Ex-Vivo 13C NMR Spectroscopy of Rodent Brain: TNF Restricts Neuronal Utilization of Astrocyte-Derived Metabolites.

Tumor necrosis factor (TNF) has well-established roles in neuroinflammatory disorders, but the effect of TNF on the biochemistry of brain cells remains poorly understood. Here, we microinjected TNF into the brain to study its impact on glial and neuronal metabolism (glycolysis, pentose phosphate pathway, citric acid cycle, pyruvate dehydrogenase, and pyruvate carboxylase pathways) using 13C NMR spectroscopy on brain extracts following intravenous [1,2-13C]-glucose (to probe glia and neuron metabolism), [2-13C]-acetate (probing astrocyte-specific metabolites), or [3-13C]-lactate. An increase in [4,5-13C]-glutamine and [2,3-13C]-lactate coupled with a decrease in [4,5-13C]-glutamate was observed in the [1,2-13C]-glucose-infused animals treated with TNF. As glutamine is produced from glutamate by astrocyte-specific glutamine synthetase the increase in [4,5-13C]-glutamine reflects increased production of glutamine by astrocytes. This was confirmed by infusion with astrocyte substrate [2-13C]-acetate. As lactate is metabolized in the brain to produce glutamate, the simultaneous increase in [2,3-13C]-lactate and decrease in [4,5-13C]-glutamate suggests decreased lactate utilization, which was confirmed using [3-13C]-lactate as a metabolic precursor. These results suggest that TNF rearranges the metabolic network, disrupting the energy supply chain perturbing the glutamine-glutamate shuttle between astrocytes and the neurons. These insights pave the way for developing astrocyte-targeted therapeutic strategies aimed at modulating effects of TNF to restore metabolic homeostasis in neuroinflammatory disorders.

Hyperpolarized [1-13C]-pyruvate MRS evaluates immune potential and predicts response to radiotherapy in cervical cancer.

BACKGROUND: Monitoring pyruvate metabolism in the spleen is important for assessing immune activity and achieving successful radiotherapy for cervical cancer due to the significance of the abscopal effect. We aimed to explore the feasibility of utilizing hyperpolarized (HP) [1-13C]-pyruvate magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) to evaluate pyruvate metabolism in the human spleen, with the aim of identifying potential candidates for radiotherapy in cervical cancer. METHODS: This prospective study recruited six female patients with cervical cancer (median age 55 years; range 39-60) evaluated using HP [1-13C]-pyruvate MRI/MRS at baseline and 2 weeks after radiotherapy. Proton (1H) diffusion-weighted MRI was performed in parallel to estimate splenic cellularity. The primary outcome was defined as tumor response to radiotherapy. The Student t-test was used for comparing 13C data between the groups. RESULTS: The splenic HP [1-13C]-lactate-to-total carbon (tC) ratio was 5.6-fold lower in the responders than in the non-responders at baseline (p = 0.009). The splenic [1-13C]-lactate-to-tC ratio revealed a 1.7-fold increase (p = 0.415) and the splenic [1-13C]-alanine-to-tC ratio revealed a 1.8-fold increase after radiotherapy (p = 0.482). The blood leukocyte differential count revealed an increased proportion of neutrophils two weeks following treatment, indicating enhanced immune activity (p = 0.013). The splenic apparent diffusion coefficient values between the groups were not significantly different. CONCLUSIONS: This exploratory study revealed the feasibility of HP [1-13C]-pyruvate MRS of the spleen for evaluating baseline immune potential, which was associated with clinical outcomes of cervical cancer after radiotherapy. TRIAL REGISTRATION: ClinicalTrials.gov NCT04951921 , registered 7 July 2021. RELEVANCE STATEMENT: This prospective study revealed the feasibility of using HP 13C MRI/MRS for assessing pyruvate metabolism of the spleen to evaluate the patients' immune potential that is associated with radiotherapeutic clinical outcomes in cervical cancer. KEY POINTS: • Effective radiotherapy induces abscopal effect via altering immune metabolism. • Hyperpolarized 13C MRS evaluates patients' immune potential non-invasively. • Pyruvate-to-lactate conversion in the spleen is elevated following radiotherapy.

