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Squamins C–F, four cyclopeptides from the seeds of Annona globiflora
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.
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)

Structures and antitumor activities of ten new and twenty known surfactins from the deep-sea bacterium Limimaricola sp. SCSIO 53532
Surfactins are natural biosurfactants with myriad potential applications in the areas of healthcare and environment. However, surfactins were almost exclusively produced by the bacterium Bacillus species in previous reported literatures, together with difficulty in isolating pure monomer, which resulted in making extensive effort to remove duplication and little discovery of new surfactins in recent years. In the present study, the result of Molecular Networking indicated that Limimaricola sp. SCSIO 53532 might well be a potential resource for surfacin-like compounds based on OSMAC strategy. To search for new surfactins with significant biological activity, further study was undertaken on the strain. As a result, ten new surfactins (1–10), along with twenty known surfactins (11–30), were isolated from the ethyl acetate extract of SCSIO 53532. Their chemical structures were established by detailed 1D and 2D NMR spectroscopy, HRESIMS data, secondary ion mass spectrometry (MS/MS) analysis, and chemical degradation (Marfey's method) analysis. Cytotoxic activities of twenty-seven compounds against five human tumor cell lines were tested, and five compounds showed significant antitumor activities with IC50 values less than 10 μM. Furtherly, analysis of structure–activity relationships revealed that the branch of side chain, the esterification of Glu or Asp residue, and the amino acid residue of position 7 possessed a great influence on antitumor activity.
Chen, Min,Chen, Rouwen,Ding, Wenping,Li, Yanqun,Tian, Xinpeng,Yin, Hao,Zhang, Si
(2022/01/11)

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)

Rational engineering ofAcinetobacter tandoiiglutamate dehydrogenase for asymmetric synthesis ofl-homoalanine through biocatalytic cascades
l-Homoalanine, a useful building block for the synthesis of several chiral drugs, is generally synthesized through biocascades using natural amino acids as cheap starting reactants. However, the addition of expensive external cofactors and the low efficiency of leucine dehydrogenases towards the intermediate 2-ketobutyric acid are two major challenges in industrial applications. Herein, a dual cofactor-dependent glutamate dehydrogenase fromAcinetobacter tandoii(AtGluDH) was identified to help make full use of the intracellular pool of cofactors when using whole-cell catalysis. Through reconstruction of the hydrophobic network between the enzyme and the terminal methyl group of the substrate 2-ketobutyric acid, the strict substrate specificity ofAtGluDH towards α-ketoglutarate was successfully changed, and the activity obtained by the most effective mutant (K76L/T180C) was 17.2 times higher than that of the wild-type protein. A three-enzyme co-expression system was successfully constructed in order to help release the mass transfer restriction. Using 1 Ml-threonine, which is close to the solubility limit, we obtained a 99.9% yield ofl-homoalanine in only 3.5 h without adding external coenzymes to the cascade, giving 99.9% ee and a 29.2 g L?1h?1space-time yield. Additionally, the activities of the engineeredAtGluDH towards some other hydrophobic amino acids were also improved to 1.1-11.2 fold. Therefore, the engineering design of some dual cofactor-dependent GluDHs could not only eliminate the low catalytic activity of unnatural substrates but also enhance the cofactor utilization efficiency of these enzymes in industrial applications.
Diao, Shiqing,Jiang, Shuiqin,Liu, Yan,Sun, Yangyang,Wang, Hualei,Wang, Liuzhu,Wei, Dongzhi
p. 4208 - 4215
(2021/06/30)

Leveraging Peptaibol Biosynthetic Promiscuity for Next-Generation Antiplasmodial Therapeutics
Malaria remains a worldwide threat, afflicting over 200 million people each year. The emergence of drug resistance against existing therapeutics threatens to destabilize global efforts aimed at controlling Plasmodium spp. parasites, which is expected to leave vast portions of humanity unprotected against the disease. To address this need, systematic testing of a fungal natural product extract library assembled through the University of Oklahoma Citizen Science Soil Collection Program has generated an initial set of bioactive extracts that exhibit potent antiplasmodial activity (EC50 25 μM, selectivity index > 250). The unique chemodiversity afforded by these fungal isolates serves to unlock new opportunities for translating peptaibols into a bioactive scaffold worthy of further development.
Lee, Jin Woo,Collins, Jennifer E.,Wendt, Karen L.,Chakrabarti, Debopam,Cichewicz, Robert H.
supporting information
p. 503 - 517
(2021/03/01)

Direct monitoring of biocatalytic deacetylation of amino acid substrates by1H NMR reveals fine details of substrate specificity
Amino acids are key synthetic building blocks that can be prepared in an enantiopure form by biocatalytic methods. We show that thel-selective ornithine deacetylase ArgE catalyses hydrolysis of a wide-range ofN-acyl-amino acid substrates. This activity was revealed by1H NMR spectroscopy that monitored the appearance of the well resolved signal of the acetate product. Furthermore, the assay was used to probe the subtle structural selectivity of the biocatalyst using a substrate that could adopt different rotameric conformations.
De Cesare, Silvia,McKenna, Catherine A.,Mulholland, Nicholas,Murray, Lorna,Bella, Juraj,Campopiano, Dominic J.
supporting information
p. 4904 - 4909
(2021/06/16)

Argicyclamides A-C Unveil Enzymatic Basis for Guanidine Bis-prenylation
Guanidine prenylation is an outstanding modification in alkaloid and peptide biosynthesis, but its enzymatic basis has remained elusive. We report the isolation of argicyclamides, a new class of cyanobactins with unique mono- and bis-prenylations on guanidine moieties, from Microcystis aeruginosa NIES-88. The genetic basis of argicyclamide biosynthesis was established by the heterologous expression and in vitro characterization of biosynthetic enzymes including AgcF, a new guanidine prenyltransferase. This study provides important insight into the biosynthesis of prenylated guanidines and offers a new toolkit for peptide modification.
Balloo, Nandani,Fujita, Kei,Matsuda, Kenichi,Okino, Tatsufumi,Phan, Chin-Soon,Wakimoto, Toshiyuki
supporting information
p. 10083 - 10087
(2021/07/26)

