Tunable heteroaromatic azoline thioethers (HATs) for cysteine profiling

Here we report a new series of hydrolytically stable chemotype heteroaromatic azoline thioethers (HATs) to achieve highly selective, rapid, and efficient covalent labeling of cysteine under physiological conditions. Although the resulting cysteine–azoline conjugate is stable, we highlight traceless decoupling of the conjugate to afford unmodified starting components in response to reducing conditions. We demonstrated that HAT probes reverse the reactivity of nucleophilic cysteine to electrophilic dehydroalanine (Dha) under mild basic conditions. We demonstrated the umpolung capability of HAT probes for the modification of cysteine on peptides and proteins with various nucleophiles. We demonstrated that HAT probes increase the mass sensitivity of the modified peptides and proteins by 100 fold as compared to the classical methods. Finally, we extended the application of HAT probes for specific modification of cysteines in a complex cell lysate mixture.

Here we report a new series of hydrolytically stable chemotype heteroaromatic azoline thioethers (HATs) to achieve highly selective, rapid, and efficient covalent labeling of cysteine under physiological conditions.     

Transition probabilities for two-photon H(1s–2s) and He(11s–21s) transitions: A partial-closure approach

Transition amplitudes and transition probabilities for the two-photon 1s–2s transition in the hydrogen atom and 1¹ s–2¹ s transition in helium atom have been calculated using a partial-closure approach. The dominant term is calculated exactly and the remaining sum over intermediate states is calculated using a mean excitation energy. Our value of the transition amplitudes agree within 2% with the exact results for the hydrogen case. Our value of the transition probability for hydrogen is 8.50 s⁻¹ which is in good accord with its known value 8.226 s⁻¹. For helium, the photon energy distribution of the metastable 2¹ s state is in good agreement with the accurate values. The corresponding transition probability is 53.7 s⁻¹ which is in good agreement with the accurate value 51.3 s⁻¹.     

(E)‐2‐[2‐(1‐Naphthyl)­vinyl]‐3‐tosyl‐2,3‐di­hydro‐1,3‐benzo­thia­zole

The title compound, C₂₆H₂₁NO₂S₂, which consists of a benzo­thia­zole skeleton with α‐naphthyl­vinyl and tosyl groups at positions 2 and 3, respectively, was prepared by palladium–copper‐catalyzed heteroannulation. The E configuration of the mol­ecule about the vinyl C=C bond is established by the benzothiazole–naphthyl C—C—C—C torsion angle of 177.5 (4)°. The five‐membered heterocyclic ring adopts an envelope conformation with the Csp³ atom 0.380 (6) Å from the C₂NS plane. The two S—C [1.751 (4) and 1.838 (4) Å] and two N—C [1.426 (5) and 1.482 (5) Å] bond lengths in the thia­zole ring differ significantly.     

Preparation of Some Benzyl D-Glucuronatesfrom 4-Methoxybenzylidene Derivatives of D-Glucuronic Acid

Summary.  Because of the low stability of the benzyl ester linkage in benzyl 1,2:3,5-di-O-benzylidene-α-D-glucofuranuronate during the removal of the benzylidene groups by acid hydrolysis and/or hydrogenolysis, 4-methoxybenzylidene groups were used to block the free hydroxyl groups of D-glucuronic acid. Several benzyl esters of D-glucuronic acid were prepared, and their relative rates of acid catalyzed hydrolysis were determined by liquid-chromatographic separation of the reaction mixture and subsequent diode array detection. Received May 22, 2000. Accepted (revised) July 17, 2000     

Supramolecular cis-“Bis(Chelation)” of [M(CN)6]3− (M = CrIII,FeIII, CoIII) by Phloroglucinol (H3PG)