Estudos de síntese de dendrons dirigidos de NFOH com potencial antichagásico e modelagem molecular do receptor de manose de macrófagos / Studying the synthesis of NFOH targeted dendrons, potentially active in Chagas disease, and the molecular modeling of manose receptor from macrophages

A doença de Chagas, considerada doença extremamente negligenciada, acomete mais de 6 milhões de pessoas ao redor do mundo e mais de 75 milhões de pessoas vivem sob risco da doença. Considerada endêmica em 21 países da América Latina. No Brasil, grassa, sobretudo, na região Norte, especialmente, na região amazônica. Apesar de se constituir em risco global, a doença de Chagas conta com apenas com dois fármacos, o benznidazol e o nifurtimox, que, além de tóxicos, não apresentam eficácia significativa na fase crônica da parasitose. Assim sendo, torna-se imperativa a busca por quimioterápicos mais eficazes, mormente na fase crônica da doença. A introdução de novos fármacos da terapêutica várias fases, consumindo tempo e recursos. No entanto, há processos que permitem a otimização de fármacos já existentes e de compostos bioativos, com vistas à busca de candidatos a fármacos, que, uma vez bem-sucedidos nos ensaios clínicos, são aprovados para uso terapêutico. Entre esses processos, destaca-se a latenciação, forma de aprimoramento de propriedades farmacêuticas, farmacocinéticas e, indiretamente, farmacodinâmicas, que utiliza, em geral, transportadores para a resolução de problemas dessas naturezas. Os transportadores variam de acordo com o problema a ser resolvido e, entre eles, os dendrons e dendrímeros podem ser ressaltados pela sua natureza química, que permite a ligação de várias moléculas de fármacos/compostos bioativos e, também, de grupos diretores para certos compartimentos ou células. Dessa forma, podem-se obter fármacos dirigidos, que se constituem em formas latentes de alta seletividade. Face ao exposto e, estimulados pela busca de novas alternativas terapêuticas para a doença de Chagas, o objetivo deste trabalho foi a obtenção de dendrons dirigidos, por meio de manose, derivados de hidroximetilnitrofural (NFOH). Esse composto foi mostrou-se altamente ativo contra T. cruzi, também na fase crônica NFOH e menos tóxico que o protótipo e o benznidazol. Efetuaram-se estudos para a síntese desses compostos derivados de dendron triazólico, sintetizado através de click chemistry, tendo a manose como grupo diretor para os macrófagos, onde, também, são encontrados os amastigotas de Trypanosoma cruzi. Obtiveram-se alguns intermediários, que foram caracterizados por RMN 1H e 13C. A rota sintética proposta não pôde ser finalizada. Por outro lado, efetuaram-se estudos de modelagem molecular, utilizando-se dinâmica molecular, com o intuito de conhecer como se dá a interação da manose e de polimanosídeos com seu respectivo receptor e como se realiza a liberação do composto bioativo da ligação com o dendron. Anteriormente, procedeu-se à caracterização da biologia estrutural do receptor de manose e de suas estruturas primárias, secundárias e terciárias, com ênfase para o domínio CRD4 o papel do cálcio principal na interação com o monossacarídeo. A movimentação do domínio foi muito pouco diferente nos meios simulados (neutro, ácido, contendo ligantes e contendo o cálcio auxiliar), evidenciado pelo RMSF e estudo de PCA desses sistemas. Foi possível concluir que este domínio não apresenta nenhuma alteração conformacional responsável pela liberação de ligantes em meio lisossômico, e que o cálcio auxiliar e os ligantes não causam impactos na estabilidade conformacional do CRD4. Há necessidade de mais estudos para o conhecimento dos requisitos estruturais envolvidos na da formação do complexo receptor-composto bioativo

