Rotating Frame Nuclear Overhauser Effect Research Articles

Preparation and physicochemical characterization of inclusion complex of pterostilbene-hydroxypropyl-β-cyclodextrin for enhancing the application of pterostilbene in cosmetics

Pterostilbene (PTS) is a kind of natural plant polyphenol with a high antioxidant capacity. However, it is a challenge to apply PTS in cosmetic formulations due to its lower water solubility and stability. In order to overcome these limitations, a PTS-hydroxypropyl-β-cyclodextrin (PTS-HP-β-CD) inclusion complex with a 1:1 host–guest molar ratio was prepared using the stirred solution method. The inclusion complex of PTS-HP-β-CD was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), proton nuclear magnetic resonance (1H NMR), two-dimensional rotating frame nuclear Overhauser effect spectroscopy (2D ROESY), thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). Additionally, the photostability and antioxidant activity of PTS and PTS-HP-β-CD were also evaluated. After complexation with HP-β-CD, the water solubility of PTS was found to be 81-fold higher by phase solubility. The results of XRD, SEM, 1H NMR, and 2D ROESY demonstrated that PTS was successfully encapsulated by HP-β-CD and formed a 1:1 inclusion complex. After the formation of the PTS-HP-β-CD inclusion complex, TG, DSC, UV irradiation, DPPH radical scavenging activity, hydroxyl radical scavenging activity, and superoxide anion radical scavenging activity revealed that the stability and antioxidant activity of PTS were enhanced. Therefore, this work could provide a promising approach to improve the application of PTS or other polyphenolic substances in cosmetic formulations.

Major Carotenoids of Meiothermus ruber Are Deinoxanthin Glucoside Esters, Not Meiothermoxanthin Glucoside Esters

Meiothermus ruber DSMZ 1279T was isolated from a hot spring in Kamchatka and was red in color. The major carotenoid present was reported to be 1'-(β-d-glucopyranosyloxy)-3,4,3',4'-tetradehydro-1',2'-dihydro-β,ψ-caroten-2-one after saponification (Burgess et al. J. Nat. Prod. 1999, 62, 859-863). In this study, we purified the major carotenoids in this species without saponification. We then reidentified the major carotenoids present using spectroscopic data, including electronic circular dichroism (ECD), 1H NMR, rotating-frame nuclear Overhauser effect spectroscopy (ROESY), 13C NMR, heteronuclear single-quantum correlation spectroscopy (HSQC), heteronuclear multiple-bond correlation spectroscopy (HMBC), and MS, and enzymatic hydrolysis of fatty acid moieties and found deinoxanthin glucoside iso fatty acid esters. The bound fatty acids present included four iso types, and their composition differed from cellular lipids. Moreover, the previously identified carotenoid glucoside was a saponification artifact of deinoxanthin glucoside esters. Ketomyxocoxanthin glucoside esters and 1'-hydroxytorulene glucoside esters were also present. On the basis of the identification of carotenoids and the whole genome sequence of M.ruber, we propose a carotenoid biosynthetic pathway and note the corresponding genes.

Remotely controllable supramolecular rotor mounted inside a porphyrinic cage

Remotely controllable supramolecular rotor mounted inside a porphyrinic cage

Dynamic enzymatic synthesis of γ-cyclodextrin using a photoremovable hydrazone template

Dynamic enzymatic synthesis of γ-cyclodextrin using a photoremovable hydrazone template

Effect of mechanochemical inclusion of triamterene into sulfobutylether-β-cyclodextrin and its improved dissolution behavior

The formation of inclusion complexes between triamterene (TT) and cyclodextrins (CDs) to increase the water apparent solubility of TT was investigated. UV data showed that the binding constant of the TT/sulfobutylether-β-cyclodextrin (SBE-β-CD) inclusion complex was 510 L/mol. The phenyl ring of TT was inserted into the secondary hydroxy face of SBE-β-CD, as demonstrated by 1H-1H rotating frame nuclear Overhauser effect spectroscopy NMR. Physicochemical properties of solid TT/SBE-β-CD complexes prepared by physical mixing, kneading, freeze-drying, and mechanochemical methods were studied by X-ray diffraction and 13C cross-polarization and magic angle spinning NMR. With the mechanochemical method, the diffraction peak corresponding to TT disappeared, indicating the formation of an inclusion complex. The results of the dissolution test revealed that the solid complex obtained by the mechanochemical method improved the dissolution of TT. The water apparent solubility of TT can be improved by simple mechanical mixing without organic solvents, and improved bioavailability after oral administration is expected.

