NMR Analysis Research Articles

Diastereomers of the Anticancer Peptide CIGB-300 with Altered β-Turn Structures

Abstract Purpose The next-generation anti-tumor drug peptide CIGB-300, developed by the Center for Genetic Engineering and Biotechnology (CIGB), targets casein kinase 2 (CK2) and its substrates, implicating significant therapeutic potential in cancer treatment. A key focus of this study was to compare CIGB-300 and a primary synthetic byproduct, CIGB-300iso, which shares the amino acid sequence with CIGB-300 but was proposed to differ due to racemization. Methods This study explores the synthesis, characterization, and structural elucidation of CIGB-300 and its isomer CIGB-300iso by a comprehensive NMR analysis of seven synthesized diastereomers including amino acid residues C15, H21, and C25. Results This study revealed that CIGB-300iso contains one D enantiomer at position H21. The structures of both isoforms derived from NMR constraints disclosed that the L and D enantiomers have an altered peptide supersecondary structure, with a β-turn type IV3 found in CIGB-300 and a type I β-turn in CIGB-300iso. Conclusion The configuration of H21 significantly impacts the peptide’s conformations, sidechain orientations and, potentially, its biological activity. These findings highlight the importance of enantiomerically pure peptides for the design and synthesis of drug peptides.

A New qNMR Compliant Savitzky-Golay Apodization Function for Resolution Enhancement.

In this work, we introduce a novel NMR apodization function designed to enhance spectral resolution while maintaining compatibility with qNMR standards. This function is based on a modified Savitzky-Golay filter, adapted for time-domain application. It effectively suppresses the negative components typically associated with derivative spectra, while also ensuring the preservation of quantitative integrity in NMR analyses.

Efficient directional biosynthesis of isoquercitrin from quercetin by Bacillus subtilis CD-2 and its anti-inflammatory activity

Isoquercetin, as the sole product, was directionally biosynthesized from quercetin in a non-aqueous system using Bacillus subtilis CD-2 (1 g/L quercetin), and its structure was identified by LC-MS and NMR analysis. CCK8 assays showed no cytotoxicity and good cell proliferation. The anti-inflammatory experiments demonstrated strong inhibition of NO release, transcriptional downregulation of classical effective cellular factors tumour necrosis factor-α, interleukin-6, interleukin-1β, and transcriptional upregulation of interleukin-10 in LPS-induced RAW264.7 cells. Its stronger anti-inflammatory activity than quercetin provided a reference for modifying the structure of quercetin to obtain more compounds with better pharmacological activities for medical industry.

Integration of MALDI glycotyping and NMR analysis to uncover an O-antigen substructure from pathogenic Escherichia coli O111

Escherichia coli O111 serotype is a critical pathogenic E. coli strain that causes severe, potentially fatal complications. Despite its reported variation, only one structure of the O-antigen polysaccharide from E. coli O111 has been reported. Here, a substructure of the O-antigen from E. coli O111 was characterized using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry and NMR analysis. MALDI glycotyping revealed differing O-antigen repeating unit masses of Δm/z 787 and 828 in the E. coli strains and lipopolysaccharides from the O111 serogroup. This variation was caused by the replacement of the hexose residue with hexosamine in the repeating units, which was further confirmed by LIFT-TOF/TOF analysis. Structural elucidation of the O111 substructure by NMR analysis further demonstrated replacement of the hydroxyl group with an N-acetyl group on the terminal glucose residue of the O-antigen pentasaccharide repeating unit. To our knowledge, this study is the first to provide a detailed structural analysis of a new O-antigen substructure from the E. coli O111 serogroup.

ZnO thin films with stable, tunable electrical and optical properties deposited by atomic layer deposition using Et2Zn:NEtMe2 precursor

ZnO thin films were deposited via atomic layer deposition (ALD), using Zn precursor, DEZDMEA (Et2Zn:NEtMe2) and H2O as a reactant. The design of DEZDMEA aimed to achieve enhanced stability and reduced decomposition compared to traditional DEZ (Et2Zn) precursor, as verified through NMR analysis, leading to the ZnO thin films with no-detectable impurities. The growth characteristics of ZnO thin films with the DEZDMEA were systematically evaluated, and high growth rate and the self-limiting reaction were observed. The comparable ZnO growth rate using DEZDMEA with those using DEZ was shown due to the selective removal of one Et and NEtMe2 ligands during the surface adsorption of DEZDMEA as established by DFT calculations. Additionally, increasing the precursor pulse and reducing the H2O pulse time resulted in decreased resistivity of the ZnO thin films, due to the modulation of n-type defects. This approach provided a consistent contour map for achieving stable, reproducible, and tailored resistivity depending on the DEZDMEA pulse time, and H2O pulse time with its vapor pressure. Moreover, the optical band gap could be modulated as well. The utilization of DEZDMEA is anticipated to be a robust and effective method in ALD for Zn-related deposition, promising substantial advantages for commercial applications.

