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DOE OSTI2014

Comparing linear and cyclic synthetic homopolypeptides: Synthesis and molecular characterization

We report the synthesis and molecular characterization of a linear and a cyclic homopolypeptide of protected l-tyrosine. The successful synthesis of polypeptides exhibiting the desired linear and cyclic structures through various characterization methods such as high temperature gel permeation chromatography, Fourier transform infrared spectroscopy, proton and carbon nuclear magnetic resonance spectroscopy, mass spectrometry, dynamic light scattering, differential scanning calorimetry, and thermogravimetric analysis was verified in this work. Our results are very promising especially if such cyclic materials will be potentially used as carriers for drug delivery, either through conjugation with specific ligands or directly through the functional hydroxyl groups of the monomeric units of poly(l-Tyr) after deprotection.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Convergent behavior of extended stalk regions from staphylococcal surface proteins with widely divergent sequence patterns

Staphylococcus epidermidis and Staphylococcus aureus are highly problematic bacteria in hospital settings. A major challenge is their ability to form biofilms on abiotic or biotic surfaces. Biofilms are well-organized, multicellular bacterial aggregates that resist antibiotic treatment and often lead to recurrent infections. Bacterial cell wall-anchored (CWA) proteins are important players in biofilm formation and infection. Many have putative stalk-like regions or regions of low complexity near the cell wall-anchoring motif. Recent work demonstrated the strong propensity of the stalk region of S. epidermidis accumulation-associated protein (Aap) to remain highly extended under solution conditions that typically induce compaction. This behavior is consistent with the expected function of a stalk-like region that is covalently attached to the cell wall peptidoglycan and projects the adhesive domains of Aap away from the cell surface. In this study, we evaluate whether the ability to resist compaction is a common theme among stalk regions from various staphylococcal CWA proteins. Circular dichroism spectroscopy was used to examine secondary structure changes as a function of temperature and cosolvents along with sedimentation velocity analytical ultracentrifugation, size-exclusion chromatography, and SAXS to characterize structural characteristics in solution. All stalk regions tested are intrinsically disordered, lacking secondary structure beyond random coil and polyproline type II helix, and they all sample highly extended conformations. Remarkably, the Ser-Asp dipeptide repeat region of SdrC exhibited nearly identical behavior in solution when compared to the Aap Pro/Gly-rich region, despite highly divergent sequence patterns, indicating conservation of function by various distinct staphylococcal CWA protein stalk regions.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2018

Aging Mechanisms and Nondestructive Aging Indicator of Filled Cross-linked Polyethylene (XLPE) Exposed to Simultaneous Thermal and Gamma Radiation

Aging mechanisms and a nondestructive aging indicator of filled cross-linked polyethylene (XLPE) cable insulation material used in nuclear power plants (NPPs) are studied. Using various material characterization techniques, likely candidates and functions for the main additives in a commercial filled-XLPE insulation material have been identified. These include decabromodiphenyl ether and Sb2O3 as flame retardants, ZnS as white pigment and polymerized 1,2-dihydro-2,2,4-trimethylquinoline as antioxidant. Gas chromatography-mass spectrometry, differential scanning calorimetry, oxidation induction time and measurements of dielectric loss tangent are utilized to monitor property changes as a function of thermal and radiation exposure of the cable material. Small-molecular-weight hydrocarbons are evolve with gamma radiation aging at 90 °C. The level of antioxidant decreases with aging by volatilization and chemical reaction with free radicals. Thermal aging at 90 °C for 25 days or less causes no observable change to the cross-linked polymer structure. Gamma radiation causes damage to crystalline polymer regions and introduces defects. Dielectric loss tangent is shown to be an effective and reliable nondestructive indicator of the aging severity of the filled-XLPE insulation material.

aging mechanisms↗

DOE OSTI2019

A new triterpene diglycoside from the roots of Bupleurum chinense DC. and its inhibitory effect on adipogensis in 3T3-L1 cells

A new triterpene diglycoside, tibesaikosaponin V (TKV), was isolated from the methanol extract of the roots of Bupleurum chinense DC. by normal and reversed phase column chromatography. The chemical structure of this new compound was elucidated based on extensive spectroscopic analysis, including 1D and 2D NMR, HR-ESI-MS, and chemical degradation method. Our results indicated that TKV inhibited lipid accumulation and triacylglycerol content occurred without cytotoxicity to 3T3-L1 adipocytes. Furthermore, TKV significantly suppressed the mRNA expression of nuclear transcription factors such as, peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα). These results suggest that TKV shows the ability to inhibit 3T3-L1 preadipocyte differentiation of and may have therapeutic potential for obesity and its associated metabolic disorders.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2019

Synthesis and antitumor activity of cyclic octapeptide, samoamide A, and its derivatives

