High-performance liquid chromatography and thin-layer chromatography assays for Devil's Club (Oplopanax horridus)

Devil's root, Oplopanax horridus, is a widely used folk medicine in Alaska and British Columbia. The inner bark of the root and stem has been used to treat colds, cough, fever, and diabetes. The present study involves the development of high-pressure liquid chromatography (HPLC) and thin-layer chromatography (TLC) methods to detect the presence of trans-nerolidol and sterols in the root bark. The HPLC and TLC analytical methods presented are suitable for the characterization and identification of Oplopanax horridus.     

Synthesis of O,O Ethane Bridged Bis-copper(II) Macrocycles. Selective Enzyme Model for Catecholase Activity

New mononuclear and dinuclear complexes [3-hydroxyethyl-1,3,5,8,11pentaazacyclotridecane]copper(II) (1)/nickel(II) (2) perchlorate and O,O ethane bridged bis-copper(II) (3)/nickel(II) (4) macrocycles have been synthesized and characterized by various spectroscopic techniques, viz. i.r., n.m.r., e.p.r., u.v.–vis. and conductance measurements. Spectral data and conductance measurements reveal that all the complexes are consistent with square-planar geometry and are ionic in nature. The catalytic activity of the dinuclear Cu(II) complex (3) in the presence of pyrocatechol was determined spectrometrically by monitoring the increase of the o-benzoquinone characteristic absorption band at 25,000 cm⁻¹ with respect to time in DMF saturated with molecular oxygen. The kinetic parameters V_max (2.8×10⁻³ M s⁻¹) and K_M (1.4×10⁻³ mm) have been determined by Michaelis–Menten method. Electrochemistry of the dinuclear Cu(II) complex has been studied in the presence of molecular oxygen with pyrocatechol and without pyrocatechol at a scan rate of 0.1 V s⁻¹ by cyclic voltammetry. On addition of pyrocatechol, complex shows a shift in E_pc, E_pa and E_1/2 values indicating the oxidation of substrate (pyrocatechol).     

Thermal and mechanical properties of PE/organoclay nanocomposites

Polyethylene/montmorillonite clay nanocomposites were obtained via direct melt intercalation. The clay was organically modified with four different types of quaternary ammonium salts. The objective of this work is to study the use of montmorillonite clay in the production of nanocomposites by means on rheological, mechanical and crystallization properties of nanocomposites and to compare to the properties of the matrix and PE/unmodified clay nanocomposites. In general, the tensile test showed that the yield strength and modulus of the nanocomposites are close to the pure PE. Apparently, the mixture with Dodigen salt seems to be more stable than the pure PE and PE/unmodified clay.     

Spectrophotometric determination of zinc in copper-base alloys with TAN

TAN reacts with zinc(II) forming a red complex with composition 1:2 Zn(II)-TAN and absorption maximum at 582 nm. Zinc can be determined with this reagent in the presence of Triton X-100, in the pH range 6.20-8.00 with a molar absorptivity of 4.5×10⁴ l/mol/cm Beer's Law was obeyed up to least 1.55 g/ml. Copper interference was eliminated with a mixture of thiosulfate and ascorbic acid and nickel separated by precipitation with dimethylglyoxime. The proposed method was used for zinc determination in several copper-base alloys and the results of analysis in comparison with certified values indicated that the procedure was accurate and precise. A derivative procedure is also proposed, allowing zinc determination with high sensitivity (5-400 ng/ml).     

New asymmetric N2S2 macrocycles,their metal chelates and the photokinetics of DNA-complex interaction

New asymmetric ligands have been synthesized by condensing o-phenylene diamine with CS₂ and PhCHO/MeCHO, and their complexes with Mn^II, Co^II, Ni^II, Cu^II and Zn^II were prepared and characterized by elemental analyses, conductivity measurements, i.r., u.v.–vis., e.p.r. and n.m.r. spectra. The transition metals in the complexes show square planar geometry and are ionic. Photokinetic studies of the DNA-metal complexes [C₁₀H₁₀S₄N₂Cu](NO₃)₂ and [C₁₀H₁₀S₄N₂Ni](NO₃)₂ were carried out and the rate constants k_{(DNA-complex)} were calculated. The results indicate that DNA reacts with the metal complex in two steps. DNA first undergoes structural degradation and is then completely hydrolysed as indicated by spectral changes consistent with earlier results. The asymmetric N₂S₂ macrocyclic metal complexes show a strong propensity for DNA inhibition and can be used as an intercalating binding model.     

Sequence-dependent conformational energy of DNA derived from molecular dynamics simulations: toward understanding the indirect readout mechanism in protein-DNA recognition

Sequence dependence of DNA conformation plays a crucial role in its recognition by proteins and ligands. To clarify the relationship between sequence and conformation, it is necessary to quantify the conformational energy and specificity of DNA. Here, we make a systematic analysis of dodecamer DNA structures including all the 136 unique tetranucleotide sequences at the center by molecular dynamics simulations. Using a simplified conformational model with six parameters to describe the geometry of adjacent base pairs and harmonic potentials along these coordinates, we estimated the equilibrium conformational parameters and the harmonic potentials of mean force for the central base-pair steps from many trajectories of the simulations. This enabled us to estimate the conformational energy and the specificity for any given DNA sequence and structure. We tested our method by using sequence-structure threading to estimate the conformational energy and the Z-score as a measure of specificity for many B-DNA and A-DNA crystal structures. The average Z-scores were negative for both kinds of structures, indicating that the potential of mean force from the simulation is capable of predicting sequence specificity for the crystal structures and that it may be used to study the sequence specificity of both types of DNA. We also estimated the positional distribution of conformational energy and Z-score within DNA and showed that they are strongly position dependent. This analysis enabled us to identify particular conformations responsible for the specificity. The presented results will provide an insight into the mechanisms of DNA sequence recognition by proteins and ligands.     

