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Fulltext A Preliminary Nuclear Magnetic Resonance Metabolomics Study Identifies Metabolites that Could Serve as Diagnostic Markers of Major Depressive Disorder

Badamasi IM, Maulidiani M, Lye MS, Ibrahim N, Shaari K, Stanslas J

Curr Neuropharmacol, 2022;20(5):965-982.
PMID: 34126904 DOI: 10.2174/1570159X19666210611095320

BACKGROUND: The evaluation of metabolites that are directly involved in the physiological process, few steps short of phenotypical manifestation, remains vital for unravelling the biological moieties involved in the development of the (MDD) and in predicting its treatment outcome.
METHODOLOGY: Eight (8) urine and serum samples each obtained from consenting healthy controls (HC), twenty-five (25) urine and serum samples each from first episode treatment naïve MDD (TNMDD) patients, and twenty (22) urine and serum samples each s from treatment naïve MDD patients 2 weeks after SSRI treatment (TWMDD) were analysed for metabolites using proton nuclear magnetic resonance (1HNMR) spectroscopy. The evaluation of patients' samples was carried out using Partial Least Squares Discriminant Analysis (PLS-DA) and Orthogonal Partial Least Square- Discriminant Analysis (OPLSDA) models.
RESULTS: In the serum, decreased levels of lactate, glucose, glutamine, creatinine, acetate, valine, alanine, and fatty acid and an increased level of acetone and choline in TNMDD or TWMDD irrespective of whether an OPLSDA or PLSDA evaluation was used were identified. A test for statistical validations of these models was successful.
CONCLUSION: Only some changes in serum metabolite levels between HC and TNMDD identified in this study have potential values in the diagnosis of MDD. These changes included decreased levels of lactate, glutamine, creatinine, valine, alanine, and fatty acid, as well as an increased level of acetone and choline in TNMDD. The diagnostic value of these changes in metabolites was maintained in samples from TWMDD patients, thus reaffirming the diagnostic nature of these metabolites for MDD.

Matched MeSH terms: Magnetic Resonance Spectroscopy/methods
Fulltext Classification of Raw Stingless Bee Honeys by Bee Species Origins Using the NMR- and LC-MS-Based Metabolomics Approach

Razali MTA, Zainal ZA, Maulidiani M, Shaari K, Zamri Z, Mohd Idrus MZ, et al.

Molecules, 2018 Aug 28;23(9).
PMID: 30154302 DOI: 10.3390/molecules23092160

The official standard for quality control of honey is currently based on physicochemical properties. However, this method is time-consuming, cost intensive, and does not lead to information on the originality of honey. This study aims to classify raw stingless bee honeys by bee species origins as a potential classifier using the NMR-LCMS-based metabolomics approach. Raw stingless bee honeys were analysed and classified by bee species origins using proton nuclear magnetic resonance (¹H-NMR) spectroscopy and an ultra-high performance liquid chromatography-quadrupole time of flight mass spectrometry (UHPLC-QTOF MS) in combination with chemometrics tools. The honey samples were able to be classified into three different groups based on the bee species origins of Heterotrigona itama, Geniotrigona thoracica, and Tetrigona apicalis. d-Fructofuranose (H. itama honey), β-d-Glucose, d-Xylose, α-d-Glucose (G. thoracica honey), and l-Lactic acid, Acetic acid, l-Alanine (T. apicalis honey) ident d-Fructofuranose identified via ¹H-NMR data and the diagnostic ions of UHPLC-QTOF MS were characterized as the discriminant metabolites or putative chemical markers. It could be suggested that the quality of honey in terms of originality and purity can be rapidly determined using the classification technique by bee species origins via the ¹H-NMR- and UHPLC-QTOF MS-based metabolomics approach.