Studies on molecular co-crystal type materials are important in the design and preparation of easy-to-absorb drugs, non-centrosymmetric, and chiral crystals for optical performance, liquid crystals, or plastic phases. From a fundamental point of view, such studies also provide useful information on various supramolecular synthons and molecular ordering, including metric parameters, molecular matching, energetical hierarchy, and combinatorial potential, appealing to the rational design of functional materials through structure–properties–application schemes. Co-crystal salts involving anionic d-metallate coordination complexes are moderately explored (compared to the generality of co-crystals), and in this context, we present a new series of isomorphous co-crystalline salts (PPh₄)₃[M(CN)₆](H₃PG)₂·2MeCN (M = Cr, 1; Fe, 2; Co 3; H₃PG = phloroglucinol, 1,3,5-trihydroxobenzene). In this study, 1–3 were characterized experimentally using SC XRD, Hirshfeld analysis, ESI-MS spectrometry, vibrational IR and Raman, ⁵⁷Fe Mössbauer, electronic absorption UV-Vis-NIR, and photoluminescence spectroscopies, and theoretically with density functional theory calculations. The two-dimensional square grid-like hydrogen-bond {[M(CN)₆]³⁻;(H₃PG)₂}_∞ network features original {[M(CN)₆]³⁻;(H₃PG)₄} supramolecular cis-bis(chelate) motifs involving: (i) two double cyclic hydrogen bond synthons M(-CN⋅⋅⋅HO-)₂Ar, {[M(CN)₆]³⁻;H₂PGH}, between cis-oriented cyanido ligands of [M(CN)₆]³⁻ and resorcinol-like face of H₃PG, and (ii) two single hydrogen bonds M-CN⋅⋅⋅HO-Ar, {[M(CN)₆]³⁻;HPGH₂}, involving the remaining two cyanide ligands. The occurrence of the above tectonic motif is discussed with regard to the relevant data existing in the CCDC database, including the multisite H-bond binding of [M(CN)₆]³⁻ by organic species, mononuclear coordination complexes, and polynuclear complexes. The physicochemical and computational characterization discloses notable spectral modifications under the regime of an extended hydrogen bond network.     

An Evidence-Based Review of Application Devices for Nitric Oxide Concentration Determination from Exhaled Air in the Diagnosis of Inflammation and Treatment Monitoring

The measurement of nitric oxide (NO) in exhaled air is used in diagnostics and monitoring the pathologies not only in the respiratory system but also in the oral cavity. It has shown a huge increase in its level in asthma and diseases of the oral cavity. It seems reasonable to undertake research on the impact of inflammation on the level of NO in exhaled air. The aim of the study is to make an evidence-based review of the application of NO levels in exhaled air in the diagnosis of inflammation and treatment monitoring on the basis of selected measuring devices. Methods and Results: This paper presents an example of the application of NO measurement in exhaled air in individual human systems. Selected measuring devices, their non-invasiveness, and their advantages are described. Discussion: The usefulness of this diagnostic method in pathologies of the oral cavity was noted. Conclusions: Measuring the level of NO in exhaled air seems to be a useful diagnostic method.     

Polyphenols and Maillard Reaction Products in Dried Prunus spinosa Fruits: Quality Aspects and Contribution to Anti-Inflammatory and Antioxidant Activity in Human Immune Cells Ex Vivo

Dried Prunus spinosa fruits (sloes) are folk phytotherapeutics applied to treat chronic inflammatory disorders. However, their pharmacological potential, activity vectors, and drying-related changes in bioactive components remain unexplored. Therefore, the present research aimed to evaluate the anti-inflammatory and antioxidant effects of dried sloes in ex vivo models of human neutrophils and peripheral blood mononuclear cells (PMBCs) and establish their main active components. It was revealed that the fruit extracts significantly and dose-dependently inhibited the respiratory burst, downregulated the production of elastase (ELA-2) and TNF-α, and upregulated the IL-10 secretion by immune cells under pro-inflammatory and pro-oxidant stimulation. The slightly reduced IL-6 and IL-8 secretion was also observed. The structural identification of active compounds, including 45 phenolics and three Maillard reaction products (MRPs) which were formed during drying, was performed by an integrated approach combining LC-MS/MS, preparative HPLC isolation, and NMR studies. The cellular tests of four isolated model compounds (chlorogenic acid, quercetin, procyanidin B2, and 5-hydroxymethylfurfural), supported by statistical correlation studies, revealed a significant polyphenolic contribution and a slight impact of MRPs on the extracts’ effects. Moreover, a substantial synergy was observed for phenolic acids, flavonoids, condensed proanthocyanidins, and MPRs. These results might support the phytotherapeutic use of dried P. spinosa fruits to relieve inflammation and establish the quality control procedure for the extracts prepared thereof.     

