- Noncovalently Functionalized Commodity Polymers as Tailor-Made Additives for Stereoselective Crystallization
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Stereoselective inhibition of the nucleation and crystal growth of one enantiomer aided by “tailor-made” polymeric additives is an efficient method to obtain enantiopure compounds. However, the conventional preparation of polymeric additives from chiral monomers are laborious and limited in structures, which impedes their rapid optimization and applicability. Herein, we report a “plug-and-play” strategy to facilitate synthesis by using commercially available achiral polymers as the platform to attach various chiral small molecules as the recognition side-chains through non-covalent interactions. A library of supramolecular polymers made up of two vinyl polymers and six small molecules were applied with seeds in the selective crystallization of seven racemates in different solvents. They showed good to excellent stereoselectivity in yielding crystals with high enantiomeric purities in conglomerates and racemic compound forming systems. This convenient, low-cost modular synthesis strategy of polymeric additives will allow for high-efficient, economical resolution of various racemates on different scales.
- Wan, Xinhua,Wang, Zhaoxu,Ye, Xichong,Zhang, Jie
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supporting information
p. 20243 - 20248
(2021/08/09)
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- Krisynomycins, Imipenem Potentiators against Methicillin-Resistant Staphylococcus aureus, Produced by Streptomyces canus
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A reinvestigation of the acetone extract of the strain CA-091830 of Streptomyces canus, producer of the imipenem potentiator krisynomycin, resulted in the isolation of two additional analogues, krisynomycins B (1) and C (2), with different chlorination patterns. Genome sequencing of the strain followed by detailed bioinformatics analysis led to the identification of the corresponding biosynthetic gene cluster (BGC) of this cyclic nonribosomal peptide family. The planar structure of the new molecules was determined using HRMS, ESI-qTOF-MS/MS, and 1D and 2D NMR data. Their absolute configuration was proposed using a combination of Marfey's and bioinformatic BGC analyses. The krisynomycins displayed weak to negligible antibiotic activity against methicillin-resistant Staphylococcus aureus (MRSA), which was significantly enhanced when tested in combination with sublethal concentrations of imipenem. The halogenation pattern plays a key role in the antimicrobial activity and imipenem-potentiating effects of the compounds, with molecules having a higher number of chlorine atoms potentiating the effect of imipenem at lower doses.
- De La Cruz, Mercedes,Genilloud, Olga,González, Ignacio,Martín, Jesús,Oves-Costales, Daniel,Pérez-Bonilla, Mercedes,Reyes, Fernando,Vicente, Francisca
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p. 2597 - 2606
(2020/10/12)
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- JBIR-78 and JBIR-95: Phenylacetylated peptides isolated from Kibdelosporangium sp. AK-AA56
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The search for metabolites of Kibdelosporangium sp. AK-AA56 resulted in the discovery of novel N-phenylacetylated peptides, JBIR-78 (1) and JBIR-95 (2). Compounds 1 and 2 were established to be N-phenylacetylated heptapeptides by extensive NMR and HRESIMS analyses. The absolute configuration of the standard amino acids including a cysteic acid moiety was determined using Marfey's method on the acid hydrolysates of 1 and 2. The relative and absolute configurations of a nonstandard amino acid, β-hydroxyleucine, were elucidated using the J-based and modified Mosher's methods, respectively. In an antimicrobial test, 1 showed antibacterial activity against Micrococcus luteus.
- Izumikawa, Miho,Takagi, Motoki,Shin-Ya, Kazuo
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experimental part
p. 280 - 284
(2012/05/19)
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- Grassypeptolides A-C, cytotoxic bis-thiazoline containing marine cyclodepsipeptides
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Grassypeptolides A-C (1-3), a group of closely related bis-thiazoline containing cyclic depsipeptides, have been isolated from extracts of the marine cyanobacterium Lyngbya confervoides. Although structural differences between the analogues are minimal, comparison of the in vitro cytotoxicity of the series revealed a structure-activity relationship. When the ethyl substituent of 1 is changed to a methyl substituent in 2, activity is only slightly reduced (3-4-fold), whereas inversion of the Phe unit flanking the bis-thiazoline moiety results in 16-23-fold greater potency. We show that both 1 and 3 cause G1 phase cell cycle arrest at lower concentrations, followed at higher concentrations by G2/M phase arrest, and that these compounds bind Cu2+ and Zn 2+. The three-dimensional structure of 2 was determined by MS, NMR, and X-ray crystallography, and the structure of 3 was established by MS, NMR, and chemical degradation. The structure of 3 was explored by in silico molecular modeling, revealing subtle differences in overall conformation between 1 and 3. Attempts to interconvert 1 and 3 with base were unsuccessful, but enzymatic conversion may be possible and could be a novel form of activation for chemical defense.
- Kwan, Jason C.,Ratnayake, Ranjala,Abboud, Khalil A.,Paul, Valerie J.,Luesch, Hendrik
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experimental part
p. 8012 - 8023
(2011/03/20)
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- Alotamide A, a novel neuropharmacological agent from the marine cyanobacterium Lyngbya bouillonii
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Alotamide A (1), a structurally Intriguing cyclic depsipeptide, was isolated from the marine mat-forming cyanobacterlum Lyngbya bouillonii collected In Papua New Guinea. It features three contiguous peptidic residues and an unsaturated heptaketide with oxidations and methylations unlike those found In any other marine cyanobacterial metabolite. Pure alotamide A (1) displays an unusual calcium influx activation profile In murine cerebrocortical neurons with an EC50 of 4.18 uU.
- Soria-Mercado, Irma E.,Pereira, Alban,Cao, Zhengyu,Murray, Thomas F.,Gerwick, William H.
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supporting information; experimental part
p. 4704 - 4707
(2009/12/26)
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- A new and expeditious asymmetric synthesis of (R)- and (S)-2-aminoalkanesulfonic acids from chiral amino alcohols
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The mechanism for the transformation of β-amino alcohol methanesulfonate hydrochlorides into sodium β-amino alkanesulfonates using sodium sulfite was investigated. The results show that sodium sulfite initially neutralizes the β-amino alcohol methanesulfonate hydrochloride to give a free β-amino alcohol methanesulfonate, which then cyclizes to a 2-alkylaziridine. Attack by the previously formed sodium bisulfite at the less hindered carbon atom of the aziridine ring then yields a β-amino alkanesulfate sodium salt. Based on this mechanistic proposal, a new and rapid asymmetric synthesis of (R)- and (S)-2-aminoalkanesulfonic acids from chiral amino alcohols was developed. Chiral amino alcohols were converted to chiral aziridines through the Wenker method or Mitsunobu reaction and the resulting aziridines were reacted with sodium bisulfite to produce chiral β-amino alkanesulfonic acids.
- Xu, Jiaxi
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p. 1129 - 1134
(2007/10/03)
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