Matched MeSH terms: Magnetic Resonance Spectroscopy*
Kinetics and mechanism of large rate enhancement in the alkaline hydrolysis of N'-morpholino-N-(2'-methoxyphenyl)phthalamide

Sim YL, Ariffin A, Khan MN

J Org Chem, 2008 May 16;73(10):3730-7.
PMID: 18410141 DOI: 10.1021/jo702695k

The apparent second-order rate constant (k OH) for hydroxide-ion-catalyzed conversion of 1 to N-(2'-methoxyphenyl)phthalamate (4) is approximately 10(3)-fold larger than k OH for alkaline hydrolysis of N-morpholinobenzamide (2). These results are explained in terms of the reaction scheme 1 --> k(1obs) 3 --> k(2obs) 4 where 3 represents N-(2'-methoxyphenyl)phthalimide and the values of k(2obs)/k(1obs) vary from 6.0 x 10(2) to 17 x 10(2) within [NaOH] range of 5.0 x 10(-3) to 2.0 M. Pseudo-first-order rate constants (k(obs)) for alkaline hydrolysis of 1 decrease from 21.7 x 10(-3) to 15.6 x 10(-3) s(-1) with an increase in ionic strength (by NaCl) from 0.5 to 2.5 M at 0.5 M NaOH and 35 degrees C. The values of k obs, obtained for alkaline hydrolysis of 2 within [NaOH] range 1.0 x 10(-2) to 2.0 M at 35 degrees C, follow the relationship k(obs) = kOH[HO(-)] + kOH'[HO (-)] (2) with least-squares calculated values of kOH and kOH' as (6.38 +/- 0.15) x 10(-5) and (4.59 +/- 0.09) x 10(-5) M (-2) s(-1), respectively. A few kinetic runs for aqueous cleavage of 1, N'-morpholino-N-(2'-methoxyphenyl)-5-nitrophthalamide (5) and N'-morpholino-N-(2'-methoxyphenyl)-4-nitrophthalamide (6) at 35 degrees C and 0.05 M NaOH as well as 0.05 M NaOD reveal the solvent deuterium kinetic isotope effect (= k(obs) (H 2) (O)/ k(obs) (D 2 ) (O)) as 1.6 for 1, 1.9 for 5, and 1.8 for 6. Product characterization study on the cleavage of 5, 6, and N-(2'-methoxyphenyl)-4-nitrophthalimide (7) at 0.5 M NaOD in D2O solvent shows the imide-intermediate mechanism as the exclusive mechanism.

Matched MeSH terms: Magnetic Resonance Spectroscopy/methods
Review of MR spectroscopy analysis and artificial intelligence applications for the detection of cerebral inflammation and neurotoxicity in Alzheimer's disease

Seriramulu VP, Suppiah S, Lee HH, Jang JH, Omar NF, Mohan SN, et al.

Med J Malaysia, 2024 Jan;79(1):102-110.
PMID: 38287765

INTRODUCTION: Magnetic resonance spectroscopy (MRS) has an emerging role as a neuroimaging tool for the detection of biomarkers of Alzheimer's disease (AD). To date, MRS has been established as one of the diagnostic tools for various diseases such as breast cancer and fatty liver, as well as brain tumours. However, its utility in neurodegenerative diseases is still in the experimental stages. The potential role of the modality has not been fully explored, as there is diverse information regarding the aberrations in the brain metabolites caused by normal ageing versus neurodegenerative disorders.
MATERIALS AND METHODS: A literature search was carried out to gather eligible studies from the following widely sourced electronic databases such as Scopus, PubMed and Google Scholar using the combination of the following keywords: AD, MRS, brain metabolites, deep learning (DL), machine learning (ML) and artificial intelligence (AI); having the aim of taking the readers through the advancements in the usage of MRS analysis and related AI applications for the detection of AD.
RESULTS: We elaborate on the MRS data acquisition, processing, analysis, and interpretation techniques. Recommendation is made for MRS parameters that can obtain the best quality spectrum for fingerprinting the brain metabolomics composition in AD. Furthermore, we summarise ML and DL techniques that have been utilised to estimate the uncertainty in the machine-predicted metabolite content, as well as streamline the process of displaying results of metabolites derangement that occurs as part of ageing.
CONCLUSION: MRS has a role as a non-invasive tool for the detection of brain metabolite biomarkers that indicate brain metabolic health, which can be integral in the management of AD.

