HSQC Research Articles

Microstructural Analysis of Poly(ethylene-co-propylene-co-1-butene) terpolymers by Multidimensional NMR Spectroscopy

Physical, rheological and optical properties of polymer depend on its molecular microstructure. Specifically, the monomer content and sequence distribution of polymer significantly affect the mechanical performance of the final product. To this base, Nuclear Magnetic Resonance Spectroscopy (NMR) has been introduced as a very powerful technique to study the microstructure of polymer. The purpose of this study was to develop a methodology to investigate the microstructure of poly(ethylene-co-propylene-co-butene) terpolymer by using multidimensional NMR spectroscopy, including pulsed-field-gradient (PFG) 1H-13C heteronuclear single quantum coherence (GHSQC), heteronuclear multiple bond coherence (gHMBC), and heteronuclear single quantum coherence-total correlation spectroscopy (GHSQC-TOCSY). The combination of 1D and 2D NMR experiments, permit the characterization of the complex structure of poly(ethylene-co-propylene-co-butene) terpolymer. The completed 13C NMR assignments provided in this work allow more accurate quantitative determination of the microstructure in these polymers.

Multi-spectroscopic characterization of bitumen and its polarity-based fractions

• Insights on H/C-ratio, aromatic systems and average molecular sizes are obtained. • NMR reveals varying chain lengths of aliphatic substituents throughout the fractions. • Characteristic NMR shifts in the resins suggest presence of some esters or amides. • 31 P NMR after derivatization, shows minor amounts of alcohols and carboxylic acids. Bitumen contains a complex mixture of molecules, ranging from simple linear alkanes to complex polyaromatic systems. Used in road construction, those structures are permanently influenced by atmospheric processes, which result in oxidation, degradation, loss of volatiles and structural rearrangements. In order to understand those molecular changes, a profound description of the unaltered system is needed. In this study, structural and chemical peculiarities of bitumen and its polarity-based fractions were analysed using nuclear magnetic resonance (NMR) techniques in combination with infrared/fluorescence spectroscopy and elemental analysis. The bitumen sample was separated into saturates, aromatics, resins and asphaltenes. Elemental analysis provided insights into variations of heteroatom content and hydrogen-carbon ratio among the fractions. Fluorescence spectroscopy showed an increase in the aromatic condensation degree with rising polarity. The combination of heteronuclear single quantum coherence (HSQC) and elemental analysis facilitated the assessment of length and branching extent of aliphatic side chains, throughout the fractions. Another 2D NMR technique, heteronuclear multiple bond coherence (HMBC) found evidence for minor contributions of carboxylic esters or amides within the resins. Hydroxyl and amino groups were analysed by 31 P NMR after derivatization, revealing minor amounts of alcohols, amides and carboxylic acids in the most polar fractions. Additionally, diffusion ordered spectroscopy was carried out to obtain estimations on average molecular sizes and weights. Applying in-depth NMR analysis to bitumen and combining it with complementary analytical techniques, this study provides a unique basis for future ageing studies and demonstrates how multi-spectroscopy can give new insights into bitumen structure and chemistry.

19F fast MAS (60–111 kHz) dipolar and scalar based correlation spectroscopy of organic molecules and pharmaceutical formulations

19F magic angle spinning (MAS) NMR spectroscopy is a powerful tool for characterization of fluorinated solids. The recent development of 19F MAS NMR probes, operating at spinning frequencies of 60–111 kHz, enabled analysis of systems spanning from organic molecules to pharmaceutical formulations to biological assemblies, with unprecedented resolution. Herein, we systematically evaluate the benefits of high MAS frequencies (60–111 kHz) for 1D and 2D 19F-detected experiments in two pharmaceuticals, the antimalarial drug mefloquine and a formulation of the cholesterol-lowering drug atorvastatin calcium. We demonstrate that 1H decoupling is essential and that scalar-based, heteronuclear single quantum coherence (HSQC) and heteronuclear multiple quantum coherence (HMQC) correlation experiments become feasible and efficient at the MAS frequency of 100 kHz. This study opens doors for the applications of high frequency 19F MAS NMR to a wide range of problems in chemistry and biology.

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.

