Characterization of fatty acid forms using benchtop NMR in omega-3 oil supplements

Omega-3 fatty acid supplements, such as fish oil and plant-based oils, have gained popularity because of their potential health benefits. However, the quality and composition of these supplements can vary widely, particularly in terms of the two main forms of omega-3 fatty acids: triacylglycerols (TAGs) and ethyl esters (EEs). TAGs are the natural form found in fish oil but are prone to oxidation, whereas EEs are more stable but less well absorbed by the body. Differentiating between these forms is crucial for assessing the efficacy and tolerance of omega-3 supplements. This article describes a novel approach to differentiate between TAG and EE forms of omega-3 fatty acids in dietary supplements, utilizing a 60-MHz benchtop nuclear magnetic resonance (NMR) spectrometer. The proposed method using 1H and 1H-1H COSY NMR provides a quick and accurate approach to screen the forms of omega-3 fatty acids and evaluate their ratios. The presence of diacylglycerol (DAGs) in some supplements was also highlighted by this method and adds some information about the process used (i.e., esterification/enrichment). The affordability and user-friendliness of benchtop NMR equipment make this method feasible for food processing companies or quality control laboratories. In this study, 24 oil supplements were analyzed using NMR analysis in order to demonstrate the potential of this method for the differentiation of TAG and EE forms in omega-3 supplements.

The POWER saga from 2007 to 2022: An example of a sexual enhancement dietary supplement tainted by different adulterants and still on the market

Ten POWER dietary supplements, chronologically called tabs, pills then caps, and advertised as 100% natural aphrodisiacs, were analyzed by ¹H NMR from 2007 to 2022. They were all tainted by PDE-5 inhibitors. Eight different adulterants were identified (sildenafil (1), sildenafil analogues (6), and vardenafil analogue (1)). Their amounts ranged from 15 to 145 mg/capsule. Four supplements contained at least 100 mg/capsule of PDE-5 inhibitor or analogue, the maximal recommended dose of sildenafil. The nature of the adulterant has changed over time, probably to evade its detection by regulatory agencies routine screening tests. Despite several warnings and/or seizures from several European food and/or health authorities, the dietary supplement POWER is still on sale on the Internet, thus demonstrating the impossibility of controlling this market. Faced with this situation, the consumer should be better informed by establishing at the European level a public database of tainted dietary supplements on the model of that of the US Food and Drug Administration. It should indicate the product name, its photo, the adulterant name, and be easily accessible to everyone.

Modulation of the crystallization of rapeseed oil using lipases and the impact on ice cream properties

We investigated the possibility to use rapeseed as a main oil in ice cream formulations by changing its functionality when using different kinds of lipases. Through a 24 h-emulsification and a centrifugation, the modified oils were further used as functional ingredients. All lipolysis was first assessed as a function of time by ¹³C NMR, where triglycerides consumption and the formation of low-molecular polar lipids (LMPL: monoacylglycerol and free fatty acids, FFAs) were selectively identified and compared. The more the FFAs, the sooner the crystallization (from -55 to -10 °C) and the later the melting temperatures (from -17 to 6 °C) measured by differential scanning calorimetry. These modifications were exploited in ice cream formulations with a significant impact on overall hardness (range of 60-216 N) and flowing during defrosting (from 1.29 to 0.35g/min). The global behavior of products can be controlled by the composition of LMPL within oil.

Tailor-Made Poly(vinylamine) via Purple LED-Activated RAFT Polymerization of N-vinylformamide

Photo-iniferter reversible addition-fragmentation chain transfer (PI-RAFT) polymerization of N-vinylformamide (NVF) is demonstrated by using purple light. PNVFs with predetermined molar masses and narrow molar mass distributions are obtained. High RAFT chain-end fidelity is confirmed by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) and electrospray-ionization time-of-flight mass spectrometry (ESI-TOF-MS), and chain extension experiment. To demonstrate the potential of this approach, an original poly(N-vinylpyrrolidone)-b-poly(N-vinylformamide) (PVP-b-PNVF) diblock copolymer is synthesized and characterized by aqueous size-exclusion chromatography (SEC), asymmetric flow field-flow fractionation (A4F), and ¹ H diffusion-ordered spectroscopy nuclear magnetic resonance (¹ H DOSY NMR). Finally, selective hydrolysis of PNVF block to corresponding pH-responsive poly(N-vinylpyrrolidone)-b-poly(N-vinylformamide) (PVP-b-PVAm) is performed.

Separation of unsaturated C18 fatty acids using perfluorinated-micellar electrokinetic chromatography: I. Optimization and separation process

Ammonium perfluorooctanoate (APFOA) was used as a surfactant for the separation of free unsaturated C18 fatty acids by micellar electrokinetic chromatography. A simple background electrolyte of 50 mM APFOA water/methanol (90:10, v/v) at pH = 10 enabled the repeatable separation of oleic acid, elaidic acid, linoleic acid, and alpha-linolenic acid in less than 20 min. Separation conditions were optimized regarding various parameters (organic solvent, counterion, APFOA concentration, and pH). Because the repulsive interactions between fluorocarbon chains and hydrogenated chains are known to lead to segregation and phase separation, the choice of perfluorinated micelles to separate such perhydrogenated long-chain acids could appear astonishing. Therefore, the critical micelle concentration, the charge density, and the mobility of the micelles have been determined, resulting in a first description of the separation process.