Method for photolysis of amido bonds
The invention discloses a method for photo-splitting amido bonds, wherein the method is mild in reaction condition and can realize splitting of amido bonds by using illumination. The method for photo-splitting the amido bonds comprises the following steps: reacting 2,4-dinitrofluorobenzene with an amino group of a substance which contains alpha amino acid at the tail end and is shown as a structural formula I to generate a compound 1 represented by a structural formula II; and under light irradiation, carrying out amido bond cleavage reaction on the compound 1, wherein R1 is a side chain group of alpha-amino acid, and R2 is aryl, aliphatic hydrocarbon, -CH(R)-COOH or polypeptide.
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Paragraph 0046; 0048-0049; 0070-0073

(2021/06/26)

Asymmetric β-Methylation of l- and d-α-Amino Acids by a Self-Contained Enzyme Cascade
This report describes a modular enzyme-catalyzed cascade reaction that transforms l- or d-α-amino acids to β-methyl-α-amino acids. In this process an α-amino acid transaminase, an α-keto acid methyltransferase, and a halide methyltransferase cooperate in two orthogonal reaction cycles that mediate product formation and regeneration of the cofactor pyridoxal-5′-phosphate and the co-substrate S-adenosylmethionine. The only stoichiometric reagents consumed in this process are the unprotected l- or d-α-amino acid and methyl iodide.
Liao, Cangsong,Seebeck, Florian P.
supporting information
p. 7184 - 7187
(2020/03/17)

Androsamide, a Cyclic Tetrapeptide from a Marine Nocardiopsis sp., Suppresses Motility of Colorectal Cancer Cells
A cyclic tetrapeptide, androsamide (1), was isolated from a marine actinomycete of the genus Nocardiopsis, strain CNT-189. The planar structure of 1 was assigned by the interpretation of 1D and 2D NMR spectroscopic data. The absolute configurations of constituent amino acids of 1 were determined by application of the Marfey's and advanced Marfey's methods. Androsamide (1) strongly suppressed the motility of Caco2 cells caused by epithelial-mesenchymal transition.
Lee, Jihye,Gamage, Chathurika. D. B.,Kim, Geum Jin,Hillman, Prima F.,Lee, Chaeyoung,Lee, Eun Young,Choi, Hyukjae,Kim, Hangun,Nam, Sang-Jip,Fenical, William
p. 3166 - 3172
(2020/11/02)

Unique polyhalogenated peptides from the marine sponge Ircinia sp.
Two new bromopyrrole peptides, haloirciniamide A (1) and seribunamide A (2), have been isolated from an Indonesian marine sponge of the genus Ircinia collected in the Thousand Islands (Indonesia). The planar structure of both compounds was assigned on the basis of extensive 1D and 2D NMR spectroscopy and mass spectrometry. The absolute configuration of the amino acid residues in 1 and 2 was determined by the application of Marfey's method. Compound 1 is the first dibromopyrrole cyclopeptide having a chlorohistidine ring, while compound 2 is a rare peptide possessing a tribromopyrrole ring. Both compounds failed to show significant cytotoxicity against four human tumor cell lines, and neither compound was able to inhibit the enzyme topoisomerase I or impair the interaction between programmed cell death protein PD1 and its ligand, PDL1.
Fernández, Rogelio,Bayu, Asep,Hadi, Tri Aryono,Bueno, Santiago,Pérez, Marta,Cuevas, Carmen,Putra, Masteria Yunovilsa
(2020/08/28)

Semi-rational hinge engineering: modulating the conformational transformation of glutamate dehydrogenase for enhanced reductive amination activity towards non-natural substrates
The active site is the common hotspot for rational and semi-rational enzyme activity engineering. However, the active site represents only a small portion of the whole enzyme. Identifying more hotspots other than the active site for enzyme activity engineering should aid in the development of biocatalysts with better catalytic performance. Glutamate dehydrogenases (GluDHs) are promising and environmentally benign biocatalysts for the synthesis of valuable chirall-amino acids by asymmetric reductive amination of α-keto acids. GluDHs contain an inter-domain hinge structure that facilitates dynamic reorientations of the domains relative to each other. Such hinge-bending conformational motions of GluDHs play an important role in regulating the catalytic activity. Thus, the hinge region represents a potential hotspot for catalytic activity engineering for GluDHs. Herein, we report semi-rational activity engineering of GluDHs with the hinge region as the hotspot. Mutants exhibiting significantly improved catalytic activity toward several non-natural substrates were identified and the highest activity increase reached 104-fold. Molecular dynamics simulations revealed that enhanced catalytic activity may arise from improving the open/closed conformational transformation efficiency of the protein with hinge engineering. In the batch production of three valuablel-amino acids, the mutants exhibited significantly improved catalytic efficiency, highlighting their industrial potential. Moreover, the catalytic activity of several active site tailored GluDHs was also increased by hinge engineering, indicating that hinge and active site engineering are compatible. The results show that the hinge region is a promising hotspot for activity engineering of GluDHs and provides a potent alternative for developing high-performance biocatalysts toward chirall-amino acid production.
Liu, Yayun,Meng, Lijun,Wu, Jianping,Yang, Lirong,Yin, Xinjian,Zhou, Haisheng
p. 3376 - 3386
(2020/06/09)

Direct Synthesis of Free α-Amino Acids by Telescoping Three-Step Process from 1,2-Diols
A practical telescoping three-step process for the syntheses of α-amino acids from the corresponding 1,2-diols has been developed. This process enables the direct synthesis of free α-amino acids without any protection/deprotection step. This method was also effective for the preparation of a 15N-labeled α-amino acid. 1,2-Diols bearing α,β-unsaturated ester moieties afforded bicyclic α-amino acids through intramolecular [3 + 2] cycloadditions. A preliminary study suggests that the resultant α-amino acids are resolvable by aminoacylases with almost complete selectivity.
Inada, Haruki,Shibuya, Masatoshi,Yamamoto, Yoshihiko
supporting information
p. 709 - 713
(2019/01/25)