Unlocking glycerol Potential: Novel pathway for hydrogen production and Value-Added chemicals

In the global fight against climate change, the bio-based supply chain represents an interesting solution as it offers the potential to produce high-value-added products and bioenergy through the utilization of waste and by-products. In this work, a new route is proposed for the conversion of bio-based glycerol to H2/CO2 and high value-added liquid and solid products. The innovative process used pure or crude glycerol or ethanol-glycerol mixture along with water and sodium metaborate as reagents at 300 °C under discontinuous conditions. The gas stream consists mainly of hydrogen, followed by biogenic CO2 (31–54 %), CO (4–13 %) and CH4 in traces. The presence of water in the tested crude glycerol improved the hydrogen selectivity to 55 %. Characterization of the liquid reaction products revealed the synthesis of products such as 1,2-propanediol, propanoic acid, acetic acid, cyclopentenones and cyclic diglycerol. In the solid phase, an aliphatic hydrocarbon resin with oxygenated carbon along the saturated chain and an aromatic cluster were also characterized by NMR, FTIR and TG analyses. Based on these findings, the global reaction route to the general reaction products was proposed.

Design, Synthesis, and Biological Studies of C-5-Substituted Diazenyl Derivatives of Uracil as Potent and Selective Antileishmanial Agents Targeting Uridine Biosynthesis Pathway Enzymes.

Herein, we describe the design and synthesis of a series of C-5-substituted diazenyl derivatives of uracil, exhibiting selective and potent antileishmanial but not antibacterial or antifungal activity. The formation of the substituted derivatives was confirmed by using FTIR, 1H, 13C NMR, and HRMS analysis. Among all of the sets of tested compounds, only three [4a, 6b, and 8b] showed the highest activity against Leishmania donovani (LD) promastigote and amastigote models of LD infections. Further, the cytotoxicity assays performed using three different cell lines, Vero cells, J774 cells, and THP1 cells, along with erythrocyte hemolysis assay showed the highest biocompatibility for the 4a, making it a lead compound for further biological assays. The LD cell death associated with 4a was not linked with ergosterol depletion, a common mechanism of action of antileishmanial drugs like amphotericin B (AmB). However, the LD cell death in the presence of 4a was reversed significantly through supplementation of uridine monophosphate (UMP), indicating the specific role of uridine biosynthesis pathway as the target of 4a. Furthermore, the in silico studies predicted ornithine monophosphate decarboxylase enzyme (OMPDCase) from LD as the plausible target for 4a. The proteomics analysis showed stronger downregulation of the aforementioned OMPDCase and also for a few other enzymes that are involved in the UMP biosynthesis pathway. This indicates that OMPDCase and other enzymes that regulate the UMP biosynthesis may be the target of 4a. Overall, the C-5-substituted diazenyl derivatives of uracil are presented here as novel and potent antileishmanial agents that can be used for treating visceral leishmaniasis (VL) wherein at present drug resistance and side effects of existing drugs demand a look for safer alternatives.

Characterization of Biocompatible Gellan Gum Fractions for Prolonged Retention in Ocular Drug Delivery Systems

ABSTRACTGellan gum (GG) emerges as a promising candidate for developing polymeric carriers with extended retention on the ocular surface, aiming to enhance the efficacy of topical ocular drug delivery systems. This study undertakes the purification of commercial GG through fractional dissolution and ultrasonic treatment, producing fractions characterized by 1H, 13C NMR, FTIR spectroscopy and thermogravimetric analysis. The intrinsic viscosity of GG samples was measured in a 0.025 M tetramethylammonium chloride solution and their molecular weights were calculated via the Mark‐Kuhn‐Houwink equation. Methodological choices regarding synthetic procedures, solvents and reagents were guided by considerations of biocompatibility, aligning with the end goal of drug delivery applications. The study further explores the mucoadhesive potential of GG fractions with varying molecular weights for ocular drug delivery, utilizing an in vitro flow‐through technique with fluorescent detection on freshly excised bovine corneal mucosa surfaces. The findings under‐score the viability of GG formulations in enhancing ocular drug retention and pave the way for future applications in topical ocular therapeutics.