Demethylation and tannin-like properties of guaiacyl/syringyl-type and syringyl-type dehydrogenation polymers using iodocyclohexane

The demethylation of guaiacyl/syringyl (G/S)-type (G/S = 1/1) and syringyl (S)-type dehydrogenation polymers (DHPs) using iodocyclohexane (ICH) under reflux in DMF was performed to afford demethylated G/S- and S-DHPs in moderate yields. Along with significant structural changes, such as side-chain cleavage and recondensation, as observed using heteronuclear single quantum coherence (HSQC) NMR spectra, the phenolic-OH content of the demethylated DHPs increased, as expected. The tannin-like properties, such as the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging ability, iron(III) binding ability, and bovine serum albumin (BSA) adsorption ability, of the demethylated DHPs increased with increasing reaction time. In particular, the BSA adsorption ability was significantly enhanced by demethylation of the G/S- and S-DHPs, and was better than that of G-DHP reported previously. These results indicate that hardwood lignin containing both G and S units is more suitable than softwood lignin containing only G units for functionalization through demethylation into a tannin-like polymer, which has applications as a natural oxidant, metal adsorbent, and protein adsorbent.

Study the effect of zeolite pore size and acidity on the catalytic pyrolysis of Kraft lignin

In this study, three zeolites with different pore sizes and acidity, H-Beta, HY and HZSM-5, were used for the preparation of bio-oil by catalytic pyrolysis of Kraft lignin at 600 °C. The three-dimensional sizes and kinetic diameters of the bio-oil components were calculated using quantum chemical calculations, and the bio-oil was analyzed by heteronuclear single quantum coherence nuclear magnetic resonance (HSQC-NMR). The effects of zeolite acidity and pore size on the bio-oil upgrading process were studied for the pyrolysis products of Kraft lignin. The results showed that optimum pore size of the zeolites ranged from 6.500 Å–8.400 Å during the catalyzed pyrolysis of lignin. Among the zeolites, the H-Beta zeolite is the most effective in the lignin pyrolysis. The results also showed that the pore size and acidity of the zeolites had a significant effect on the product yields, coking and deoxygenation. The pore size affects the coking and dehydration reactions, while the acidity can promote the rearrangement of ether bonds or the breaking of lignin side chains and deoxygenation reactions. This study would be beneficial to improve the zeolite catalytic activity and minimize the oxygen content in bio-oil produced from the pyrolysis of Kraft lignin.

Composition analysis of exudates produced by conifers grown in Taiwan and their antifungal activity

Exudates are involved in the defense mechanism of trees; they could work against insects or microorganisms through a physical or chemical system. The main components of exudates are terpenoids. This study identified the main compounds of exudates from 13 conifers of Taiwan using gas chromatogram–mass spectrometry (GC–MS) and spectroscopic analysis. The results revealed that the main volatiles were α-pinene, β-ocimene, β-pinene, sabinene, and caryophyllene. On the other hand, the main nonvolatile compounds were diterpenoids, which were classified into three skeletons (abietane-, labdane-, and pimarane-types). Among these, abietane-type presented in Pinaceae and in most of Cupressaceae; labdane-type presented in Pinaceae and in all of Cupressaceae and Araucariaceae; pimarane-type existed in both Pinaceae and Cupressaceae. Furthermore, the epigenetics of conifers analysis results by GC–MS and heteronuclear single quantum coherence (HSQC) of nuclear magnetic resonance (NMR) fingerprints were similar to traditional taxonomy classification; it indicated that exudates chemotaxonomy by using GC–MS and HSQC profiling is a useful technology to classify the conifers. Besides, the exudates of Pinus elliottii, Pinus taiwanensis, Calocedrus macrolepis and Chamaecyparis formosensis possessed the strong antifungal activity. For white-rot fungus, Trametes versicolor, Pinus morrisonicola, Chamaecyparis obtusa, and Araucaria heterophylla exhibited the higher antifungal index. For brown-rot fungus, Laetiporus sulphureus, Pinus elliottii, Pinus morrisonicola, and Chamaecyparis formosensis revealed a good antifungal activity.

NMR Reveals Functionally Relevant Thermally Induced Structural Changes within the Native Ensemble of G-CSF.

