other cytotoxic metabolites from the filamentous fungus Trichothecium sp. (MSX 51320)
-
Two new cyclodepsipeptides (1 and 2), two new sesquiterpenoids (3 and 4), and the known compounds guangomide A (5), roseotoxin S, and three simple trichothecenes were isolated from the cytotoxic organic extract of a terrestrial filamentous fungus, Trichothecium sp. The structures were determined using NMR spectroscopy and mass spectrometry. Absolute configurations of the cyclodepsipeptides were established by employing chiral HPLC, while the relative configurations of 3 and 4 were determined via NOESY data. The isolation of guangomide A was of particular interest, since it was reported previously from a marine-derived fungus.
- Sy-Cordero, Arlene A.,Graf, Tyler N.,Adcock, Audrey F.,Kroll, David J.,Shen, Qi,Swanson, Steven M.,Wani, Mansukh C.,Pearce, Cedric J.,Oberlies, Nicholas H.
-
experimental part
p. 2137 - 2142
(2011/12/14)
-
- Cyclohexadepsipeptides from Acremonium sp. BCC 28424
-
Six new cyclohexadepsipeptides, beauvenniatins A-E (1-5), and beauvericin J (6), together with the known beauvericin (7) and enniatin B (8), were isolated from the fungus Acremonium sp. BCC 28424. The productions of minor derivatives 3-6, possessing an N-
- Isaka, Masahiko,Yangchum, Arunrat,Sappan, Malipan,Suvannakad, Rapheephat,Srikitikulchai, Prasert
-
experimental part
p. 7929 - 7935
(2011/11/07)
-
- Malyngamide 3 and cocosamides A and B from the marine cyanobacterium lyngbya majuscula from cocos lagoon, guam
-
Malyngamide 3 (1) and cocosamides A (2) and B (3) were isolated from the lipophilic extract of a collection of Lyngbya majuscula from Cocos Lagoon, Guam. The planar structures of compounds 1-3 were determined by spectroscopic methods. The absolute configuration of 1 was determined by modified Mosher's method, NOESY data, and comparison with lyngbic acid (4). The absolute configurations of 2 and 3 were assigned by enantioselective HPLC analysis and comparison with the closely related compound pitipeptolide A (5). Compounds 1-3 showed weak cytotoxicity against MCF7 breast cancer and HT-29 colon cancer cells.
- Gunasekera, Sarath P.,Owle, Chivas S.,Montaser, Rana,Luesch, Hendrik,Paul, Valerie J.
-
experimental part
p. 871 - 876
(2011/06/21)
-
- Revised structure and structure-activity relationship of bisebromoamide and structure of norbisebromoamide from the marine cyanobacterium Lyngbya sp.
-
Novel potent cytotoxic peptides bisebromoamide (1) and norbisebromoamide (2) have been isolated from the marine cyanobacterium Lyngbya sp. The planar structure of these peptides was elucidated through the extensive application of 1D and 2D NMR techniques. The absolute stereostructure of 1 was determined by chemical degradation followed by chiral HPLC analysis. Recently, Tao and co-workers achieved synthesis of bisebromoamide, and the configuration of thiazoline moiety was revised. We re-investigated the stereochemistry of thiazoline moiety of 1. The structure-activity relationships of bisebromoamide (1) were investigated with the use of natural and synthetic analogs. Furthermore, bisebromoamide (1) potently inhibited protein kinase: the phosphorylation of ERK in NRK cells by PDGF-stimulation was selectively inhibited by treatment with 10-0.1 μM of 1.
- Sasaki, Hiroaki,Teruya, Toshiaki,Fukazawa, Hidesuke,Suenaga, Kiyotake
-
experimental part
p. 990 - 994
(2011/03/19)
-
- Grassypeptolides A-C, cytotoxic bis-thiazoline containing marine cyclodepsipeptides
-
Grassypeptolides A-C (1-3), a group of closely related bis-thiazoline containing cyclic depsipeptides, have been isolated from extracts of the marine cyanobacterium Lyngbya confervoides. Although structural differences between the analogues are minimal, comparison of the in vitro cytotoxicity of the series revealed a structure-activity relationship. When the ethyl substituent of 1 is changed to a methyl substituent in 2, activity is only slightly reduced (3-4-fold), whereas inversion of the Phe unit flanking the bis-thiazoline moiety results in 16-23-fold greater potency. We show that both 1 and 3 cause G1 phase cell cycle arrest at lower concentrations, followed at higher concentrations by G2/M phase arrest, and that these compounds bind Cu2+ and Zn 2+. The three-dimensional structure of 2 was determined by MS, NMR, and X-ray crystallography, and the structure of 3 was established by MS, NMR, and chemical degradation. The structure of 3 was explored by in silico molecular modeling, revealing subtle differences in overall conformation between 1 and 3. Attempts to interconvert 1 and 3 with base were unsuccessful, but enzymatic conversion may be possible and could be a novel form of activation for chemical defense.