Inclusion complexation of 4′,6-diamidino-2-phenylindole (DAPI) with cucurbit[7]uril and cyclodextrins (native β-, 2,6-di-O-methylated β-, and γ-cyclodextrin): characteristic inclusion behaviour and fluorescence enhancement

Herein, we investigated the inclusion complexation of a fluorescent probe [4′,6-diamidino-2-phenylindole (DAPI)] using various cyclodextrins (CDs) and cucurbit[7]uril (CB7). Using the continuous variation method, DAPI was found to form a 1:1 inclusion complex with CDs and CB7. 1H-NMR and 2D ROESY (1H-1H rotating frame nuclear Overhauser effect) spectroscopy indicated that the inclusion of DAPI by the CDs and CB7 occurs via the encapsulation of the phenyl group and indole moiety of DAPI. The stability of the CB7 inclusion complex was higher than that of the CDs: the stability was attributed to the extra interaction formed between the dicationic dye (DAPI) and polar carbonyl groups at the portals of CB7. Furthermore, we determined the fluorescence quantum yield (Φ) of the inclusion complexes. The Φ values of DAPI were significantly enhanced upon its inclusion by CB7 and increased as the empirical solvent polarity parameter (ET(30)) decreased. Based on these results, we concluded that the polarity of the microenvironment and protonation ability of the excited state of DAPI play important roles in emission efficiency.

Facile Synthesis of Aryl-Substituted Cycloarenes via Bismuth(III) Triflate-Catalyzed Cyclization of Vinyl Ethers

Cycloarenes are an essential class of polycyclic aromatic hydrocarbons with unique electronic structure, but their synthesis is very challenging. Herein, we report a facile synthetic strategy prima...

Litoralimycins A and B, New Cytotoxic Thiopeptides from Streptomonospora sp. M2.

Streptomonospora sp. M2 has been isolated from a soil sample collected at the Wadden Sea beach in our ongoing program aimed at the isolation of rare Actinobacteria, ultimately targeting the discovery of new antibiotics. Because crude extracts derived from cultures of this strain showed inhibitory activity against the indicator organism Bacillus subtilis, it was selected for further analysis. HPLC–MS analysis of its culture broth revealed the presence of lipophilic metabolites. The two major metabolites of those were isolated by preparative reversed-phase HPLC and preparative TLC. Their planar structures were elucidated using high-resolution electrospray ionization mass spectrometry (HRESIMS), 1D and 2D NMR data as new thiopeptide antibiotics and named litoralimycin A (1) and B (2). Although rotating frame nuclear Overhauser effect spectroscopy (ROESY) data established a Z configuration of the Δ21,26 double bond, the stereochemistry of C-5 and C-15 were assigned as S by Marfey’s method after ozonolysis. The biological activity spectrum of 1 and 2 is highly uncommon for thiopeptide antibiotics, since they showed only insignificant antibacterial activity, but 1 showed strong cytotoxic effects.

Characterization of group-inclusion complexations of rhodamine derivatives with native and 2,6-di-O-methylated β-cyclodextrins

The inclusion complexations of rhodamine derivatives with native and 2,6-di-O-methylated β-cyclodextrins (β-CD and DM-β-CD) were studied spectrophotometrically. Rhodamine derivatives were shown to form 1:1 inclusion complexes with β-CDs by the continuous variation method. The structures of the inclusion complexes were characterized by 1H-1H rotating frame nuclear Overhauser effect spectroscopy (ROESY) NMR measurements. It was found that native β-CD encapsulates the xanthenyl ring of rhodamines into the cyclodextrin cavity, while DM-β-CD forms two group-in complexes (phenyl-in and xanthenyl-in (bidirectional (bimodal) inclusion complexes)) with rhodamines bearing moderately bulky functional groups. Furthermore, we demonstrated the unique thermodynamics for the group-inclusion complex formation by DM-β-CD. The quantum yields for the inclusion complexes of rhodamines were determined using a quantum measurement apparatus equipped with a half-moon unit. The results indicated that the cyclodextrin inclusion of rhodamines with the bulky amino substituents on the xanthenyl ring largely decreases the quantum yield values. Based on these results, the substituent effects on the fluorescence process for the cyclodextrin inclusion complexes of rhodamines were discussed. This study provides useful insights for the functional group recognition of native and modified β-CDs.