Inhibition of alkaline phosphatase impairs dyslipidemia and protects mice from atherosclerosis

Calcium accumulation in atherosclerotic plaques predicts cardiovascular mortality, but the mechanisms responsible for plaque calcification and how calcification impacts plaque stability remain debated. Tissue-nonspecific alkaline phosphatase (TNAP) recently emerged as a promising therapeutic target to block cardiovascular calcification. In this study, we sought to investigate the effect of the recently developed TNAP inhibitor SBI-425 on atherosclerosis plaque calcification and progression. TNAP levels were investigated in ApoE-deficient mice fed a high-fat diet from 10 weeks of age and in plaques from the human ECLAGEN biocollection (101 calcified and 14 non-calcified carotid plaques). TNAP was inhibited in mice using SBI-425 administered from 10 to 25 weeks of age, and in human vascular smooth muscle cells (VSMCs) with MLS-0038949. Plaque calcification was imaged in vivo with ¹⁸F-NaF-PET/CT, ex vivo with osteosense, and in vitro with alizarin red. Bone architecture was determined with µCT. TNAP activation preceded and predicted calcification in human and mouse plaques, and TNAP inhibition prevented calcification in human VSMCs and in ApoE-deficient mice. More unexpectedly, TNAP inhibition reduced the blood levels of cholesterol and triglycerides, and protected mice from atherosclerosis, without impacting the skeletal architecture. Metabolomics analysis of liver extracts identified phosphocholine as a substrate of liver TNAP, who's decreased dephosphorylation upon TNAP inhibition likely reduced the release of cholesterol and triglycerides into the blood. Systemic inhibition of TNAP protects from atherosclerosis, by ameliorating dyslipidemia, and preventing plaque calcification.

Study of rapeseed oil gelation induced by commercial monoglycerides using a chemometric approach

Commercial oleogelators rich in monoglycerides (MGs) are complex mixtures of acylglycerides with variable gelling properties, depending on the oil used and their concentration. In this study we developed a chemometric approach to identify the key parameters involved in gelling process. Analytical parameters have been defined, using GC and NMR analysis to identify fatty acids and acylglycerides composing the mixtures. Specific acylglyceride families and compound ratios were calculated to streamline the analytical results. To determine the key analytical parameters, artificial neural networks were used in a QSPR study related to the gelling properties measured by rheology through oscillatory experiments. At low oleogelator concentrations, the MGs especially rich in C16:0 and the ratio of specific isomers both have a positive influence on G'. For high oleogelator concentrations, C18:0-rich acylglycerides and unsaturated/saturated fatty acid ratios have a positive influence on G'. Conversely, at low concentrations, C18:0-rich acylglycerides show a lesser effect on G'.

RAFT polymerisation of N-vinylformamide and the corresponding double hydrophilic block copolymers

Polyvinylamine-based double hydrophilic block copolymers are synthesised from RAFT polymerisation of N-vinylformamide.

The tryptophan pathway and nicotinamide supplementation in ischaemic acute kidney injury

Background

Down-regulation of the enzymes involved in tryptophan-derived nicotinamide (NAM) adenine dinucleotide (NAD⁺) production was identified after acute kidney injury (AKI), leading to the hypothesis that supplementation with NAM may increase the kidney NAD⁺ content, rescuing tryptophan pathways and subsequently improving kidney outcomes.

Methods

Urinary measurement of tryptophan and kynurenin using liquid chromatography–mass spectrometry metabolomics was used in a cohort of 167 cardiac bypass surgery patients along with tests for correlation to the development of postoperative AKI. A mouse model of ischaemic AKI using ischaemia–reperfusion injury (bilateral clamping of renal arteries for 25 min) was also used.

Results

We identified a significant decrease in urinary tryptophan and kynurenin in patients developing AKI, irrespective of the Kidney Disease: Improving Global Outcomes (KDIGO) stage. Although a significant difference was observed, tryptophan and kynurenin moderately discriminated for the development of all AKI KDIGO stages {area under the curve [AUC] 0.82 [95% confidence interval (CI) 0.75–0.88] and 0.75 [0.68–0.83], respectively} and severe KDIGO Stages 2–3 AKI [AUC 0.71 (95% CI 0.6–0.81) and 0.66 (0.55–0.77), respectively]. Sparked by this confirmation in humans, we aimed to confirm the potential preventive effect of NAM supplementation in wild-type male and female C57BL/6 mice subjected to ischaemic AKI. NAM supplementation had no effect on renal function (blood urea nitrogen at Day 1, sinistrin–fluorescein isothiocyanate glomerular filtration rate), architecture (periodic acid–Schiff staining) and injury or inflammation (kidney injury molecule 1 and IL18 messenger RNA expression). In addition, NAM supplementation did not increase post-AKI NAD⁺ kidney content.

Conclusion

Notwithstanding the potential role of NAM supplementation in the setting of basal NAD⁺ deficiency, our findings in mice and the reanalysis of published data do not confirm that NAM supplementation can actually improve renal outcomes after ischaemic AKI in unselected animals and probably patients.

Hepatocyte nuclear factor-1β shapes the energetic homeostasis of kidney tubule cells

Energetic metabolism controls key steps of kidney development, homeostasis, and epithelial repair following acute kidney injury (AKI). Hepatocyte nuclear factor-1β (HNF-1β) is a master transcription factor that controls mitochondrial function in proximal tubule (PT) cells. Patients with HNF1B pathogenic variant display a wide range of kidney developmental abnormalities and progressive kidney fibrosis. Characterizing the metabolic changes in PT cells with HNF-1β deficiency may help to identify new targetable molecular hubs involved in HNF1B-related kidney phenotypes and AKI. Here, we combined ¹ H-NMR-based metabolomic analysis in a murine PT cell line with CrispR/Cas9-induced Hnf1b invalidation (Hnf1b^-/- ), clustering analysis, targeted metabolic assays, and datamining of published RNA-seq and ChIP-seq dataset to identify the role of HNF-1β in metabolism. Hnf1b^-/- cells grown in normoxic conditions display intracellular ATP depletion, increased cytosolic lactate concentration, increased lipid droplet content, failure to use pyruvate for energetic purposes, increased levels of tricarboxylic acid (TCA) cycle intermediates and oxidized glutathione, and a reduction of TCA cycle byproducts, all features consistent with mitochondrial dysfunction and an irreversible switch toward glycolysis. Unsupervised clustering analysis showed that Hnf1b^-/- cells mimic a hypoxic signature and that they cannot furthermore increase glycolysis-dependent energetic supply during hypoxic challenge. Metabolome analysis also showed alteration of phospholipid biosynthesis in Hnf1b^-/- cells leading to the identification of Chka, the gene coding for choline kinase α, as a new putative target of HNF-1β. HNF-1β shapes the energetic metabolism of PT cells and HNF1B deficiency in patients could lead to a hypoxia-like metabolic state precluding further adaptation to ATP depletion following AKI.