The Effect of Standardised Leaf Extracts of Gaultheria procumbens on Multiple Oxidants,Inflammation-Related Enzymes,and Pro-Oxidant and Pro-Inflammatory Functions of Human Neutrophils

The leaves of Gaultheria procumbens are polyphenol-rich traditional medicines used to treat inflammation-related diseases. The present study aimed to optimise the solvent for the effective recovery of active leaf components through simple direct extraction and verify the biological effects of the selected extract in a model of human neutrophils ex vivo. The extracts were comprehensively standardised, and forty-one individual polyphenols, representing salicylates, catechins, procyanidins, phenolic acids, and flavonoids, were identified by UHPLC–PDA–ESI–MS³. The chosen methanol–water (75:25, v/v) extract (ME) was obtained with the highest extraction yield and total phenolic levels (397.9 mg/g extract’s dw), including 98.9 mg/g salicylates and 299.0 mg/g non-salicylate polyphenols. In biological tests, ME revealed a significant and dose-dependent ability to modulate pro-oxidant and pro-inflammatory functions of human neutrophils: it strongly reduced the ROS level and downregulated the release of pro-inflammatory cytokines and tissue remodelling enzymes, especially IL-1β and elastase 2, in cells stimulated by fMLP, LPS, or fMLP + cytochalasin B. The extracts were also potent direct scavengers of in vivo relevant oxidants (O₂^•−, ^•OH, and H₂O₂) and inhibitors of pro-inflammatory enzymes (cyclooxygenase-2, hyaluronidase, and lipoxygenase). The statistically significant correlations between the tested variables revealed the synergic contribution of individual polyphenols to the observed effects and indicated them as useful active markers for the standardisation of the extract/plant material. Moreover, the safety of ME was confirmed in cytotoxicity tests. The obtained results might partially explain the ethnomedicinal application of G. procumbens leaves and support the usage of the standardised leaf extract in the adjuvant treatment of oxidative stress and inflammation-related chronic diseases.     

Human and Bacterial Toll-Interleukin Receptor Domains Exhibit Distinct Dynamic Features and Functions

Toll-interleukin receptor (TIR) domains have emerged as critical players involved in innate immune signaling in humans but are also expressed as potential virulence factors within multiple pathogenic bacteria. However, there has been a shortage of structural studies aimed at elucidating atomic resolution details with respect to their interactions, potentially owing to their dynamic nature. Here, we used a combination of biophysical and biochemical studies to reveal the dynamic behavior and functional interactions of a panel of both bacterial TIR-containing proteins and mammalian receptor TIR domains. Regarding dynamics, all three bacterial TIR domains studied here exhibited an inherent exchange that led to severe resonance line-broadening, revealing their intrinsic dynamic nature on the intermediate NMR timescale. In contrast, the three mammalian TIR domains studied here exhibited a range in terms of their dynamic exchange that spans multiple timescales. Functionally, only the bacterial TIR domains were catalytic towards the cleavage of NAD⁺, despite the conservation of the catalytic nucleophile on human TIR domains. Our development of NMR-based catalytic assays allowed us to further identify differences in product formation for gram-positive versus gram-negative bacterial TIR domains. Differences in oligomeric interactions were also revealed, whereby bacterial TIR domains self-associated solely through their attached coil-coil domains, in contrast to the mammalian TIR domains that formed homodimers and heterodimers through reactive cysteines. Finally, we provide the first atomic-resolution studies of a bacterial coil-coil domain and provide the first atomic model of the TIR domain from a human anti-inflammatory IL-1R8 protein that undergoes a slow inherent exchange.     

Determination of Relative Stabilities of Metal-Peptide Bonds in the Gas Phase

Understanding binding site preferences in biological systems as well as affinities to binding partners is a crucial aspect in metallodrug development. We here present a mass spectrometry-based method to compare relative stabilities of metal-peptide adducts in the gas phase. Angiotensin 1 and substance P were used as model peptides. Incubation with isostructural N-heterocyclic carbene (NHC) complexes of Ru^II, Os^II, Rh^III, and Ir^III led to the formation of various adducts, which were subsequently studied by energy-resolved fragmentation experiments. The gas-phase stability of the metal-peptide bonds depended on the metal and the binding partner. Of the four complexes used, the Os^II derivative bound strongest to Met, while Ru^II formed the most stable coordination bond with His. Rh^III was identified as the weakest peptide binder and Ir^III formed peptide adducts with intermediate stability. Probing these intrinsic gas-phase properties can help in the interpretation of biological activities and the design of site-specific protein binding metal complexes.