Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 20
Filter
Add more filters










Publication year range
1.
Food Sci Nutr ; 12(7): 4783-4799, 2024 Jul.
Article in English | MEDLINE | ID: mdl-39055205

ABSTRACT

Huajiao (Zanthoxylum bungeanum Maxim.) is extensively cultivated in various countries, including China, Korea, and India, owing to its adaptability to diverse environments. This study comprehensively analyzed the volatile substance composition of 14 varieties of red huajiao with distinct geographical origins. Thermal analysis methods, gas chromatography-mass spectrometry (GC-MS), and headspace-ion mobility chromatography (HS-IMS) were employed to evaluate the total volatile substance composition and content. The study revealed minor variations in water content, volatile matter content, and fractions among the geographically sourced huajiao samples. Utilizing correlation analysis based on GC-MS and orthogonal partial least squares discriminant analysis (OPLS-DA) with HS-IMS, a robust classification method for the 14 types of huajiao was developed. Applying the variable importance in the projection (VIP) method, seven distinctive components were identified as potential markers for distinguishing the geographical origins of red huajiao. By integrating climatic and topographical factors of the 14 huajiao varieties, the correlation analysis of GC-MS, and OPLS-DA classification outcomes from HS-IMS elucidated the influence of geo-environmental factors on huajiao components and contents. This research provides insights into the impact of diverse geographic environments on the constituents and characteristics of huajiao. It offers valuable guidance for selecting optimal cultivation locations to enhance huajiao quality, aiding consumers in making informed choices.

2.
J Agric Food Chem ; 2024 Jul 05.
Article in English | MEDLINE | ID: mdl-38966982

ABSTRACT

Flavors and fragrances (F&F) are interesting organic compounds in chemistry. These compounds are widely used in the food, cosmetic, and medical industries. Enzymatic synthesis exhibits several advantages over natural extraction and chemical preparation, including a high yield, stable quality, mildness, and environmental friendliness. To date, many oxidoreductases and hydrolases have been used to biosynthesize F&F. Ene-reductases (ERs) are a class of biocatalysts that can catalyze the asymmetric reduction of α,ß-unsaturated compounds and offer superior specificity and selectivity; therefore, ERs have been increasingly considered an ideal alternative to their chemical counterparts. This review summarizes the research progress on the use of ERs in F&F synthesis over the past 20 years, including the achievements of various scholars, the differences and similarities among the findings, and the discussions of future research trends related to ERs. We hope this review can inspire researchers to promote the development of biotechnology in the F&F industry.

3.
RSC Adv ; 14(26): 18453-18458, 2024 Jun 06.
Article in English | MEDLINE | ID: mdl-38860250

ABSTRACT

Asymmetric catalytic processes promoted by N-heterocyclic carbenes (NHCs) hold great potential for the sustainable preparation of chiral molecules. However, catalyzing the reactions by manipulating the reactive intermediates is challenging. We report herein that the known NHC-catalyzed [3 + 2] annulation reaction between ketimine and enal can also be turned into a [2 + 3] annulation reaction for the highly enantioselective direct synthesis of trifluoroethyl 3,2'-spirooxindole γ-lactams (4) through timely catalysis of the intermediates. DFT calculations revealed that this transformation included the key step of the nucleophilic attack of the Breslow intermediate M2 derived from NHC and enal (2) to the unattacked ketimine (1). Our study demonstrates that it is possible to tune the desired selectivities through the dynamic catalysts of the reactive intermediates.