Synthetic cannabinoids in e-liquids: A proton and fluorine NMR analysis from a conventional spectrometer to a compact one

The ¹H NMR profiles of 13 samples of e-liquids supplied by French customs were obtained with high-field and low-field NMR. The high-field ¹H NMR spectra allowed the detection of matrix signals, synthetic cannabinoids, and flavouring compounds. Quantitative results were obtained for the five synthetic cannabinoids detected: JWH-210, 5F-MDMB-PICA, 5F-ADB, 5F-AKB48, and ADB-FUBINACA. Conventional GC-MS analysis was used to confirm compound identification. Fluorine-19 NMR was proposed for the quantification of fluorinated synthetic cannabinoids and was successfully implemented on both 400 MHz and 60 MHz NMR spectrometers. This study based on few examples explored the potentiality of low-field NMR for quantitative and quantitative analysis of synthetic cannabinoids in e-liquids.

Isolation and identification of ten new sildenafil derivatives in an alleged herbal supplement for sexual enhancement

A sexual enhancer dietary supplement in pre-commercialization phase was analyzed. It contained the two phosphodiesterase-5 inhibitors (PDE-5i) sildenafil and methisosildenafil as major adulterants. Fourteen more sildenafil derivatives were detected and after isolation, their structures were elucidated thanks to NMR, high resolution and tandem mass spectrometry, and UV spectroscopy. Ten of them were never described. All these compounds are probably by-products of different reaction steps during the synthesis of the two PDE-5i that were not properly eliminated during the purification procedure. The total amount of sildenafil-related compounds was estimated at 68 mg per capsule, sildenafil and methisosildenafil accounting for 20 mg and 38 mg respectively.

Comparative Chemical Profiling and Monacolins Quantification in Red Yeast Rice Dietary Supplements by 1H-NMR and UHPLC-DAD-MS

Red yeast rice dietary supplements (RYR DS) are largely sold in Western countries for their cholesterol-lowering/regulating effect due to monacolins, mainly monacolin K (MK), which is, in fact, lovastatin, the first statin drug on the market. 1H-NMR was used as an easy, rapid and accurate method to establish the chemical profiles of 31 RYR DS and to quantify their monacolin contents. Among all the 1H resonances of the monacolins found in RYR, only those of the ethylenic protons of the hexahydronaphthalenic ring at 5.84 and 5.56 ppm are suitable for quantification because they show no overlap with the matrix signals. The total content in monacolins per capsule or tablet determined in 28 DS (the content in 3 DS being below the limit of quantification of the method, ≈ 0.25 mg per unit dose) was close to that measured by UHPLC, as shown by the good linear correlation between the two sets of values (slope 1.00, y-intercept 0.113, r2 0.986). Thirteen of the 31 RYR DS analyzed (i.e., 42%) did not provide label information on the concentration of monacolins and only nine of the 18 formulations with an indication (i.e., 50%) actually contained the declared amount of monacolins.

Benchtop low-field 1H Nuclear Magnetic Resonance for detecting falsified medicines

Falsified medicines represent a serious threat to public health. Among the different measures to effectively combat this scourge, analytical methods play a key role in their detection and removal from the market before they reach patients. The present study evaluates for the first time the potential of a benchtop low-field (LF) Nuclear Magnetic Resonance (NMR) spectrometer for uncovering drug falsification by focusing on the analysis of fifteen erectile dysfunction and nine antimalarial medicines, the most commonly reported falsified medicines in developed and developing countries respectively. After a simple and rapid sample preparation and ≈ 5 min of spectrum recording, LF ¹H NMR allows to conclude on the quality of the medicine: presence or absence of the expected active pharmaceutical ingredient (API), presence of unexpected API, absence of any API. Some 2D experiments are also described but although conclusive they are hampered by the duration of the experiments. The LF ¹H NMR assay, based on the internal standard method, is validated by the determination of its accuracy, repeatability, limits of detection (LOD) and quantification (LOQ), and by comparison of the data obtained on some medicines after 45 min of spectrum recording to those measured with high-field ¹H NMR. Because of its saving capabilities (cost, space, user experience), LF ¹H NMR spectroscopy might become a routine screening tool in laboratories in charge of detecting falsified medicines.

New polyaminocarboxylate macrocycles containing phenolate binding units: synthesis, luminescent and relaxometric properties of their lanthanide complexes