Chagas disease, considered an extremely neglected one, affects more than 6 million people all over de world, with more than 75 million people living under its risk, while endemics in 21 countries in Latin America. In Brazil, it propagates, mainly in North region, especially in Amazon region. Although being a global risk, only two drugs, benznidazole and nifurtimox, are currently available for Chagas disease. These drugs are toxic and not significantly efficient against the chronic phase of the disease. Therefore, the search for more active chemotherapeutic agents, mainly against the chronic phase of the parasitosis, is imperative. The introduction of new drugs in the therapeutics involves many phases, consuming time, and money. Notwithstanding, there are processes that allow either drugs or bioactive compounds to be optimized, towards drug candidates. These derivatives, once well-succeeded in the clinical trials, can be approved for therapeutic uses. Among those processes, prodrug design stands out. It is a way to improve the pharmaceutics, pharmacokinetics and, indirectly, pharmacodynamics, properties of drugs/bioactive compounds, which requires adequate carriers, in general, for these problems´ solution. The carriers vary according to the problem to be solved, and, among them, dendrons and dendrimers can be emphasized due to their chemical nature, which allows the link of many molecules/bioactive compounds and of directing groups to specific compartments or cells. Thus, targeted drugs, which are latent forms of drugs/bioactive compounds with high selectivity. In this connection and stimulated by the search for new therapeutic alternatives for Chagas disease, the objective of this work was obtaining hydroxymethylnitrofurazone (NFOH) targeted dendrons, by means of mannose, as directing groups. NFOH is highly active against T. cruzi, even in chronic phase of the disease, and less toxic than the prototype and benznidazole. Studies have been developed to synthesize these compounds with a triazole dendron, planned to be obtained by click chemistry. Mannose was designed to be the directing groups to macrophages, where the T. cruzi amastigotes can also be found. Some intermediaries have been obtained and structurally characterized by 1H and 13C NMR, but the proposed synthetic route could not be finished. On the other hand, molecular modeling studies have been developed, using molecular dynamics, with the aim to know how the interaction of mannose, and also of polymannoside, occur with the specific receptor, and how NFOH is released from its linkage to the dendron. The structural biology characterization, as well as of primary, secondary and tertiary structures of the mannose receptor was previously performed, with emphasis onCRD4 and main calcium role in the interaction of the mannoside. All systems simulated (neutral medium, acid medium, complexes with ligands and auxiliary calcium) showed little movement differences when analyzed by RMSF and PCA calculations. It was possible to conclude that this domain shows no conformational changes involved in ligand releasing in lysosomal environment and its conformation is not altered when in presence of ligands or the auxiliary calcium. Much more studies are needed to the knowledge of the structural requirements to the complex receptor-drug-compound bioactive to the receptor

Evaluation of biological activities of Barbarea integrifolia and isolation of a new glucosinolate derivated compound.

The aim of the present study is to determine the potent biological activities and carry out isolation studies on Barbarea integrifolia. The antioxidant capacity of the species was evaluated by total phenolic content, FRAP, CUPRAC, and DPPH radical scavenging activity. Anticancer activity studies were performed by MTT assay in MDA-MB-231, MCF-7, Hep3B, PC-3, A549, HCT116, L-929 cell lines. It was observed that the remaining aqueous fraction has higher total phenolic content while higher activity in the CUPRAC and FRAP assays was displayed for the methanolic extract and chloroform fraction. The extracts showed anticancer activity as compared with vincristine. It was observed that chloroform fraction has the highest anticancer activity on MCF-7 cell line, while ethyl acetate fraction has the highest anticancer activity on Hep-3B and A549 cell lines. Methanolic extract has the highest anticancer activity on HCT116 and MDA-MB-23 cell lines. The isolation studies have been performed using several chromatographic methods. The chemical structures of compounds have been identified by means of 1H NMR, 13C NMR, 2D-NMR, and MS. Five major compounds, one steroid (ß-Sitosterol), one phenolic acid (Rosmarinic acid), one flavonol heteroside (kaempferol 7-O-α-l-rhamnoside-3-O-ß-d-(2-O-ß- d -glucosyl)-ß-d-glucoside), and two glucosinolates (Gluconasturtiin, Gluconasturtiin choline salt) have been isolated.

Hyperpolarized Carbon (13C) MRI of the Kidneys: Basic Concept.

Existing clinical markers for renal disease are limited. Hyperpolarized (HP) 13C MRI is based on the technology of dissolution dynamic nuclear polarization (DNP) and provides new avenues for imaging kidney structure, function, and most notably, renal metabolism, addressing some of these prior limitations. Changes in kidney structure and function associated with kidney disease can be evaluated using [13C]urea, a metabolically inert tracer. Metabolic changes can be assessed using [1-13C]pyruvate and a range of other rapidly metabolized small molecules, which mainly probe central carbon metabolism. Results from numerous preclinical studies using a variety of these probes demonstrated that this approach holds great potential for monitoring renal disease, although more work is needed to bridge intelligently into clinical studies. Here we introduce the general concept of HP 13C MRI and review the most relevant probes and applications to renal disease, including kidney cancer, diabetic nephropathy and ischemic kidney injury.This chapter is based upon work from the PARENCHIMA COST Action, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This introduction chapter is complemented by two separate chapters describing the experimental procedure and data analysis.

Biomedical Applications of the Dynamic Nuclear Polarization and Parahydrogen Induced Polarization Techniques for Hyperpolarized 13C MR Imaging.

