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Two piperazic acid-containing cyclic hexapeptides from Streptomyces alboflavus 313
Two novel cyclic hexapeptides, designated NW-G10 (1) and NW-G11 (2), were isolated from the fermentation broth of Streptomyces alboflavus 313. Their relative structures were elucidated on the basis of extensive spectroscopic analysis, and the absolute con
Wei, Shaopeng,Fan, Lixia,Wu, Wenjun,Ji, Zhiqin
p. 2191 - 2198
(2012)
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Cyclic Tetrapeptides with Synergistic Antifungal Activity from the Fungus Aspergillus westerdijkiae Using LC-MS/MS-Based Molecular Networking
Fungal natural products play a prominent role in the development of pharmaceuticalagents. Two new cyclic tetrapeptides (CTPs), westertide A (1) and B (2), with eight known compounds (3-10) were isolated from the fungus Aspergillus westerdijkiae guided by
Chen, Baosong,Dai, Huanqin,Han, Junjie,Li, Erwei,Liu, Hongwei,Lyu, Zhitang,Song, Fuhang,Sun, Jingzu,Wang, Hanying,Wang, Tao,Wang, Wenzhao,Zhang, Rui
(2022/02/17)

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, structure elucidation and biological evaluation of lagunamide D: A new cytotoxic macrocyclic depsipeptide from marine cyanobacteria
Lagunamide D, a new cytotoxic macrocyclic depsipeptide, was discovered from a collection of marine cyanobacteria from Loggerhead Key in the Dry Tortugas, Florida. An intramolecular ester exchange was observed, where the 26-membered macrocycle could contract to a 24-membered compound via acyl migration at the 1,3-diol unit, and the transformation product was named lagunamide D'. The planar structures of both compounds were elucidated using a combination of nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectroscopy (HRMS). The absolute configurations were determined on the basis of enantioselective analysis, modified Mosher's analysis, Kishi NMR database, and direct comparison with lagunamide A, a structure closely resembling lagunamide D. Lagunamides A and D displayed low-nanomolar antiproliferative activity against A549 human lung adenocarcinoma cells, while the structural transformation from the 26-membered lagunamide D macrocycle to the 24-membered ring structure for lagunamide D' led to a 9.6-fold decrease in activity. Lagunamide D also displayed potent activity in triggering apoptosis in a dose- and time-dependent manner. Further investigation on the mechanism of action of the lagunamide scaffold is needed to fully explore its therapeutic potential as an anticancer agent.
Luo, Danmeng,Putra, Masteria Y.,Ye, Tao,Paul, Valerie J.,Luesch, Hendrik
(2019/02/19)

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)

Preparation method of N-methylamino acid with optical configurations
The invention belongs to the field of medicine synthesis, relates to a preparation method of N-methylamino acid with optical configurations and in particular relates to a preparation method of N-methylamino acid with an R configuration and an S configuration. The preparation method is shown in the description. According to the preparation method provided by the invention, the configurations of reactants are transformed to obtain the N-methylamino acid with corresponding opposite configurations, and the preparation method is suitable for commercial scale production.
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Paragraph 0038; 0039

(2017/08/29)

Cyclombandakamines A1 and A2, Oxygen-Bridged Naphthylisoquinoline Dimers from a Congolese Ancistrocladus Liana
Cyclombandakamines A1 (1) and A2 (2), both with an unprecedented pyrane-cyclohexenone-dihydrofuran sequence and six stereocenters and two chiral axes, are the first oxygen-bridged dimeric naphthylisoquinoline alkaloids. They were isolated from the leaves of an as yet unidentified Congolese Ancistrocladus species. Their stereostructures were established by spectroscopic, chemical, and chiroptical methods in combination with DFT and TDDFT calculations. They apparently originate from a cascade of oxidative cyclization reactions of open-chain naphthylisoquinoline dimers and exhibit significant antiprotozoal activities.
Lombe, Blaise Kimbadi,Bruhn, Torsten,Feineis, Doris,Mudogo, Virima,Brun, Reto,Bringmann, Gerhard
supporting information
p. 1342 - 1345
(2017/03/23)