The synthesis of two new polyaminocarboxylate macrocycles incorporating one or two intracyclic phenol units (H₄L¹ and H₈L², respectively) is described. The 12-membered H₄L¹ macrocycle leads to soluble and stable mononuclear Ln^III complexes of [(L¹)Ln(H₂O)₂]^- composition (Ln = Eu, Tb and Gd) in aqueous solutions. In Tris buffer (pH 7.4), the [(L¹)Tb(H₂O)₂]^- complex displays a suitable efficiency for sensitized emission (η_sens = 48%) and a high luminescence quantum yield (Φ = 22%), which is worthy of note for a bis-hydrated terbium complex. Besides, luminescence experiments show that bidentate endogenous anions (citrate, carbonate, and phosphate) do not displace the two inner-sphere water molecules of this complex. In contrast, the possible presence of LMCT states causes the europium complex to be weakly luminescent. The [(L¹)Gd(H₂O)₂]^- complex is characterized by high relaxivity (r = 7.2 s^-1 mM^-1 at 20 MHz) and a very short water residence time of the coordinated water molecules (τ = 9 ns), promising values for the realisation of macromolecular systems with high relaxivities. Thus, the Tb and Gd complexes of the H₄L¹ macrocycle exhibit several improvements in terms of luminescent (lower excitation energy, higher brightness) and relaxometric (shorter τ_M) properties compared to the corresponding LnPCTA complexes, where a phenol moiety substitutes a pyridine ring. On the other hand, the 24-membered H₈L² macrocycle including two phenol units in its structure leads to dinuclear complexes of [(L²)Ln₂]^2- composition. Its terbium complex shows a long luminescence lifetime (2 ms) and a high quantum yield (43%) in aqueous solutions, making this compound a new promising candidate for time-resolved applications.

Screening of "spice" herbal mixtures: From high-field to low-field proton NMR

Forty one samples of herbal spices intended to be introduced into the European market and seized by the French customs were analysed with high-field ¹H NMR. Nine synthetic cannabinoids (MAM-2201, JWH-073, JWH-210, JWH-122, JWH-081, JWH-250, UR-144, XLR-11 and AKB-48-5F) were detected and quantified. The ability of a compact benchtop low-field NMR spectrometer for a rapid screening of the content of herbal blends was then successfully explored for the first time. Even if low-field ¹H NMR spectra are much less resolved than high-field spectra, we demonstrate that they provide valuable clues on the chemical structures of synthetic cannabinoids with the detection of some typical signals.

Identification of altered brain metabolites associated with TNAP activity in a mouse model of hypophosphatasia using untargeted NMR-based metabolomics analysis

Tissue non-specific alkaline phosphatase (TNAP) is a key player of bone mineralization and TNAP gene (ALPL) mutations in human are responsible for hypophosphatasia (HPP), a rare heritable disease affecting the mineralization of bones and teeth. Moreover, TNAP is also expressed by brain cells and the severe forms of HPP are associated with neurological disorders, including epilepsy and brain morphological anomalies. However, TNAP's role in the nervous system remains poorly understood. To investigate its neuronal functions, we aimed to identify without any a priori the metabolites regulated by TNAP in the nervous tissue. For this purpose we used ¹ H- and ³¹ P NMR to analyze the brain metabolome of Alpl (Akp2) mice null for TNAP function, a well-described model of infantile HPP. Among 39 metabolites identified in brain extracts of 1-week-old animals, eight displayed significantly different concentration in Akp2^-/- compared to Akp2^+/+ and Akp2^+/- mice: cystathionine, adenosine, GABA, methionine, histidine, 3-methylhistidine, N-acetylaspartate (NAA), and N-acetyl-aspartyl-glutamate, with cystathionine and adenosine levels displaying the strongest alteration. These metabolites identify several biochemical processes that directly or indirectly involve TNAP function, in particular through the regulation of ecto-nucleotide levels and of pyridoxal phosphate-dependent enzymes. Some of these metabolites are involved in neurotransmission (GABA, adenosine), in myelin synthesis (NAA, NAAG), and in the methionine cycle and transsulfuration pathway (cystathionine, methionine). Their disturbances may contribute to the neurodevelopmental and neurological phenotype of HPP.

Metabolic rewiring in cancer cells overexpressing the glucocorticoid-induced leucine zipper protein (GILZ): Activation of mitochondrial oxidative phosphorylation and sensitization to oxidative cell death induced by mitochondrial targeted drugs

Cancer cell metabolism is largely controlled by oncogenic signals and nutrient availability. Here, we highlighted that the glucocorticoid-induced leucine zipper (GILZ), an intracellular protein influencing many signaling pathways, reprograms cancer cell metabolism to promote proliferation. We provided evidence that GILZ overexpression induced a significant increase of mitochondrial oxidative phosphorylation as evidenced by the augmentation in basal respiration, ATP-linked respiration as well as respiratory capacity. Pharmacological inhibition of glucose, glutamine and fatty acid oxidation reduced the activation of GILZ-induced mitochondrial oxidative phosphorylation. At glycolysis level, GILZ-overexpressing cells enhanced the expression of glucose transporters in their plasmatic membrane and showed higher glycolytic reserve. ¹H NMR metabolites quantification showed an up-regulation of amino acid biosynthesis. The GILZ-induced metabolic reprograming is present in various cancer cell lines regardless of their driver mutations status and is associated with higher proliferation rates persisting under metabolic stress conditions. Interestingly, high levels of OXPHOS made GILZ-overexpressing cells vulnerable to cell death induced by mitochondrial pro-oxidants. Altogether, these data indicate that GILZ reprograms cancer metabolism towards mitochondrial OXPHOS and sensitizes cancer cells to mitochondria-targeted drugs with pro-oxidant activities.

Proton NMR for detection, identification and quantification of adulterants in 160 herbal food supplements marketed for weight loss

One hundred and sixty food supplements (FS) marketed for weight loss and mainly purchased on the Internet were analyzed. All the FS were claimed as 100% natural containing only natural compounds, plant extracts and/or vitamins and the presence of an active pharmaceutical ingredient (API) was never mentioned. (1)H NMR spectroscopy was used for detecting the presence of adulterants and for their identification and quantification. Mass spectrometry was used as a complementary method for supporting their identification. Among the 164 samples considered because capsules from 5 different blisters of the same FS were analyzed, 56% were tainted with six API. Forty three contained sibutramine as single adulterant (26%), 9 phenolphthalein (6%) and 23 a mixture of these API (14%) that were both withdrawn from the market several years ago because of toxicity concerns. Sildenafil was found in 12 samples, either as a single adulterant (n=5) or in combination with sibutramine (n=3), phenolphthalein (n=3) and both sibutramine and phenolphthalein (n=1). Fluoxetine was present in 4 formulations, alone (n=3) or in combination with sibutramine and orlistat (n=1). At last, lorcaserine was detected in one FS. The content of sibutramine per dosage unit was comprised between 0.1 and 22 mg and that of phenolphthalein between 0.05 and 56 mg. The study also highlights poor manufacturing practices as evidenced for instance by the variability of API in capsules from different blisters of the same box. This paper demonstrates the need for more effective quality control of weight loss FS and the efficiency of (1)H NMR spectroscopy for the detection of tainted FS.