Matched MeSH terms: Magnetic Resonance Spectroscopy/methods
Synthesis, X-ray, NMR, FT-IR, UV/vis, DFT and TD-DFT studies of N-(4-chlorobutanoyl)-N'-(2-, 3- and 4-methylphenyl)thiourea derivatives

Abosadiya HM, Anouar el H, Hasbullah SA, Yamin BM

Spectrochim Acta A Mol Biomol Spectrosc, 2015 Jun 5;144:115-24.
PMID: 25748989 DOI: 10.1016/j.saa.2015.01.092

A new isomers of thiourea derivatives, namely N-(4-chlorobutanoyl)-N'-(2-methylphenyl)-thiourea (1a), N-(4-chlorobutanoyl)-N'-(3-methylphenyl)thiourea (1b) and N-(4-chlorobutanoyl)-N'-(4-methylphenyl)thiourea (1c) have been synthesized by refluxing mixture of equimolar amounts of 4-chlorobutanoylisothiocyanate with 2, 3 or 4-toluidine, respectively. The three isomers were characterized by spectroscopic (UV/vis, FT-IR and NMR) and X-ray crystallography techniques. To investigate the isomerization effect on spectroscopic data, DFT and TD-DFT calculations have been carried out using five hybrid functionals (B3LYP, B3P86, CAM-B3LYP, M06-2X and PBE0) to predict UV/vis absorption bands (n→π∗ and π→π∗), (1)H and (13)C NMR chemical shifts, FT-IR vibration modes and X-ray parameters (bonds, bond angles and torsion angles) for 1a, 1b and 1c isomers. The results showed that the isomerization effect is significant on λ(MAX) absorption bands, while for IR and NMR the effect is negligible. In accordance with previous studies, B3LYP, B3P86 and PBE0 gave the most reliable to predict the excitation energies of thiourea derivatives.

Matched MeSH terms: Magnetic Resonance Spectroscopy*; Carbon-13 Magnetic Resonance Spectroscopy; Proton Magnetic Resonance Spectroscopy
Fulltext Polymerization degrees, molecular weights and protein-binding affinities of condensed tannin fractions from a Leucaena leucocephala hybrid

Saminathan M, Tan HY, Sieo CC, Abdullah N, Wong CM, Abdulmalek E, et al.

Molecules, 2014 Jun 12;19(6):7990-8010.
PMID: 24927368 DOI: 10.3390/molecules19067990

Condensed tannins (CTs) form insoluble complexes with proteins and are able to protect them from degradation, which could lead to rumen bypass proteins. Depending on their degrees of polymerization (DP) and molecular weights, CT fractions vary in their capability to bind proteins. In this study, purified condensed tannins (CTs) from a Leucaena leucocephala hybrid were fractionated into five different molecular weight fractions. The structures of the CT fractions were investigated using 13C-NMR. The DP of the CT fractions were determined using a modified vanillin assay and their molecular weights were determined using Q-TOF LC-MS. The protein-binding affinities of the respective CT fractions were determined using a protein precipitation assay. The DP of the five CT fractions (fractions F1-F5) measured by the vanillin assay in acetic acid ranged from 4.86 to 1.56. The 13C-NMR results showed that the CT fractions possessed monomer unit structural heterogeneity. The number-average molecular weights (Mn) of the different fractions were 1265.8, 1028.6, 652.2, 562.2, and 469.6 for fractions F1, F2, F3, F4, and F5, respectively. The b values representing the CT quantities needed to bind half of the maximum precipitable bovine serum albumin increased with decreasing molecular weight--from fraction F1 to fraction F5 with values of 0.216, 0.295, 0.359, 0.425, and 0.460, respectively. This indicated that higher molecular weight fractions of CTs from L. leucocephala have higher protein-binding affinities than those with lower molecular weights.