Structure–function relationships in proteins refer to a trade-off between stability and bioactivity, molded by evolution of the molecule. Identifying which protein amino acid residues jeopardize global or local stability for the benefit of bioactivity would reveal residues pivotal to this structure–function trade-off. Here, we use 15N–1H heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectroscopy to probe the microenvironment and dynamics of residues in granulocyte colony-stimulating factor (G-CSF) through thermal perturbation. From this analysis, we identified four residues (G4, A6, T133, and Q134) that we classed as significant to global stability, given that they all experienced large environmental and dynamic changes and were closely correlated to each other in their NMR characteristics. Additionally, we observe that roughly four structural clusters are subject to localized conformational changes or partial unfolding prior to global unfolding at higher temperature. Combining NMR observables with structure relaxation methods reveals that these structural clusters concentrate around loop AB (binding site III inclusive). This loop has been previously implicated in conformational changes that result in an aggregation prone state of G-CSF. Residues H43, V48, and S63 appear to be pivotal to an opening motion of loop AB, a change that is possibly also important for function. Hence, we present here an approach to profiling residues in order to highlight their potential roles in the two vital characteristics of proteins: stability and bioactivity.

KOH catalyzed oxidation of kraft lignin to produce green fertilizer

Due to the population growth, there is an urgent need for sustainable technologies and products to address the imbalance between the availability of arable land and growing food needs. Increasing crop productivity in a cost-efficient and environmentally-friendly pathway is one approach to address this issue. In this study, lignin, a low-cost and underutilized by-product of the pulping industry, was converted to a fertilizer via oxidation in the presence of KOH. The oxidation of lignin in water (15 wt%) under the conditions of 195 °C temperature, 300 psi pressure, and KOH dosage of 30 wt% (based on dried lignin) generated water-soluble lignin enriched with carboxylate groups. The X-ray photoelectron spectroscopy (XPS) and proton nuclear magnetic resonance (1H NMR) analyses confirmed the introduction of carboxylate groups to lignin, while 31P NMR and heteronuclear single quantum coherence (HSQC) NMR studies confirmed the alterations in the aliphatic and aromatic structures of lignin. The fertilizing effects of oxidized lignin were investigated on Zea mays (maize) plants. The results confirmed that the average length and dry weight of the plants grown in the presence of oxidized kraft lignin were 27% and 92% greater than those produced without lignin, and they were 12% and 81% higher than those grown in the presence of humic acid, respectively. After 30 days, the plants grown in the presence of oxidized kraft lignin contained 14% and 32% more chlorophyll than those generated in the presence of humic acid and control samples, respectively. Finally, the ash content analysis of the plants shows that applying oxidized kraft lignin as a fertilizer can reduce the ash content and increase the organic content of plants. These results confirmed that the oxidation of kraft lignin in the presence of KOH could be a strategy to induce a green fertilizer for crop cultivation.

3-[(1H-Benzo[d][1,2,3]triazol-1-yl)oxy]propyl 9-hydroxy-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)icosahydro-3aH-cyclopenta[a]chrysene-3a-carboxylate

We herein report on the synthesis of a pentacyclic triterpene functionalized through derivation of betulinic acid with hydroxybenzotriazole. The compound was fully characterized by proton (1H-NMR), carbon-13 (13C-NMR), heteronuclear single quantum coherence (HSQC) and distortionless enhancement by polarization transfer (DEPT-135 and DEPT-90) nuclear magnetic resonance. Ultraviolet (UV), and Fourier-transform infrared (FTIR) spectroscopies as well as and high-resolution mass spectrometry (HRMS) were also adopted. Computational studies were conducted to foresee the interactions between compound 3 and phosphodiesterase 9, a relevant target in the field of neurodegenerative diseases. Additionally, preliminary calculation of physico-chemical descriptors was performed to evaluate the drug-likeness of compound 3.

Molecular Mechanism of Antimicrobial Excipient-Induced Aggregation in Parenteral Formulations of Peptide Therapeutics.