- Kwan, Jason C.,Ratnayake, Ranjala,Abboud, Khalil A.,Paul, Valerie J.,Luesch, Hendrik
-
experimental part
p. 8012 - 8023
(2011/03/20)
-
- Bisebromoamide, a potent cytotoxic peptide from the marine cyanobacterium lyngbya sp.: Isolation, stereostructure, and biological activity
-
A novel cytotoxic peptide, termed bisebromoamide (1), has been Isolated from the marine cyanobacterium Lyngbya sp. Its planar structure was determined by 1D and 2D NMR spectroscopy. The absolute stereostructure of 1 was determined by chemical degradation
- Teruya, Toshiaki,Sasaki, Hiroaki,Fukazawa, Hidesuke,Suenaga, Kiyotake
-
supporting information; experimental part
p. 5062 - 5065
(2010/01/06)
-
- Homotyrosine-containing cyanopeptolins 880 and 960 and anabaenopeptins 908 and 915 from Planktothrix agardhii CYA 126/8
-
Two homotyrosine-bearing cyanopeptolins are described from Planktothrix agardhii CYA 126/8. The compounds feature a common homotyrosine-containing cyclohexadepsipeptide and differ by sulfation of an exocyclically located 2-O-methyl-D-glyceric acid residue. In addition we describe two anabaenopeptins, which contain two homotyrosine residues, one of which is N-methylated. The anabaenopeptins have a common cyclopentapeptide portion and differ in the amino acid linked to it via an ureido bond, arginine and tyrosine, respectively.
- Okumura, Hilary S.,Philmus, Benjamin,Portmann, Cyril,Hemscheidt, Thomas K.
-
experimental part
p. 172 - 176
(2009/06/27)
-
- Resolution of racemic N-benzyl α-amino acids by liquid-liquid extraction: A practical method using a lipophilic chiral cobalt(III) salen complex and mechanistic studies
-
The efficient resolution of racemic N-benzyl α-amino acids (N-Bn-AA) has been achieved by a liquid-liquid extraction process using the lipophilic chiral salen-cobalt(III) complex [CoIII(3)(OAc)]. As a result of the resolution by extraction, one enantiomer (S) of the N-benzyl α-amino acid predominated in the aqueous phase, while the other enantiomer (R) was driven into the organic phase by complexation to cobalt. The complexed amino acid (R) was then quantitatively released by a reductive (CoIII→Co II) counter-extraction with aqueous sodium dithionite or L-ascorbic acid in methanol. The reductive cleavage allowed to recover the [Co II(3)] complex in good yield, which could be easily re-oxidized to [CoIII(3)(OAc)] with air/AcOH and reused with essentially no loss of reactivity and selectivity. Investigation on the nitrogen substitution indicates that the presence of a single benzyl group on the amino acid nitrogen is important to obtain high enantioselectivity in the extraction process. The kinetic vs. thermodynamic nature of the resolution process was also investigated with an enantiomeric exchange experiment, which shows that the liquid-liquid extraction with [CoIII(3)-(OAc)] is an equilibrium process operating under thermodynamic control. In the absence of a suitable crystal structure of the [CoIII(3)(N-Bn-AA)] complexes, computational and spectroscopic studies were used to investigate how the N-benzyl α-amino acids are accommodated in the "binding pocket" of the chiral cobalt complex. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Dzygiel, Pawel,Reeve, Toby B.,Piarulli, Umberto,Krupicka, Martin,Tvaroska, Igor,Gennari, Cesare
-
supporting information; experimental part
p. 1253 - 1264
(2009/04/07)
-
- ES-242 derivatives and cycloheptapeptides from Cordyceps sp. strains BCC 16173 and BCC 16176
-
Five new ES-242 analogues (1-5) were isolated together with nine known compounds (6-14) from the insect pathogenic fungus Cordyceps sp. BCC 16173. A closely related strain, BCC 16176, provided cordyheptapeptide A (15) and small amount of its new analogue, cordyheptapeptide B (16), along with known ES-242s. Structures of the new bioxanthracenes, 1-5, were determined to be 6′-O-desmethyl analogues of 6 (ES-242-4), 8, 9 (ES-242-2), 12, and 13, respectively, primarily by spectroscopic analyses. Cordyheptapeptide B (16) has an N-methyl-L-phenylalanine residue instead of the N-methyl-L-tyrosine in 15.