Matched MeSH terms: Magnetic Resonance Spectroscopy
Possible intermolecular association in triphenyltin chloride in the solution state as detected by NMR spectroscopy

Ng S, Sathasivam RV, Lo KM

Magn Reson Chem, 2011 Nov;49(11):749-52.
PMID: 22002760 DOI: 10.1002/mrc.2827

NMR measurements ((119)Sn chemical shift, line width and (13)C relaxation) were made on triphenyltin chloride in two solutions, 2.5 and 0.75 mol% in CDCl(3), at several temperatures. The (13)C spin-lattice relaxation time and NOE data for the phenyl carbons provide the corresponding correlation times for the overall molecular reorientational motion and the internal rotation of the phenyl groups. The results are indicative of a weak intermolecular association of the triphenyltin chloride molecules in solution and are discussed with reference to a model for intermolecular phenyl ring π-π stacking interactions.

Matched MeSH terms: Magnetic Resonance Spectroscopy
Fulltext Magnetic resonance-guided focused ultrasound surgery (MRgFUS) treatment for uterine fibroids

Abdullah B, Subramaniam R, Omar S, Wragg P, Ramli N, Wui A, et al.

Biomed Imaging Interv J, 2010 Apr-Jun;6(2):e15.
PMID: 21611036 MyJurnal DOI: 10.2349/biij.6.2.e15

Magnetic Resonance-guided focused Ultrasound Surgery (MRgFUS) is gaining popularity as an alternative to medical and surgical interventions in the management of symptomatic uterine fibroids. Studies have shown that it is an effective non-invasive treatment with minimal associated risks as compared to myomectomy and hysterectomy. MRgFUS can be offered to a majority of patients suffering from symptomatic uterine fibroids. It has been suggested that the use of broader inclusion criteria as well as the mitigation techniques makes it possible to offer MRgFUS to a much larger subset of patients than previously believed. This paper will describe how MRgFUS treatment for uterine fibroids is performed at the University of Malaya Medical Centre, Kuala Lumpur, Malaysia.

Matched MeSH terms: Magnetic Resonance Spectroscopy
Fulltext A new cembrane diterpene from the Bornean soft coral Nephthea sp

Ishii T, Zhaoqi Z, Vairappan CS

Molecules, 2010 May 26;15(6):3857-62.
PMID: 20657412 DOI: 10.3390/molecules15063857

A new cembrane diterpene, 6-acetoxy-7,8-epoxynephthenol acetate (1) was isolated along with a known compound, epoxynephthenol acetate (2), from the organic extract of a Bornean soft coral Nephthea sp. Their structures were elucidated on the basis of spectroscopic analyses and comparison with those previous literature data.

Matched MeSH terms: Magnetic Resonance Spectroscopy
Methyl chanofruticosinate alkaloids from Kopsia arborea

Lim KH, Kam TS

Phytochemistry, 2008 Jan;69(2):558-61.
PMID: 17631924

Six alkaloids belonging to the methyl chanofruticosinate group, viz., prunifolines A-F, in addition to six other known methyl chanofruticosinate alkaloids, were isolated from the leaf extract of Kopsia arborea. The structures were determined using NMR and MS analysis and comparison with known related compounds.

Matched MeSH terms: Magnetic Resonance Spectroscopy
Fulltext Synthesis and Characterization of the Inclusion Complex of β-cyclodextrin and Azomethine

Sambasevam KP, Mohamad S, Sarih NM, Ismail NA

Int J Mol Sci, 2013;14(2):3671-82.
PMID: 23434664 DOI: 10.3390/ijms14023671

A β-cyclodextrin (β-Cyd) inclusion complex containing azomethine as a guest was prepared by kneading method with aliquot addition of ethanol. The product was characterized by Fourier Transform Infrared (FTIR) spectrometer, 1H Nuclear Magnetic Resonance (1H NMR) and Thermogravimetric Analyzer (TGA), which proves the formation of the inclusion complex where the benzyl part of azomethine has been encapsulated by the hydrophobic cavity of β-Cyd. The interaction of β-Cyd and azomethine was also analyzed by means of spectrometry by UV-Vis spectrophotometer to determine the formation constant. The formation constant was calculated by using a modified Benesi-Hildebrand equation at 25 °C. The apparent formation constant obtained was 1.29 × 104 L/mol. Besides that, the stoichiometry ratio was also determined to be 1:1 for the inclusion complex of β-Cyd with azomethine.