Antimicrobial preservatives are used as functional excipients in multidose formulations of biological therapeutics to destroy or inhibit the growth of microbial contaminants, which may be introduced by repeatedly administering doses. Antimicrobial agents can also induce the biophysical instability of proteins and peptides, which presents a challenge in optimizing the drug product formulation. Elucidating the structural basis for aggregation aids in understanding the underlying mechanism and can offer valuable knowledge and rationale for designing drug substances and drug products; however, this remains largely unexplored due to the lack of high-resolution characterization. In this work, we utilize solution nuclear magnetic resonance (NMR) as an advanced biophysical tool to study an acylated 31-residue peptide, acyl-peptide A, and its interaction with commonly used antimicrobial agents, benzyl alcohol and m-cresol. Our results suggest that acyl-peptide A forms soluble octamers in the aqueous solution, which tumble slowly due to an increased molecular weight as measured by diffusion ordered spectroscopy and 1H relaxation measurement. The addition of benzyl alcohol does not induce aggregation of acyl-peptide A and has no chemical shift perturbation in 1H-1H NOESY spectra, suggesting no detectable interaction with the peptide. In contrast, the addition of 1% (w/v) m-cresol results in insoluble aggregates composed of 25% (w/w) peptides after a 24-hour incubation at room temperature as quantified by 1H NMR. Interestingly, 1H-13C heteronuclear single-quantum coherence and 1H-1H total correlation experiment spectroscopy have identified m-cresol and peptide interactions at specific residues, including Met, Lys, Glu, and Gln, suggesting that there may be a combination of hydrophobic, hydrogen bonding, and electrostatic interactions with m-cresol driving this phenomenon. These site-specific interactions have promoted the formation of higher-order oligomerization such as dimers and trimers of octamers, eventually resulting in insoluble aggregates. Our study has elucidated a structural basis of m-cresol-induced self-association that can inform the optimized design of drug substances and products. Moreover, it has demonstrated solution NMR as a high-resolution tool to investigate the structure and dynamics of biological drug products and provide an understanding of excipient-induced peptide and protein aggregation.

Pretreatment of lignin by electrochemical hydrogenation to enhance the olefins and aromatic products during rapid pyrolysis

Lignin is one of the most promising biopolymers for producing hydrocarbons and aromatic compounds in nature. Electrochemical conversion of lignin is regarded as an attractive technology for producing various aromatic chemicals which are generally derived from fossil fuels. The author reports an electrochemical approach for hydrogenating alkaline lignin (AL), which uses relatively low-cost Ni foam as a working electrode under alkali electrolyte. The primary factors (such as power input, reactor type, temperature, reaction time, catalysts, and electrode substrates) of electrochemical hydrogenation were used to control the products' yield and features. The redox characteristics of the reaction system were directly compared with the cyclic voltammetry measurement under different parameters. After electrochemical hydrogenation (ECH), rapid pyrolysis was conducted on HAL samples to investigate the influence of electrochemical reactions on lignin. The maximum olefins and aromatics yield from HAL was increased to more than three times AL, accounting for 2.22 wt% and 4.07 wt%, respectively. Then, thermogravimetric analysis (TGA), elemental analysis (EA), Fourier-transform infrared spectroscopy (FTIR), and heteronuclear single quantum coherence (HSQC) NMR were employed to characterize hydrogenated lignin samples (HAL), as well as gas chromatography–mass spectrometry (GC-MS) was conducted to investigate the oil-phase products. This work focused on this electrochemical hydrogenation coupled with rapid pyrolysis process to give a possibility that converting lignin into not only liquid oil products, but solid hydrogenated lignin can be used to produce more olefins and aromatics in rapid pyrolysis, and presented the advantages and disadvantages of this two-stage process finally.

Effect of Different Processing Methods on the Chemical Constituents of Scrophulariae Radix as Revealed by 2D NMR-Based Metabolomics.

Scrophulariae Radix (SR) is one of the oldest and most frequently used Chinese herbs for oriental medicine in China. Before clinical use, the SR should be processed using different methods after harvest, such as steaming, “sweating”, and traditional fire-drying. In order to investigate the difference in chemical constituents using different processing methods, the two-dimensional (2D) 1H-13C heteronuclear single quantum correlation (1H-13C HSQC)-based metabolomics approach was applied to extensively characterize the difference in the chemical components in the extracts of SR processed using different processing methods. In total, 20 compounds were identified as potential chemical markers that changed significantly with different steaming durations. Seven compounds can be used as potential chemical markers to differentiate processing by sweating, hot-air drying, and steaming for 4 h. These findings could elucidate the change of chemical constituents of the processed SR and provide a guide for the processing. In addition, our protocol may represent a general approach to characterizing chemical compounds of traditional Chinese medicine (TCM) and therefore might be considered as a promising approach to exploring the scientific basis of traditional processing of TCM.