Discovery of Neolignan Glycosides with Acetylcolinesterase Inhibitory Activity from Huangjinya Green Tea Guided by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry Data and Global Natural Product Social Molecular Networking.

Global Natural Product Social feature-based networking was applied to follow the phytochemicals, including nine flavonoid glycosides, six catechins, and three flavonols in Huangjinya green tea. Further, a new 8-O-4'-type neolignan glycoside, camellignanoside A (1), and 15 known compounds (2-16) were isolated through a variety of column chromatographies, and the structure was elucidated extensively by ultra performance liquid chromatography-quadrupole-time-of-flight-tandem mass spectrometry, 1H and 13C nuclear magnetic resonance, heteronuclear single-quantum correlation, heteronuclear multiple-bond correlation, 1H-1H correlation spectroscopy, rotating frame nuclear Overhauser effect spectroscopy, and Nuclear Overhauser effect spectroscopy, and circular dichroism spectroscopies. Compounds 1 and 2 showed acetylcolinesterase inhibition activity, with IC50 = 0.75 and 0.18 μM, respectively.

Preparation and physicochemical characterization of inclusion complexes derived from phytosterols and β-cyclodextrin

Phytosterols (PS), that is vegetable sterols, are compounds widely recognized for lowering the absorption of cholesterol and decreasing cancer risk, with βsitosterol, stigmasterol and campesterol being the most abundant. As PS is poorly soluble in aqueous solutions, many approaches have been proposed to increase their solubility and bioavailability. β-cyclodextrin (β-CD) could be used to increase PS aqueous solubility because of its capacity to entrap a variety of hydrophobic guest molecules in its cavity. In this work, the formation of β-CD/PS inclusion complexes was confirmed by Differential Scanning Calorimetry (DSC), Electrospray Ionization-High Resolution Mass Spectrometry (ESIHRMS) and Fourier Transform Infrared Spectroscopy (FT-IR), while structural characteristics were determined by one- and two-dimensional Nuclear Magnetic Resonance (NMR) techniques. Results confirmed 1:1 binding stoichiometry, which suggests the total inclusion of rings and chains of the different PS. The hypothesis of folding of the lateral chains into the cavity may be supported by the multiple correlations observed in the Nuclear Overhauser Effect Spectroscopy (NOESY) and rotatingframe Nuclear Overhauser Effect Spectroscopy (ROESY) spectra.

Preparation and characterization of the inclusion complexes of equol with sulfobutylether-β-cyclodextrin: their antioxidant activity and dissolution evaluation

The formation of inclusion complexes between S-(−)-equol (SEq) and cyclodextrins (CDs) was investigated. The binding constant (Kc) of the SEq/sulfobutylether-β-cyclodextrin (SBE-β-CD) inclusion complex was determined to be 1600 L/mol based on UV data. The phenyl ring of the SEq molecule was found to be inserted from the secondary hydroxyl face of the SBE-β-CD as evidenced from 1H–1H rotating frame nuclear Overhauser effect spectroscopy (ROESY) NMR. The thermal properties of the solid SEq/SBE-β-CD inclusion complexes prepared by physical mixing, kneading and freeze-drying methods were studied by differential scanning calorimetry. For the solid complex obtained by the freeze-drying method, the endothermic peak corresponding to the melting point of SEq disappeared. The solid SEq/SBE-β-CD complexes exhibited a high score in antioxidant activity evaluation tests compared to SEq alone. Dissolution test revealed that the solid complex obtained by freeze-drying method had improved dissolution of SEq.