Cyclic tetrapeptides from the marine strain Streptomyces sp. PNM-161a with activity against rice and yam phytopathogens
Two cyclotetrapeptides, henceforth named Provipeptides A (1) and B (2), along with five known diketopiperazines (3–7) were isolated from the liquid culture of marine Streptomyces sp. 161a recovered from a sample of sea grass Bryopsis sp. The structures of cyclotetrapeptides and diketopiperazines (DKPs) were established by 1D and 2D NMR data, MS, and by comparison with literature data. The absolute stereochemistry of compounds cyclo-(l-Pro-l-Leu-d-Pro-l-Phe) 1 and cyclo-(-Pro-Ile-Pro-Phe) 2 was established by the Marfey’s method. Compound 1 showed antibacterial activity against rice phytopathogenic strains Burkholderia glumae (MIC = 1.1 mM) and Burkholderia gladioli (MIC = 0.068 mM), compound 2 was active only against B. glumae (MIC = 1.1 mM), and DKP cyclo-[l-Pro-l-Leu] 5 showed to be active against B. gladioli (MIC = 0.3 mM) and B. glumae (MIC = 2.4 mM). Compounds 1 and 2 showed 65% and 50% inhibition of Colletotrichum gloeosporioides (yam pathogen) conidia germination, respectively at a concentration of 1.1 mM.
Betancur, Luz A.,Forero, Abel M.,Romero-Otero, Adriana,Sepúlveda, Lady Yohanna,Moreno-Sarmiento, Nubia C.,Castellanos, Leonardo,Ramos, Freddy A.
p. 744 - 751
(2019/07/05)

Discovery of Amantamide, a Selective CXCR7 Agonist from Marine Cyanobacteria
CXCR7 plays an emerging role in several physiological processes. A linear peptide, amantamide (1), was isolated from marine cyanobacteria, and the structure was determined by NMR and mass spectrometry. The total synthesis was achieved by solid-phase method. After screening two biological target libraries, 1 was identified as a selective CXCR7 agonist. The selective activation of CXCR7 by 1 could provide the basis for developing CXCR7-targeted therapeutics and deciphering the role of CXCR7 in different diseases.
Liang, Xiao,Luo, Danmeng,Yan, Jia-Lei,Rezaei, Mohammad A.,Salvador-Reyes, Lilibeth A.,Gunasekera, Sarath P.,Li, Chenglong,Ye, Tao,Paul, Valerie J.,Luesch, Hendrik
supporting information
p. 1622 - 1626
(2019/03/07)

Isolation and structure determination of a new cytotoxic peptide, curacozole, from Streptomyces curacoi based on genome mining
Using genome mining, a new cytotoxic peptide named curacozole was isolated from Streptomyces curacoi. Through ESI-MS and NMR analyses, curacozole was determined to be a macrocyclic peptide containing two isoleucine, two thiazole and three oxazole moieties. Curacozole exhibited potent cytotoxic activity against HCT116 and HOS cancer cells. The proposed biosynthetic gene cluster of curacozole was identified and compared with that of the related compound YM-216391.
Kaweewan, Issara,Komaki, Hisayuki,Hemmi, Hikaru,Hoshino, Kanata,Hosaka, Takeshi,Isokawa, Gouchi,Oyoshi, Takanori,Kodani, Shinya
p. 1 - 7
(2018/10/20)

Preparation and characterization of a new open-tubular capillary column for enantioseparation by capillary electrochromatography
In order to use the enantioseparation capability of cationic cyclodextrin and to combine the advantages of capillary electrochromatography (CEC) with open-tubular (OT) column, in this study, a new OT-CEC, coated with cationic cyclodextrin (1-allylimidazolium-β-cyclodextrin [AI-β-CD]) as chiral stationary phase (CSP), was prepared and applied for enantioseparation. Synthesized AI-β-CD was characterized by infrared (IR) spectrometry and mass spectrometry (MS). The preparation conditions for the AI-β-CD-coated column were optimized with the orthogonal experiment design L9(34). The column prepared was characterized by scanning electron microscopy (SEM) and elemental analysis (EA). The results showed that the thickness of stationary phase in the inner surface of the AI-β-CD-coated columns was about 0.2 to 0.5?μm. The AI-β-CD content in stationary phase based on the EA was approximately 2.77?mmol·m?2. The AI-β-CD-coated columns could separate all 14 chiral compounds (histidine, lysine, arginine, glutamate, aspartic acid, cysteine, serine, valine, isoleucine, phenylalanine, salbutamol, atenolol, ibuprofen, and napropamide) successfully in the study and exhibit excellent reproducibility and stability. We propose that the column, coated with AI-β-CD, has a great potential for enantioseparation in OT-CEC.
Li, Yingjie,Tang, Yimin,Qin, Shili,Li, Xue,Dai, Qiang,Gao, Lidi
p. 283 - 292
(2019/02/05)

Driving Transamination Irreversible by Decomposing Byproduct Α-Ketoglutarate into Ethylene Using Ethylene-Forming Enzyme
The transformations of transaminases have been extensively studied as an approach to the production of chiral amino moieties. However, the low equilibrium conversion of the reaction is a critical disadvantage to transaminase application, and a strategy for shifting the reaction equilibrium is essential. Herein, we have developed a novel method to effectively prevent the reversibility of transamination by fully decomposing byproduct α-ketoglutarate into ethylene and carbon dioxide in situ using ethylene-forming enzyme (EFE). Two transaminases and one EFE were expressed in E. coli and purified to be used in the cascade reaction. After optimal reaction conditions were determined based on the enzymatic properties, a cascade reaction coupling transaminase with EFE was conducted and showed high efficiency in the synthesis of l-phosphinothricin. Finally, using this approach with only an equivalent amount of amino donor l-glutamate increased the conversions of various keto acids from 99%. This strategy shows great potential for transamination using glutamate as the amino donor.
Meng, Li-Jun,Liu, Ya-Yun,Zhou, Hai-Sheng,Yin, Xin-Jian,Wu, Jian-Ping,Wu, Mian-Bin,Xu, Gang,Yang, Li-Rong
p. 3309 - 3314
(2018/10/02)