Using 2-chloro-trityl chloride resin as a solid phase carrier, a linear peptide was synthesized by Fmoc solid phase synthesis followed by liquid phase cyclization. After separation and purification by high-performance liquid chromatography (HPLC), cyclic octapeptide samoamide A was prepared. The synthesis yield was 54.5%. The structure of cyclic octapeptide samoamide A was characterized by electrospray ionization–mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectrometry. The biological activity was evaluated by the CCK-8 assay and DPP4 enzyme activity inhibition assay. This compound exhibited high antitumor activity. Using samoamide A as a lead compound, eight cyclic octapeptide samoamide A derivatives (a, b, c, d, e, f, g, and h) were designed and synthesized using the alanine scanning method. The molecular weight and chemical structure of these derivatives were verified by ESI-MS and NMR, and the antitumor activity of the derivatives was analyzed. The antitumor activity of compound f was similar to that of samoamide A, and its replacement site is the non-active site of samoamide A, providing a theoretical basis for further modification and transformation of samoamide A.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2019

Oxidative stress induced apoptosis mediated anticancer activity of Rhus typhina fruits extract in human colon cancer

The present work was tested the anti-proliferation activity of Rhus typhina fruits extract (RTFE) in HEK293 and HT-29 cells, and studied their underlying mechanisms through the analysis of oxidative stress and apoptosis-related genes expressions by flow cytometer and RT-qPCR. In addition, the bioactive constituents were identified from RTFE by chromatography and NMR analysis. Among the various type of the fractions from the RTFE, the ethyl acetate fraction (EAF) was showed the potent anti proliferation effect in HT-29 cells. Thus EAF was selected for the further extensive analysis. Cytotoxcity and RT-qPCR results revealed that the treatment of EAF significantly inhibit the growth of the HT-29 cells by the up regulating of Bax and down regulation of Bcl-2, Survivn, AIF and SOD-2 gene expressions in time and dose dependent manner. Followed by sub G1 accumulation and the G0/G1 phase arrest, ROS production, and mitochondrial transmembrane potential (ΔΨm). Finally, the active anti-proliferations agents such as luteolin and luteolin-7-O-glucuronide were identified from EAF by NMR. This work suggests that EAF could be a functional food to treat the chronic diseases.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2019

Structure-activity relationship for vanilloid compounds from extract of Zingiber officinale var rubrum rhizomes: effect on extracellular melanogenesis inhibitory activity

The components in the methanol extract of Zingiber officinale var rubrum (red ginger) were isolated by a series of column chromatography and identified by Nuclear Magnetic Resonance (NMR) and Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOFMS). Thirteen components, including eleven vanilloid compounds, were isolated from the extract. All the isolated components reduced extracellular melanin contents. Structure-activity relationship studies suggested that elongation of the carbon chain of shogaol and gingerol increased the extracellular melanogenesis inhibitory activity, and that the carbonyl and hydroxyl groups on the carbon chain in gingerol played an important role in this effect. In order to reveal the importance of the vanillyl group for the melanogenesis inhibitory activity, 6-gingerol (1) and 6-shogaol (5), which were the main compounds in the extract, were glucosylated and their effects were evaluated. The glucosylated 6-shogaol resulted in improved melanogenesis inhibitory activity, while the glucosylated 6-gingerol had no such effect. These results indicated different mechanisms for the melanogenesis inhibitory activity of the two vanilloid compounds.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2019

Identification and Characterization of Herbicide Penoxsulam Transformation Products in Aqueous Media by UPLC-QTOF-MS

Photodegradation is an important non-biodegradation process of pesticide degradation in aquatic environments. In this study, the effect of different forms of nitrogen on the photodegradation kinetics of penoxsulam was investigated. The photodegradation of penoxsulam was accelerated by NO{sup 3−} and NO{sup 2−} but was not affected by NH{sup 4+}. Ultra-high-performance liquid chromatography coupled with time-of-flight mass spectrometry was used to separate and identify the transformation products (TPs)converted by photodegradation of penoxsulam in an aqueous solution under UV–Vis (290–800 nm) irradiation. Seven major transformation products were identified based on mass spectral data. The structure was determined by elemental composition calculations, comparison of structural analogs, and existing literature. The main pathways of photodegradation were found to be sulfonamide bond cleavage, rearrangement, triazole ring cleavage, and hydroxylation. These findings are critical to elucidate the environmental fate of penoxsulam in aquatic ecosystems and provide a basis for further environmental risk assessment.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2013

Chemical Renal Denervation in the Rat

Introduction: The recent success of renal denervation in lowering blood pressure in drug-resistant hypertensive patients has stimulated interest in developing novel approaches to renal denervation including local drug/chemical delivery. The purpose of this study was to develop a rat model in which depletion of renal norepinephrine (NE) could be used to determine the efficacy of renal denervation after the delivery of a chemical to the periadventitial space of the renal artery. Methods: Renal denervation was performed on a single renal artery of 90 rats (n = 6 rats/group). The first study determined the time course of renal denervation after surgical stripping of a renal artery plus the topical application of phenol in alcohol. The second study determined the efficacy of periadventitial delivery of hypertonic saline, guanethidine, and salicylic acid. The final study determined the dose–response relationship for paclitaxel. In all studies, renal NE content was determined by liquid chromatography–mass spectrometry. Results: Renal NE was depleted 3 and 7 days after surgical denervation. Renal NE was also depleted by periadventitial delivery of all agents tested (hypertonic saline, salicylic acid, guanethidine, and paclitaxel). A dose response was observed after the application of 150 μL of 10{sup −5} M through 10{sup −2} M paclitaxel. Conclusion: We developed a rat model in which depletion of renal NE was used to determine the efficacy of renal denervation after perivascular renal artery drug/chemical delivery. We validated this model by demonstrating the efficacy of the neurotoxic agents hypertonic saline, salicylic acid, and guanethidine and increasing doses of paclitaxel.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