Correlation Spectroscopy (COSY), Exclusive Correlation Spectroscopy (ECOSY), Total Correlation Spectroscopy (TOCSY), Incredible Natural-Abundance Double-Quantum Transfer Experiment (INADEQUATE), Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC), Heteronuclear Multiple-Bond Correlation Spectroscopy (HMBC), Nuclear Overhauser Effect Spectroscopy (NOESY) and Rotating Frame Nuclear Overhauser Effect Spectroscopy (ROESY) Comparative Study on Malignant and Benign Human Cancer Cells and Tissues Under Synchrotron Radiation

In the current study, we have experimentally and comparatively investigated and compared malignant human cancer cells and tissues before and after irradiating of synchrotron radiation using Correlation Spectroscopy (COSY), Exclusive Correlation Spectroscopy (ECOSY), Total Correlation Spectroscopy (TOCSY), Incredible Natural-Abundance Double-Quantum Transfer Experiment (INADEQUATE), Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC), Heteronuclear Multiple-Bond Correlation Spectroscopy (HMBC), Nuclear Overhauser Effect Spectroscopy (NOESY) and Rotating Frame Nuclear Overhauser Effect Spectroscopy (ROESY).

Supramolecular Complexation of Biologically Important Thioflavin‐T with p‐Sulfonatocalix[4]arene

AbstractThe inclusion of thioflavin T (ThT) with p‐sulfonatocalix[4]arene (p‐SC4) is briefly discussed in solution as well as solid state. The restricted rotation of C−C single bond between indole and benzene ring system is the reason for emission property of ThT. The encapsulation of ThT using a flexible charged host molecule exploit the correlation between the C−C single bond rotation and emission enhancement. The binding of ThT with p‐SC4 in solution state is studied using absorption, emission, electrochemical, 1H NMR and rotating frame nuclear overhauser effect spectroscopy (ROESY) techniques. A stable water insoluble supramolecular complex is synthesized from water soluble ThT and p‐SC4. The structural features of the prepared solid complex is established from infrared (FT‐IR), powder X‐ray diffraction (XRD), Mass, 1H NMR and nuclear overhauser effect spectroscopy (NOESY) analyses.

Incredible natural–abundance double–quantum transfer experiment (INADEQUATE), nuclear overhauser effect spectroscopy (NOESY) and rotating frame nuclear overhauser effect spectroscopy (ROESY) comparative study on malignant and benign human cancer cells and tissues under synchrotron radiation

Incredible natural–abundance double–quantum transfer experiment (INADEQUATE), nuclear overhauser effect spectroscopy (NOESY) and rotating frame nuclear overhauser effect spectroscopy (ROESY) comparative study on malignant and benign human cancer cells and tissues under synchrotron radiation

A novel approach to correlation spectroscopy (COSY), exclusive correlation spectroscopy (ECOSY), total correlation spectroscopy (TOCSY), incredible natural–abundance double–quantum transfer experiment (INADEQUATE), heteronuclear single–quantum correlation spectroscopy (HSQC), heteronuclear multiple–bond correlation spectroscopy (HMBC), nuclear overhauser effect spectroscopy (NOESY) and rotating frame nuclear overhauser effect spectroscopy (ROESY) comparative study on malignant and benign human cancer cells and tissues under synchrotron radiation

A novel approach to correlation spectroscopy (COSY), exclusive correlation spectroscopy (ECOSY), total correlation spectroscopy (TOCSY), incredible natural–abundance double–quantum transfer experiment (INADEQUATE), heteronuclear single–quantum correlation spectroscopy (HSQC), heteronuclear multiple–bond correlation spectroscopy (HMBC), nuclear overhauser effect spectroscopy (NOESY) and rotating frame nuclear overhauser effect spectroscopy (ROESY) comparative study on malignant and benign human cancer cells and tissues under synchrotron radiation

Solvent-Induced Molecular Folding and Self-Assembled Nanostructures of Tyrosine and Tryptophan Analogues in Aqueous Solution: Fascinating Morphology of High Order.