Design, Synthesis, QSAR Studies, and Molecular Modeling of Some Novel Bis Methyl 2-[3-(benzo[d]thiazol-2-yl)-2-terephthaloyl-bis-4-oxo-thiazolidin- 5-ylidene]acetates and Screening of their Antioxidant and Enzyme Inhibition Properties.

Benzothiazolamine-based bisthiourea precursors were prepared in good yields. These bisthiourea derivatives were cyclized into symmetrical Bis Methyl 2-[3-(benzothiazol- 2-yl)-2-terephthaloyl-bis-4-oxo-thiazolidin-5-ylidene]acetates, by their condensation with (DMAD) dimethyl but-2-meditate in the presence of dry methanol. All these compounds were evaluated for their biological applications. Antioxidant activities were performed by adopting a DPPH radical assay, and an in vitro enzyme inhibition assay was performed to investigate their enzyme inhibitory potential against butyrylcholinesterase (BChE) and acetylcholinesterase (AChE). Molecular modeling and QSAR studies were performed to monitor the binding propensity of imidathiazolidinone derivatives with enzymes and DNA. Also, electronic and steric descriptors were calculated to determine the effect of structure on the activity of imidathiazolidinone derivatives. The characterization of all the synthesized compounds was done by their physical data, FT-IR, NMR and elemental analysis.

Drying temperature effect on the characteristics of cationically polymerized kraft lignin

In this work, the effect of drying temperature (55–130 °C) on the properties of kraft lignin (KL) polymerized with [2-(methacryloyloxy)ethyl] trimethyl ammonium chloride, as a sustainable polymer (KLM) was investigated. KLM exhibited a 3-fold drop in charge density and a 10 % reduction in water solubility. These alterations were found to be associated with both chemical and physical changes determined by NMR and XPS analyses. At 55 °C, chain interactions were predominant due to electrostatic interactions amongst the pMETAC chains with the electronegative atoms present in KL. At 80, 105, and 130 °C drying temperatures, hydrolysis reactions predominated. The KLM polymer possessed, comparatively, a lesser resistance to thermal degradation than KL, and the KLM polymer had a more uniform thermal degradation behavior across the drying temperatures. Glass transition temperature, Tg, was shown to be comparable for KL across the various drying temperatures. KLM, however, showed an increasing trend as drying temperature increased, up to 130 °C, at which point Tg dropped due to KL degradation. Therefore, the drying temperature has a significant impact on the properties of kraft lignin and its cationic polymerized derivative, and it should be carefully selected to minimize the undesired changes in lignin properties.

1H NMR and chemical analysis to characterize camellia oil obtained by different extraction methods: A comparative study using chemometrics

Camellia oil has become one of the most popular edible vegetable oils especially in China. It can be obtained by cold-pressing (CPE), soxhlet extraction (SE), aqueous enzymatic extraction (AEE), and supercritical carbon dioxide extraction (SC-CO2), while research on their efficient identification is limited. Thus, in this study, proton nuclear magnetic resonance (1H NMR) and conventional chemical analysis, respectively coupled to chemometrics, were employed to compare the camellia oils, produced by CPE, SE, AEE, and SC-CO2. The results showed an obviously overlapping among those four different extracted camellia oils, in both principal component analysis (PCA) and hierarchical clustering analysis (HCA), when using fatty acids as input variables. While two obtained PCA models showed good discrimination, according to the minor component compositions (α-tocopherol, squalene, stigmasterol, β-sitosterol, β-amyrin and lanosterol) and 1H NMR spectra, respectively. Additionally, by means of variable importance for the projection (VIP) scores, less 10 dominant 1H NMR spectra signals were screened out as detailed markers for different camellia oils classification. Therefore, 1H NMR combined with chemometrics may be applied as an efficient technique to classify different extracted camellia oils and potentially other vegetable oils.

