Deuterated Disaccharides for the Investigation of Protein-Carbohydrate Interactions-Application of Bioaffinity-and STD-NMR

ABSTRACT

NMR spectroscopic analysis of carbohydrates often suffers from severe overlap of resonance signals, especially in ¹H NMR spectra. Therefore, we synthesized four 2,3,4-trideuterio-α-L-fucose containing disaccharides, α-L-Fuc-(1→6)-β-D-GlcNAc-OMe 1, α-L-Fuc-(1→4)-β-D-GlcNAc-OMe 2, α-L-Fuc-(1→3)-β-D-GlcNAc-OMe 3, and α-L-Fuc-(1→2)-β-D-Gal-OMe 4. Compounds 1 to 4 are well suited to be subjected to NMR conformational analysis because their ¹H NMR spectra show almost no overlap of signals. The deuterated disaccharides 1 to 4 will therefore be used as NMR probes for the exploration of fucose-binding proteins. With a mixture of the corresponding non-deuterated disaccharides it is demonstrated that recently developed parallel NMR screening protocols, Bio-Affinity NMR and STD-NMR, deliver fast and robust tools to assay the compounds synthesized for protein-binding affinity.     

含氨基酸单元的手性主体的合成及手性识别研究

以L-丙氨酸和2,7-二萘酚为原料通过简单的方法合成了二种带有荧光基团萘的手性阴离子主体(1和2), 用红外光谱、质谱、元素分析、核磁共振氢谱及碳谱表征了它们的结构. 用荧光光谱及核磁共振氢谱研究了主体与二苯甲酰酒石酸阴离子的相互作用, 结果表明1, 2与D-或L-二苯甲酰酒石酸阴离子均形成1∶1的配合物, 主体1展现出良好的对二苯甲酰酒石酸阴离子对映选择性识别能力.     

13C, 15N and 113Cd NMR and Molecular Orbital Studies of Novel Bile Acid N-(2-aminoethyl)amides and Their Cd2+-complexes

Lithocholic acid N-(2-aminoethyl)amide (1) and deoxycholic acid N-(2-aminoethyl)amide(2) have been prepared and characterized by¹H, ¹³C and ¹⁵N NMR. The accurate molecular masses of 1 and 2 have been determined by ESI MS. The formation of the Cd²⁺-complexes (1+Cd and 2+Cd) in CD₃OD solution have been detected by ¹H,¹³C, ¹⁵N and ¹¹³Cd NMR. The ¹³C NMR chemical shift assignments of 1 and 2 and their Cd²⁺-complexes are based on DEPT-135 and z-GS ¹H,¹³C HMQC experiments as well as comparison with the assignments of the related structures. The ¹⁵N NMR chemical shiftassignments of the ligands and theirCd²⁺-complexes are based on z-GS¹H,¹⁵N HMBC experiments. ¹³C NMR chemical shift differences between 1and its 1:1 Cd²⁺-complex based on ab initiocalculations at Hartree-Fock SCI-PCM level using3-21G(d) basis set are in agreement with theexperimental shift changes observed onCd²⁺-complexation.     

玉米须中的一个新黄酮和两个尿素苷

玉米须是我国传统中药, 具有多种生物活性. 为了寻找玉米须中的生物活性成分, 对玉米须的化学成分进行了研究, 从中分离得到一个新黄酮1和两个尿素苷2和3. 应用多种波谱学方法(¹H NMR, ¹³C NMR, HSQC, HMBC, ¹H-¹H COSY, ESI-MS等), 确定了3个化合物的化学结构. 化合物1为新化合物, 鉴定为6-乙酰基-木犀草素; 化合物2和3是两个新的天然产物, 分别鉴定为鼠李糖尿素苷和1,3-二鼠李糖尿素苷. 首次对两个新天然产物的氢谱和碳谱数据进行了全归属.     

酰基硫脲衍生物的合成、结构表征及生物活性研究

在超声波辐射下, 以PEG-400为固-液相转移催化剂, 用芳胺与双酰基异硫氰酸酯反应, 合成出了15种新的结构不对称的双酰基硫脲类化合物(6和6')和9种新的分子中含酰胺基团的单酰基硫脲类化合物(7和7'). 利用元素分析, IR, ¹H NMR, ¹³C NMR, APT, 1D NOE及2D NMR技术确定了所合成化合物6和6'及7和7'的结构, 并对它们NMR谱中低场C, H进行了归属. 杀菌、杀虫和除草活性筛选测定实验结果表明, 所测试化合物对瓜炭疽病菌均具有抑制作用, 其中6e抑制率最高, 达到62.4%; 目标化合物7a对黄瓜白粉病菌有一定的抑制作用. 单胺氧化酶活性测定实验表明：大部分目标化合物对单胺氧化酶具有一定的抑制活性, 其中浓度在1×10^－3 mol•L^－1时目标化合物6'c和6'd的抑制活性较强, 明显高于其它化合物. 目标化合物没有抗惊厥活性.     