Since the first pioneering report of hyperpolarized [1-13C]pyruvate magnetic resonance imaging (MRI) of the Warburg effect in prostate cancer patients, clinical dissemination of the technique has been rapid; close to 10 sites worldwide now possess a polarizer fit for the clinic, and more than 30 clinical trials, predominantly for oncological applications, are already registered on the US and European clinical trials databases. Hyperpolarized 13C probes to study pathophysiological processes beyond the Warburg effect, including tricarboxylic acid cycle metabolism, intra-cellular pH and cellular necrosis have also been demonstrated in the preclinical arena and are pending clinical translation, and the simultaneous injection of multiple co-polarized agents is opening the door to high-sensitivity, multi-functional molecular MRI with a single dose. Here, we review the biomedical applications to date of the two polarization methods that have been used for in vivo hyperpolarized 13C molecular MRI; namely, dissolution dynamic nuclear polarization and parahydrogen-induced polarization. The basic concept of hyperpolarization and the fundamental theory underpinning these two key 13C hyperpolarization methods, along with recent technological advances that have facilitated biomedical realization, are also covered.

Neuroprotective constituents of Actaea acuminata (Wall. ex Royle) H. Hara roots.

The methanol extract and its ethyl acetate fraction (EAF) of Actaea acuminata (Wall. ex. Royle) H. Hara roots were reported to exhibit significant antianxiety, anticonvulsant and antidepressant activities, and mild sedative activity. But the constituents responsible for these activities have not been isolated. The present study was undertaken to isolate neuroprotective compounds of A. acuminata following bioactivity-guided-fractionation. The column chromatography of EAF and its sub-fractions led to the isolation of four phenolic compounds (bergenin, gallic acid, acetyl bergenin and racemic mixture of diacetyl bergenin), which were characterized by IR and NMR spectral analysis. All the compounds exhibited significant antianxiety and antidepressant activities with respect to control. The gallic acid and bergenin did not show anticonvulsant activity, whereas acetyl bergenin and racemic mixture of diacetyl bergenin exhibited significant anticonvulsant activity. Neuropharmacological activities of A. acuminata are attributed due to polyphenolic compounds. Scientific validation of traditional claims of A. acuminata has opened up roadmap of research for the development of CNS affecting lead molecules.

Denigrins and Dactylpyrroles, Arylpyrrole Alkaloids from a Dactylia sp. Marine Sponge.

Seven new arylpyrrole alkaloids (1-7), along with four known compounds, were isolated from an extract of a Dactylia sp. nov. marine sponge, and their structures were elucidated by interpretation of NMR and MS spectroscopic data. Denigrins D-G (1-4) have highly substituted pyrrole or pyrrolone rings in their core structures, while dactylpyrroles A-C (5-7) have tricyclic phenanthrene cores. Due to the proton-deficient nature of these scaffolds, key heteronuclear correlations from 1H-15N HMBC and LR-HSQMBC NMR experiments were used in the structure assignment of denigrin D (1). Dictyodendrin F (8), a previously described co-metabolite, inhibited transcription driven by the oncogenic PAX3-FOXO1 fusion gene with an IC50 value of 13 µM.

Functional Genetic Screening Enables Theranostic Molecular Imaging in Cancer.

PURPOSE: Targeted therapies for cancer have accelerated the need for functional imaging strategies that inform therapeutic efficacy. This study assesses the potential of functional genetic screening to integrate therapeutic target identification with imaging probe selection through a proof-of-principle characterization of a therapy-probe pair using dynamic nuclear polarization (DNP)-enhanced magnetic resonance spectroscopic imaging (MRSI). EXPERIMENTAL DESIGN: CRISPR-negative selection screens from a public dataset were used to identify the relative dependence of 625 cancer cell lines on 18,333 genes. Follow-up screening was performed in hepatocellular carcinoma with a focused CRISPR library targeting imaging-related genes. Hyperpolarized [1-13C]-pyruvate was injected before and after lactate dehydrogenase inhibitor (LDHi) administration in male Wistar rats with autochthonous hepatocellular carcinoma. MRSI evaluated intratumoral pyruvate metabolism, while T2-weighted segmentations quantified tumor growth. RESULTS: Genetic screening data identified differential metabolic vulnerabilities in 17 unique cancer types that could be imaged with existing probes. Among these, hepatocellular carcinoma required lactate dehydrogenase (LDH) for growth more than the 29 other cancer types in this database. LDH inhibition led to a decrease in lactate generation (P < 0.001) and precipitated dose-dependent growth inhibition (P < 0.01 overall, P < 0.05 for dose dependence). Intratumoral alanine production after inhibition predicted the degree of growth reduction (P < 0.001). CONCLUSIONS: These findings demonstrate that DNP-MRSI of LDH activity using hyperpolarized [1-13C]-pyruvate is a theranostic strategy for hepatocellular carcinoma, enabling quantification of intratumoral LDHi pharmacodynamics and therapeutic efficacy prediction. This work lays the foundation for a novel theranostic platform wherein functional genetic screening informs imaging probe selection to quantify therapeutic efficacy on a cancer-by-cancer basis.

