Characterization of insoluble calcium alginates by solid-state NMR

Three series of 9 insoluble calcium alginate powders with different average calcium contents (1.5, 3.5 and 8%, w/w) are investigated by means of ¹³C solid-state NMR spectroscopy. The effect of the increased calcium content on the determination of the mannuronate (M) to guluronate (G) ratio from spectral deconvolution of the ¹³C CP/MAS spectra is discussed, and the variations observed are commented in function of possible structural modifications related to the interaction with the divalent cations. The possibility of using solid-state NMR spectroscopy for the quantification of the calcium content in unknown alginate samples is explored performing principal component analysis (PCA) of the spectra. The results obtained show that a clear separation of alginates with slightly different calcium content is possible. The proposed method relies on the sole use of the chemical shifts of the signals corresponding to pyranose carbons, suggesting that PCA of solid-state NMR data holds promises as a rapid and undestructive method for screening the calcium content of alginate-based materials with biomedical uses.     

Intra- and inter-metabolite correlation spectroscopy of tomato metabolomics data obtained by liquid chromatography-mass spectrometry and nuclear magnetic resonance

Nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LCMS) are frequently used as technological platforms for metabolomics applications. In this study, the metabolic profiles of ripe fruits from 50 different tomato cultivars, including beef, cherry and round types, were recorded by both ¹H NMR and accurate mass LC-quadrupole time-of-flight (QTOF) MS. Different analytical selectivities were found for these both profiling techniques. In fact, NMR and LCMS provided complementary data, as the metabolites detected belong to essentially different metabolic pathways. Yet, upon unsupervised multivariate analysis, both NMR and LCMS datasets revealed a clear segregation of, on the one hand, the cherry tomatoes and, on the other hand, the beef and round tomatoes. Intra-method (NMR–NMR, LCMS–LCMS) and inter-method (NMR–LCMS) correlation analyses were performed enabling the annotation of metabolites from highly correlating metabolite signals. Signals belonging to the same metabolite or to chemically related metabolites are among the highest correlations found. Inter-method correlation analysis produced highly informative and complementary information for the identification of metabolites, even in de case of low abundant NMR signals. The applied approach appears to be a promising strategy in extending the analytical capacities of these metabolomics techniques with regard to the discovery and identification of biomarkers and yet unknown metabolites. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

In situ and in vitro suppressive effect of agricultural composts and their water extracts on some phytopathogenic fungi

In situ and in vitro experiments were carried out to determine the effect of various composts (leafy fruit compost (LFC), garden compost (GC), and crops compost (CC)) and their water extract on Pythium debaryanum, Fusarium oxysporum f.sp. lycopersici, Sclerotium bataticola. Compost water extract (CWE) of LFC, GC, and CC were found to contain Bacillus spp., Micrococcus spp., Staphylococcus spp. and Corynebacterium spp., and the fungi Aspergillus spp., Rhizopus spp., and Drechslera spp., and various Actinomycetes. In situ results indicated considerable decrease in fungal growth around the unautoclaved compost especially in the case of S. bataticola and F. oxysporum f.sp. lycopersici, compared to the autoclaved compost. In vitro tests showed that concentration of CWE at 5, 10 and 15% (v/v) suppressed the hyphal growth of S. bataticola by 83% using 5% CC and by 94.4% using 5% LFC or 10% GC, and F. oxysporum f.sp. lycopersici by 94.4% using either composts. CWE of GC decreased fungal dry weight of F. oxysporum f.sp. lycopersici by 97.7%, P. debaryanum by 92.8%, and S. bataticola by 84.4%; CC decreased F. oxysporum f.sp. lycopersici by 94%, P. debaryanum by 86.2%, and S. bataticola by 63.3%, while CWE of LFC was the least effective against the tested fungi. CWE produced clear inhibition zones against all the tested fungi. Microflora found in CWE have an important role in suppressing the growth of tested fungi. CWE contained neither antibiotics nor siderophores. The presence of protease, chitinase, lipase and -1,3 glucanase (lysogenic enzymes) in CWE indicates a possible role in fungal degradation.     

基于时间聚类分析和独立成分分析的癫痫fMRI盲分析方法

提出了一种基于时间聚类分析和独立成分分析的癫痫fMRI数据盲分析方法,并将两种方法有效联合,提取发作间期的癫痫fMRI激活时空信息.该方法首先由时间聚类分析得到与激活相关的时间峰度特征曲线,以此特征作为时间参考信息;再由空间独立成分分析分解fMRI信号得到空间独立成分;最后将每个独立成分所对应的时间曲线与参考曲线做相关分析提取相应脑激活图.提出的方法无需任何关于癫痫fMRI的先验假设信息,有效解决了独立成分的排序问题,实现了对数据的盲分析.仿真试验结果阐明了这一方法的有效性及可靠性,对癫痫数据的试验结果显示空间定位准确性优于统计参数图方法.     