Purification, structural characterization and bioactivity evaluation of a novel proteoglycan produced by Corbicula fluminea
A novel proteoglycan, named CFPS-11, was isolated from Corbicula fluminea, which is a food source of freshwater bivalve mollusk. CFPS-11 had an average molecular weight of 807.7 kDa and consisted of D-glucose and D-glucosamine in a molar ratio of 12.2:1.0. The protein moiety (～5%) of CFPS-11 was covalently bonded to the polysaccharide chain in O-linkage type through both serine and thereonine residues. The polysaccharide chain of CFPS-11 was composed of (1 → 4)-α-D-glucopyranosyl and (1 → 3,6)-α-D-glucopyranosyl residues, which branched at O-6. The branch chain consisted of (1 →)-α-D-glucopyranosyl and (1 →)-α-D-N-acetylglucosamine residues. CFPS-11 exhibited significant antioxidant activity in a dose-dependent manner and remarkable inhibition activities against α-amylase and α-glucosidase by in vitro assays. These findings indicated that the CFPS-11 from C. fluminea has the potential for development as a health food ingredient.
Yan, Jing-Kun,Wang, Yao-Yao,Qiu, Wen-Yi,Wu, Li-Xia,Ding, Zhi-Chao,Cai, Wu-Dan
p. 11 - 18
(2017/08/29)

Chromatographic Resolution of α-Amino Acids by (R)-(3,3'-Halogen Substituted-1,1'-binaphthyl)-20-crown-6 Stationary Phase in HPLC
Three new chiral stationary phases (CSPs) for high-performance liquid chromatography were prepared from R-(3,3'-halogen substituted-1,1'-binaphthyl)-20-crown-6 (halogen = Cl, Br and I). The experimental results showed that R-(3,3'-dibromo-1,1'-binaphthyl)-20-crown-6 (CSP-1) possesses more prominent enantioselectivity than the two other halogen-substituted crown ether derivatives. All twenty-one α-amino acids have different degrees of separation on R-(3,3'-dibromo-1,1'-binaphthyl)-20-crown-6-based CSP-1 at room temperature. The enantioselectivity of CSP-1 is also better than those of some commercial R-(1,1'-binaphthyl)-20-crown-6 derivatives. Both the separation factors (α) and the resolution (Rs) are better than those of commercial crown ether-based CSPs [CROWNPAK CR(+) from Daicel] under the same conditions for asparagine, threonine, proline, arginine, serine, histidine and valine, which cannot be separated by commercial CR(+). This study proves the commercial usefulness of the R-(3,3'-dibromo-1,1'-binaphthyl)-20-crown-6 chiral stationary phase.
Wu, Peng,Wu, Yuping,Zhang, Junhui,Lu, Zhenyu,Zhang, Mei,Chen, Xuexian,Yuan, Liming
supporting information
p. 1037 - 1042
(2017/07/25)

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)

Vanadium(V)-catalyzed epimerization of isoleucine
All stereoisomers of isoleucine were transformed to the mixtures of the corresponding epimers by epimerization in alkaline aqueous solution. The catalyst was formed in situ by condensation of salicylaldehyde and isoleucine followed by complexation with va
Krivosudsky, Luká?,Schwendt, Peter,Filo, Juraj
p. 96 - 99
(2016/08/24)

Neopeapyran, an unusual furo[2,3b]pyran analogue and turnagainolide C from a soil Streptomyces sp. S2236
Neopeapyran (1), an unusual furo[2,3b]pyran analogue, together with a new cyclopeptide, turnagainolide C (2), were isolated from Streptomyces sp. S2236 associated with the rhizosphere soil of Panax notoginseng. The planar structure and relative configuration of neopeapyran (1) were elucidated on the basis of spectroscopic techniques, while the absolute configuration was determined by TDDFT calculation. The absolute configuration of turnagainolide C (2) was determined by partial hydrolysis, together with the advanced Marfey's method and spectroscopic analysis. The antimicrobial activities of these two compounds were also investigated.
Zhou, Hao,Yang, Ya-Bin,Duan, Rong-Ting,Yang, Xue-Qiong,Zhang, Ju-Cheng,Xie, Xiao-Guang,Zhao, Li-Xing,Ding, Zhong-Tao
supporting information
p. 1044 - 1047
(2016/07/29)

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)

Pembamide, a N-methylated linear peptide from a sponge Cribrochalina sp.
A new highly N-methylated linear peptide, pembamide (1), has been isolated from the marine sponge Cribrochalina sp. (family Niphatidae) collected off the coast of Pemba (Tanzania). The planar structure of 1 was assigned on the basis of extensive 1D and 2D NMR spectroscopy and mass spectrometry. The absolute configuration of the amino acid residues in 1 was determined by application of the Advanced Marfey's method. Compound 1 displayed significant cytotoxicity against three human tumor cell lines with GI50values in the micromolar range.
Urda, Carlos,Pérez, Marta,Rodríguez, Jaime,Jiménez, Carlos,Cuevas, Carmen,Fernández, Rogelio
supporting information
p. 3239 - 3242
(2016/07/11)