Janadolide, a Cyclic Polyketide-Peptide Hybrid Possessing a tert-Butyl Group from an Okeania sp. Marine Cyanobacterium
Janadolide, a new cyclic polyketide-peptide hybrid possessing a tert-butyl group, was isolated from an Okeania sp. marine cyanobacterium. The gross structure was elucidated by spectroscopic analyses, and the absolute configurations of the amino acid moieties were determined by acid hydrolysis and chiral-phase HPLC analyses. The absolute configuration of the two stereogenic centers in the polyketide moiety was elucidated based on a combination of degradation reactions and spectroscopic analyses including the phenyl-glycine methyl ester method. Janadolide showed potent antitrypanosomal activity with an IC50 value of 47 nM without cytotoxicity against human cells at 10 μM.
Ogawa, Hidetoshi,Iwasaki, Arihiro,Sumimoto, Shinpei,Kanamori, Yuki,Ohno, Osamu,Iwatsuki, Masato,Ishiyama, Aki,Hokari, Rei,Otoguro, Kazuhiko,Omura, Satoshi,Suenaga, Kiyotake
p. 1862 - 1866
(2016/08/02)

Urumamide, a novel chymotrypsin inhibitor with a β-amino acid from a marine cyanobacterium Okeania sp.
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.
Kanamori, Yuki,Iwasaki, Arihiro,Sumimoto, Shinpei,Suenaga, Kiyotake
supporting information
p. 4213 - 4216
(2016/08/25)

Odoamide, a cytotoxic cyclodepsipeptide from the marine cyanobacterium Okeania sp.
The bioassay-guided fractionation of the Okinawan marine cyanobacterium Okeania sp. led to the isolation of the 26-membered cyclodepsipeptide odoamide (1). The gross structure of 1 was determined by 1D and 2D NMR analyses, whereas its absolute stereochemistry was determined using a variety of different methods, including synthesis and chemical degradation followed by chiral HPLC analysis. Notably, odoamide (1) showed potent cytotoxicity against HeLa S3 human cervical cancer cells with an IC50value of 26.3?nM.
Sueyoshi, Kosuke,Kaneda, Masato,Sumimoto, Shinpei,Oishi, Shinya,Fujii, Nobutaka,Suenaga, Kiyotake,Teruya, Toshiaki
p. 5472 - 5478
(2016/08/05)

Jubanines F-J, cyclopeptide alkaloids from the roots of Ziziphus jujuba
Five Ib-type cyclopeptide alkaloids, jubanines F-J (1-5), and three known compounds, nummularine B (6), daechuine-S3 (7), and mucronine K (8) were isolated from the roots of Ziziphus jujuba. Their structures were fully characterized by spectroscopic analyses in combination with chemical derivatization. Compounds 1-3, and 6 were evaluated for their antiviral activity against the porcine epidemic diarrhea virus (PEDV). Compounds 2, 3, and 6 showed potent inhibitory effects on PEDV replication.
Kang, Kyo Bin,Ming, Gao,Kim, Geum Jin,Ha, Thi-Kim-Quy,Choi, Hyukjae,Oh, Won Keun,Sung, Sang Hyun
p. 90 - 95
(2016/03/04)

Foxo3a Inhibitors of Microbial Origin, JBIR-141 and JBIR-142
JBIR-141 (1) and JBIR-142 (2) were discovered as potent Foxo3a inhibitors that consist of three quite unique substructures, a 1-((dimethylamino)ethyl)-5-methyl-4,5-dihydrooxazole-4-carboxylic acid that is originated from Ala-Thr amino acid residues, a 3-acetoxy-4-amino-7-(hydroxy(nitroso)amino)-2,2-dimethylheptanoic acid, and an α-acyl tetramic acid fused with a 2-methylpropan-1-ol moiety. Their structures involving absolute configurations were determined by spectroscopic data, chemical degradation, anisotropy methods, and LC-MS analyses of diastereomeric derivatives. Compounds 1 and 2 exhibited specific inhibition against Foxo3a transcriptional activity with IC50 values of 23.1 and 166.2 nM, respectively.
Kawahara, Teppei,Kagaya, Noritaka,Masuda, Yuichi,Doi, Takayuki,Izumikawa, Miho,Ohta, Kumiko,Hirao, Atsushi,Shin-Ya, Kazuo
supporting information
p. 5476 - 5479
(2015/11/18)