4.
J Chem Inf Model ; 64(8): 3400-3410, 2024 Apr 22.
Article in English | MEDLINE | ID: mdl-38537611

ABSTRACT

Lactobacillus kefir alcohol dehydrogenase (LkADH) and ketoreductase from Chryseobacterium sp. CA49 (ChKRED12) exhibit different chemoselectivity and stereoselectivity toward a substrate with both keto and aldehyde carbonyl groups. LkADH selectively reduces the keto carbonyl group while retaining the aldehyde carbonyl group, producing optically pure R-alcohols. In contrast, ChKRED12 selectively reduces the aldehyde group and exhibits low reactivity toward ketone carbonyls. This study investigated the structural basis for these differences and the role of specific residues in the active site. Molecular dynamics (MD) simulations and quantum chemical calculations were used to investigate the interactions between the substrate and the enzymes and the essential cause of this phenomenon. The present study has revealed that LkADH and ChKRED12 exhibit significant differences in the structure of their respective active pockets, which is a crucial determinant of their distinct chemoselectivity toward the same substrate. Moreover, residues N89, N113, and E144 within LkADH as well as Q151 and D190 within ChKRED12 have been identified as key contributors to substrate stabilization within the active pocket through electrostatic interactions and van der Waals forces, followed by hydride transfer utilizing the coenzyme NADPH. Furthermore, the enantioselectivity mechanism of LkADH has been elucidated using quantum chemical methods. Overall, these findings not only provide fundamental insights into the underlying reasons for the observed differences in selectivity but also offer a detailed mechanistic understanding of the catalytic reaction.


Subject(s)
Aldehydes , Ketones , Molecular Dynamics Simulation , Ketones/chemistry , Ketones/metabolism , Aldehydes/chemistry , Aldehydes/metabolism , Substrate Specificity , Quantum Theory , Lactobacillus/enzymology , Lactobacillus/metabolism , Catalytic Domain , Alcohol Dehydrogenase/metabolism , Alcohol Dehydrogenase/chemistry
5.
J Ethnopharmacol ; 326: 117944, 2024 May 23.
Article in English | MEDLINE | ID: mdl-38382656

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: Panax ginseng C. A. Mey., one of the most used herbs in the world, shows effective treatment in reproductive injury. Recent studies have proven that the processed product, red ginseng, which is more active than ginseng itself. Therefore, it is speculated that its main functional component, rare ginsenosides (heat-transformed saponin, HTS), may be effective in treating premature ovarian failure (POF), but its efficacy has not yet been experimentally confirmed. AIM OF THE STUDY: To evaluate whether HTS could attenuate cyclophosphamide-induced inflammation and oxidative damage in POF model rats and the human granulosa-like KGN cell line and protect granulosa cell proliferation. MATERIAL AND METHODS: HTS were isolated from ginsenosides and high performance liquid chromatography (HPLC) analysis was used to analyze the HTS components. Cyclophosphamide (CP) was used to establish a POF rat model and KGN cell injury model. Reactive oxygen species (ROS) and antioxidant enzyme production was determined using specific assays, while inflammatory cytokine secretion was measured by enzyme-linked immunosorbent assay (ELISA). The proliferative function of granulosa cells was assessed using high-content screening and immunohistochemistry to determine the Ki67 protein level. Protein expression in ovarian tissues and KGN cells was analyzed by Western blotting, quantitative real-time PCR (qRT-PCR) was used to determine the transcriptional changes in ovarian tissues and KGN cells. RESULTS: In CP-treated POF model rats, HTS significantly decreased malondialdehyde (MDA), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) levels, increased glutathione oxidase (GSH) levels, and upregulated Ki67 expression in ovarian granulosa cells. In addition, HTS significantly increased cell survival and Ki67 expression levels in CP-treated cells, and superoxide dismutase (SOD) levels were significantly increased. HTS significantly downregulated IL-6, TNF-α, and interleukin-1ß (IL-1ß) mRNA expression and significantly inhibited nuclear factor kappa-B p65 (NF-κB p65) and p38 mitogen activated protein kinase (p38 MAPK) phosphorylation in POF model rats and KGN cells. Moreover, NF-κB p65 and p38 MAPK levels were significantly increased in ovarian granulosa cells. p65 and p38 protein and gene expression was significantly downregulated. CONCLUSION: HTS ameliorated CP-induced POF and human granulosa cell injury, possibly by inhibiting inflammation and oxidative damage mediated by the p38 MAPK/NF-κB p65 signaling pathway.