Metabolomic fingerprinting using nuclear magnetic resonance and multivariate data analysis as a tool for biodiversity informatics: A case study on the classification of Rosa x damascena

Metabolomics is the comprehensive and simultaneous identification and quantification of metabolites in living cells. The term metabolome is used to describe the observable chemical profile or fingerprint of the metabolites in a whole tissue. Although being a new approach to study natural compounds, metabolomics uses traditional analytical techniques, including extraction methods, which can be followed by nuclear magnetic resonance (NMR) spectroscopy and multivariate data analysis. Although metabolomics has been successfully applied to quality control issues, the examples of its use for chemosystematics are few. Thus, the analysis of four taxa of Rosa x damascena (R. damascena Mill., R. damascenasemperflorens, R. damascenatrigintipetala and R. duchesse of Portland) was carried out by NMR spectroscopy as a tool for their classification. A principal component analysis of the ¹H NMR spectra, based on the metabolites found in organic and aqueous fractions, showed a clear similarity of the samples. In particular, the major contributions from the aqueous fraction, preliminarily considered as a biomarker of R. x damascena group, are the flavonoids kaempferol and quercetin, glycosilated with glucose and rhamnose units. Our analysis demonstrated a close chemotaxonomic correlation among the four taxa, making this method a reliable tool for chemosystematics.     

Myocardial gene expression profiling of rewarming shock in a rodent model of accidental hypothermia

Background

Severe accidental hypothermia represents a cardiovascular emergency associated with high mortality and poor recovery of cardiac function. The biochemical changes occurring within the heart during the development of hypothermia and subsequent resuscitation are not known.

Methods

By mRNA expression profiling, we have characterized gene expression changes occurring within the myocardium in an intact rat model of accidental hypothermia during cooling to a core temperature of 15 °C and subsequent rewarming to 37 °C. During the rewarming phase, these animals develop a profound low-output cardiac failure.

Results

Hypothermia induces expression of known mediators of thermotolerance, including heat-shock protein 70 and several factors involved in protection against apoptotic cell death. Upregulation of genes involved in autophagy and increased abundance of autophagosomal vesicles suggest involvement of autophagic degeneration in the development of myocardial dysfunction occurring during rewarming from hypothermia. Rewarming from hypothermia also induces expression of several pro-inflammatory genes involved in the nuclear factor kappa B (NFκB) signaling cascade.

Conclusions

Our data demonstrate that rewarming from hypothermia is associated with the induction of a cellular stress–response, including upregulation of autophagy and activation of pro-inflammatory signaling cascades. These data provide a framework for understanding the molecular changes that occur during induction of and rewarming from severe hypothermia, and identifies potential targets for cardioprotective interventions in resuscitation of victims of hypothermia.     

NMR based structure-activity relationship analysis of an antimicrobial peptide, thanatin, engineered by site-specific chemical modification: Activity improvement and spectrum alteration

Activity improvement of an antimicrobial peptide, thanatin, has been achieved up to 4-fold higher than natural original one by site-specific chemical modifications with tert-butyl group at two cysteine residues which form an intramoleular disulfide bridge. The chemically modified thanatin (C11tBu/C18tBu) exhibited improved antimicrobial activity toward Gram-positive bacteria, Micrococcus luteus, whereas lowered activity toward Gram-negative bacteria, Escherichia coli. This finding suggests that disulfide-bridge formation is not only indispensable for exhibition of antimicrobial activity of thanatin but also closely related to the activity specificity towards bacteria. NMR analysis indicates that thanatin acts against E.coli stereospecifically by taking advantage of its C-terminal β-hairpin structure, while the activity against M. luteus does not relate to structures and correlates very well to side-chain hydrophobicity.     

Conformational analysis by NMR and molecular dynamics of adamantane-doxorubicin prodrugs and their assemblies with β-cyclodextrin: A focus on the design of platforms for controlled drug delivery

Nanoscale design and construction of affinity-based drug delivery systems (ADDS) is an active research area with enormous potential for the improvement of cancer treatment. For the therapeutic load of these ADDS, a promising strategy is the design of pH-sensitive prodrugs based on the construction of conjugates between adamantane and doxorubicin (Ad-Dox), which stands out as an excellent model system to obtain novel supramolecular materials. Construction of these prodrugs involves a modification of three zones of doxorubicin which in principle does not affect the action mechanism: the carbonyl group C13 (hydrazone linker), the primary alcohol neighboring the carbonyl (ester linker) and the 3′ amino group of daunosamine sugar (amide linker). These modifications are aimed to improve the efficacy and reduce the systemic toxicity of the drug chemotherapy by controlling its release in cancer cells. In this work, we performed 2D NMR experiments and molecular dynamics simulations to characterize the conformational changes of three constructed prodrugs. Our results demonstrated that ring A and the daunsamine sugar of the hydrazone and amide linkers conserve the half-chair state ⁹H₈, while the ester linker disrupts this conformation. Our study also showed that the hydrazone-linked compound (Ad-h-Dox) does not modify the conformation of the original drug and maintains cytotoxic activity. Moreover, the inclusion complex (IC) of Ad-h-Dox with β-cyclodextrin (βCD) generated a highly soluble platform in water, whereas the ester-linked compound (Ad-e-Dox) causes the loss of biological activity. This study proves that Ad-h-Dox prodrug can be an optimum prodrug and act as a building block for a more complex drug transport system.     

Natural products as modulators of the nuclear receptors and metabolic sensors LXR,FXR and RXR

Nuclear receptors (NRs) represent attractive targets for the treatment of metabolic syndrome-related diseases. In addition, natural products are an interesting pool of potential ligands since they have been refined under evolutionary pressure to interact with proteins or other biological targets.This review aims to briefly summarize current basic knowledge regarding the liver X (LXR) and farnesoid X receptors (FXR) that form permissive heterodimers with retinoid X receptors (RXR). Natural product-based ligands for these receptors are summarized and the potential of LXR, FXR and RXR as targets in precision medicine is discussed.