Photochemical Degradation of the Anticancer Drug Bortezomib by V-UV/UV (185/254 nm) Investigated by (1)H NMR Fingerprinting: A Way to Follow Aromaticity Evolution

We have investigated the removal of bortezomib, an anticancer drug prescribed in multiple myeloma, using the photochemical advanced oxidation process of V-UV/UV (185/254 nm). We used two complementary analytical techniques to follow the removal rate of bortezomib. Nuclear magnetic resonance (NMR) is a nonselective method requiring no prior knowledge of the structures of the byproducts and permits us to provide a spectral signature (fingerprinting approach). This untargeted method provides clues to the molecular structure changes and information on the degradation of the parent drug during the irradiation process. This holistic NMR approach could provide information for monitoring aromaticity evolution. We use liquid chromatography, coupled with high-resolution mass spectrometry (LC-MS), to correlate results obtained by (1)H NMR and for accurate identification of the byproducts, in order to understand the mechanistic degradation pathways of bortezomib. The results show that primary byproducts come from photoassisted deboronation of bortezomib at 254 nm. A secondary byproduct of pyrazinecarboxamide was also identified. We obtained a reliable correlation between these two analytical techniques.

Detection, identification and quantification by 1H NMR of adulterants in 150 herbal dietary supplements marketed for improving sexual performance

One hundred and fifty dietary supplements (DS) marketed to increase sexual performance were analyzed. All these formulations were claimed to contain only natural compounds, plant extracts and/or vitamins. (1)H NMR spectroscopy was used for detecting the presence of adulterants and for their identification and quantification. Mass spectrometry was used as a complementary method for confirming the chemical structures. 61% of DS were adulterated with phosphodiesterase-5 inhibitors (PDE-5i) (27% with the PDE-5i medicines sildenafil, tadalafil and vardenafil, and 34% with their structurally modified analogues). Among them, 64% contained only one PDE-5i and 36% mixtures of two, three and even four. The amounts of PDE-5i medicines were higher than the maximum recommended dose in 25% of DS tainted with these drugs. Additional 5.5% DS included other drugs for the treatment of sexual dysfunction (yohimbine, flibanserin, phentolamine, dehydroepiandrosterone or testosterone). Some DS (2.5%) contained products (osthole, icariin) extracted from plants known to improve sexual performance. Only 31% of the samples could be considered as true herbal/natural products. A follow-up over time of several DS revealed that manufacturers make changes in the chemical composition of the formulations. Lack of quality or consistent manufacture (contamination possibly due to inadequate cleaning of the manufacturing chain, presence of impurities or degradation products, various compositions of a given DS with the same batch number, inadequate labelling) indicated poor manufacturing practices. In conclusion, this paper demonstrates the power of (1)H NMR spectroscopy as a first-line method for the detection of adulterated herbal/natural DS and the need for more effective quality control of purported herbal DS.

Mitochondrial oxidative stress is the Achille's heel of melanoma cells resistant to Braf-mutant inhibitor

Vemurafenib/PLX4032, a selective inhibitor of mutant BRAFV600E, constitutes a paradigm shift in melanoma therapy. Unfortunately, acquired resistance, which unavoidably occurs, represents one major limitation to clinical responses. Recent studies have highlighted that vemurafenib activated oxidative metabolism in BRAFV600E melanomas expressing PGC1α. However, the oxidative state of melanoma resistant to BRAF inhibitors is unknown. We established representative in vitro and in vivo models of human melanoma resistant to vemurafenib including primary specimens derived from melanoma patients. Firstly, our study reveals that vemurafenib increased mitochondrial respiration and ROS production in BRAFV600E melanoma cell lines regardless the expression of PGC1α. Secondly, melanoma cells that have acquired resistance to vemurafenib displayed intrinsically high rates of mitochondrial respiration associated with elevated mitochondrial oxidative stress irrespective of the presence of vemurafenib. Thirdly, the elevated ROS level rendered vemurafenib-resistant melanoma cells prone to cell death induced by pro-oxidants including the clinical trial drug, elesclomol. Based on these observations, we propose that the mitochondrial oxidative signature of resistant melanoma constitutes a novel opportunity to overcome resistance to BRAF inhibition.

1H NMR metabolomic signatures in five brain regions of the AβPPswe Tg2576 mouse model of Alzheimer's disease at four ages

In the quest for biomarkers of onset and progression of Alzheimer's disease, a 1H NMR-based metabolomic study was performed on the simple single-transgenic Tg2576 mouse model. These mice develop a slow cognitive decline starting by 6 months and express amyloid plaques from 10 months of age. The metabolic profiles of extracts from five brain regions (frontal cortex, rhinal cortex, hippocampus, midbrain, and cerebellum) of Tg2576 male mice were compared to those of controls, at 1, 3, 6 and 11 months of age. The most obvious differences were due to brain regions. Age was also a discriminating parameter. Metabolic perturbations were already detected in the hippocampus and the rhinal cortex of transgenic mice as early as 1 month of age with decreased concentrations of glutamate (Glu) and N-acetylaspartate (NAA) compared to those in wild-type animals. Metabolic changes were more numerous in the hippocampus and the rhinal cortex of 3 month-old transgenic mice and involved Glu, NAA, myo-inositol, creatine, phosphocholine, and γ-aminobutyric acid (only in the hippocampus) whose concentrations decreased. A metabolic disruption characterized by an increase in the hippocampal concentrations of Glu, creatine, and taurine was detected in 6 month-old transgenic mice. At this time point, the chemical profile of the cerebellum was slightly affected. At 11 months, all the brain regions analyzed (except the frontal cortex) were metabolically altered, with mainly a marked increase in the formation of the neuroprotective metabolites creatine and taurine. Our findings demonstrate that metabolic modifications occur long before the onset of behavioral impairment.