Subject(s)
Ginsenosides , Primary Ovarian Insufficiency , Rats , Humans , Animals , Female , NF-kappa B/metabolism , Ginsenosides/pharmacology , Ginsenosides/therapeutic use , Interleukin-6/metabolism , Tumor Necrosis Factor-alpha/genetics , Tumor Necrosis Factor-alpha/metabolism , Primary Ovarian Insufficiency/chemically induced , Primary Ovarian Insufficiency/drug therapy , Ki-67 Antigen/metabolism , MAP Kinase Signaling System , Inflammation/metabolism , p38 Mitogen-Activated Protein Kinases/metabolism
6.
Reprod Toxicol ; 123: 108502, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37984602

ABSTRACT

The impact of pesticides on reproductive health has been increasingly recognized. ß-cypermethrin (ß-CYP) and emamectin benzoate (EMB) are commonly used with agricultural workers. There are few published studies on the effects of combined poisoning of these two pesticides on the reproductive system. This study investigated the toxic effects and mechanism of ß-CYP and EMB on the reproductive system of female rats based on the hypothalamic-pituitary-ovarian (HPO) axis. The hypothalamic GnRH content tended to decrease, and Kiss-1 and GPR-54 mRNA and protein expression tended to increase in exposed rats. FSH content was elevated for the pituitary gland, and Kiss-1 and GPR-54 mRNA and protein expression were enhanced in all experimental groups compared with the control group. E2 content in rat ovaries and ERα mRNA and protein expression were reduced by ß-CYP and EMB. Furthermore, there were interactive effects of ß-CYP and EMB on FSH and E2 release, pituitary GPR-54 mRNA and protein, and ovarian ERα mRNA expression. To investigate causes of damage, oxidative damage indicators were tested and showed that exposure to ß-CYP and EMB decreased GSH-Px and SOD activities in the HPO axis, increased MDA levels in the hypothalamus and ovary together with LDH activities in the HPO axis, with an interaction effect on GSH-Px and SOD activities in the hypothalamus and pituitary gland as well as on MDA in the ovary. The above results support the screening of sensitive molecular biomarkers and evaluation of the adverse effects of pesticide exposure in greenhouse operations on reproductive health.


Subject(s)
Ivermectin/analogs & derivatives , Ovary , Pesticides , Pyrethrins , Rats , Female , Animals , Ovary/metabolism , Estrogen Receptor alpha/metabolism , Kisspeptins/metabolism , Gonadotropin-Releasing Hormone/metabolism , Follicle Stimulating Hormone , Oxidative Stress , Homeostasis , RNA, Messenger/metabolism , Superoxide Dismutase/metabolism
7.
J Sci Food Agric ; 104(4): 2417-2428, 2024 Mar 15.
Article in English | MEDLINE | ID: mdl-37989713

ABSTRACT

BACKGROUND: Hyperlipidemia is characterized by abnormally elevated blood lipids. Quinoa saponins (QS) have multiple pharmacological activities, including antitumor, bactericidal and immune-enhancing effects. However, the lipid-lowering effect and mechanisms of QS in vivo have been scarcely reported. METHODS: The effect of QS against hyperlipidemia induced by high-fat diet in rats was explored based on gut microbiota and serum non-targeted metabolomics. RESULTS: The study demonstrated that the supplementation of QS could reduce serum lipids, body weight, liver injury and inflammation. 16S rRNA sequencing demonstrated that QS mildly increased alpha-diversity, altered the overall structure of intestinal flora, decreased the relative richness of Firmicutes, the ratio of Firmicutes/Bacteroidetes (P < 0.05) and increased the relative richness of Actinobacteria, Bacteroidetes, Bifidobacterium, Roseburia and Coprococcus (P < 0.05). Simultaneously, metabolomics analysis showed that QS altered serum functional metabolites with respect to bile acid biosynthesis, arachidonic acid metabolism and taurine and hypotaurine metabolism, which were closely related to bile acid metabolism and fatty acid ß-oxidation. Furthermore, QS increased protein levels of farnesoid X receptor, peroxisome proliferator-activated receptor α and carnitine palmitoyltransferase 1, which were related to the screened metabolic pathways. Spearman correlation analysis showed that there was a correlation between gut microbiota and differential metabolites. CONCLUSION: QS could prevent lipid metabolism disorders in hyperlipidemic rats, which may be closely associated with the regulation of the gut microbiota and multiple metabolic pathways. This study may provide new evidence for QS as natural active substances for the prevention of hyperlipidemia. © 2023 Society of Chemical Industry.