CONFORMATION OF EIGHT-MEMBERED DIOXATHIASILOCIN HETEROCYCLES IN SOLUTION

Abstract

The dibenzo[d,g][1,3,6,2]dioxathiasilocin derivatives 3a-f were prepared by the reaction of the thiobisphenols 1a-b with the corresponding dichlorosilanes 2a-e using triethylamine as an acid acceptor. The free energy of activation for ring inversion of the 2,4,8,10-tetra-tert-butyl-substituted 3a was determined by variable temperature ¹H NMR to be 13.9 kcal/mol. The ¹H NMR spectral data of 3a requires that the ring conformer possess a σ plane of symmetry passing through the silicon and bridging sulfur atoms. In the variable temperature ¹H NMR spectra of the 2,4,8,10-tetramethyl-substituted 3b no evidence was observed for the slowing of ring inversion at-55^oC, suggesting that the energy of activation for ring inversion is less than 10.9 kcal/mol. The ¹H NMR spectral data of 3e-f indicates the presence of equilibrating conformational isomers. The results of this study supports the suggestion that steric factors are a major contributor to the barrier of ring inversion for the dibenzo-[d, g][1,3,6,2]dioxathiasilocin ring system.     

Two novel steroidal derivatives from chloroform-soluble extract of Hoya longifolia

The structures of two novel steroidal derivatives (1 and 4) were elucidated. Steroidal derivatives namely fologenin (1) and hoyagenin (4) have been isolated from chloroform-soluble extract of the whole plant of Hoya longifolia (family: Asclepiadaceae), and their structures were determined by using ¹H NMR, ¹³C NMR, ¹H–¹H COSY and FAB-MS techniques as well as chemical degradation and derivatisation.     

Antifungal activity against Botrytis cinerea of labdane-type diterpenoids isolated from the resinous exudate of Haplopappus velutinus Remy (Asteraceae)

Two labdane diterpenoids were isolated, from the resinous exudate of Haplopappus velutinus Remy (Asteraceae); the main compound was identified as 7,13-(E)-labdadien-15,18-dioic-acid-18-methyl ester (1) and the minor compound identified as 7-labden-15,18-dioic-acid-18-methyl ester (2). Their structures were obtained using FTIR, MS, HRMS and NMR data: 1D NMR (¹H, ¹³C and DEPT-135), 2D homonuclear NMR (COSY and NOESY) and heteronuclear NMR (HSQC and HMBC). The trans stereochemistry of the decalin moiety of compounds 1 and 2 was established through NOESY experiments of the reduction product of 1; 7-labden-15,18-diol (1a). Diterpenoids 1 and 1a are described for the first time and showed antifungal activity, inhibiting approximately 40% mycelial growth of Botrytis cinerea.     

Synthesis of Novel Chalcone Analogues of Ferrocene Biarenes

Abstract

The novel structures of organometallic compounds, 1-biaryl-3-ferrocenyl-2-propene-1-one (5) and 3-biaryl-1-ferrocenyl-2-propene-1-one (9) were synthesized for nonlinear optical chromophores by Suzuki cross-coupling reaction. Their structures were determined with elemental analyses, IR spectra, ¹H NMR spectra, and ¹³C NMR spectra.     

Determination of a new chromone from Aurantii Fructus Immaturus by DFT/GIAO method

Investigation of EtOAc fraction from the 95% ethanol extract of Aurantii Fructus Immaturus led to the isolation of one new chromone (1) and seven known flavonoids (2–8). Their structures were elucidated mainly by NMR and HR-ESI-MS, as well as on comparison with the reported NMR data. The final substituent pattern of 1 was defined by comparison of ¹³C NMR data calculated by DFT/GIAO with those of experimental NMR data.     

A new anthraquinone and eight constituents from Hedyotis caudatifolia Merr. et Metcalf: isolation,purification and structural identification

Hedyotis caudatifolia Merr. et Metcalf. (HC), a folk medicine in Yao nationalities areas in China, was used to investigate the chemical constituents. Through silica gel and Sephadex LH-20 column chromatography, nine compounds were isolated and purified. By physical and chemical properties, IR, MS (EI-MS, high resolution EI-MS), 1D NMR (¹H NMR, ¹³C NMR) and 2D NMR (HSQC, ¹H–¹H COSY, HMBC), their structures were identified as β-sitosterol (1), stigmasterol (2), scopolin (3), 2-hydroxy-1,7,8-trimethoxyanthracene-9,10-dione (4), oleanolic acid (5), ursolic acid (6), methyl barbinervate (7), β-daucosterol (8) and p-Hydroxybenzoic acid (9). These compounds were isolated from HC for the first time, and 4 a new anthraquinone whose biological activities are worth to be investigated in future. These compounds may contribute to the HC’s pharmacological effects on treating diseases, and may be used as candidates for control index in establishing the quality control standard of HC.     