A novel thyroglobulin-binding lectin from the brown alga Hizikia fusiformis and its antioxidant activities
A lectin (HFL) was isolated from the brown alga, Hizikia fusiformis, through ion exchange on cellulose DE52 and HPLC with a TSK-gel G4000PWXL column. SDS-PAGE showed that HFL had a molecular mass of 16.1 kDa. The HPLC (with a TSK-gel G4000PWXL column) indicated that HFL is a tetramer in its native state. The total carbohydrate content was 41%. Glucose, galactose and fucose were the monosaccharide units of HFL, and the normalized mol% values were 6, 14 and 80, respectively. HFL contains a large amount of the acidic amino acid, Asx. The β-elimination reaction suggested that the oligosaccharide and peptide moieties of HFL may belong to the N-glucosidic linkage. The amino acid sequences, of about five segments of HFL, were acquired by MALDI-TOF/TOF, and the sequences have no homology with other lectins. HFL was found to agglutinate sheep erythrocytes. The hemagglutination activity was inhibited by thyroglobulin, from bovine thyroid, but not by any of the monosaccharides tested. The lectin reaction was independent of the presence of the divalent cation Ca2+. HFL showed free radical scavenging activity against hydroxyl, DPPH and ABTS+ radicals.
Wu, Mingjiang,Tong, Changqing,Wu, Yue,Liu, Shuai,Li, Wei
p. 7 - 13
(2016/02/03)

MBJ-0110, a novel cyclopeptide isolated from the fungus Penicillium sp. f25267
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Kawahara, Teppei,Itoh, Masashi,Kozone, Ikuko,Izumikawa, Miho,Sakata, Noriaki,Tsuchida, Toshio,Shin-Ya, Kazuo
p. 66 - 68
(2016/02/03)

Deciphering the Biosynthetic Origin of L-allo-Isoleucine
The nonproteinogenic amino acid l-allo-isoleucine (l-allo-Ile) is featured in an assortment of life forms comprised of, but not limited to, bacteria, fungi, plants and mammalian systems including Homo sapiens. Despite its ubiquity and functional importance, the specific origins of this unique amino acid have eluded characterization. In this study, we describe the discovery and characterization of two enzyme pairs consisting of a pyridoxal 5′-phosphate (PLP)-linked aminotransferase and an unprecedented isomerase synergistically responsible for the biosynthesis of l-allo-Ile from l-isoleucine (l-Ile) in natural products. DsaD/DsaE from the desotamide biosynthetic pathway in Streptomyces scopuliridis SCSIO ZJ46, and MfnO/MfnH from the marformycin biosynthetic pathway in Streptomyces drozdowiczii SCSIO 10141 drive l-allo-Ile generation in each respective system. In vivo gene inactivations validated the importance of the DsaD/DsaE pair and MfnO/MfnH pair in l-allo-Ile unit biosynthesis. Inactivation of PLP-linked aminotransferases DsaD and MfnO led to significantly diminished desotamide and marformycin titers, respectively. Additionally, inactivation of the isomerase genes dsaE and mfnH completely abolished production of all l-allo-Ile-containing metabolites in both biosynthetic pathways. Notably, in vitro biochemical assays revealed that DsaD/DsaE and MfnO/MfnH each catalyze a bidirectional reaction between l-allo-Ile and l-Ile. Site-directed mutagenesis experiments revealed that the enzymatic reaction involves a PLP-linked ketimine intermediate and uses an arginine residue from the C-terminus of each isomerase to epimerize the amino acid β-position. Consequently, these data provide important new insight into the origins of l-allo-Ile in natural products with medicinal potential and illuminate new possibilities for biotool development.
Li, Qinglian,Qin, Xiangjing,Liu, Jing,Gui, Chun,Wang, Bo,Li, Jie,Ju, Jianhua
supporting information
p. 408 - 415
(2016/01/25)

Jamaicensamide A, a Peptide Containing β-Amino-α-keto and Thiazole-Homologated η-Amino Acid Residues from the Sponge Plakina jamaicensis
A new cyclic peptide, jamaicensamide A, composed of six amino acids, including a thiazole-homologated amino acid, was isolated from the Bahamian sponge Plakina jamaicensis, along with known compounds bitungolide A and franklinolide A. The structure of the title peptide was solved by integrated analysis of MS, 1D and 2D NMR data, oxidation-hydrolyses to α-amino acids, and their stereodetermination by Marfey's method. The close structural resemblance of Western Atlantic-derived jamaicensamide A to known Western Pacific-derived peptides of lithistid sponges in the genus Theonella and Discodermia suggests a common origin: the symbiotic bacterium Entotheonella sp., a so-called "talented producer" responsible for biosynthesis of most Theonella-associated peptides. Similar natural products from sponges of disparate genera evince the likelihood that these invertebrates harbor the same or a very similar symbiont.
Jamison, Matthew T.,Molinski, Tadeusz F.
supporting information
p. 2243 - 2249
(2016/10/04)

Versiquinazolines A-K, Fumiquinazoline-Type Alkaloids from the Gorgonian-Derived Fungus Aspergillus versicolor LZD-14-1
Eleven fumiquinazoline-type alkaloids, namely, versiquinazolines A-K (1-11), along with cottoquinazolines B-D, were isolated from the gorgonian-derived fungus Aspergillus versicolor LZD-14-1. Their structures were determined by extensive analyses of the spectroscopic data (1D and 2D NMR, HRESIMS), in addition to the experimental and calculated ECD data and X-ray single-crystal diffraction analysis for the assignments of the absolute configurations. Versiquinazolines A, B, and F (1, 2, and 6), bearing a methanediamine or an aminomethanol unit and representing a unique subtype of fumiquinazolines, were found from nature for the first time. Possible biogenetic relationships of the versiquinazolines are postulated. In addition, the structures of cottoquinazolines B (12), D (13), and C (14) should be revised to the enantiomers. Compounds 1, 2, 7, and 11 exhibited inhibitory activities against thioredoxin reductase (IC50 values ranging from 12 to 20 μM).
Cheng, Zhongbin,Lou, Lanlan,Liu, Dong,Li, Xiaodan,Proksch, Peter,Yin, Sheng,Lin, Wenhan
p. 2941 - 2952
(2016/12/07)

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)

