91-09-8Relevant articles and documents
Synthesis and structural insights into the binding mode of the albomycin δ1 core and its analogues in complex with their target aminoacyl-tRNA synthetase
De Graef, Steff,Gadakh, Bharat,Nautiyal, Manesh,Pang, Luping,Strelkov, Sergei V.,Van Aerschot, Arthur,Vondenhoff, Gaston,Weeks, Stephen D.
, (2020/07/21)
Despite of proven efficacy and well tolerability, albomycin is not used clinically due to scarcity of material. Several attempts have been made to increase the production of albomycin by chemical or biochemical methods. In the current study, we have synthesized the active moiety of albomycin δ1 and investigated its binding mode to its molecular target seryl-trna synthetase (SerRS). In addition, isoleucyl and aspartyl congeners were prepared to investigate whether the albomycin scaffold can be extrapolated to target other aminoacyl-tRNA synthetases (aaRSs) from both class I and class II aaRSs, respectively. The synthesized analogues were evaluated for their ability to inhibit the corresponding aaRSs by an in vitro aminoacylation experiment using purified enzymes. It was observed that the diastereomer having the 5′S, 6′R-configuration (nucleoside numbering) as observed in the crystal structure, exhibits excellent inhibitory activity in contrast to poor activity of its companion 5′R,6′S-diasteromer obtained as byproduct during synthesis. Moreover, the albomycin core scaffold seems well tolerated for class II aaRSs inhibition compared with class I aaRSs. To understand this bias, we studied X-ray crystal structures of SerRS in complex with the albomycin δ1 core structure 14a, and AspRS in complex with compound 16a. Structural analysis clearly showed that diastereomer selectivity is attributed to the steric restraints of the active site of SerRS and AspRS.
Methyl glycosides via Fischer glycosylation: translation from batch microwave to continuous flow processing
Aronow, Jonas,Stanetty, Christian,Baxendale, Ian R.,Mihovilovic, Marko D.
, p. 11 - 19 (2018/11/27)
Abstract: A continuous flow procedure for the synthesis of methyl glycosides (Fischer glycosylation) of various monosaccharides using a heterogenous catalyst has been developed. In-depth analysis of the isomeric composition was undertaken and high consistency with corresponding results observed under microwave heating was obtained. Even in cases where addition of water was needed to achieve homogeneity—a prerequisite for the flow experiments—no detrimental effect on the conversion was found. The scalability was demonstrated on a model case (mannose) and as part of the target-oriented synthesis of d-glycero-d-manno heptose, both performed on multigram scale.
Biosynthetic Origin of the Atypical Stereochemistry in the Thioheptose Core of Albomycin Nucleoside Antibiotics
Ushimaru, Richiro,Liu, Hung-Wen
supporting information, (2019/02/14)
Albomycins are peptidyl thionucleoside natural products that display antimicrobial activity against clinically important pathogens. Their structures are characterized by a thioheptose with atypical stereochemistry including a d-xylofuranose ring modified with a d-amino acid moiety. Herein it is demonstrated that AbmH is a pyridoxal 5′-phosphate (PLP)-dependent transaldolase that catalyzes a threo-selective aldol-type reaction to generate the thioheptose core with a d-ribofuranose ring and an l-amino acid moiety. The conversion of l-to d-amino acid configuration is catalyzed by the PLP-dependent epimerase AbmD. The d-ribo to d-xylo conversion of the thiofuranose ring appears according to gene deletion experiments to be mediated by AbmJ, which is annotated as a radical S-adenosyl-l-methionine (SAM) enzyme. These studies establish several key steps in the assembly of the thioheptose core during the biosynthesis of albomycins.
TRITERPENE SAPONIN SYNTHESIS, INTERMEDIATES AND ADJUVANT COMBINATIONS
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Page/Page column 82; 83; 84, (2018/11/10)
The present application relates to triterpene glycoside saponin-derived adjuvants, syntheses thereof, and intermediates thereto. The application also provides pharmaceutical compositions comprising compounds of the present invention and methods of using said compounds or compositions in the treatment of and immunization for infectious diseases.
Ring-opened 4-hydroxy-δ-valerolactone subunit as a key structural fragment of polyesters that degrade without acid formation
Nifant'ev, Ilya E.,Shlyakhtin, Andrey V.,Bagrov, Vladimir V.,Ezhov, Roman N.,Lozhkin, Boris A.,Churakov, Andrei V.,Ivchenko, Pavel V.
, p. 629 - 631 (2018/12/13)
Random copolymers of ?-caprolactone with O-benzyl-protected 4-hydroxy- or 2,4-dihydroxy-δ-valerolactone after hydrogenation form γ-hydroxy functionalized polyesters that degrade via the cyclization to γ-butyrolactone fragments without carboxylic acid formation.