Stellettapeptins A and B, HIV-inhibitory cyclic depsipeptides from the marine sponge Stelletta sp.
Two new HIV-inhibitory depsipeptides, stellettapeptins A (1) and B (2), were isolated from an extract of the marine sponge Stelletta sp., collected from northwestern Australia. Structures of these cyclic nonribosomal peptides were elucidated on the basis of extensive NMR data analysis, and chemical degradation and derivatization studies. Stellettapeptins contain numerous nonproteinogenic amino acid residues and they are the first peptides reported to contain a 3-hydroxy-6,8-dimethylnon-4-(Z)-enoic acid moiety. Compounds 1 and 2 potently inhibit infection of human T-lymphoblastoid cells by HIV-1RF with EC50 values of 23 and 27 nM, respectively.
Shin, Hee Jae,Rashid, Mohammad A.,Cartner, Laura K.,Bokesch, Heidi R.,Wilson, Jennifer A.,McMahon, James B.,Gustafson, Kirk R.
supporting information
p. 4215 - 4219
(2015/06/22)

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)

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.
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(2015/06/10)

Psychrophilins E-H and versicotide C, cyclic peptides from the marine-derived fungus aspergillus versicolor ZLN-60
Four new cyclic peptides, psychrophilins E-H (1-4), possessing a rare amide linkage between the carboxylic acid in anthranilic acid (ATA) and the nitrogen from an indole moiety, along with a new ATA-containing hexapeptide, versicotide C (5), were obtained from the culture of the marine-derived fungus Aspergillus versicolor ZLN-60. The structures, including absolute configurations, were elucidated by a combination of HRESIMS, NMR, X-ray crystallography, TDDFT ECD calculations, and Marfeys method. Versicotide C (5) is the first natural cyclic hexapeptide containing two anthranilic acids. Compounds 1-5 were not cytotoxic, and compound 3 showed potent lipid-lowering effects.
Peng, Jixing,Gao, Huquan,Zhang, Xiaomin,Wang, Shuai,Wu, Chongming,Gu, Qianqun,Guo, Peng,Zhu, Tianjiao,Li, Dehai
p. 2218 - 2223
(2014/12/11)

NOVEL SELECTIVE ANDROGEN RECEPTOR MODULATORS
The present invention relates to a compound of Formula 1, 2 or 3: wherein A is N or —CR0—, where R0 is hydrogen, C1-C6 linear or branched chain alkyl, etc., Z is —CRe—, or, —N—, where Re is hydrogen, C1-C6 linear or branched chain alkyl,etc.; R1 is hydrogen, C1-C6 linear or branched chain alkyl, etc.; R2 are independently hydrogen or C1-C6 linear or branched chain alkyl; R3 and R4 are independently hydrogen, C1-C6 linear or branched chain alkyl, etc.;. R5 and R6 are independently hydrogen or C1-C6 linear or branched chain alkyl, etc.; R8 is hydrogen, C1-C6 linear or branched chain alkyl, etc.; R9 and R10 are independently hydrogen or C1-C6 linear or branched chain alkyl, etc.; Q is —CO—, —(CH2)q—, —(CHRs)q—, or (CRsRt)q—, where Rs and Rt are independently C1-C6 linear or branched chain alkyl, aryl, alkylaryl, heteroaryl or alkylheteroaryl; where q is 0, 1, 2, or 3; and, where n is 0, 1, 2, 3, 4 or 5; or, a pharmaceutically acceptable salt thereof, to compositions containing such compounds; and to the uses of such compounds in the treatment of various diseases, particularly, those affected or mediated by the androgen receptor.
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(2014/06/23)

Microbial enantioselective removal of the N-benzyloxycarbonyl amino protecting group
In order to deprotect N-carbobenzoxy-l-aminoacids (Cbz-AA) and related compounds, a series of microorganisms was selected from soil by enrichment cultures with Cbz-l-Glu as sole nitrogen source. A lyophilized whole-cell preparation of two Arthrobacter sp. strains grown on Cbz-Glu or Cbz-Gly exhibited a high cleavage activity. The conditions of hydrolysis have been optimized and a quantitative enantioselective deprotection of several Cbz-dl-amino acids was obtained, as well as the deprotection of N-carbamoylester derivatives of several synthetic amino compounds. The preparation of Cbz-d-allylglycine and l-allylglycine in high yield and high optical purity is described as an application of this method.
Maurs, Michele,Acher, Francine,Azerad, Robert
p. 22 - 26
(2012/10/29)