Subject(s)
Chenopodium quinoa , Gastrointestinal Microbiome , Hyperlipidemias , Rats , Animals , Diet, High-Fat/adverse effects , Chenopodium quinoa/metabolism , Hyperlipidemias/drug therapy , Hyperlipidemias/etiology , Hyperlipidemias/metabolism , RNA, Ribosomal, 16S , Lipids/pharmacology , Metabolic Networks and Pathways , Bile Acids and Salts
8.
RSC Adv ; 13(42): 29408-29418, 2023 Oct 04.
Article in English | MEDLINE | ID: mdl-37818274

ABSTRACT

Quinoa saponins have outstanding activity, and there are an increasing number of extraction methods, but there are few research programs on green preparation technology. The extraction conditions of quinoa saponins with deep eutectic solvents (DESs) were optimized by single-factor experiments combined with response surface methodology. The antioxidant capacity of saponins extracted by DESs and traditional methods was evaluated by the DPPH clearance rate, iron ion chelation rate and potassium ferricyanide reducing power. The results show that the optimal DES is choline chloride: 1,2-propylene glycol (1 : 1), and its water content is 40%. The optimal extraction conditions were as follows: the solid-to-solvent ratio was 0.05 g mL-1, the extraction time was 89 min, and the extraction temperature was 75 °C. Under these conditions, the extraction of quinoa saponins by DES was more effective than the traditional extraction methods. The saponins extracted by DES and traditional methods were analyzed by UPLC-MS, and five main saponins were identified. Quantitative analysis by HPLC-UV showed that Q1 (m/z = 971) and Q2 (m/z = 809) had higher contents of saponins. In vitro antioxidant experiments showed that all DES saponin extracts showed good antioxidant capacity. This study provides new insight into the development and utilization of quinoa saponins.

9.
J Med Chem ; 66(20): 13968-13990, 2023 10 26.
Article in English | MEDLINE | ID: mdl-37839070

ABSTRACT

Hepatitis B virus (HBV) capsid assembly modulators (CAMs) represent a promising therapeutic approach for the treatment of HBV infection. In this study, we designed and synthesized five series of benzamide derivatives based on a multisite-binding strategy at the tolerant region and diversity modification in the solvent-exposed region. Among them, thioureidobenzamide compound 17i exhibited significantly increased anti-HBV activity in HepAD38 (EC50 = 0.012 µM) and HBV-infected HLCZ01 cells (EC50 = 0.033 µM). Moreover, 17i displayed a better inhibitory effect on the assembly of HBV capsid protein compared with NVR 3-778 and a inhibitory effect similar to the clinical drug GLS4. In addition, 17i showed moderate metabolic stability in human microsomes, had excellent oral bioavailability in Sprague-Dawley (SD) rats, and inhibited HBV replication in the HBV carrier mice model, which could be considered as a promising candidate drug for further development.


Subject(s)
Hepatitis B virus , Hepatitis B , Animals , Mice , Rats , Humans , Capsid Proteins/metabolism , Capsid , Virus Replication , Antiviral Agents/chemistry , Rats, Sprague-Dawley , Hepatitis B/drug therapy
10.
Ecotoxicol Environ Saf ; 264: 115429, 2023 Oct 01.
Article in English | MEDLINE | ID: mdl-37660532