Characterization of heroin samples by 1H NMR and 2D DOSY 1H NMR

Twenty-four samples of heroin from different illicit drug seizures were analyzed using proton Nuclear Magnetic Resonance ((1)H NMR) and two-dimensional diffusion-ordered spectroscopy (2D DOSY) (1)H NMR. A careful assignment and quantification of (1)H signals enabled a comprehensive characterization of the substances present in the samples investigated: heroin, its main related impurities (6-acetylmorphine, acetylcodeine, morphine, noscapine and papaverine) and cutting agents (caffeine and acetaminophen in nearly all samples as well as lactose, lidocaine, mannitol, piracetam in one sample only), and hence to establish their spectral signatures. The good agreement between the amounts of heroin, noscapine, caffeine and acetaminophen determined by (1)H NMR and gas chromatography, the reference method in forensic laboratories, demonstrates the validity of the (1)H NMR technique. In this paper, 2D DOSY (1)H NMR offers a new approach for a whole characterization of the various components of these complex mixtures.

Inactivation of the HIF-1α/PDK3 signaling axis drives melanoma toward mitochondrial oxidative metabolism and potentiates the therapeutic activity of pro-oxidants

Cancer cells can undergo a metabolic reprogramming from oxidative phosphorylation to glycolysis that allows them to adapt to nutrient-poor microenvironments, thereby imposing a selection for aggressive variants. However, the mechanisms underlying this reprogramming are not fully understood. Using complementary approaches in validated cell lines and freshly obtained human specimens, we report here that mitochondrial respiration and oxidative phosphorylation are slowed in metastatic melanomas, even under normoxic conditions due to the persistence of a high nuclear expression of hypoxia-inducible factor-1α (HIF-1α). Pharmacologic or genetic blockades of the HIF-1α pathway decreased glycolysis and promoted mitochondrial respiration via specific reduction in the expression of pyruvate dehydrogenase kinase-3 (PDK3). Inhibiting PDK3 activity by dichloroacetate (DCA) or siRNA-mediated attenuation was sufficient to increase pyruvate dehydrogenase activity, oxidative phosphorylation, and mitochondrial reactive oxygen species generation. Notably, DCA potentiated the antitumor effects of elesclomol, a pro-oxidative drug currently in clinical development, both by limiting cell proliferation and promoting cell death. Interestingly, this combination was also effective against BRAF V600E-mutant melanoma cells that were resistant to the BRAF inhibitor vemurafenib. Cotreatment of melanomas with DCA and elesclomol in vivo achieved a more durable response than single agent alone. Our findings offer a preclinical validation of the HIF-1/PDK3 bioenergetic pathway as a new target for therapeutic intervention in metastatic melanoma, opening the door to innovative combinations that might eradicate this disease.

Quality assessment of commercial Magnoliae officinalis Cortex by ¹H-NMR-based metabolomics and HPLC methods

INTRODUCTION

The quality control of Magnoliae officinalis Cortex, a commonly used traditional Chinese medicine, is currently based on the assay of the two active compounds, honokiol and magnolol, by TLC or HPLC.

OBJECTIVE

To compare ¹H-NMR-based metabolomics with the HPLC method for controlling the quality of Magnoliae officinalis Cortex. To identify the metabolites contributing to the differences between the samples and to discriminate different medicinal parts and geographic origins of these samples by ¹H-NMR-based metabolomics.

METHODOLOGY

¹H-NMR and several multivariate analysis techniques were applied to analyse the extracts of 18 batches of Magnoliae officinalis Cortex commercial samples, and the contents of honokiol and magnolol in these samples were determined by HPLC. The correlation analysis between the data from ¹H-NMR and HPLC was performed with the mixOmics software based on an unsupervised method.

RESULTS

Honokiol and magnolol were the main compounds responsible for the discrimination of samples from different batches, thus proving that the choice of these two compounds as markers for quality assessment by HPLC is relevant. The two sources of Magnoliae officinalis Cortex recorded in the Chinese Pharmacopoeia, Magnolia officinalis and Magnolia officinalis var. biloba, could be differentiated from ¹H-NMR data, but the pattern recognition analysis by PLS-DA was unsuccessful in discriminating samples from various geographical origins.

CONCLUSION

The combination of ¹H-NMR that gives a comprehensive profile of the metabolites and HPLC that targets two biomarkers is an efficient means for a better quality control of Magnoliae officinalis Cortex.

1H, 13C and 15N resonance assignment of a 114-residue fragment of Engrailed 2 homeoprotein, a partially disordered protein

Engrailed 2 is a transcription factor belonging to the class of homeoproteins. These proteins possess a 60-residue DNA binding globular domain and play an important role in the early stages of development. We expressed and purified a 13.4 kDa fragment of Engrailed 2, which comprises a 54-residue N-terminal extension in addition to the homeodomain region. Almost all backbone and side-chain resonances have been assigned. The weak dispersion in the proton dimension of the (1)H-(15)N HSQC spectrum indicates the presence of disordered regions that do not belong to the homeodomain. This work is a first step toward the NMR investigation of the structure and dynamics of Engrailed 2 protein that contains a well-structured globular domain and partially disordered regions.