Hyperpolarized 13C MRI: A novel approach for probing cerebral metabolism in health and neurological disease.

Cerebral metabolism is tightly regulated and fundamental for healthy neurological function. There is increasing evidence that alterations in this metabolism may be a precursor and early biomarker of later stage disease processes. Proton magnetic resonance spectroscopy (1H-MRS) is a powerful tool to non-invasively assess tissue metabolites and has many applications for studying the normal and diseased brain. However, the technique has limitations including low spatial and temporal resolution, difficulties in discriminating overlapping peaks, and challenges in assessing metabolic flux rather than steady-state concentrations. Hyperpolarized carbon-13 magnetic resonance imaging is an emerging clinical technique that may overcome some of these spatial and temporal limitations, providing novel insights into neurometabolism in both health and in pathological processes such as glioma, stroke and multiple sclerosis. This review will explore the growing body of pre-clinical data that demonstrates a potential role for the technique in assessing metabolism in the central nervous system. There are now a number of clinical studies being undertaken in this area and this review will present the emerging clinical data as well as the potential future applications of hyperpolarized 13C magnetic resonance imaging in the brain, in both clinical and pre-clinical studies.

Active pyruvate dehydrogenase and impaired gluconeogenesis in orthotopic hepatomas of rats.

BACKGROUND: Therapies targeting altered activity of pyruvate dehydrogenase (PDH) and pyruvate carboxylase (PC) have been proposed for hepatomas. However, the activities of these pathways in hepatomas in vivo have not been distinguished. Here we examined pyruvate entry into the tricarboxylic acid (TCA) cycle through PDH versus PC in vivo using hepatoma-bearing rats. METHODS: Hepatoma-bearing rats were generated by intrahepatic injection of H4IIE cells. Metabolism of 13C-labeled glycerol, a physiological substrate for both gluconeogenesis and energy production, was measured with 13C NMR analysis. The concentration of key metabolites and the expression of relevant enzymes were measured in hepatoma, surrounding liver, and normal liver. RESULTS: In orthotopic hepatomas, pyruvate entry into the TCA cycle occurred exclusively through PDH and the excess PDH activity compared to normal liver was attributed to downregulated pyruvate dehydrogenase kinase (PDK) 2/4. However, pyruvate carboxylation via PC and gluconeogenesis were minimal, which was linked to downregulated forkhead box O1 (FoxO1) by Akt activity. In contrast to many studies of cancer metabolism, lactate production in hepatomas was not increased which corresponded to reduced expression of lactate dehydrogenase. The production of serine and glycine in hepatomas was enhanced, but glycine decarboxylase was downregulated. CONCLUSIONS: The combination of [U-13C3]glycerol and NMR analysis enabled investigation of multiple biochemical processes in hepatomas and surrounding liver. We demonstrated active PDH and other related metabolic alterations in orthotopic hepatomas that differed substantially not only from the host organ but also from many earlier studies with cancer cells.

Understanding the Fate of Environmental Chemicals Inside Living Organisms: NMR-Based 13C Isotopic Suppression Selects Only the Molecule of Interest within 13C-Enriched Organisms.

In vivo nuclear magnetic resonance (NMR) is rapidly evolving as a critical tool as it offers real-time metabolic information, which is crucial for delineating complex toxic response pathways in living systems. Organisms such as Daphnia magna (water fleas) and Hyalella azteca (freshwater shrimps) are commonly 13C-enriched to increase the signal in NMR experiments. A key goal of in vivo NMR is to monitor how molecules (nutrients, contaminants, or drugs) are metabolized. Conventionally, these studies would normally involve using a 13C-enriched probe molecule and feeding this to an organism at natural abundance, in turn allowing the fate of the probe molecule to be selectively analyzed. The drawback of such an approach is that there is a limited range of 13C-enriched probe molecules, and if available, they are extremely cost prohibitive. Uniquely, when utilizing 13C organisms, a reverse strategy of isotopic filtering becomes possible. The concept described here uses 1H detection in combination with a 13C filter on living organisms. The purpose is to suppress all 1H signals from the organism (i.e., 1H attached to 13C), leaving only the probe molecule (1H attached to 12C). Because the probe molecule can be selectively observed using this approach, it then makes it possible to follow and discern processes such as bioconversion, bioaccumulation, and excretion in vivo. As the approach uses 1H detection, it provides excellent detection limits in the nanogram range. In this article, the approach is introduced, optimized on standards, and then applied to follow nicotine biotransformation and lipid assimilation in vivo to demonstrate the concept.