Lagunamide C, a cytotoxic cyclodepsipeptide from the marine cyanobacterium Lyngbya majuscula
Lagunamide C (1) is a cytotoxic cyclodepsipeptide isolated from the marine cyanobacterium, Lyngbya majuscula, from the western lagoon of Pulau Hantu Besar, Singapore. The complete structural characterization of the molecule was achieved by extensive NMR spectroscopic analysis as well as chemical manipulations. Several methods, including the advanced Marfey's method, a modified method based on derivatization with Mosher's reagents and analysis using LC-MS, and the use of 3JH-H coupling constant values, were utilized for the determination of its absolute configuration. Compound 1 is related to the aurilide-class of molecules and it differs mainly in the macrocyclic structure by having a 27 membered ring system due to additional methylene carbon in the polyketide moiety. Lagunamide C displayed potent cytotoxic activity against a panel of cancer cell lines, such as P388, A549, PC3, HCT8, and SK-OV3 cell lines, with IC50 values ranging from 2.1 nM to 24.4 nM. Compound 1 also displayed significant antimalarial activity with IC50 value of 0.29 μM when tested against Plasmodium falciparum. In addition, lagunamide C exhibited weak anti-swarming activity when tested at 100 ppm against the Gram-negative bacterial strain, Pseudomonas aeruginosa PA01.
Tripathi, Ashootosh,Puddick, Jonathan,Prinsep, Michele R.,Rottmann, Matthias,Chan, Kok Ping,Chen, David Yu-Kai,Tan, Lik Tong
experimental part
p. 2369 - 2375
(2012/02/03)

Systematic chemical mutagenesis identifies a potent novel apratoxin A/E hybrid with improved in vivo antitumor activity
Apratoxins are cytotoxic marine natural products that prevent cotranslational translocation early in the secretory pathway. We showed that apratoxins downregulate receptors and growth factor ligands, giving a one"two punch to cancer cells, particularly those that rely on autocrine loops. Through total synthesis, we tested the effects of amino acid substitutions, including alanine scanning, on the downregulation of receptor tyrosine kinases and vascular endothelial growth factor A (VEGF-A) and probed the stereospecificity of target engagement by epimerization of selected chiral centers. Differential effects on two types of secretory molecules suggest that the apratoxins' substrate selectivity with respect to inhibition of secretion may be tuned through structural modifications to provide tailored therapy. Our structure"activity relationship studies and medicinal chemistry efforts led to a potent inhibitor with in vivo efficacy in a colorectal tumor xenograft model without irreversible toxicity exerted by apratoxin A, demonstrating that this novel mechanism of action has therapeutic potential.
Chen, Qi-Yin,Liu, Yanxia,Luesch, Hendrik
supporting information; experimental part
p. 861 - 865
(2012/01/05)

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)

Evolved diversification of a modular natural product pathway: Apratoxins F and G, two cytotoxic cyclic depsipeptides from a palmyra collection of Lyngbya bouillonii
A collection of Lyngbya bouillonii from Palmyra Atoll in the Central Pacific, a site several thousand kilometers distant from all previous collections of this chemically prolific species of cyanobacterium, was found to contain two new cancer cell cytotoxins of the apratoxin family. The structures of the new compounds, apratoxins F and G, were determined by 1D and 2D NMR techniques in combination with mass spectrometric methods. Stereochemistry was explored by using chromatographic analyses of the hydrolytically released fragments in combination with NMR and optical rotation comparisons with known members of the apratoxin family. Apratoxins F and G add fresh insights into the SAR of this family because they incorporate an N-methyl alanine residue at a position where all prior apratoxins have possessed a proline unit, yet they retain high potency as cytotoxins to H-460 cancer cells with IC50 values of 2 and 14 nM, respectively. Additional assays using zone inhibition of cancer cells and clonogenic cells give a comparison of the activities of apratoxin F to apratoxin A. Additionally, the clonogenic studies in combination with maximum tolerated dose (MTD) studies provided insights as to dosing schedules that should be used for in vivo studies, and preliminary in vivo evaluation validated the predicted in vivo efficacy for apratoxin A. These new apratoxins are illustrative of a mechanism (the modification of an NRPS adenylation domain specificity pocket) for evolving a biosynthetic pathway so as to diversify the suite of expressed secondary metabolites.
Tidgewell, Kevin,Engene, Niclas,Byrum, Tara,Media, Joseph,Doi, Takayuki,Valeriote, Fred A.,Gerwick, William H.
experimental part
p. 1458 - 1466
(2011/05/02)