Exploiting mitochondrial dysfunction for effective elimination of imatinib-resistant leukemic cells

Challenges today concern chronic myeloid leukemia (CML) patients resistant to imatinib. There is growing evidence that imatinib-resistant leukemic cells present abnormal glucose metabolism but the impact on mitochondria has been neglected. Our work aimed to better understand and exploit the metabolic alterations of imatinib-resistant leukemic cells. Imatinib-resistant cells presented high glycolysis as compared to sensitive cells. Consistently, expression of key glycolytic enzymes, at least partly mediated by HIF-1α, was modified in imatinib-resistant cells suggesting that imatinib-resistant cells uncouple glycolytic flux from pyruvate oxidation. Interestingly, mitochondria of imatinib-resistant cells exhibited accumulation of TCA cycle intermediates, increased NADH and low oxygen consumption. These mitochondrial alterations due to the partial failure of ETC were further confirmed in leukemic cells isolated from some imatinib-resistant CML patients. As a consequence, mitochondria generated more ROS than those of imatinib-sensitive cells. This, in turn, resulted in increased death of imatinib-resistant leukemic cells following in vitro or in vivo treatment with the pro-oxidants, PEITC and Trisenox, in a syngeneic mouse tumor model. Conversely, inhibition of glycolysis caused derepression of respiration leading to lower cellular ROS. In conclusion, these findings indicate that imatinib-resistant leukemic cells have an unexpected mitochondrial dysfunction that could be exploited for selective therapeutic intervention.

pH optimization for a reliable quantification of brain tumor cell and tissue extracts with (1)H NMR: focus on choline-containing compounds and taurine

The aim of this study was to define the optimal pH for (1)H nuclear magnetic resonance (NMR) spectroscopy analysis of perchloric acid or methanol-chloroform-water extracts from brain tumor cells and tissues. The systematic study of the proton chemical shift variations as a function of pH of 13 brain metabolites in model solutions demonstrated that recording (1)H NMR spectra at pH 10 allowed resolving resonances that are overlapped at pH 7, especially in the 3.2-3.3 ppm choline-containing-compounds region. (1)H NMR analysis of extracts at pH 7 or 10 showed that quantitative measurements of lactate, alanine, glutamate, glutamine (Gln), creatine + phosphocreatine and myo-inositol (m-Ino) can be readily performed at both pHs. The concentrations of glycerophosphocholine, phosphocholine and choline that are crucial metabolites for tumor brain malignancy grading were accurately measured at pH 10 only. Indeed, the resonances of their trimethylammonium moieties are cleared of any overlapping signal, especially those of taurine (Tau) and phosphoethanolamine. The four non-ionizable Tau protons resonating as a singlet in a non-congested spectral region permits an easier and more accurate quantitation of this apoptosis marker at pH 10 than at pH 7 where the triplet at 3.43 ppm can be overlapped with the signals of glucose or have an intensity too low to be measured. Glycine concentration was determined indirectly at both pHs after subtracting the contribution of the overlapped signals of m-Ino at pH 7 or Gln at pH 10.

Counterfeit drugs: analytical techniques for their identification

In recent years, the number of counterfeit drugs has increased dramatically, including not only "lifestyle" products but also vital medicines. Besides the threat to public health, the financial and reputational damage to pharmaceutical companies is substantial. The lack of robust information on the prevalence of fake drugs is an obstacle in the fight against drug counterfeiting. It is generally accepted that approximately 10% of drugs worldwide could be counterfeit, but it is also well known that this number covers very different situations depending on the country, the places where the drugs are purchased, and the definition of what constitutes a counterfeit drug. The chemical analysis of drugs suspected to be fake is a crucial step as counterfeiters are becoming increasingly sophisticated, rendering visual inspection insufficient to distinguish the genuine products from the counterfeit ones. This article critically reviews the recent analytical methods employed to control the quality of drug formulations, using as an example artemisinin derivatives, medicines particularly targeted by counterfeiters. Indeed, a broad panel of techniques have been reported for their analysis, ranging from simple and cheap in-field ones (colorimetry and thin-layer chromatography) to more advanced laboratory methods (mass spectrometry, nuclear magnetic resonance, and vibrational spectroscopies) through chromatographic methods, which remain the most widely used. The conclusion section of the article highlights the questions to be posed before selecting the most appropriate analytical approach.

Improving metabolite knowledge in stable atherosclerosis patients by association and correlation of GC-MS and 1H NMR fingerprints

The plasma of patients with stable carotid atherosclerosis (n = 9), and healthy subjects (n = 10) have been fingerprinted with both GC-MS and (1)H NMR. Principal component analysis (PCA), partial least-squares-discriminant analysis (PLS-DA) and orthogonal partial least-squares-discriminant analysis (OPLS-DA) have been applied to the profiles from each technique both separately and in combination. These techniques complement each other and enable a clearer picture of the biological samples to be interpreted not only for classification purposes, but also more importantly to define the metabolic state of patients with carotid atherosclerosis. The results showed at least 24 metabolites that were significantly modified in the group of atherosclerotic patients by this nontargeted procedure. Most of the changes can be associated to alterations of the metabolism characteristics of insulin resistance that can be strongly related to the metabolic syndrome. In addition, correlations among variables accounting for the classification show amino acids as variables whose changes showed a high degree of correlation. GC-MS and (1)H NMR fingerprints can provide complementary information in the identification of altered metabolic pathways in patients with carotid atherosclerosis. Moreover, correlations among the results with both techniques, instead of a single study, can provide a deeper insight into the patient state.