ABSTRACT

Rare ginsenosides have already been widely applied in many fields, including health food and bio-medicine. The human being can expose to rare ginsenosides directly or indirectly increasingly. However, there are few studies on the safety assessment of rare ginsenoside mixtures. In the present study, the sub-chronic toxicity of rare ginsenosides for 90 days on SD rats was performed by combining the intestinal flora analysis and urine metabonomics aiming to illustrate the safety of long-term consumption of rare ginsenosides and the potential damage for liver and intestinal. 48 adult rats were divided into four groups: control (0 mg/kg), low-dose (60 mg/kg), medium-dose (200 mg/kg), and high-dose (600 mg/kg). Rats in the high-dose group showed inflammatory changes in their livers and intestines. The strong bactericidal effect of rare ginsenosides caused intestinal flora disorder and changed the structure of intestinal flora in rats, thus inducing intestinal damage in rats. In the high-dose group, levels of alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and alkaline phosphatase (AKP) increased significantly. As a result of the high-dose treatment, certain metabolic pathways were altered, such as vitamin B6 metabolism, methionine metabolism, glutathione metabolism, and others. These results indicated that high doses of rare ginsenosides induced liver injury by affecting the above metabolic pathways. Rare ginsenosides with no observed adverse effect level (NOAEL) were below 200 mg/kg/day in vivo. Thus, this present study provides insight into the rational use of rare ginsenosides.


Subject(s)
Gastrointestinal Microbiome , Ginsenosides , Panax , Animals , Rats , Metabolomics , Plant Leaves , Rats, Sprague-Dawley
11.
Front Pharmacol ; 14: 1196158, 2023.
Article in English | MEDLINE | ID: mdl-37288115

ABSTRACT

Background: Colorectal cancer (CRC) is one of the most common malignancies causing the third highest mortality rate in the world. It is particularly urgent to explore effective therapeutic strategies to overcome this disease. We identified a novel benzothiazole derivative (BTD) that may serve as a potentially effective agent against CRC. Method: MTT assays, cell colony formation assays, EdU staining assays, flow cytometry, RNA-seq, Western blotting, and migration and invasion assays were used to examine the effects of BTD on cell proliferation, apoptosis, metastasis, and the cell cycle. The antitumor activity of BTD in vivo was investigated in a CT26 tumor-bearing mouse model. Immunohistochemistry (IHC) was performed to examine the protein expression in mouse tumors. Hematology, biochemical analysis, and H&E staining were used to assess the biosafety of BTD. Results: We observed that BTD suppressed cell proliferation and metastasis and promoted the apoptosis of tumor cells in vitro. Treatment with BTD at a tolerable dose significantly reduced tumor growth in CT26-tumor-bearing mice and appeared to be safe. Treatment of BTD induced apoptosis by increasing the generation of reactive oxygen species (ROS) and evoking the loss of mitochondrial transmembrane potential. Overall, BTD suppressed cell proliferation and metastasis, and induced apoptosis of colorectal tumor cells through the ROS-mitochondria-mediated apoptotic pathway. The preliminary proof of the antitumor activity and relative safety of BTD were validated in a mouse model. Conclusion: Our findings suggest that BTD could serve as a potentially safe and effective candidate for CRC treatment.

12.
Environ Sci Pollut Res Int ; 30(9): 22176-22187, 2023 Feb.
Article in English | MEDLINE | ID: mdl-36282392

ABSTRACT

Titanium nanoparticles and pyrethroid pesticides are now being widely used in industrial, agriculture, and biomedical applications. In recent years, their health safety profiles have aroused concerns among health scientists. This study mainly explored the combined effects of titanium dioxide nanoparticles (TiO2NPs) and cypermethrin (CYP) on reproductive toxicity in male rats by gavage for 90 days. Thirty-two male Sprague-Dawley rats were assigned to four groups: the control group, the TiO2NPs group, the CYP group, and the combined titanium dioxide nanoparticles with cypermethrin (TiO2NPs + CYP) group. The results of biochemical analysis on testicular tissue homogenate showed that TiO2NPs and CYP mixtures decreased the activities of glutathione peroxidase (GSH-Px) and catalase (CAT) while increasing the activity of malondialdehyde (MDA) and lactate dehydrogenase (LDH). Meanwhile, the results of two-way factorial analysis of variance (ANOVA) showed a significant effect on GSH-Px, CAT, LDH, testicular cell apoptosis, and sperm quality in rats after exposure. Furthermore, the combined exposure group exhibited apoptosis of testicular cells and DNA damage. The results indicated that exposure to a mixture of TiO2NPs and CYP had adverse effects on the reproductive status of male rats.