Site-specific labeling of synthetic peptide using the chemoselective reaction between N-methoxyamino acid and isothiocyanate
Site-specific labeling of synthetic peptides carrying N-methoxyglycine (MeOGly) by isothiocyanate is demonstrated. A nonapeptide having MeOGly at its N-terminus was synthesized by the solid-phase method and reacted with phenylisothiocyanate under various conditions. In acidic solution, the reaction specifically gave a peptide having phenylthiourea structure at its N-terminus, leaving side chain amino group intact. The synthetic human β-defensin-2 carrying MeOGly at its N-terminus or the side chain amino group of Lys10 reacted with phenylisothiocyanate or fluorescein isothiocyanate also at the N-methoxyamino group under the same conditions, demonstrating that this method is generally useful for the site-specific labeling of linear synthetic peptides as well as disulfide-containing peptides.
Hara, Toshiaki,Purwati, Euis Maras,Tainosyo, Akira,Kawakami, Toru,Hojo, Hironobu,Aimoto, Saburo
p. 765 - 769
(2015/09/21)

Enantiospecific C-H Activation Using Ruthenium Nanocatalysts
The activation of C-H bonds has revolutionized modern synthetic chemistry. However, no general strategy for enantiospecific C-H activation has been developed to date. We herein report an enantiospecific C-H activation reaction followed by deuterium incorporation at stereogenic centers. Mechanistic studies suggest that the selectivity for the α-position of the directing heteroatom results from a four-membered dimetallacycle as the key intermediate. This work paves the way to novel molecular chemistry on nanoparticles.
Taglang, Céline,Martínez-Prieto, Luis Miguel,Del Rosal, Iker,Maron, Laurent,Poteau, Romuald,Philippot, Karine,Chaudret, Bruno,Perato, Serge,Sam Lone, Ana?s,Puente, Céline,Dugave, Christophe,Rousseau, Bernard,Pieters, Grégory
supporting information
p. 10474 - 10477
(2015/09/02)

Microseiramide from the freshwater cyanobacterium Microseira sp. UIC 10445
Abstract Microseiramide (1), a cyclic heptapeptide, was isolated from a sample of the freshwater cyanobacterium Microseira sp. UIC 10445 collected in a shallow lake in Northern Indiana. Taxonomic identification of UIC 10445 was performed by a combination of morphological and phylogenetic characterization. Phylogenetic analysis revealed that UIC 10445 was a member of the recently described genus Microseira, which is phylogenetically distinct from the morphologically similar genera, Moorea and Lyngbya. The planar structure of microseiramide (1) was determined by extensive 1D and 2D NMR experiments as well as HRESIMS analysis. The absolute configurations of amino acid residues were determined using acid hydrolysis followed by the advanced Marfey's analysis. Microseiramide (1) is the first cyclic peptide reported from a Microseira sp., and the structure of microseiramide (1) is distinct from the previously known metabolites from cyanobacteria of the genera Moorea and Lyngbya.
Luo, Shangwen,Krunic, Aleksej,Chlipala, George E.,Orjala, Jimmy
p. 47 - 52
(2015/06/08)

Cystargolides, 20S proteasome inhibitors isolated from Kitasatospora cystarginea
Two novel β-lactone-containing natural products, cystargolides A (1) and B (2), were isolated from the actinomycete Kitasatospora cystarginea. The production of these two natural products was highlighted using a methodology associating liquid chromatography-high-resolution mass spectrometry (LC-HRMS) analysis and the statistical analysis tool principal component analysis (PCA). Their structures were elucidated by interpretation of NMR experiments and tandem mass spectrometry. The absolute configurations of the amino acid residues were determined using Marfey's method, and the relative configurations of the β-lactone substituents were determined on the basis of the vicinal 3JHH coupling value. Due to the presence of the β-lactone, 1 and 2 were evaluated for their ability to inhibit the human 20S proteasome. 1 and 2 both inhibited the 20S proteasome in vitro with IC50 values of 0.35 and 0.93 μM, respectively.
Gill, Krista A.,Berrué, Fabrice,Arens, Jennifer C.,Carr, Gavin,Kerr, Russell G.
supporting information
p. 822 - 826
(2015/05/13)

Rapid, effective deprotection of tert-butoxycarbonyl (Boc) amino acids and peptides at high temperatures using a thermally stable ionic liquid
A method for high temperature Boc deprotection of amino acids and peptides in a phosphonium ionic liquid is described. The ionic liquid had low viscosity, high thermal stability and demonstrated a beneficial effect. The study extended the possibility for extraction of water soluble polar organic molecules using ionic liquids. Trace water significantly improved product purity and yield, while only 2 equiv. TFA led to deprotection within 10 min. The trityl group was also deprotected.
Bhawal, Sumit S.,Patil, Rahul A.,Armstrong, Daniel W.
p. 95854 - 95856
(2015/11/24)

Biochemical characterisation and assessment of fibril-forming ability of collagens extracted from Bester sturgeon Huso huso × Acipenser ruthenus
Collagens purified from Bester sturgeon organs were characterised biochemically, and their fibril-forming abilities and fibril morphologies formed in vitro clarified. Yields of collagens were 2.1%, 11.9%, 0.4%, 18.1%, 0.4%, 0.8% and 0.03% (collagen dry weight/tissue wet weight) from scales, skin, muscle, swim bladder, digestive tract, notochord and snout cartilage, respectively. Using SDS-PAGE and amino acid composition analyses, collagens from scales, skin, muscle, the swim bladder and digestive tract were characterised as type I, and collagens from the notochord and snout cartilage as type II. Denaturation temperatures of the collagens, measured using circular dichroism, were 29.6, 26.8, 29.0, 32.9, 31.6 and 36.3 °C in scales, skin, muscle, swim bladder, digestive tract, and notochord, respectively. For fibril formation, swim bladder and skin collagen showed a more rapid rate of increase in turbidity, a shorter time to attain the maximum turbidity, and formed thicker fibrils compared with porcine tendon type I collagen.
Zhang, Xi,Ookawa, Mika,Tan, Yongkai,Ura, Kazuhiro,Adachi, Shinji,Takagi, Yasuaki
p. 305 - 312
(2014/05/06)

Structures and solution conformational dynamics of stylissamides G and H from the Bahamian Sponge Stylissa caribica
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.
Wang, Xiao,Morinaka, Brandon I.,Molinski, Tadeusz F.
supporting information
p. 625 - 630
(2014/04/17)