A simple and highly selective chalcone fluorescent chemical sensor for the detection of tryptophane

In this study, 1-ferrocenyl-3-(2-hydroxyphenyl) allyl ketone (probe A) was synthesized using a solvent-free method in conjunction with solid-phase grinding and employed as a probe for the detection of tryptophan (Trp). The probe exhibits selective recognition of Trp as evidenced by UV–Vis and fluorescence spectra. In complex scenarios, the probe’s recognition of Trp remains unaffected by both the presence of interfering substances and the duration of exposure. A pH range of 8 to 12 is found to be optimal for the detection of Trp. Job’s curve analysis revealed that the binding ratio between the probe and Trp is 1:1. Based on the Benesi-Hildebrand equation, the binding constant for the interaction between probe A and Trp is calculated to be 1.5 × 107 M−1. The detection limit for Trp was determined to be 9.55 × 10−5 M. The sensing mechanism of the probe for Trp was elucidated through 1H NMR and FT-IR analyses.

Novel Benzohydrazide Derivative as a Potential Anticarcinogenic Agent for Breast Cancer: Synthesis, Crystal Structure, In Vitro and In Silico Assessments

Polycyclic aromatic compounds (PACs) are a class of organic molecules known for their significant biological activity, including anticancer properties. These compounds often interact with biological macromolecules, making them crucial in the development of new therapeutic agents. In this study, we report a new benzohydrazide derivative, (E)-4-(hexyloxy)-N'-(1-(naphthalen-2-yl)ethylidene)benzohydrazide (2), which incorporates a naphthalene ring, a typical PAC, as a core structural element. The structure of the compound was analyzed using FTIR, 1H NMR, 13C NMR and elemental analysis. Moreover, single crystal X-ray crystallography studies demonstrated that the compound adapted monoclinic crystal system with C 2/c space group. In the crystal structure, the intermolecular N–H···O hydrogen bonds link the molecules into infinite chains along the b-axis direction. The dominant interactions formed in the crystal packing were found to be hydrogen bonding and van der Waals interactions according to the Hirshfeld surface (HS) analysis. The evaluation of energy frameworks showed that stabilization of the compound was dominated by dispersion energy contribution. The anticancer activity of the compound was tested by employing several cellular assays. The compound showed strong anticancer effects, with IC50 values of 85 µM for MCF7 cells and 115 µM for MDA-MB-231 cells, indicating dose-dependent suppression of cell viability, migration, and colony formation. Computational analyses indicated favorable binding of compound 2 to ERRγ and predicted good oral availability of the generated compound. Pathway analysis using KEGG pathways identified significant enrichment in pathways related to cancer. These results highlight the compound's promise as a potential treatment option for breast cancer, prompting further exploration in future studies.

Bioavailability Improvement by Atomic Layer Coating: Fenofibrate A Case Study

Biopharmaceutical Classification Systems (BCS) class II drugs show poor solubility and high permeability in the body. Fenofibrate (FF) is a classic example of a BCS class II drug, used to treat high cholesterol and triglyceride (fat-like substances) levels in the blood. Atomic layer coating (ALC) is a surface engineering technology adapted from the semiconductor industry, where metal oxides are coated one atomic layer at a time over the active pharmaceutical ingredients (API) particles. ALC coating was proven to improve the processability, alter the hydrophilicity, improve the stability, and fine-tune the release of drugs. Herein, we report the intervention of ALC coating in enhancing the bioavailability of a poorly water-soluble drug (fenofibrate) in the animal model. The physical properties of uncoated fenofibrate were compared with those of zinc oxide-coated and silicon oxide-coated fenofibrate. Following the application of the coatings, the structural integrity (both chemical stability and solid-state stability) of the active pharmaceutical ingredient (API) remained uncompromised, as corroborated by 1H NMR and powder X-ray diffraction analyses. Notably, zinc oxide-coated fenofibrate exhibited favorable flow characteristics, whereas no discernible enhancement in flow behavior was observed for silicon oxide-coated fenofibrate. The results from contact angle measurements suggest that the silicon oxide-coated fenofibrate exhibits superior wetting behavior, as indicated by a contact angle nearing 0°. The application of ALC demonstrates an enhanced dissolution rate when compared to the uncoated active pharmaceutical ingredient (API) while leaving its equilibrium solubility unaffected. Coating the API with silicon oxide improves particle hydrophilicity and wetting properties, whereas zinc oxide coating aids in particle de-agglomeration, thereby enhancing their interaction with an aqueous medium. In vivo bioavailability studies conducted on rodents and larger animal (dog) models indicate a substantial increase in bioavailability (approximately 2 times) for the silicon oxide-coated API in comparison to the uncoated API, as determined by the area under the curve (AUC). Furthermore, the Cmax values for the silicon oxide-coated API also demonstrate a significant increase (approximately 3 times) over the uncoated API. Notably, an oral subacute toxicity study of ALC silicon-coated fenofibrate revealed no toxic effects attributable to the coating. This study underscores the potential of ALC in augmenting the bioavailability of BCS(II) drugs.