4-(4-(((1H-Benzo[d][1,2,3]triazol-1-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl)-7-chloroquinoline

The 1,2,3-triazole ring system can be easily obtained by widely used copper-catalyzed click reaction of azides with alkynes. 1,2,3-triazole exhibits myriad of biological activities, including antibacterial antimalarial, and antiviral activities. We herein reported the synthesis of quinoline-based [1,2,3]-triazole hybrid derivative via Cu(I)-catalyzed click reaction of 4-azido-7-chloroquinoline with alkyne derivative of hydroxybenzotriazole (HOBt). The compound was fully characterized by proton nuclear magnetic resonance (1H-NMR), carbon-13 nuclear magnetic resonance (13C-NMR), correlated spectroscopy (1H-1H-COSY), heteronuclear single quantum coherence (HSQC) and distortionless enhancement by polarization transfer (DEPT-135 and DEPT-90) NMR, ultraviolet (UV) and Fourier-transform infrared (FTIR) spectroscopies, and high-resolution mass spectrometry (HRMS). Computational studies were enrolled to predict the interaction of the synthesized compound with acetylcholinesterase, a target of primary relevance for developing new therapeutic options to counteract neurodegeneration. Moreover, the drug-likeness of the compound was also investigated by predicting its pharmacokinetic properties.

Quantification of Phosphonate Drugs by 1H-31P HSQC Shows That Rats Are Better Models of Primate Drug Exposure than Mice.

The phosphonate group is a key pharmacophore in many antiviral, antimicrobial, and antineoplastic drugs. Due to its high polarity and short retention time, detecting and quantifying such phosphonate-containing drugs with LC/MS-based methods are challenging and require derivatization with hazardous reagents. Given the emerging importance of phosphonate-containing drugs, developing a practical, accessible, and safe method for their quantitation in pharmacokinetics (PK) studies is desirable. NMR-based methods are often employed in drug discovery but are seldom used for compound quantitation in PK studies. Here, we show that proton-phosphorous (1H-31P) heteronuclear single quantum correlation (HSQC) NMR allows for the quantitation of the phosphonate-containing enolase inhibitor HEX in plasma and tissues at micromolar concentrations. Although mice were shown to rapidly clear HEX from circulation (over 95% in <1 h), the plasma half-life of HEX was more than 1 h in rats and nonhuman primates. This slower clearance rate affords a significantly higher exposure of HEX in rat models compared to that in mouse models while maintaining a favorable safety profile. Similar results were observed for the phosphonate-containing antibiotic, fosfomycin. Our study demonstrates the applicability of the 1H-31P HSQC method to quantify phosphonate-containing drugs in complex biological samples and illustrates an important limitation of mice as preclinical model species for phosphonate-containing drugs.

Bamboo Lignin Fractions with In Vitro Tyrosinase Inhibition Activity Downregulate Melanogenesis in B16F10 Cells via PKA/CREB Signaling Pathway.

Cosmetic ingredients originating from natural resources have garnered considerable attention, and the demand for whitening ingredients is increasing, particularly in Asian countries. Lignin is a natural phenolic biopolymer significantly effective as a natural sunscreen, as its ultraviolet protection efficacy ranges from 250 to 400 nm. However, using different types of lignin as cosmetic ingredients is difficult owing to the heterogeneity of lignin and the lack of in vitro and in vivo safety and efficacy data. Thus, steam-exploded lignin (SEL) was prepared from bamboo, fractionated via successive organic solvent extraction, and sequentially fractionated using ethyl acetate, methanol, and acetone to investigate its potential as a natural whitening material. Gel permeation chromatography showed that the molecular weight of acetone-soluble and acetone-insoluble SEL fractions were the lowest and the highest, respectively. Monomer structures of the four lignin fractions were elucidated using 1H, 13C, and 2D heteronuclear single quantum coherence nuclear magnetic resonance and pyrolysis gas chromatography/mass spectrometry. The antioxidant and tyrosinase inhibition activities of the four fractions were compared. The methanol-soluble SEL fraction (SEL-F2) showed the highest antioxidant activity (except 2,2-diphenyl-1-picrylhydrazyl scavenging activity), and the enzyme inhibition kinetics were confirmed. In this study, the expression pattern of the anti-melanogenic-related proteins by SEL-F2 was confirmed for the first time via the protein kinase A (PKA)/cAMP-response element-binding (CREB) protein signaling pathway in B16F10 melanoma cells. Thus, SEL may serve as a valuable cosmetic whitening ingredient.