- Isaka, Masahiko,Srisanoh, Urarat,Lartpornmatulee, Nattapat,Boonruangprapa, Tanapong
-
p. 1601 - 1604
(2008/03/13)
-
- Synthesis of optically active α-methylamino acids and amides through biocatalytic kinetic resolution of amides
-
Catalyzed by Rhodococcus sp. AJ270, a nitrile hydratase and amidase containing microbial whole-cell catalyst, under very mild conditions, a number of racemic α-methylamino amides were resolved into the corresponding optically active (S)-(+)-α-methylamino acids and (R)-(-)-α- methylamino amides. The steric requirement of the amidase against α-amino phenylacetamides bearing methyl group(s) at α-amino nitrogen and/or α-carbon was also studied. Coupled with the chemical hydrolysis of amide, the biotransformation process provided a direct synthesis of α-methylamino acids in both enantiomeric forms from readily available racemic amides.
- Wang, Mei-Xiang,Liu, Jun,Wang, De-Xian,Zheng, Qi-Yu
-
p. 2409 - 2416
(2007/10/03)
-
- The total synthesis and stereochemical revision of yanucamide A
-
(Matrix presented) The first total synthesis of yanucamide A is reported via amide and ester couplings of the key components. This synthesis has established the configuration at the previously ambiguous 3-position, and also revised the stereochemistry at the 22-position, to give 3S,12S,17S,22S for the natural product.
- Xu, Zhengshuang,Peng, Yungui,Ye, Tao
-
p. 2821 - 2824
(2007/10/03)
-
- Asymmetric pictet-spengler reactions: Synthesis of 1,2,3,4-tetrahydroisoquinoline carboxylic acid (Tic) chimeras
-
A preparatively simple diastereoselective synthesis of the amino acid chimera (1S,3S)-1,2,3,4-tetrahydroisoquinoline-1,3-dicarboxylic acid from hexafluoroacetone-protected phenylalanine and glyoxylic acid hydrate via Pictet-Spengler reaction is described. The potential of the reaction of hexafluoroacetone-protected phenylalanine with other aldehydes was scrutinized.
- Spengler,Schedel,Sieler,Quaedflieg,Broxterman,Duchateau,Burger
-
p. 1513 - 1518
(2007/10/03)
-
- Preparation of N-Z-protected N-methylated amino acids
-
A process for preparing N-protected N-alkylated amino acids of the formula I: in which the substituents have the meanings stated in the description, comprises mixing a compound of the formula II with a solution of potassium tert-butanolate in a non-protic organic solvent, and subsequently adding a C1-2-alkyl halide.
- -
-
-
- Argifin, a new chitinase inhibitor, produced by Gliocladium sp. FTD-0668 II. Isolation, physico-chemical properties, and structure elucidation
-
A new chitinase inhibitor, named argifin, was isolated from the cultured broth of a fungal strain Gliocladium sp. FTD-0668. Argifin was purified from the cultured mycelium by the combination of cation exchange, anion exchange, adsorption, and gel filtration Chromatographie methods. The structure of argifin was elucidated as cyclo(N-(β-methylcarbamoyl)-L-arginylN-methyl-L-phenyIalanyl-β-L- aspartyl-β-L-aspartyl-D-alanyl) by NMR experiments and other spectroscopic analyses.
- Arai, Noriko,Shiomi, Kazuro,Iwai, Yuzuru,Oemura, Satoshi
-
p. 609 - 614
(2007/10/03)
-
- A practical approach for the optically pure N-Methyl-α- amino acids
-
A new practical synthesis of N-Methyl-α-amino acids by racemization free methodology has been developed. The method involves the reductive cleavage of N-protected oxazotidinones using hydrogen in the presence of Pd/C to give the title compounds in quantitative yields.
- Reddy, G. Vidyasagar,Rao, G. Venkat,Iyengar
-
p. 1985 - 1986
(2007/10/03)
-
- Pmc-protected amino acid esters as substrates in N-alkylamino acid synthesis
-
N-alkylamino acids may be synthesised via Mitsunobu reaction of N-(2,2,5,7,8-pentamethylchroman-6-sulphonyl-)-amino acid esters with various alcohols and subsequent deprotection.
- Wisniewski, Kazimierz,Kollodziejczyk, Aleksandra S.