Lagunamides A and B: Cytotoxic and antimalarial cyclodepsipeptides from the marine cyanobacterium Lyngbya majuscula
Lagunamides A (1) and B (2) are new cyclic depsipeptides isolated from the marine cyanobacterium Lyngbya majuscula obtained from Pulau Hantu Besar, Singapore. The planar structural characterization of these molecules was achieved by extensive spectroscopic analysis, including 2D NMR experiments. In addition to Marfey's method and 3JH-H coupling constant values, a modified method based on Mosher's reagents and analysis using LC-MS was deployed for the determination of the absolute configuration. Lagunamides A and B displayed significant antimalarial properties, with IC50 values of 0.19 and 0.91 μM, respectively, when tested against Plasmodium falciparum. Lagunamides A and B also possessed potent cytotoxic activity against P388 murine leukemia cell lines, with IC50 values of 6.4 and 20.5 nM, respectively. Furthermore, these cyanobacterial compounds exhibited moderate antiswarming activities when tested against Pseudomonas aeruginosa PA01.
Tripathi, Ashootosh,Puddick, Jonathan,Prinsep, Michele R.,Rottmann, Matthias,Tan, Lik Tong
supporting information; experimental part
p. 1810 - 1814
(2011/02/28)

Cyclic tripeptides from the halotolerant fungus Aspergillus sclerotiorum PT06-1
Eleven new aspochracin-type cyclic tripeptides, sclerotiotides A-K (1-11), together with three known compounds, JBIR-15 (12), aspochracin (13), and penicillic acid, were isolated from the ethyl acetate extract of the fermentation broth of the halotolerant Aspergillus sclerotiorum PT06-1 in a hypersaline nutrient-rich medium. Their structures were elucidated by spectroscopic analysis and chemical methods. Chemical transformations of 12 and 13 proved that sclerotiotides D-K (4-11) were artifacts probably formed during the fermentation or subsequent isolation steps. All 13 cyclic tripeptides have been evaluated for their antimicrobial and cytotoxic effects. Only sclerotiotides A (1), B (2), F (6), and I (9) and JBIR-15 (12) showed selective antifungal activity against Candida albicans with MIC values of 7.5, 3.8, 30, 6.7, and 30 μM, respectively.
Zheng, Jinkai,Xu, Zhihong,Wang, Yi,Hong, Kui,Liu, Peipei,Zhu, Weiming
experimental part
p. 1133 - 1137
(2010/09/10)

Halogenated fatty acid amides and cyclic depsipeptides from an eastern Caribbean collection of the cyanobacterium Lyngbya majuscula
A lipophilic extract of an eastern Caribbean collection of Lyngbya majuscula yielded two new halogenated fatty acid amides, grenadamides B (1) and C (2), and two new depsipeptides, itralamides A (3) and B (4), along with the known compounds hectochlorin a
Jimenez, Jorge I.,Vansach, Tifanie,Yoshida, Wesley Y.,Sakamoto, Bryan,Poerzgen, Peter,Horgen, F. David
supporting information; experimental part
p. 1573 - 1578
(2010/03/31)

Synthesis of N-alkyl-N-methyl amino acids. Scope and limitations of base-induced N-alkylation of Cbz-amino acids
The reaction of N-benzyloxycarbonyl derivatives of aliphatic amino acids with NaH/alkyl iodides gave the corresponding N-Cbz-N-alkyl derivatives in good to high yields. The scope and limitations of this simple N-alkylation reaction were investigated as a convenient and flexible attempt to prepare unsymmetrically N,N-diprotected α-amino acids. The procedure is based on the N-alkylation of N-carbamoyl amino acids, a one-pot deprotection/protection sequence without extensive purification of the products. Protection of the carboxyl function is not required while the starting materials are inexpensive and commercially available.
Stodulski, Maciej,Mlynarski, Jacek
p. 970 - 975
(2008/09/21)

Apratoxin E, a cytotoxic peptolide from a guamanian collection of the marine cyanobacterium Lyngbya bouillonii
A collection of the marine cyanobacterium Lyngbya bouillonii from Guam afforded apratoxin E (1), a new peptide-polyketide hybrid of the apratoxin class of cytotoxins. The planar structure of 1 was elucidated by NMR spectroscopic analysis and mass spectrometry. Configurational assignments of stereocenters in the peptide portion were made by chiral HPLC analysis of the acid hydrolysate. The relative configuration in the polyketide moiety was assigned by comparison of NMR data including proton-proton coupling constants with those of the known analogues. Apratoxin E (1) displayed strong cytotoxicity against several cancer cell lines derived from colon, cervix, and bone, ranging from 21 to 72 nM, suggesting that the α,β-unsaturation of the modified cysteine residue is not essential for apratoxin activity. The 5- to 15-fold reduced activity compared with apratoxin A (2) is attributed to the dehydration in the long-chain polyketide unit, which could affect the conformation of the molecule.
Matthew, Susan,Schupp, Peter J.,Luesch, Hendrik
experimental part
p. 1113 - 1116
(2009/04/06)