Design, synthesis of antipyrine-based Schiff bases and investigation of their cholinesterase and carbonic anhydrase activities by in vitro and in silico approaches

In this study, a series of antipyrine-based Schiff bases (1-10) was designed, synthesized, and evaluated as potential inhibitors of various metabolic enzymes, including acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and human erythrocyte carbonic anhydrase I and II (hCA I and hCA II). The target molecules were characterized by UV-Vis, FT-IR, 1H NMR, 13CNMR, LC-HRMS, and elemental analysis. All tested derivatives demonstrated low nanomolar inhibition with Ki values of in the range of 20.58 ± 0.35 to 53.11 ± 1.02 nM against AChE, 21.84 ± 0.40 to 54.41 ± 1.05 nM against BChE, 27.45 ± 0.41 to 48.22 ± 0.91 nM against cytosolic hCA I isoform associated with epilepsy, and 6.02 ± 0.11 to 29.32 ± 0.54 nM against cytosolic hCA II isoform associated with glaucoma. In general, most these molecules, except for a few, inhibited these enzymes more than acetazolamide (AZA) and neostigmine. Among them, compounds 5, 7, 8, and 9 showed the best inhibitory activities against AChE, BChE, hCA I, and hCA II, respectively. Docking results were calculated for the compounds that showed the best inhibitory activity against these enzymes and for reference compounds. Based on the molecular docking results, they were determined to have high binding energies, including hydrogen bonds, electrostatic interactions, and hydrophobic interactions. Absorption, distribution, metabolism, and excretion (ADME) parameters determined that all the synthesized pyrazolone ring-bearing Schif base derivatives (1-10) have the expected physicochemical properties in terms of drug-likeness and can be evaluated as orally active potential. Properties such as the electrophilicity index and chemical hardness were also investigated by density functional theory (DFT) at the B3LYP/6-311G** level of theory.

Isolation of Natural Veratrylidenehydrazide Compound from Wedelia Biflora and Synthesis of Veratrylidenehydrazide Analogue: Investigation of Larvicidal Activity Against Culex Quinquefasciatus and Toxicity Analysis in Nontarget Aquatic Species

AbstractIn this study, veratrylidenehydrazide was isolated from Wedelia biflora, and compounds (1a, 2a, and 3a–j) were synthesised to evaluate their larvicidal and antifeedant activities. Veratrylidenehydrazide 1a was verified using GC‐MS. The veratrylidenehydrazide analogues 2a and 3a–j were synthesised via a condensation method with yield range 71%–92%. The compounds (1a, 2a, and 3a–j) were synthesised and characterised through FT–IR, 1H NMR, 13C NMR, mass spectrometry, and elemental analysis. Veratrylidenehydrazide 1a was verified using GC‐MS analysis. Natural veratrylidenehydrazide compound 1a and the synthesised veratrylidenehydrazide analogues (2a, 3a–j) were screened for larvicidal activity against Culex quinquefasciatus. The larvicidal activity of compound 3g was found to be highly active, while low toxicity was observed against Oreochromis mossambicus nontarget aquatic species compared to natural veratrylidenehydrazide. Compound 3g exhibited a higher binding affinity (−8.8 kcal/mol) compared to standard of temephos (−4.5 kcal/mol), equipotential binding affinity against permethrin (−9.1 kcal/mol), and diflubenzuron (−8.5 kcal/mol). Lead molecules have larvicidal properties, and their use as insecticides makes them important.