A new naphthoquinone and a new neolignan from <Emphasis Type="Italic">Ligularia vellerea</Emphasis> rhizomes

In the course of phytochemical investigations of Ligularia vellerea rhizomes, a new naphthoquinone, 2,5-dihydroxy-6,7-dimethylnaphthoquinone (1), and a new neolignan, 4-[(3',4'-dihydroxycinnamoyl)-oxy]methyl cinnamate (2), have been isolated and characterized on the basis of spectroscopic methods (¹H NMR, ¹³C NMR, 2D NMR, and MS).     

Regioselective synthesis and structures of anti-cancer 20(R)-ginsenoside Rg3 derivatives

Abstract

Regioselective synthesis of three novel palmitates of 20(R)-ginsenoside Rg₃ was accomplished via a facile strategy, along with complete assignment of their ¹H and ¹³C NMR resonances by 1D and 2D NMR (¹H-¹H COSY, DEPT 135, HSQC, HMBC, and NOESY) techniques. The derivatives were tested for in vitro anti-proliferative activities against pancreatic cancer PANC-1 cells. Compounds 2, 3, and 4 exhibited more potent activity than did 20(R)-ginsenoside Rg₃.     

Diterpenoid acids from <Emphasis Type="Italic">Pinus koraiensis</Emphasis>

Two new diterpenoid acids, pinusenocarp (1) and pinusenoid (2), were isolated from the pine cone of Pinus koraiensis. All the compounds were characterized on the basis of spectral analysis, viz. ¹H NMR, ¹³C NMR, IR, UV, ESI-MS, and elemental analysis.     

Synthesis and Characterization of New Chalcone Derivatives from cis-Bicyclo[3.2.0]hept-2-en-6-one

A series of chalcone derivatives (3a–k) were prepared via the reaction of cis-bicyclo[3.2.0]hept-2-en-6-one (1) with the respective arylaldehydes (2a–k) and were then characterized by Fourier transform infrared (FT-IR), ¹H NMR, ¹³C NMR, and elemental analyses.     

A NOVEL SYNTHESIS OF ISOXAZOLES VIA 1,3-DIPOLAR CYCLOADDITION OF NITRILE OXIDES TO ACETYL ACETONE

ABSTRACT

Nitrile oxides (2) isolated from the oxidative dehydrogenation of aldoximes (1) by chloramines-T react with acetyl acetone (3) to afford 4-acetyl-3-aryl-5-methyl isoxazoles (5) in good yield. All new compounds were characterized by IR, ¹H NMR, ¹³C NMR, MS studies and elemental analysis.     

Isolation and characterisation of three new anthraquinone secondary metabolites from Symplocos racemosa

Three new anthraquinone secondary metabolites were isolated from Symplocos racemosa, a small tree of family symplocaceae. The structures of compounds (1–3) were elucidated to be 1,4-dihydroxy-6-(ethoxymethyl)-8-propylanthracene-9,10-dione (1), 1,4-dihydroxy-6-(hydroxymethyl)-8-butylanthracene-9,10-dione (2) and 1,4-dihydroxy-6-(hydroxymethyl)-8-propyl anthracene-9,10-dione (3) using their spectral data, i.e. through IR, UV, ¹H NMR, ¹³C NMR and two-dimensional (2D) NMR techniques including heteronuclear multiple quantum coherence, heteronuclear multiple bond correlation and correlation spectroscopy.     

A mycophenolic acid derivative from the fungus Penicillium sp. SCSIO sof101

Abstract

Mycophenolic acid (MPA) is a group of metabolite derived from several species of Penicillium, which shows potent bioactivity. In this study, a new derivative of MPA compound named penicacid D (1), was isolated from the marine derived fungus Penicillium sp. SCSIO sof101, along with seven known compounds (2-8). Their structures were elucidated based on the HR-ESI-MS and NMR data. Moreover, the ¹H and ¹³C NMR data of compound 2 and the ¹³C NMR data of compound 3 are reported. Compounds 1, 4 and 6 exhibited weak activities against Escherichia coli (clinical isolation number 100385570) and Acinetobacter baumannii (clinical isolation number 100069).     

A novel naphthoquinone from <Emphasis Type="Italic">Plumbago zeylanica</Emphasis> roots

A novel naphthoquinone (1) was isolated from the methanol extract of P. zeylanica roots in addition to a known compound plumbagin (2). Their structures were determined by UV, IR, MS, ¹H, and ¹³C NMR spectroscopic analysis, including 2D NMR.     

Synthesis,NMR, and Computational Study of 1,2-Diethyl-3-(trimethylsilyl)cyclopropenylium Hexachloroantimonate

Preparation and ¹³C NMR identification of 1,2-diethyl-3-(trimethylsilyl)cyclopropenylium hexachloroantimonate (4) is described. The assignment of the NMR data was corroborated by calculating ¹³C NMR chemical shifts of the corresponding model ion 4M. The total stabilization of the parent cyclopropenylium ion 1 substituted by the silyl and the two methyl groups is found to be only slightly lower than stabilization of the trimethyl derivative. The computed NICS(1) parameters reveal that all of the examined ions possess substantial aromatic character.