Subject(s)
Nanoparticles , Pyrethrins , Rats , Male , Animals , Titanium/toxicity , Rats, Sprague-Dawley , Semen , Pyrethrins/toxicity , Nanoparticles/toxicity , Glutathione Peroxidase , Oxidative Stress
13.
Molecules ; 27(21)2022 Oct 24.
Article in English | MEDLINE | ID: mdl-36364013

ABSTRACT

Monoterpene pyridine alkaloids (MTPAs) are alkaloids derived from iridoid glycosides (IGs). The common molecular structure of MTPAs is the pyridine ring, while some of them have a cyclopenta[c]pyridine skeleton. Some compounds containing this structure are potentially bioactive medicinal agents. In this paper, seven drug candidates (A-G), ninety natural source products (1-90), thirty-seven synthesized compounds (91-127), as well as twenty-six key intermediates (S1-S26) were summarized. We categorized five types of MTPAs and one type of cyclopenta[c]pyridine alkaloids in all. Additionally, their possible genetic pathways were proposed. Then, the chemical transformation, biotransformation, chemical synthesis, as well as the bioactivity of MTPAs and cyclopenta[c]pyridine derivatives were analyzed and summarized. Cyclopenta[c]pyridine derivatives can be concisely and chirally synthesized, and they have shown potentials with antibacterial, insecticidal, antiviral, anti-inflammatory, and neuropharmacological activities.


Subject(s)
Alkaloids , Biological Products , Monoterpenes , Alkaloids/pharmacology , Alkaloids/chemistry , Molecular Structure , Pyridines/pharmacology , Pyridines/chemistry , Biological Products/chemistry
14.
RSC Adv ; 12(21): 13087-13092, 2022 Apr 28.
Article in English | MEDLINE | ID: mdl-35497007

ABSTRACT

A highly efficient potassium carbonate-mediated [3 + 2] cycloaddition reaction of hydrazonoyl chlorides with cinnamic aldehydes to furnish multi-substituted pyrazoles under nontoxic and mild conditions has been developed. A plausible stepwise cycloaddition reaction mechanism is proposed. This protocol featured broad substrate coverage, good functional group tolerance, wide scalability, and operational simplicity, as well as conveniently constructed pyrazole scaffolds.

15.
Food Chem ; 327: 127079, 2020 Oct 15.
Article in English | MEDLINE | ID: mdl-32446028

ABSTRACT

Two water-soluble red color-related proteins with the molecular masses of 24 and 73 kDa were purified from the shell of Procambarus clarkii. Initial color changes of these two proteins were detected at 30 °C and the large amount of red precipitate were obtained at 80 °C. PAGE analysis showed that the 24 kDa protein was the monomer, while the 73 kDa protein was the trimer. Identification revealed that these two proteins belonged to the hemocyanin subunit 2 family. With respect to the amino acid sequence similarity, the red color-related proteins shared the highest sequence identity with the hemocyanin derived from giant freshwater prawn (Macrobrachium rosenbergii). The phylogenetic tree analysis also clearly supported this finding. The shell-derived red color-related proteins show potential use as the edible thermal-sensitive indicator in food processing field.


Subject(s)
Astacoidea/chemistry , Fish Proteins/chemistry , Amino Acid Sequence , Animals , Astacoidea/genetics , Astacoidea/metabolism , Color , Computational Biology , Fish Proteins/genetics , Fish Proteins/isolation & purification , Fish Proteins/metabolism , Hemocyanins/chemistry , Hemocyanins/metabolism , Phylogeny
16.
Food Sci Biotechnol ; 28(4): 983-990, 2019 Aug.
Article in English | MEDLINE | ID: mdl-31275698

ABSTRACT

A new fluorescent probe made from (E)-2-(benzo[d]thiazol-2-yl)-3-(6-hydroxynaphthalen-2-yl) acrylonitrile (Probe 1) was synthesized for the determination of bisulfite concentrations in real food samples (red wine and sugar). Adding bisulfite to a Probe 1 solution caused a marked decrease in fluorescence intensity and a visual color change from yellow to light yellow. This distinct color response indicates that Probe 1 could be used as a visual sensor for bisulfite. Probe 1 can detect bisulfite quantitatively in the range 0-400 µM with a detection limit of 0.10 µM. This makes Probe 1 a convenient signaling instrument for determining bisulfite levels in sugar and red wine samples.