Matched MeSH terms: Magnetic Resonance Spectroscopy
Clathration of Two-Dimensional Coordination Polymers: Synthesis and Structures of [M(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(2).(2,4'-bpy)(2).H(2)O and [Cu(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(4).(4,4'-H(2)Bpy) (M = Cd(II), Zn(II) and bpy = Bipyridine)

Tong ML, Ye BH, Cai JW, Chen XM, Ng SW

Inorg Chem, 1998 Jun 01;37(11):2645-2650.
PMID: 11670398

In the presence of guest 2,4'-bpy molecules or under acidic conditions, three compounds, [Cd(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(2).(2,4'-bpy)(2).H(2)O (1), [Zn(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(2).(2,4'-bpy)(2).H(2)O (2), and [Cu(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(4).(4,4'-H(2)bpy) (3), were obtained from the reactions of the metal salts and 4,4'-bpy in an EtOH-H(2)O mixture. 1 has a 2-D square-grid network structure, crystallizing in the monoclinic space group P2/n, with a = 13.231(3) Å, b = 11.669(2) Å, c = 15.019(3) Å, beta = 112.82(3) degrees, Z = 2; 2 is isomorphous with 1, crystallizing in the monoclinic space group P2/n, with a = 13.150(3) Å, b = 11.368(2) Å, c = 14.745(3) Å, beta = 110.60(3) degrees, Z = 2. The square grids superpose on each other into a channel structure, in which each layer consists of two pairs of shared edges, perfectly square-planar with an M(II) ion and a 4,4'-bpy at each corner and side, respectively. The square cavity has dimensions of 11.669(2) x 11.788(2) and 11.368(2) x 11.488(2) Å for 1 and 2, respectively. Every two guest 2,4'-bpy molecules are clathrated in each hydrophobic host cavity and are further stabilized by pi-pi stacking and hydrogen bonding interactions. The NMR spectra clearly confirm that both 1 and 2 contain 4,4'-bpy and 2,4'-bpy molecules in a 1:1 ratio, which have stacking interaction with each other in the solution. 3 crystallizes in the orthorhombic space group Ibam, with a = 11.1283(5) Å, b = 15.5927(8) Å, c = 22.3178(11) Å, Z = 4. 3 is made up of two-dimensional square [Cu(4)(4,4'-bpy)(4)] grids, where the square cavity has dimensions of 11.13 x 11.16 Å. Each [4,4'-H(2)bpy](2+) cation is clathrated in a square cavity and stacks with one pair of opposite edges of the host square cavity in an offset fashion with the face-to-face distance of ca. 3.95 Å. Within each cavity, the [4,4'-H(2)bpy](2+) cation forms twin three-center hydrogen bonds with two pairs of ClO(4)(-) anions. The results suggest that the guest 2,4'-bpy molecules and protonated [4,4'-H(2)bpy](2+) cations present in the reaction systems serve as structure-directing templates in the formation of the crystal structures and exclude self-inclusion of the networks having larger square cavities.

Matched MeSH terms: Magnetic Resonance Spectroscopy
Re-examination of the structure of calcichrome (calcion) and its complexation with polyaromatic hydrocarbons in water

Poh BL, Khairuddean M

Talanta, 1996 Oct;43(10):1727-31.
PMID: 18966659

A non-cyclic tetrameric structure has been suggested for calcichrome (calcion). This structure is consistent with its mass spectrum, proton NMR spectrum, elemental composition and complexing ability with polyaromatic hydrocarbons in water. The stability constants of the 1:1 complexes formed between calcichrome and seven polyaromatic hydrocarbons in water at room temperature have been measured.