Hyperpolarized Pyruvate MR Spectroscopy Depicts Glycolytic Inhibition in a Mouse Model of Glioma.

BackgroundA generation of therapies targeting tumor metabolism is becoming available for treating glioma. Hyperpolarized MRI is uniquely suited to directly measure the metabolic effects of these emerging treatments.PurposeTo explore the feasibility of the use of hyperpolarized [1-carbon 13 {13C}]-pyruvate for real-time measurement of metabolism and response to treatment with a glycolytic inhibitor in an orthotopic mouse model of glioma.Materials and MethodsIn this animal study, anatomic MRI and dynamic 13C MR spectroscopy were performed at 7 T during intravenous injection of hyperpolarized [1-13C]-pyruvate on mice with orthotopic U87MG glioma and healthy control mice. Anatomic MRI and dynamic 13C MR spectroscopy were repeated after administration of the glycolytic inhibitor WP1122, a prodrug of 2-deoxy-d-glucose. All experiments were conducted in athymic nude mice between October 2016 and March 2017. Hyperpolarized lactate production was quantified as an apparent reaction rate, or kPL, and normalized lactate ratio (nLac). The Wilcoxon signed-rank test was used to assess changes in paired measures of lactate production before and after treatment.ResultsThirteen 12-16-week-old female mice and five healthy female mice underwent anatomic MRI and hyperpolarized [1-13C]-pyruvate spectroscopy. Large contrast agent-enhanced tumors were shown in mice with glioma at T2-weighted and T1-weighted postcontrast MRI by postimplantation day 40. After treatment with WP1122, a decrease in lactate was observed in mice with glioma (baseline and treatment mean kPL, 0.027 and 0.018 sec-1, respectively, P = .01; baseline and posttreatment mean nLac, 0.28 and 0.22, respectively, P = .01) whereas no significant decrease was observed in healthy control mice (baseline and posttreatment mean kPL, 0.011 and 0.017 sec-1, respectively, P = .91; baseline and posttreatment mean nLac, 0.16 and 0.21, respectively, P = .84).ConclusionHyperpolarized carbon 13 measurements of pyruvate metabolism can provide rapid feedback for monitoring treatment response in glioma.© RSNA, 2019.

Toward Understanding the Silk Fiber Structure: 13C Solid-State NMR Studies of the Packing Structures of Alanine Oligomers before and after Trifluoroacetic Acid Treatment.

Polyalanine (poly-A) sequences with tightly packed antiparallel ß sheet (AP-ß) structures are frequently observed in silk fibers and serve as a key contributor to the exceptionally high-fiber tensile strength. In general, the poly-A sequence embedded in the amorphous glycine-rich regions has different lengths depending on the fiber type from spiders or wild silkworms. In this paper, the packing structures of AP-ß alanine oligomers with different lengths were studied using 13C solid-state NMR as a model of the poly-A sequences. These included alanine oligomers with and without the protection groups (i.e., 9-fluorenylmethoxycarbonyl and polyethylene glycol groups at the N- and C-terminals, respectively). The fractions of the packing structures as well as the conformations were determined by deconvolution analyses of the methyl NMR peaks. Trifluoroacetic acid was used to promote the staggered packing structures, and the line shapes changed significantly for oligomers without the protected groups but only slightly for oligomers with the protected groups. Through NMR analysis of the 3-13C singly labeled alanine heptamer and refined crystal structure of the staggered packing units, a possible mechanism of the staggered packing formation is proposed for the AP-ß alanine heptamer.

A critical review of analytical methods used for the chemical characterisation and quantification of phlorotannin compounds in brown seaweeds.

INTRODUCTION: Phlorotannins, the phenolic compounds found in brown seaweeds, are a unique and diverse class of compounds showing a huge potential for food and pharmaceutical applications. OBJECTIVE: This review will give an account of the colorimetric assays used and a discussion of their quantitative and qualitative analytical shortcomings. It will also discuss other more complex and modern analytical chemistry methods that are currently being developed to study phlorotannins. The purpose of this review is to increase awareness of these bioactive compounds and promote further development of robust analytical methods for use in biology, food science, pharmacology and biomedical and cosmeceutical sciences. RESULTS: Whilst the biological activity and huge commercial potential of the phlorotannins has been widely reported throughout the literature, the chemical structures and reactivity of these compounds is still not well understood. The phlorotannin content of seaweed is usually characterised using colorimetric assays. However, although these methods give a reasonable overall estimation of the total phenolic content, they lack precision and specificity. CONCLUSION: This review highlights the strengths and weaknesses of commonly used colorimetric assays. Novel techniques are highlighted using more selective chemistry to identify this class of compounds.