-
p. 483 - 486
(2007/10/03)
-
- Highly practical methodology for the synthesis of D- and L-α-amino acids, N-protected α-amino acids, and N-methyl-α-amino acids
-
Full details are provided for an exceedingly practical method to synthesize D- and L-α-amino acids, N-protected α-amino acids, and N-methyl-α-amino acids, employing as a key step the asymmetric alkylation of pseudoephedrine glycinamide (1) or pseudoephedrine sarcosinamide (2). Practical procedures for the synthesis of 1 and 2 from pseudoephedrine and glycine methyl ester or sarcosine methyl ester, respectively, are presented. Optimum protocols for the enolization and subsequent alkylation of 1 and 2 are described. Alkylation reactions of 1 and 2 are found to be quite efficient with a wide range of alkyl halide substrates, and the products are formed with high diastereoselectivity. The products of these alkylation reactions are hydrolyzed efficiently and with little to no racemization simply by heating in water or water-dioxane mixtures. This protocol provides an exceedingly practical method for the preparation of salt-free α-amino acids of high enantiomeric purity. Alternatively, the alkylation products may be hydrolyzed in high yield and with little to no racemization by heating with aqueous sodium hydroxide. The alkaline hydrolyzate can then be treated with an acylating reagent to provide directly highly enantiomerically enriched N-protected derivatives such as N-Boc and N-Fmoc. Key features necessary for the successful execution of these experimental procedures are identified.
- Myers, Andrew G.,Gleason, James L.,Yoon, Taeyoung,Kung, Daniel W.
-
p. 656 - 673
(2007/10/03)
-
- Structural identification of the degradation products of the antitumor peptide antagonist [Arg6, D-Trp7,9, MePhe8]substance P (6-11)
-
The basic hexapeptide antagonist [Arg6, D-Trp7,9, MePhe8]substance P (6-11) was degraded in acid and alkaline media. In acid solution, only one degradation product is found whereas in alkaline solution at least six products are formed. These compounds were analytically characterized and structurally identified by reversed-phase high-performance liquid chromatography, capillary electrophoresis, liquid chromatography/mass spectrometry, fast atom bombardment tandem mass spectrometry, optical rotation analysis, and chiral gas chromatography. The product formed in acidic solution is the terminally deamidated antagonist [Arg6, D-Trp7,9, MePhe8]substance P (6-11); this product was also found in alkaline degradation mixtures. Other important degradation products originate from racemization of the amino acid residue L-Met, formation of ornithine from Arg, and the oxidation of Met to its sulfoxide form.
- Reubsaet,Beijnen,Bult,Hop,Vermaas,Kellekule,Kettenes-Van Den Bosch,Underberg
-
p. 4431 - 4436
(2007/10/02)
-
- AN ALTERNATIVE ROUTE TO Nα-METHYLAMINO ACID DERIVATIVES: SYNTHESIS AND CONFORMATION OF SOME Nα-acetyl-Nα-METHYLAMINO ACID METHYLAMIDES
-
The methylation of tert-butyl- or isopropyl esters of Nα-4-toluenesulfonyl-amino acids by dimethylsulfate in aqueous alkaline solution in the presence of a detergent gives the corresponding Nα-methylderivatives.Using this synthetic route the Nα-acetylderivatives of MeAla, MeLeu, MeOrn and MePhe methylamides have been prepared and the solution conformation of these dipeptide units has been investigated. 1H and 13C NMR spectra show that, while in dimethylsulfoxide the tertiary amide group is mostly in cis-conformation, in protic solvents the equilibrium is shifted towards trans-conformation.Circular dichroism spectra reveal some specific features (e.g. high band intensities in protic solvents) which cannot be explained solely on the basis of the increased rigidity caused by the Nα-methyl group.We tried to explain these effects supposing that the tertiary amide group is deviated from the planar arrangement (due to the interaction between the methyl groups, a substituent on Cα and solvent molecule attached to the oxygen atom) and contributes to the observed circular dichroism as the inherently chiral chromophore.
- Hlavacek, Jan,Fric, Ivo,Budesinsky, Milos,Blaha, Karel
-
p. 2473 - 2494
(2007/10/02)
-
- NITROGEN ALKYLATION OF SCHIFF BASES AND AMIDINES AS A ROUTE TO N-ALKYL AMINO ACIDS
-
Schiff base and amidine esters 3 are alkylated and then hydrolyzed to yield N-alkyl amino acids 4 in 41-75percent yield with hight to complete retention of optical activity.
- O'Donnell, Martin J.,Bruder, William A.,Daugherty, Byron W.,Liu, Deshan,Wojciechowski, Krzisztof
-
p. 3651 - 3654
(2007/10/02)
-
- Amino-acids and Peptides, Part 44. Synthesis of Protected Peptides related to Sequence 23-30 of Bovine Insulin B-Chain
-
Protected peptides related to the C-terminal octapeptide sequence (1) of the B-chain of bovine insulin, including those in which phenylalanine-24 and -25 have been replaced by alanine and by N-methylphenylalanine, have been synthesized by the picolyl este
- Warnke, Jonathan G.,Young, Geoffrey T.
-
p. 2797 - 2800
(2007/10/02)
-