Matched MeSH terms: Magnetic Resonance Spectroscopy
A Novel Optical Complex between an Organic Substrate and a Polyoxometalate. Crystal and Molecular Structure of alpha-H(4)SiW(12)O(40).4HMPA.2H(2)O (HMPA = Hexamethylphosphoramide)

Niu Jy Jy, You Xz Xz, Duan Cy Cy, Fun Hk Hk, Zhou Zy Zy

Inorg Chem, 1996 Jul 03;35(14):4211-4217.
PMID: 11666630

A solvated complex of alpha-H(4)SiW(12)O(40).4HMPA.2H(2)O composed the heteropolytungstate alpha-H(4)SiW(12)O(40) and the organic substrate hexamethylphosphoramide (HMPA) has been synthesised, purified, and characterized. The electronic spectra (lambda = 220-500 nm) as well as the (1)H NMR spectra for the title compound dissolved in CD(3)CN establish that this complex dissociates into free SiW(12)O(40)(4)(-) and HMPA moieties in solution unless the organic substrate HMPA is present in very high concentrations. The solid reflectance electronic spectra and IR spectra indicate that there is interaction between the alpha-H(4)SiW(12)O(40) and the organic substrate. The complex has no photosensitivity under irradiation of sunlight, but under the near-UV light result in a charge transfer by oxidation of the HMPA and the reduction of the polyoxometalate. Light yellow polyhedrons of the title compound crystallize from the aqueous solvent of acetonitrile and aqueous solution as the formula of alpha-H(4)SiW(12)O(40).4HMPA.2H(2)O in the monoclinic, space group P2(1). The unit cell has a = 12.791(3) Å, b = 22.103(6) Å, c = 15.532(4) Å, beta = 102.860(10) degrees, and Z = 2. From the bond-valence parameters, it was found that the four hydrogen atoms of the polyoxometalate were combined with the N atoms of the four HMPA respectively. The title compound shows a certain second-order and third-order nonlinear optical response of I(2)(omega) = 0.7I(2)(omega)(KDP) and chi((3)) = 2.63 x 10(-)(11) esu, respectively.

Matched MeSH terms: Magnetic Resonance Spectroscopy
The assessment of three dimensional modelling design for single strand DNA aptamers for computational chemistry application

Sabri MZ, Hamid AAA, Hitam SMS, Rahim MZA

Biophys Chem, 2020 12;267:106492.
PMID: 33035750 DOI: 10.1016/j.bpc.2020.106492

Aptamers are oligonucleotides and peptides around 15-100 bases in length and are suitable as detection probes or as therapeutics molecules. There are growing interests in the aptamer screening approach through computational simulation methods. DNA and RNA modelling lacks of validation on their predicted 3D structures due to less number of validation tools, unlike protein structures. We suggest an approach to design the stem-loop/hairpin for the three dimensional structure of DNA aptamers through serial applications of computational prediction methods by comparing the simulated structures with the experimental data deposited in PDB Data bank, followed by MD simulations. The result shows minimal structural differences were observed between the designed and the original NMR aptamers, and the stem-loop conformational structures were also retained during the MD thus suggesting the proposed aptamers designing methods are able to synthesize a high quality molecular structure of hairpin aptamers, comparable to the NMR structures.

Matched MeSH terms: Magnetic Resonance Spectroscopy
Fulltext Role of cardiac MRI in detecting familial hypertrophic cardiomyopathy: review

Koshy M, Bushra Johari, Mohd Farhan Hamdan, Mohammad Hanafiah

Journal of Clinical and Health Sciences, 2016;1:44-9.

Hypertrophic cardiomyopathy (HCM) is a global disease affecting people of various ethnic origins and both genders. HCM is a genetic disorder with a wide range of symptoms, including the catastrophic presentation of sudden cardiac death. Proper diagnosis and treatment of this disorder can relieve symptoms and prolong life. Non-invasive imaging is essential in diagnosing HCM. We present a review to deliberate the potential use of cardiac magnetic resonance (CMR) imaging in HCM assessment and also identify the risk factors entailed with risk stratification of HCM based on Magnetic Resonance Imaging (MRI).

Matched MeSH terms: Magnetic Resonance Spectroscopy
Phytochemical study of hedychium malayanum (zingiberaceae)

Mohammed Yahya Abdo, Wan Yaacob Wan Ahmad, Laily Bin Din, Nazlina Ibrahim

Sains Malaysiana, 2017;46:83-89.