NMR quantification of lactate production and efflux and glutamate fractional enrichment in living human prostate biopsies cultured with [1,6-13 C2 ]glucose.

PURPOSE: Image-guided prostate biopsies are routinely acquired in the diagnosis and treatment monitoring of prostate cancer, yielding useful tissue for identifying metabolic biomarkers and therapeutic targets. We developed an optimized biopsy tissue culture protocol in combination with [1,6-13 C2 ]glucose labeling and quantitative high-resolution NMR to measure glycolysis and tricarboxcylic acid (TCA) cycle activity in freshly acquired living human prostate biopsies. METHODS: We acquired 34 MRI-ultrasound fusion-guided prostate biopsies in vials on ice from 22 previously untreated patients. Within 15 min, biopsies were transferred to rotary tissue culture in 37°C prostate medium containing [1,6-13 C2 ]glucose. Following 24 h of culture, tissue lactate and glutamate pool sizes and fractional enrichments were quantified using quantitative 1 H high resolution magic angle spinning Carr-Purcell-Meiboom-Gill (CPMG) spectroscopy at 1°C with and without 13 C decoupling. Lactate effluxed from the biopsy tissue was quantified in the culture medium using quantitative solution-state high-resolution NMR. RESULTS: Lactate concentration in low-grade cancer (1.15 ± 0.78 nmol/mg) and benign (0.74 ± 0.15 nmol/mg) biopsies agreed with prior published measurements of snap-frozen biopsies. There was substantial fractional enrichment of [3-13 C]lactate (≈70%) and [4-13 C]glutamate (≈24%) in both low-grade cancer and benign biopsies. Although a significant difference in tissue [3-13 C]lactate fractional enrichment was not observed, lactate efflux was significantly higher (P < 0.05) in low-grade cancer biopsies (0.55 ± 0.14 nmol/min/mg) versus benign biopsies (0.31 ± 0.04 nmol/min/mg). CONCLUSION: A protocol was developed for quantification of lactate production-efflux and TCA cycle activity in single living human prostate biopsies, allowing metabolic labeling on a wide spectrum of human tissues (e.g., metastatic, post-non-surgical therapy) from patients not receiving surgery.

Identification and Quantitative Determination of Resin Acids from Corsican Pinus pinaster Aiton Oleoresin Using 13 C-NMR Spectroscopy.

Twenty-three resin samples have been obtained by tapping from individual Pinus pinaster adult trees grown in Corsica and submitted to acido-basic partition. Identification and quantitative determination of resin acids has been carried out using 13 C-NMR spectroscopy following a method developed by our group. The main components were dehydroabietic acid (up to 37.6 %), levopimaric acid (up to 35.5 %) and abietic acid (up to 24.7 %). A lignan, pinoresinol, has been identified in some samples. Within the 23 compositions, submitted to k-means analysis and Principal Component Analysis, two clusters have been perfectly differentiated, whose compositions were dominated by dehydroabietic acid (Group I, M=23.5 %, SD=6.3) and levopimaric acid (Group II, M=21.2 %; SD=6.2), respectively. Both compositions have been observed in the three locations of harvest.

Semi-preparative isolation and purification of phenolic compounds from Achyrocline satureioides (Lam) D.C. by high-performance counter-current chromatography.