SEPARATING AGENT AND MANUFACTURING METHOD THEREOF
An embodiment of the present invention is a separating agent wherein a group represented by a chemical formula of: or a group represented by a chemical formula of: is introduced on a surface thereof.
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Paragraph 0067; 0068; 0069; 0070; 0071; 0072; 0083; 0084

(2015/01/07)

The specificity and kinetic mechanism of branched-chain amino acid aminotransferase from Escherichia coli studied with a new improved coupled assay procedure and the enzyme's potential for biocatalysis
Branched-chain amino acid aminotransferase (BCAT) plays a key role in the biosynthesis of hydrophobic amino acids (such as leucine, isoleucine and valine), and its substrate spectrum has not been fully explored or exploited owing to the inescapable restrictions of previous assays, which were mainly based on following the formation/consumption of the specific branched-chain substrates rather than the common amino group donor/acceptor. In our study, detailed measurements were made using a novel coupled assay, employing (R)-hydroxyglutarate dehydrogenase from Acidaminococcus fermentans as an auxiliary enzyme, to provide accurate and reliable kinetic constants. We show that Escherichia coli BCAT can be used for asymmetric synthesis of a range of non-natural amino acids such as l-norleucine, l-norvaline and l-neopentylglycine and compare the kinetic results with the results of molecular modelling. A full two-substrate steady-state kinetic study for several substrates yields results consistent with a bi-bi ping-pong mechanism, and detailed analysis of the kinetic constants indicates that, for good 2-oxoacid substrates, release of 2-oxoglutarate is much slower than release of the product amino acid during the transamination reaction. The latter is in fact rate-limiting under conditions of substrate saturation.
Yu, Xuejing,Wang, Xingguo,Engel, Paul C.
p. 391 - 400
(2014/01/23)

Reniochalistatins A-E, cyclic peptides from the marine sponge Reniochalina stalagmitis
Five new cyclic peptides (including four heptapeptides and one octapeptide), reniochalistatins A-E (1-5), were isolated and characterized from the marine sponge Reniochalina stalagmitis collected off Yongxing Island in the South China Sea. Their structures were assigned on the basis of HRESIMS, 1D and 2D NMR spectroscopic data, and MALDI-TOF/TOF data for sequence analysis. The absolute configurations of all of the amino acid residues were determined using chiral-phase HPLC and Marfey's analysis. The cyclic octapeptide reniochalistatin E showed biological activity in various cytotoxicity assays employing different tumor cell lines (RPMI-8226, MGC-803, HL-60, HepG2, and HeLa).
Zhan, Kai-Xuan,Jiao, Wei-Hua,Yang, Fan,Li, Jing,Wang, Shu-Ping,Li, Yu-Shan,Han, Bing-Nan,Lin, Hou-Wen
p. 2678 - 2684
(2015/02/05)

Facile synthesis of α-hydroxy carboxylic acids from the corresponding α-amino acids
An effective and improved procedure is developed for the synthesis of α-hydroxy carboxylic acids by treatment of the corresponding protonated α-amino acid with tert-butyl nitrite in 1,4-dioxane-water. The amino moiety must be protonated and located α to a carboxylic acid function in order to undergo initial diazotization and successive hydroxylation, since neither β-amino acids nor acid derivatives such as esters and amides undergo hydroxylations. The method is successfully applied for the synthesis of 18 proteinogenic amino acids.
Stuhr-Hansen, Nicolai,Padrah, Shahrokh,Str?mgaard, Kristian
supporting information
p. 4149 - 4151
(2015/02/02)

Nostosins, trypsin inhibitors isolated from the terrestrial cyanobacterium Nostoc sp. strain FSN
Two new trypsin inhibitors, nostosin A (1) and B (2), were isolated from a hydrophilic extract of Nostoc sp. strain FSN, which was collected from a paddy field in the Golestan Province of Iran. Nostosins A (1) and B (2) are composed of three subunits, 2-hydroxy-4-(4-hydroxyphenyl)butanoic acid (Hhpba), l-Ile, and l-argininal (1) or argininol (2). Nostosins A (1) and B (2) exhibited IC50 values of 0.35 and 55 μM against porcine trypsin, respectively, suggesting that the argininal aldehyde group plays a crucial role in the efficient inhibition of trypsin. Molecular docking of nostosin A (1) (449 Da), leupeptin (426 Da, IC50 0.5 μM), and spumigin E (610 Da, IC50 A (1) and leupeptin but only partial binding similarity with spumigin E. The number of hydrogen bonds between ligands and trypsin increased according to the length and size of the ligand molecule, and the docking affinity values followed the measured IC50 values. Nostosin A (1) is the first highly potent three-subunit trypsin inhibitor with potency comparable to the known commercial trypsin inhibitor leupeptin. These findings expand the known diversity of short-chain linear peptide protease inhibitors produced by cyanobacteria.
Liu, Liwei,Jokela, Jouni,Wahlsten, Matti,Nowruzi, Bahareh,Permi, Perttu,Zhang, Yue Zhou,Xhaard, Henri,Fewer, David P.,Sivonen, Kaarina
p. 1784 - 1790
(2014/10/16)

Biocatalytic asymmetric synthesis of unnatural amino acids through the cascade transfer of amino groups from primary amines onto keto acids
Flee to the hills: An unfavorable equilibrium in the amino group transfer between amino acids and keto acids catalyzed by α-transaminases was successfully overcome by coupling with a ω-transaminase reaction as an equilibrium shifter, leading to efficient asymmetric synthesis of diverse unnatural amino acids, including L-tert-leucine and D-phenylglycine. Copyright
Park, Eul-Soo,Dong, Joo-Young,Shin, Jong-Shik
p. 3538 - 3542
(2014/01/06)