Selective C?O Bond Cleavage of Sugars with Hydrosilanes Catalyzed by Piers’ Borane Generated In Situ
Zhang, Jianbo,Park, Sehoon,Chang, Sukbok
supporting information, p. 13757 - 13761 (2017/10/09)
Described herein is the selective reduction of sugars with hydrosilanes catalyzed by using Piers’ borane [(C6F5)2BH] generated in situ. The hydrosilylative C?O bond cleavage of silyl-protected mono- and disaccharides in the presence of a (C6F5)2BH catalyst, generated in situ from (C6F5)2BOH, takes place with excellent chemo- and regioselectivities to provide a range of polyols. A study of the substituent effects of sugars on the catalytic activity and selectivity revealed that the steric environment around the anomeric carbon (C1) is crucial.
Synthesis of a novel polyester building block from pentoses by tin-containing silicates
Elliot,Andersen,Tolborg,Meier,Sádaba,Daugaard,Taarning
, p. 985 - 996 (2017/01/13)
We report here the direct formation of the new chemical product trans-2,5-dihydroxy-3-pentenoic acid methyl ester from pentoses using tin-containing silicates as catalysts. The product is formed under alkali-free conditions in methanol at temperatures in the range 140-180 °C. The highest yields are found using Sn-Beta as the catalyst. Under optimised conditions, a yield of 33% is achieved. Purified trans-2,5-dihydroxy-3-pentenoic acid methyl ester was used for co-polymerisation studies with ethyl 6-hydroxyhexanoate using Candida antarctica lipase B as the catalyst. The co-polymerisation yields a product containing functional groups originating from trans-2,5-dihydroxy-3-pentenoic acid methyl ester in the polyester backbone. The reactivity of the incorporated olefin and hydroxyl moieties was investigated using trifluoroacetic anhydride and thiol-ene chemistry, thus illustrating the potential for functionalising the new co-polymers.
Binding pattern of intermediate UDP-4-keto-xylose to human UDP-xylose synthase: Synthesis and STD NMR of model keto-saccharides
Puchner, Claudia,Eixelsberger, Thomas,Nidetzky, Bernd,Brecker, Lothar
, p. 50 - 58 (2016/12/14)
Human UDP-xylose synthase (hUXS1) exclusively converts UDP-glucuronic acid to UDP-xylose via intermediate UDP-4-keto-xylose (UDP-Xyl-4O). Synthesis of model compounds like methyl-4-keto-xylose (Me-Xyl-4O) is reported to investigate the binding pattern thereof to hUXS1. Hence, selective oxidation of the desired hydroxyl function required employment of protecting group chemistry. Solution behavior of synthesized keto-saccharides was studied without enzyme via1H and13C NMR spectroscopy with respect to existent forms in deuterated potassium phosphate buffer. Keto-enol tautomerism was observed for all investigated keto-saccharides, while gem-diol hydrate forms were only observed for 4-keto-xylose derivatives. Saturation transfer difference (STD) NMR was used to study binding of synthesized keto-gylcosides to wild type hUXS1. Resulting epitope maps were correlated to earlier published molecular modeling studies of UDP-Xyl-4O. STD NMR results of Me-Xyl-4O are in good agreement with simulations of the intermediate UDP-Xyl-4O indicating a strong interaction of proton H3 with the enzyme, potentially caused by active site residue Ala79. In contrast, pyranoside binding pattern studies of methyl uronic acids showed some differences compared to previously published STD NMR results of UDP-glycosides. In general, obtained results can contribute to a better understanding in binding of UDP-glycosides to other UXS enzyme family members, which have high structural similarities in the active site.
Efficient isomerization of methyl arabinofuranosides into corresponding arabinopyranosides in presence of pyridine
Prabhakar, Sunchu,Lemiègre, Lo?c,Benvegnu, Thierry,Hotha, Srinivas,Ferrières, Vincent,Legentil, Laurent
, p. 63 - 66 (2016/07/22)
Fisher glycosylation, the oldest but efficient reaction towards alkyl glycosides, suffers nonetheless from lack of selectivity, especially when dealing with pentoses. In this case, a mixture of the four isomers, namely the furanosides and the pyranosides, is formed. According to previous studies, the rate and selectivity of the reaction depend greatly on the reaction time and the temperature. In this report, another factor was evaluated, the introduction of a weak nucleophilic base. Interestingly, addition of pyridine few hours after the reaction has started allowed rapid isomerization of the methyl pentofuranosides into its pyranoside counterparts. The reaction proceeds with great diastereoselectivity using arabinose, ribose, xylose and lyxose as starting pentoses. Corresponding methyl pyranosides were obtained as the sole isomers with yields ranging from 65% to 75%.
Flavonoid glycosides from Siparuna gigantotepala leaves and their antioxidant activity
Casta?eda, Harlen Gerardo Torres,Dulcey, Ana Julia Colmenares,Martínez, José Hipólito Isaza
, p. 502 - 506 (2016/06/01)
Two new flavonol g1lycosides were isolated from the leaves of Siparuna gigantotepala. Their structures were determined to be kaempferol 3-O-β-xylopyranosyl-(1→2)-α-arabinofuranoside (1) and kaempferol 3,7-di-O-methyl-4′-O-α-rhamnopyranosyl-(1→2)-β-glucopy