INTRODUCTION: Phenolic compounds present in Achyrocline satureioides are known to have therapeutic benefits like antioxidant, anti-inflammatory, and antitumour properties. The main polyphenols present in the plant are quercetin (QCT), luteolin (LUT), 3-O-methylquercetin (3OMQ), and achyrobichalcone (ACB). However, the effective isolation and purification of these compounds from A. satureioides inflorescences are not an easy task. OBJECTIVE: To develop an efficient high-performance counter-current chromatography (HPCCC) method for quick separation and purification of naturally occurring phenolic compounds from the extract of A. satureioides. METHODOLOGY: A two-step HPCCC semi-preparative isolation method was developed using a solvent system composed of n-hexane/ethyl acetate/methanol/water (0.8:1.0:0.8:1.0) and dichloromethane/methanol/water (3.5:3.5:2.5). RESULTS: The HPCCC method was used to obtain two fractions. The first fraction (F1 ) contained high levels of ACB, among other constituents, while the second fraction (F2 ) contained mostly QCT, LUT, and 3OMQ. Besides the high ACB content, F1 contained three other flavonoid-aglycones (kaempferol, 97.3%; isokaempferide, 92.4%; and 3,3'-di-O-methylquercetin, 95.2%) identified by an ultra-performance liquid chromatography system coupled to a quadrupole time-of-flight with high-definition mass spectrometry (UPLC-QTOF/HDMS) and nuclear magnetic resonance (NMR) analysis. Purity levels of ACB, 3OMQ, QCT, and LUT were 98.0, 97.0, 97.5, and 90.2%, respectively. CONCLUSION: This is the first time that high purity ACB and six other flavonoids were obtained from A. satureioides inflorescences by HPCCC. These excellent results reveal the potential and versatility of HPCCC as a technique to produce different types of products from this plant species on a semi-preparative scale: enriched fractions, new metabolites, or high purity compounds.

Dynamic diffusion-weighted hyperpolarized 13 C imaging based on a slice-selective double spin echo sequence for measurements of cellular transport.

PURPOSE: To develop a pulse sequence to dynamically measure the ADC of hyperpolarized substrates during their perfusion, metabolic conversion, and transport. METHODS: We proposed a slice-selective double spin echo sequence for dynamic hyperpolarized 13 C diffusion-weighted imaging. The proposed pulse sequence was optimized for a high field preclinical scanner through theoretical analysis and simulation. The performance of the method was compared to non-slice-selective double spin echo via in vivo studies. We also validated the sequence for dynamic ADC measurement in both phantom studies and transgenic mouse model of prostate cancer studies. RESULTS: The optimized pulse sequence outperforms the traditional sequence with smaller saturation effects on the magnetization of hyperpolarized compounds that allowed more dynamic imaging frames covering a longer imaging time window. In pre-clinical studies (N = 8), the dynamic hyperpolarized lactate ADC maps of 6 studies in the prostate tumors showed an increase measured ADC over time, which might be related to lactate efflux from the tumor cells. CONCLUSIONS: The proposed sequence was validated and shown to improve dynamic diffusion weighted imaging compared to the traditional double spin echo sequence, providing ADC maps of lactate through time.

900MHz 1H-/13C-NMR analysis of 2-hydroxyglutarate and other brain metabolites in human brain tumor tissue extracts.

PURPOSE: To perform in vitro high-resolution 900 MHz magnetic resonance spectroscopy (NMR) analysis of human brain tumor tissue extracts and analyze for the oncometabolite 2-hydroxyglutarate (2HG) and other brain metabolites, not only for 1H but also for 13C with indirect detection by heteronuclear single quantum correlation (HSQC). MATERIAL AND METHODS: Four surgically removed human brain tumor tissue samples were used for extraction and preparation of NMR samples. These tissue samples were extracted with 4% perchloric acid and chloroform, freeze-dried, then dissolved into 0.28 mL of deuterium oxide (D2O, 99.9 atom % deuterium) containing 0.025 wt % sodium 3-(trimethylsilyl)propionate-2,2,3,3-d4 (TSP). All samples were adjusted to pH range of 6.9-7.1 before finally transferred to 5 mm Shigemi™ NMR microtube. NMR experiments were performed on Bruker DRX 900 MHz spectrometer with 1H/13C/15N Cryo-probe™ with Z-gradient, without further temperature control for the samples. All chemical shift values were presented relative to TSP at 0.00 ppm for both 1H and 13C. 1H 1D, 1H-13C HSQC, 1H-1H correlation spectroscopy (COSY) and 1H-13C heteronuclear multiple bond correlation (HMBC) spectra were acquired and analyzed. RESULTS: 2-hydroxyglutarate, an oncometabolite associated with gliomas with IDH mutations, was successfully detected and assigned by both 1H-13C HSQC and 1H-1H COSY experiments as well as 1H 1D experiments in two of the tissue samples. In particular, to our knowledge this work shows the first example of detecting 900 MHz 13C-NMR spectral lines of 2-hydroxyglutarate in human brain tumor tissue samples. In addition to the oncometabolite 2-hydroxyglutarate, at least 42 more metabolites were identified from our series of NMR experiment. CONCLUSION: The detection of 2-hydroxyglutarate and other metabolites can be facilitated by homonuclear and heteronuclear two-dimensional 900 MHz NMR spectroscopy even in case of real tumor tissue sample extracts without physical separation of metabolites.