Champacyclin, a new cyclic octapeptide from Streptomyces strain C42 isolated from the Baltic Sea
New isolates of Streptomyces champavatii were isolated from marine sediments of the Gotland Deep (Baltic Sea), from the Urania Basin (Eastern Mediterranean), and from the Kiel Bight (Baltic Sea). The isolates produced several oligopeptidic secondary metabolites, including the new octapeptide champacyclin (1a) present in all three strains. Herein, we report on the isolation, structure elucidation and determination of the absolute stereochemistry of this isoleucine/leucine (Ile/Leu = Xle) rich cyclic octapeptide champacyclin (1a). As 2D nuclear magnetic resonance (NMR) spectroscopy could not fully resolve the structure of (1a), additional information on sequence and configuration of stereocenters were obtained by a combination of multi stage mass spectrometry (MSn) studies, amino acid analysis, partial hydrolysis and subsequent enantiomer analytics with gas chromatography positive chmical ionization/electron impact mass spectrometry (GC-PCI/EI-MS) supported by comparison to reference dipeptides. Proof of the head-to-tail cyclization of (1a) was accomplished by solid phase peptide synthesis (SPPS) compared to an alternatively side chain cyclized derivative (2). Champacyclin (1a) is likely synthesized by a non-ribosomal peptide synthetase (NRPS), because of high content of (D)-amino acids. The compound (1a) showed antimicrobial activity against the phytopathogen Erwinia amylovora causing the fire blight disease of certain plants.
Pesic, Alexander,Baumann, Heike I.,Kleinschmidt, Katrin,Ensle, Paul,Wiese, Jutta,Suessmuth, Roderich D.,Imhoff, Johannes F.
p. 4834 - 4857
(2014/02/14)

Structure and biosynthesis of xenoamicins from entomopathogenic xenorhabdus
During the search for novel natural products from entomopathogenic Xenorhabdus doucetiae DSM17909 and X. mauleonii DSM17908 novel peptides named xenoamicins were identified in addition to the already known antibiotics xenocoumacin and xenorhabdin. Xenoamicins are acylated tridecadepsipeptides consisting of mainly hydrophobic amino acids. The main derivative xenoamicin A (1) was isolated from X. mauleonii DSM17908, and its structure elucidated by detailed 1 D and 2 D NMR experiments. Detailed MS experiments, also in combination with labeling experiments, confirmed the determined structure and allowed structure elucidation of additional derivatives. Moreover, the xenoamicin biosynthesis gene cluster was identified and analyzed in X. doucetiae DSM17909, and its participation in xenoamicin biosynthesis was confirmed by mutagenesis. Advanced Marfey's analysis of 1 showed that the absolute configuration of the amino acids is in agreement with the predicted stereochemistry deduced from the nonribosomal peptide synthetase XabABCD. Biological testing revealed activity of 1 against Plasmodium falciparum and other neglected tropical diseases but no antibacterial activity.
Zhou, Qiuqin,Grundmann, Florian,Kaiser, Marcel,Schiell, Matthias,Gaudriault, Sophie,Batzer, Andreas,Kurz, Michael,Bode, Helge B.
supporting information
p. 16772 - 16779
(2014/01/06)

SEPARATING AGENT FOR CHROMATOGRAPHY
A separating agent for chromatography is provided that is useful for the separation of specific compounds, e.g., for the optical resolution of amino acids. This separating agent for chromatography provides a higher productivity and contains a crown ether-like cyclic structure and optically active binaphthyl. This separating agent for chromatography containing a crown ether-like cyclic structure and optically active binaphthyl is provided by introducing a substitution group for binding to carrier into a specific commercially available 1,1′-binaphthyl derivative that has substituents at the 2, 2′, 3, and 3′ positions, then introducing a crown ether-like cyclic structure, and subsequently chemically bonding the binaphthyl derivative to the carrier through the substitution group for binding to carrier.
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Paragraph 0074; 0075

(2013/08/15)

Surugamides A-E, cyclic octapeptides with four D-amino acid residues, from a marine streptomyces sp.: LC-MS-aided inspection of partial hydrolysates for the distinction of D- and L-amino acid residues in the sequence
Surugamides A-E (1-5), cyclic octapeptides with four d-amino acid residues, were isolated from the broth of marine-derived Streptomyces sp. Their planar structures were determined by analyses of spectroscopic data, and the absolute configuration of constituent amino acid residues was determined by the Marfey's method. Differentiation of d-Ile and l-Ile in the sequence was established by chiral analysis of fragment peptides obtained from the partial hydrolysate, whose identification was conducted by LC-MS/MS.
Takada, Kentaro,Ninomiya, Akihiro,Naruse, Masato,Sun, Yi,Miyazaki, Masayuki,Nogi, Yuichi,Okada, Shigeru,Matsunaga, Shigeki
p. 6746 - 6750
(2013/07/26)

Isolation and synthesis of falcitidin, a novel myxobacterial-derived acyltetrapeptide with activity against the malaria target falcipain-2
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.
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
(2013/07/27)

Structure elucidation and antimalarial activity of apicidin F: An apicidin-like compound produced by Fusarium fujikuroi
Apicidins are cyclic tetrapeptides with histone deacetylase inhibitory activity. Since their discovery in 1996 a multitude of studies concerning the activity against protozoa and certain cancer cell lines of natural and synthetic apicidin analogues have been published. Until now, the only published natural sources of apicidin are the fungus Fusarium pallidoroseum, later known as F. semitectum and two unspecified Fusarium strains. The biosynthetic origin of apicidins could be associated with a gene cluster, and a biosynthetic pathway has been proposed. Recently, our group was able to identify for the first time an apicidin-like gene cluster in F. fujikuroi that apparently does not lead to the production of any known apicidin analogue. By overexpressing the pathway-specific transcription factor we were able to identify a new apicidin-like compound. The present study provides the complete structure elucidation of the new compound, named apicidin F. Activity evaluation against Plasmodium falciparum showed good in vitro activity with an IC50 value of 0.67 μM.
Von Bargen, Katharina Walburga,Niehaus, Eva-Maria,Bergander, Klaus,Brun, Reto,Tudzynski, Bettina,Humpf, Hans-Ulrich
p. 2136 - 2140
(2014/01/06)