Pharmacokinetic Evaluation of Two Paclitaxel-Coated Balloons with Different Drug Load in a Short-Term Porcine Study

PurposeThe aim of the study was to evaluate the pharmacokinetics and tissue absorption of 2 paclitaxel (PTX) drug-coated balloons (DCB) using different drug loads in a porcine-injured iliac artery model.Materials and MethodsTwenty-eight pigs were randomized into 2 groups. In group B1, angioplasty was performed with a 1.0 µg/mm{sup 2} DCB with PTX and in group B3, with a 3.0 µg/mm{sup 2} DCB with PTX. An overstretched model of the iliac artery was used for angioplasty under fluoroscopy. Blood and vessel wall PTX were measured with liquid-chromatography mass spectrometry at 1, 5, 30 min, 1, 7, and 28 days. Remaining drug in the balloon was analyzed.ResultsMean PTX in blood was significantly higher in the group B3 0.269 ± 0.085 µg/ml compared with the B1 0.218 ± 0.085 µg/ml; p = 0.01. Peak blood PTX concentration was detected at 1 min, and PTX was undetectable 24 h post-angioplasty. There were no statistically significant differences in the mean arterial wall concentration from the treated iliac artery between group-B1 (15.24 ± 21.29 ng/mg) and B3 (15.68 ± 16.33 ng/mg), or in the PTX wall concentration measured at different time points. Mean remaining drug in assayed balloons was lower for group-B1 and represented 8 % of the initial dose.ConclusionsBlood PTX was higher when using 3.0 µg/mm{sup 2} DCB, with a peak drug concentration at 1-min, although the drug was undetectable at 24 h, independently of the loading dose. This study demonstrates no difference in arterial wall uptake of a low dose DCB (1.0 µg/mm{sup 2}), when compared to a common dose DCB (3.0 µg/mm{sup 2}) suggesting that the dose of drug in the DCB could be reduced obtaining a similar clinical effect.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2011

Proteomic and targeted qPCR analyses of subsurface microbial communities for presence of methane monooxygenase

The Test Area North (TAN) site at the Idaho National Laboratory near Idaho Falls, ID, USA, sits over a trichloroethylene (TCE) contaminant plume in the Snake River Plain fractured basalt aquifer. Past observations have provided evidence that TCE at TAN is being transformed by biological natural attenuation that may be primarily due to co-metabolism in aerobic portions of the plume by methanotrophs. TCE co-metabolism by methanotrophs is the result of the broad substrate specificity of microbial methane monooxygenase which permits non-specific oxidation of TCE in addition to the primary substrate, methane. Arrays of experimental approaches have been utilized to understand the biogeochemical processes driving intrinsic TCE co-metabolism at TAN. In this study, aerobic methanotrophs were enumerated by qPCR using primers targeting conserved regions of the genes pmoA and mmoX encoding subunits of the particulate MMO (pMMO) and soluble MMO (sMMO) enzymes, respectively, as well as the gene mxa encoding the downstream enzyme methanol dehydrogenase. Identification of proteins in planktonic and biofilm samples from TAN was determined using reverse phase ultraperformance liquid chromatography (UPLC) coupled with a quadrupole-time-of-flight (QToF) mass spectrometer to separate and sequence peptides from trypsin digests of the protein extracts. Detection of MMO in unenriched water samples from TAN provides direct evidence of intrinsic methane oxidation and TCE co-metabolic potential of the indigenous microbial population. Mass spectrometry is also well suited for distinguishing which form of MMO is expressed in situ either soluble or particulate. Using this method, pMMO proteins were found to be abundant in samples collected from wells within and adjacent to the TCE plume at TAN.

03 NATURAL GAS↗

DOE OSTI2018

Applied Aspects of the Study of Thermodynamic Parameters of Oil Disperse Systems

For intensification of oil refining without using secondary processes, thermodynamic parameters of gas condensate and residual fuel oil blends were calculated from experimental investigations involving inverse gas chromatography. Apparently, from thermodynamic parameters of gas condensate and residual fuel oil blend, it is possible to determine the optimal ratio of the components for increasing the yield of light fractions. It is likely that the new colloidal structure of the blend of the disperse system (residual fuel oil) with the homogeneous system (gas condensates) forms via formation of a semicolloidal system followed by restructurization due to intermolecular interaction and dissolution processes.