Hydrophobic derivatives of tyrosine and tryptophan, viz. octyl and dodecyl esters of tyrosine and octyl ester of tryptophan, are synthesized, and the interfacial and bulk properties in aqueous media are investigated as models for the membrane proteins. Molecular modeling by the density functional theory method is carried out to understand the molecular conformation and geometry for the purpose of determining the packing parameters. Water-induced molecular folding of the esters of both tyrosine and tryptophan, as observed using rotating frame nuclear Overhauser effect spectroscopy, indicates that the segregation of the hydrophobic and hydrophilic blocks in water is the key to the development of fascinating interfacial property displayed by the aromatic amino acid esters. The unusually high-order morphology of the aggregates, as observed using high-resolution transmission electron microscopy, is highly uncommon for single-chain amphiphiles and points to the fact that the self-assembly behavior of the present systems resembles that of block copolymers. The study of the growth of mesosized hollow aggregates with internal bilayer structures from tyrosine and tryptophan-based model systems would add to the understanding of biochemistry and biotechnology relevant to the cell membrane. The potential of biocompatible nanostructured motifs as the drug carriers is discussed. The highly functional role played by the aromatic amino acids at the membrane-water interface will be considered with the present amphiphilic models for future perspective.

Inclusion complexes of β-cyclodextrin with tricyclic drugs: an X-ray diffraction, NMR and molecular dynamics study.

Tricyclic fused-ring cyclobenzaprine (1) and amitriptyline (2) form 1:1 inclusion complexes with β-cyclodextrin (β-CD) in the solid state and in water solution. Rotating frame NOE experiments (ROESY) showed the same geometry of inclusion for both 1/β-CD and 2/β-CD complexes, with the aromatic ring system entering the cavity from the large rim of the cyclodextrin and the alkylammonium chain protruding out of the cavity and facing the secondary OH rim. These features matched those found in the molecular dynamics (MD) simulations in solution and in the solid state from single-crystal X-ray diffraction of 1/β-CD and 2/β-CD complexes. The latter complex was found in a single conformation in the solid state, whilst the MD simulations in explicit water reproduced the conformational transitions observed experimentally for the free molecule.

Conformational Analysis of an Antibacterial Cyclodepsipeptide Active against Mycobacterium tuberculosis by a Combined ROE and RDC Analysis.

Griselimycin (GM) and methylgriselimycin (MGM), naturally produced by microorganisms of the genus Streptomyces, are cyclic depsipeptides composed of ten amino acids. They exhibit antibacterial activity against Mycobacterium species by inhibiting the sliding clamp of prokaryotic DNA polymerase III and are therefore considered as potential anti-tuberculosis drugs. The difference between the peptides is the presence of l-(R)-4-methyl-proline in MGM instead of l-proline in GM at position 8 of the amino acid sequence. Methylation increases both metabolic stability and activity of MGM compared to GM. To get deeper insight into the structure-activity relationship, the solution structure of the cyclic part of MGM was determined using rotating-frame nuclear Overhauser effect (ROE) distance restraints and residual dipolar couplings (RDC). The structure of MGM in solution is compared to the structure of GM in a co-crystal with DNA polymerase III subunit beta. As a result, a highly defined structural model of MGM is obtained, which shows related characteristics to the bound GM.

Study on Micelle Formation of Bile Salt Using Nuclear Magnetic Resonance Spectroscopy.

1H-nuclear magnetic resonance (1H-NMR) measurements can identify the specific protons that contribute to interactions between molecules. Using this technique, micelles formed by four bile salts: sodium taurocholate (NaTC), taurodeoxycholate (NaTDC), taurochenodeoxycholate (NaTCDC), and tauroursodeoxycholate (NaTUDC) were measured and compared in viewpoint of molecular interactions. Rotating-frame nuclear Overhauser effect and exchange spectroscopy (ROESY) analysis of the four bile salts showed differences with respect to the type of micelle formation. For all four bile salts, the key protons contributing to hydrophobic interactions were found to be the methyl protons at positions 18 and 19. The cross-peak patterns for the four bile salt species indicated pairs of characteristic proton depending on a bile salt species. The spin-lattice relaxation time (T1) of the alkyl side-chain in NaTC was relatively long compared to that of the three other bile salts, even when the concentration was higher than the critical micelle concentration (cmc). This unique behavior indicates that the hydrophilic region of NaTC molecules is flexible within their micelles. Moreover, T1 values for the typically hydrophobic methyl protons at sites C18 and C19 of NaTC were almost constant above the cmc. These results may suggest that NaTC micelles remain as small primary structures in solution unlike the three other bile salt molecules investigated in the study.