Capsular polysaccharide structure of Acinetobacter baumannii K58 from clinical isolate MRSN31468

Capsular polysaccharides (CPS) of Acinetobacter baumannii is a virulence factor with diverse structures. CPS are produced by the CPS biosynthesis gene cluster in their K locus (KL). However, CPS variations may occur due to insertion of additional genes from external sources, e.g., prophages. Recently, the CPS structure from a clinical isolate, BAL062 which includes KL58 locus, was found to have a pseudaminic acid isomer (8ePse5NAc7NAc) as a result of prophage inserted epaA/epaB genes. Here, we report a CPS structure produced by A. baumannii strain MRSN31468 which also belongs to a KL58 type. The K58 CPS structure was determined by 1D and 2D NMR analysis of the oligosaccharides derived from the CPS by a phage depolymerase, and supported by the sugar composition analysis. The K58 CPS structure has the following tetra saccharide repeating unit: [Display omitted] The K58 CPS differs from the CPS from BAL062 only by replacing 8-epimerized β-8ePse5NAc7NAc with β-Pse5NAc7NAc.

Use of optimized 1H selTOCSY for identification and individualization of petrol samples from fire debris

Detection and identification of ignitable liquids in fire investigation is ongoing challenge for forensics investigators. This study uses the analytical power of NMR analysis and permits the identification of trace amounts of olefinic compounds the complex mixture of petrol that aids the individualization of petrol sources. The 1H selTOCSY NMR method has proven to be successful in the investigation of the four sets of alkenes namely: 3-methyl-1-butene (set 1), a mixture of 3-methyl-1-butene and 1-pentene (set 2), 2-methyl-2-butene (set 3) and a mixture of cis and trans-2-pentene (set 4) in petrol samples evaporated to different extents, simulating the action of weathering of actual casework samples, and still achieved significant discrimination of petrol brands at 25 % and 50 % evaporation. Discrimination of burned samples also proved possible, both of burnt petrol its own and then petrol burned on different substrates including wood, carpet, fabric, and paper materials representing common household fire debris residues. 1H selTOCSY NMR experiments on these alkene signals remove most of the non-alkene-related signals from the spectra and thus provide additional clarity in heavily burnt and contaminated samples, increasing the capacity to discriminate between samples using the four alkene markers.

Formation and Stability of Benzylic Amide [2]- and [3]Rotaxanes: An Intercomponent Interactions Study.

One of the most recent focuses in supramolecular chemistry is developing molecules designed to exhibit programmable properties at the molecular level. Rotaxanes, which function as molecular machines with movements controlled by external stimuli, are prime candidates for this purpose. However, the controlled synthesis of rotaxanes, especially amide-benzylic rotaxanes with more than two components, remains an area ripe for exploration. In this study, we aim to elucidate the formation of amide-benzylic [3]rotaxanes using a thread that includes a conventional succinamide station and an innovative triazole-carbonyl station. Including the triazole-carbonyl station introduces new perspectives into the chemistry of rotaxanes, influencing their conformation and dynamics. The synthesis of two-station rotaxanes with varying stoppers demonstrated that the macrocycle consistently occupies the succinamide station, providing greater stability as evidenced by NMR and SC-XRD analyses. The presence of a triazole-carbonyl station facilitated the formation of a second macrocycle exclusively when a secondary amide was employed as the stopper group, presumably due to decreased steric hindrance. Moreover, the second macrocycle directly forms at the triazole-carbonyl station. This investigation reveals that slight modifications in the thread structure can dramatically impact the formation, stability, and interactions between components of rotaxanes.

Nitrile glove composition and performance-Substandard properties and inaccurate packaging information.

The durability and mechanical properties of synthetic medical gloves, such as those made from nitrile, vary drastically depending on the manufacturer. This study reports the chemical composition of several brands of nitrile gloves via FTIR and solid-state NMR analysis and relates composition to glove durability (found via GAD), mechanical performance (found via Instron), and whether the gloves meet or fail ASTM International standards. Out of the four nitrile examination glove brands tested, American Nitrile Slate brand had superior durability results and was found to be made of acrylonitrile butadiene rubber, as expected. The U.S. Medical glove brand, which was also found to be pure nitrile, had the superior tensile results, consistently reaching over 800% elongation before breaking. Although Restore Touch brand exam gloves were made of nitrile, they exhibited substandard tensile strength and durability due to the thinness of the glove, which barely met the ASTM minimum thickness value. The Vglove brand glove had the overall worst mechanical properties, did not meet ASTM requirements, and had an NMR spectrum consistent with that of a polyvinyl chloride glove, rather than nitrile. Gloves that fail to meet the minimum performance requirements should not be used for medical purposes to protect the health and safety of consumers.