The usefulness of 2D DOSY and 3D DOSY-COSY 1H NMR for mixture analysis: application to genuine and fake formulations of sildenafil (Viagra)

Two-dimensional diffusion ordered spectroscopy (DOSY) (1)H NMR is proposed to analyze drugs that are complex mixtures in order to discriminate genuine from fake formulations. The method was applied to the analysis of 17 formulations of sildenafil, one being genuine Viagra and the others illegally manufactured formulations of this drug coming from India, Syria and China. It enabled (i) distinguishing imitations or counterfeit from the authentic formulation, (ii) detecting the presence of sildenafil or adulterants, (iii) gaining information on the formulation process by detection of various excipients, thus giving a precise and global 'signature' of the manufacturer. Even though some samples are slightly overdosed, the quality of products manufactured in India and Syria was better than that of Chinese formulations which were adulterated with vardenafil and homosildenafil. This study also presents a three-dimensional DOSY-COSY (1)H NMR experiment that provides both virtual separation and structural information.

Combining two-dimensional diffusion-ordered nuclear magnetic resonance spectroscopy, imaging desorption electrospray ionization mass spectrometry, and direct analysis in real-time mass spectrometry for the integral investigation of counterfeit pharmaceuticals

During the past decade, there has been a marked increase in the number of reported cases involving counterfeit medicines in developing and developed countries. Particularly, artesunate-based antimalarial drugs have been targeted, because of their high demand and cost. Counterfeit antimalarials can cause death and can contribute to the growing problem of drug resistance, particularly in southeast Asia. In this study, the complementarity of two-dimensional diffusion-ordered (1)H nuclear magnetic resonance spectroscopy (2D DOSY (1)H NMR) with direct analysis in real-time mass spectrometry (DART MS) and desorption electrospray ionization mass spectrometry (DESI MS) was assessed for pharmaceutical forensic purposes. Fourteen different artesunate tablets, representative of what can be purchased from informal sources in southeast Asia, were investigated with these techniques. The expected active pharmaceutical ingredient was detected in only five formulations via both nuclear magnetic resonance (NMR) and mass spectrometry (MS) methods. Common organic excipients such as sucrose, lactose, stearate, dextrin, and starch were also detected. The graphical representation of DOSY (1)H NMR results proved very useful for establishing similarities among groups of samples, enabling counterfeit drug "chemotyping". In addition to bulk- and surface-average analyses, spatially resolved information on the surface composition of counterfeit and genuine antimalarial formulations was obtained using DESI MS that was performed in the imaging mode, which enabled one to visualize the homogeneity of both genuine and counterfeit drug samples. Overall, this study suggests that 2D DOSY (1)H NMR, combined with ambient MS, comprises a powerful suite of instrumental analysis methodologies for the integral characterization of counterfeit antimalarials.

Two-dimensional DOSY experiment with Excitation Sculpting water suppression for the analysis of natural and biological media

The Bipolar Pulse Pair Stimulated Echo NMR pulse sequence was modified to blend the original Excitation Sculpting water signal suppression. The sequence is a powerful tool to generate rapidly, with a good spectrum quality, bidimensional DOSY experiments without solvent signal, thus allowing the analysis of complex mixtures such as plant extracts or biofluids. The sequence has also been successfully implemented for a protein at very-low concentration in interaction with a small ligand, namely the salivary IB5 protein binding the polyphenol epigallocatechine gallate. The artifacts created by this sequence can be observed, checked and removed thanks to NPK and NMRnotebook softwares to give a perfect bidimensional DOSY spectrum.

2D and 3D DOSY 1H NMR, a useful tool for analysis of complex mixtures: application to herbal drugs or dietary supplements for erectile dysfunction

Seventeen herbal dietary supplements, marketed as natural substances for the enhancement of sexual function, were analyzed by diffusion ordered spectroscopy (DOSY) (1)H NMR. The method allowed a global analysis of the samples with detection of both active and inactive ingredients present in these complex matrixes. Eight formulations contained compounds related to the synthetic phosphodiesterase-5 inhibitors. Sildenafil, tadalafil, vardenafil, hydroxyhomosildenafil, thiosildenafil, and the newly identified adulterant thiomethisosildenafil were detected. Quantification of these active ingredients was carried out by HPLC or NMR. In addition to these actives, about 30 compounds or excipients were characterized. This study ended up with a three-dimensional DOSY-COSY (1)H NMR experiment on a herbal formulation which provided both virtual separation and structural information.

Quality assessment of fluoxetine and fluvoxamine pharmaceutical formulations purchased in different countries or via the Internet by 19F and 2D DOSY 1H NMR

A simple and selective (19)F NMR method has been validated for the quantitation of fluoxetine (FLX) and fluvoxamine (FLV) in methanol solutions and in human plasma and urine. The regression equations for FLX and FLV showed a good linearity in the range of 1.4-620 microg mL(-1) (3.3 x 10(-6)-1.8 x 10(-3) mol L(-1)) with a limit of detection of approximately 0.5 microg mL(-1) (1.3 x 10(-6) mol L(-1)) and a limit of quantification of approximately 2 microg mL(-1) (4.6 x 10(-6) mol L(-1)). The precision of the assay depends on the concentrations and is comprised between 1.5 and 9.5% for a range of concentrations between 1.2 x 10(-3) and 3.2 x 10(-6) mol L(-1). The accuracy evaluated through recovery studies ranged from approximately 96 to 103% in methanol solutions and in urine, and from approximately 93 to 104% in plasma, with standard deviations <7.5%. The low sensitivity of the method precludes its use for the assay of these antidepressants in biofluids at least at therapeutic doses as the ranges of FLX and FLV plasma levels are 0.15-0.5 microg mL(-1) and 0.15-0.25 microg mL(-1), respectively. The method was applied successfully to the determination of FLX and FLV contents in pharmaceutical samples (brand-named and generic) purchased in several countries or via the Internet. All the commercial formulations contain the active ingredient in the range 94-103% of stated concentration. A "signature" of the formulations (solid and liquid) was obtained with 2D Diffusion-Ordered SpectroscopY (DOSY) (1)H NMR which allowed the characterisation of the active ingredient and excipients present in the formulations studied. Finally, the DOSY separation of FLX and FLV whose molecular weights are very close was obtained by using beta-cyclodextrin as host-guest complexing agent.