Integrated global optimization and process modelling for biodiesel production from non-edible silk-cotton seed oil by microwave-assisted transesterification with heterogeneous calcium oxide catalyst

Second generation feedstock like non-edible seed oil, used cooking oil, and animal fats for biodiesel production has huge potential, yet these feedstocks have been underutilised. In this current study, non-edible Ceiba pentandra seed oil (CPSO) was used to produce biodiesel. Ceiba pentandra seed yielded an oil content of 18.6% after extraction. CPSO had 6.87% free fatty acid, 0.911 specific gravity, 98.9 g I2/100 g oil iodine value, 1.47 refractive index, 189.14 mg KOH/g oil saponification, 13.67% acid value, and 3.29 meq O2/kg oil peroxide value. CPSO was characterized using Fourier transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC-MS) analysis. The free fatty acid value of CPSO was reduced to 0.83% using the esterification process at 60°C for 60 min with a 3:1 methanol to oil volumetric ratio, 5% sulfuric acid. The microwave-assisted transesterification process (MATP) was carried out by CPSO and methanol as reactants and calcium oxide (CaO) as a catalyst. CaO was characterised using FT-IR, scanning electron microscope, energy dispersive X-ray analysis, and Brunauer–Emmett–Teller analysis. To optimise the process variable of the MATP, response surface methodology was used, followed by an artificial neural network coupled with a genetic algorithm. At 270 W and 114 s reaction time, 0.3 wt.% CaO, and 18:1 alcohol to oil molar ratio, 97.4% biodiesel yield was obtained. FT-IR, GC-MS, 1H &13C Nuclear magnetic resonance, Heteronuclear single quantum coherence spectroscopy, and Heteronuclear multiple-bond correlation were used to characterise the biodiesel. In conclusion, CPSO has the potential to produce a large quantity of quality biodiesel by the application of the CaO catalyst.

Quantification of Isomaltulose in Food Products by Using Heteronuclear Single Quantum Coherence NMR-Experiments.

Isomaltulose is a commonly used sweetener in sports nutrition and in products intended for consumption by diabetics. Because previously established chromatographic methods for quantification of isomaltulose suffer from long analysis times (60–210 min), faster quantitative approaches are required. Here, an HSQC (heteronuclear single quantum coherence) experiment with reduced interscan delay was established in order to quantify isomaltulose next to potential additional sugars such as d-glucose, d-fructose, d-galactose, sucrose, lactose, and maltose in 53 min. By using HSQC coupled to non-uniform sampling (NUS) as well as ASAP-HSQC (acceleration by sharing adjacent polarization), analysis times were reduced to a few minutes. Application of NUS-HSQC with reduced interscan delay takes 27 min, resulting in accurate and precise data. In principle, application of ASAP-HSQC approaches (with analysis times as low as 6 min) can be used; however, precision data may not suffice all applications.

Upcycling Polytetrahydrofuran to Polyester

Upcycling Polytetrahydrofuran to Polyester

Steroid glycosides isolated from Paris polyphylla var. chinensis aerial parts and paris saponin II induces G1/S-phase MCF-7 cell cycle arrest

In our previous research on Vietnamese medicinal plants, we found that the ethanolic extract of the aerial parts of Paris polyphylla var. chinensis exhibited cytotoxic effects in vitro in the MCF-7 human cancer cell line. Here, we used combined chromatographic separations to isolate six compounds including a new steroid glycoside, paripoloside A (3), and five known compounds, from the butanol extract of the aerial parts of P. polyphylla. We unambiguously elucidated their structures based on spectroscopic data (proton and carbon-13 nuclear magnetic resonance, heteronuclear single quantum coherence, heteronuclear multiple bond correlation, correlation spectroscopy, and high-resolution electrospray ionization mass spectroscopy data), and chemical reactions. Among the isolated compounds, paris saponin II (PSII) had the strongest cytotoxic effects against MCF-7 breast cancer cells. Interestingly, PSII significantly increased the expression of p53, p21, p27, and Bax protein levels and significantly suppressed the expression of cyclin D1 and retinoblastoma protein. These data suggest that PSII may induce G1/S phase cell cycle arrest and apoptosis pathway development in MCF-7 cells. Furthermore, the MCF-7 breast cancer cells mechanism of PSII was also investigated using molecular docking. Together, our results demonstrate that isolated compounds from P. polyphylla are promising candidates as breast cancer inhibitors.