Reductive methylation of primary and secondary amines and amino acids by aqueous formaldehyde and zinc
Amines can be methylated when treated with formaldehyde and zinc in aqueous medium. Selective mono- or dimethylation can be achieved by proper choice of pH, stoichiometry and reaction time. This method can also be applied for amino acids.
da Silva, Renato A.,Estevam, Idália H.S.,Bieber, Lothar W.
p. 7680 - 7682
(2008/03/30)

Influence of solvent viscosity on the rate of hydrolysis of dipeptides by carboxypeptidase Y
The influence of solvent viscosity on the rate of enzymatic hydrolysis of a series of dipeptides (Z-Phe-Gly, Z-Phe-Sar, Z-Phe-Ala, Z-Phe-NMeAla, Z-Phe-Aib and Z-Phe-Pro) by carboxypeptidase Y was investigated. The effect of solvent viscosity on the enzymatic hydrolysis revealed that whereas all Kcat values decreased with viscosity, those of the N-alkyl peptides decreased more than those of the N-H peptides. The kinetic behaviour implies the involvement of conformational changes of the enzyme in terms of the 'induced-fit' process. Copyright
Kanosue, Yoshifumi,Kojima, Satoshi,Ohkata, Katsuo
p. 448 - 457
(2007/10/03)

Relationship between the hydrophobicity of dipeptides and the Michaelis-Menten constant Km of their hydrolysis by carboxypeptidase-Y and carboxypeptidase-A
The enzymatic hydrolysis of dipeptides by carboxypeptidase-Y and carboxypeptidase-A was investigated. In the enzymatic hydrolysis of the dipeptides, a good linear relationship (r = 0.997 and 0.999) was found between the Michaelis-Menten constant (Km) and the hydrophobicity of the substrates evaluated from relative elution volume in reversed-phase HPLC. The correlation suggests that the hydrophobicity of the C-terminal amino acid is a major factor in governing the stability of the enzyme-substrate complex. The difference in the slope of the linear-regression lines seems to reflect the degree of relative hydrophobicity of the binding pockets in carboxypeptidase-Y and carboxypeptidase-A.
Kanosue, Yoshifumi,Kojima, Satoshi,Hiraga, Yoshikazu,Ohkata, Katsuo
p. 1187 - 1193
(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.
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(2008/06/13)

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)

General method for the synthesis of N-methyl amino acids and N-alkyl amino esters from O'Donnell's Schiff bases
N-methyl amino acids, including L-abrine, and N-alkyl amino esters, were synthesized by reductive amination of O'Donnell's Schiff base amino esters with NaBH3CN and formaldehyde, or the appropriate aldehyde in CH3CN or THF in good to excellent yields, and with high purity.
Chruma, Jason J.,Sames, Dalibor,Polt, Robin
p. 5085 - 5086
(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)

Preparation of N-protected N-alkylated amino acids
A process for preparing N-protected N-alkylated amino acids of the formula STR1 where Rs and R1 -R3 have the meanings indicated in the description comprises adding a compound of the abovementioned formula where R3 is hydrogen to a solution of a base in a non-protic solvent and subsequently adding an alkylating agent.
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(2008/06/13)

Enantioselective synthesis of α-N-alkylamino acids via sultam-directed 'enolate' hydroxyamination
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Oppolzer,Cintas-Moreno,Tamura,Cardinaux
p. 187 - 196
(2007/10/02)

Enzymatische Gewinnung enantiomerenreiner N-Alkyl-aminosaeuren
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Groeger, Ulrich,Drauz, Karlheinz,Klenk, Herbert
p. 222 - 224
(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)

Theonellamine B, a novel peptidal Na,K-ATPase inhibitor, from an Okinawan marine sponge of the genus Theonella
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Nakamura,Kobayashi,Nakamura,et al.
p. 4319 - 4322
(2007/10/02)

3-Acylamino-1-carboxymethylaminocarbonyl-2-azetidinones
Antibacterial activity is exhibited by 2-azetidinones having a 3-acylamino substituent and a 1-substituent of the formula STR1 (or a salt or ester thereof).
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(2008/06/13)