A phytochemical study was conducted on the stems and leaves of Hedychium malayanum (Zingiberaceae). Three steroids
namely stigmasterol (1), sitostenone (2) and stigmast-4-ene-3,6-dione (3) as well as one triterpene, lupenone (4) and
one oxygenated sesquiterpene, caryophyllene oxide (5) were successfully isolated from the respective stems and leaves,
utilizing several chromatographic techniques. Their structures were elucidated by spectroscopic means (IR, MS, NMR),
and by comparison with the literature data.

Matched MeSH terms: Magnetic Resonance Spectroscopy
Synthesis and structural characterization of 6-(N-Methyl-pyridin-2-ylcarbamoyl)-pyridine-2-carboxylic Acid Methyl Ester Isomers

Maisara Abdul Kadir, Nafisah Mansor, Uwaisulqarni M. Osman

Sains Malaysiana, 2017;46:725-731.

A series of monoamide isomers have been successfully synthesised and characterised using combination of common spectroscopic techniques such Fourier Transform Infrared (FT-IR), 1H and 13C Nuclear Magnetic Resonance (NMR) and Ultraviolet-visible (UV-vis). The monoamide compounds namely 6-(3-methyl-pyridin-2-ylcarbamoyl)-pyridine2-carboxylic acid methyl ester (L1), 6-(4-methyl-pyridin-2-ylcarbamoyl)-pyridine-2-carboxylic acid methyl ester (L2), 6-(5-methyl-pyridin-2-ylcarbamoyl)-pyridine-2-carboxylic acid methyl ester (L3) and 6-(6-methyl-pyridin-2ylcarbamoyl)-pyridine-2-carboxylic acid methyl ester (L4) were prepared from reaction between 6-(methoxycarbonyl) pyridine-2-carboxylic acid with 2-amino-N-methylpyridine (where N = 3, 4, 5 and 6) by using acyl chloride reaction. In this present studies, the synthesis and characterization of these compounds are discussed along with the inductive effects contributed by methyl substituted groups at the pyridine ring.

Matched MeSH terms: Magnetic Resonance Spectroscopy
Fulltext Synthesis and Thermal Properties of Resorcinol-Furfural Thermosetting Resin

Liu J, Xuan D, Chai J, Guo D, Huang Y, Liu S, et al.

ACS Omega, 2020 May 05;5(17):10011-10020.
PMID: 32391489 DOI: 10.1021/acsomega.0c00365

A mild and effective synthesis of resorcinol-furfural (RF) thermosetting resin was proposed with ethanol as a distinctive solvent, which, as a usually neglected factor, was shown to not only help form a homogeneous reaction system but also observably reduce the energy barriers between the early intermediates and transition states in addition reactions by explicit solvent effects, drawn from theoretical calculation conclusions. Besides, the para-additions on aromatic rings were more dominant than ortho-additions with the same reactants, which affected the final link types of monomers verified by Fourier transform infrared spectroscopy and two-dimensional nuclear magnetic resonance tests. The prepared resin can be assigned to a relatively fast gel speed and a high residual mass (65.25%) after pyrolysis in a N2 atmosphere by adjusting the molar ratios of F to R, and the curing of that was a complex reaction, with a curing temperature around 149 °C and an activation energy of about 49.11 kJ mol-1 obtained by the Kissinger method.

Matched MeSH terms: Magnetic Resonance Spectroscopy
Limonoids from the fruits of Chisocheton lasiocarpus (Meliaceae)

Katja DG, Hilmayanti E, Nurlelasari, Mayanti T, Harneti D, Maharani R, et al.

J Asian Nat Prod Res, 2023 Jan;25(1):36-43.
PMID: 35128999 DOI: 10.1080/10286020.2022.2032678

Two new azadirone-type limonoids, namely lasiocarpine A (1) and lasiocarpine B (2) were isolated from the fruit of Chisocheton lasiocarpus along with three known limonoids (3-5). UV, IR, one- and two- dimensional NMR, and mass spectrometry were used to determine the chemical structure of the isolated compounds. Furthermore, their cytotoxic activity against breast cancer cell line MCF-7 was evaluated using PrestoBlue reagent. From these compounds, lasiocarpine A (1) showed the strongest activity with an IC50 value of 43.38 μM.

Matched MeSH terms: Magnetic Resonance Spectroscopy

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