17.
Anal Sci ; 34(11): 1297-1302, 2018 Nov 10.
Article in English | MEDLINE | ID: mdl-30058602

ABSTRACT

A new highly selective and visible colorimetric fluorescent probe (probe 1) was developed to detect hydrazine (N2H4) concentration in real water samples. As different concentrations of N2H4 were added, the color of the probe solution was graded gradually from colorless to pink, which could be observed by the naked eye under UV light at 365 nm. Our research indicates that probe 1 offers a certain practical significance for use as a visible detection agent to detect N2H4 efficiently by distinct color response. Furthermore, our work showed that probe 1 can be successfully applied to detect N2H4 concentrations in real water samples.

18.
Carbohydr Polym ; 174: 146-153, 2017 Oct 15.
Article in English | MEDLINE | ID: mdl-28821053

ABSTRACT

In this work, crystalline structural variations of cellulose during pulp beating of tobacco stems were characterized through X-ray diffraction (XRD) and FT-IR spectroscopy. The results showed that the correlation between the cellulose crystallinity index and the degree of beating was not a linear but an initially upward and then downward trend followed by a repeating fluctuation as a result of the beating action on amorphous regions first and then on crystalline cellulose. It was proposed that the whole beating process might be presumably divided into two phases in the case of the evolution of the crystallinity index. The crystallite sizes of 101 and 101¯ lattice planes showed an obvious fluctuation during the beating while the crystallite sizes and d-spacings from representative 002 lattice planes exhibited little change. Complementally, FT-IR characterization of cellulose structural properties further proved that the crystallinity index was highly affected by mechanical beating and the intact beating process might be divided into two stages characteristic of a first ascending and then descending tendency.

19.
Bioorg Chem ; 56: 67-74, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25123542

ABSTRACT

A cobalt porphyrin (CY-B) was presented, and its interaction with tobacco-specific nitrosamines (TSNAs) was investigated by UV-Vis spectroscopy and high-resolution mass spectrometry. The results revealed that the stoichiometry of the host-guest interaction was 1:2 and that the binding constant between CY-B and TSNAs was within the range of 0.78×10(8)-7.83×10(8)M(-2). The coordination strength between CY-B and TSNAs decreased in the sequence of NNN>NAB>NAT>NNK based on the binding constant. The interaction mechanism of CY-B with TSNAs involved a coordination interaction, and the π-π interaction between the porphyrin macrocycle and the aromatic frame of the TSNAs pyridines may also have been a driving force. The measured thermodynamic properties demonstrated that the reaction of CY-B with TSNAs was spontaneous and that the driving force for the interaction was a change in enthalpy. The reaction was exothermic, and an increasing temperature inhibited the interaction. The IR spectrum of the complex revealed that the NNO group of TSNAs and the metal cobalt of CY-B formed the six-coordinate complex.


Subject(s)
Cobalt/chemistry , Metalloporphyrins/chemistry , Neoplasms/chemistry , Nicotiana/chemistry , Nitrosamines/chemistry , Molecular Structure , Thermodynamics
20.
Amino Acids ; 37(4): 603-7, 2009 Oct.
Article in English | MEDLINE | ID: mdl-18836682

ABSTRACT

L-beta-Haloalanines are physiologically active unnatural amino acids and they are useful intermediates for the synthesis of natural and unnatural amino acids, S-linked glycopeptides, and lanthionines. In general L-beta-haloalanines were prepared predominantly from L-serine via functional group transformation. Here we reported an alternative approach for the preparation of L-beta-haloalanines via halogenation of protected L-cysteine esters which was obtained from L-cysteine or L-cystine, respectively. The mercapto group of protected L-cysteine esters was efficiently transformed to halo groups by triphenylphosphine/N-halosuccinimides. It has been proved to be a versatile desulfurization strategy via this functional group transformation.


Subject(s)
Cysteine/chemistry , Cystine/chemistry , Halogenation , beta-Alanine/analogs & derivatives , Halogens/chemistry
SELECTION OF CITATIONS
SEARCH DETAIL
...