Integrated System Pharmacology Approaches to Elucidate Multi-Target Mechanism of Solanum surattense against Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant liver tumors with high mortality. Chronic hepatitis B and C viruses, aflatoxins, and alcohol are among the most common causes of hepatocellular carcinoma. The limited reported data and multiple spectra of pathophysiological mechanisms of HCC make it a challenging task and a serious economic burden in health care management. Solanum surattense (S. surattense) is the herbal plant used in many regions of Asia to treat many disorders including various types of cancer. Previous in vitro studies revealed the medicinal importance of S. surattense against hepatocellular carcinoma. However, the exact molecular mechanism of S. surattense against HCC still remains unclear. In vitro and in silico experiments were performed to find the molecular mechanism of S. surattense against HCC. In this study, the network pharmacology approach was used, through which multi-targeted mechanisms of S. surattense were explored against HCC. Active ingredients and potential targets of S. surattense found in HCC were figured out. Furthermore, the molecular docking technique was employed for the validation of the successful activity of bioactive constituents against potential genes of HCC. The present study investigated the active “constituent–target–pathway” networks and determined the tumor necrosis factor (TNF), epidermal growth factor receptor (EGFR), mammalian target of rapamycin (mTOR), Bcl-2-like protein 1(BCL2L1), estrogen receptor (ER), GTPase HRas, hypoxia-inducible factor 1-alpha (HIF1-α), Harvey Rat sarcoma virus, also known as transforming protein p21 (HRAS), and AKT Serine/Threonine Kinase 1 (AKT1), and found that the genes were influenced by active ingredients of S. surattense. In vitro analysis was also performed to check the anti-cancerous activity of S. surattense on human liver cells. The result showed that S. surattense appeared to act on HCC via modulating different molecular functions, many biological processes, and potential targets implicated in 11 different pathways. Furthermore, molecular docking was employed to validate the successful activity of the active compounds against potential targets. The results showed that quercetin was successfully docked to inhibit the potential targets of HCC. This study indicates that active constituents of S. surattense and their therapeutic targets are responsible for their pharmacological activities and possible molecular mechanisms for treating HCC. Lastly, it is concluded that active compounds of S. surattense act on potential genes along with their influencing pathways to give a network analysis in system pharmacology, which has a vital role in the development and utilization of drugs. The current study lays a framework for further experimental research and widens the clinical usage of S. surattense.     

Chemical and Pharmacological Profiling of Wrightia coccinea (Roxb. Ex Hornem.) Sims Focusing Antioxidant,Cytotoxic, Antidiarrheal,Hypoglycemic, and Analgesic Properties

The aim of the study was to conduct phytochemical and pharmacological investigations of Wrightia coccinea (Roxb. ex Hornem.) Sims via several in vitro, in vivo, and in silico models. A total of four compounds were identified and isolated from the methanol extract of the bark and the methanol extract of the seed pulp of W. coccinea through successive chromatographic techniques and were characterized as 3β-acetyloxy-olean-12-en-28-ol (1), wrightiadione (2), 22β-hydroxylupeol (3), and β-sitosterol (4) by spectroscopic analysis. The aqueous fraction of the bark and chloroform fraction of the fruits provided the most potent antioxidant capacity (IC₅₀ = 7.22 and 4.5 µg/mL, respectively) in DPPH free radical scavenging assay compared with the standard ascorbic acid (IC₅₀ = 17.45 µg/mL). The methanol bark extract and the methanol fruit coat extract exerted anti-diarrheal activity by inhibiting 74.55 ± 0.67% and 77.78 ± 1.5% (mean ± SEM) of the diarrheal episode in mice, respectively, after four hours of loading the samples. In the hypoglycemic test, the methanol bark extract and the methanol fruit coat extract (400 mg/kg) produced a significant (p < 0.05) reduction in the blood glucose level in mice. Both doses of the plant extracts (200 mg/kg and 400 mg/kg) used in the study induced a significant (p < 0.05) increase in pain reaction time. The in vitro and in vivo findings were supported by the computational studies. The isolated compounds exhibited higher binding affinity compared with the standard drugs towards the active binding sites of glutathione reductase, epidermal growth factor receptor (EGFR), kappa opioid receptor, glucose transporter 3 (GLUT 3), Mu opioid receptor, and cyclooxygenase 2 (COX-2) proteins due to their potent antioxidant, cytotoxic, anti-diarrheal, hypoglycemic, and central and peripheral analgesic properties, respectively. The current findings concluded that W. coccinea might be a potential natural source for managing oxidative stress, diarrhea, hyperglycemia, and pain. Further studies are warranted for extensively phytochemical screening and establishing exact mechanisms of action.     

Potentiometrie

Ohne Zusammenfassung     

The oxidative addition of diphenylphosphine and monophenylphosphine to the electron-rich rhenium-rhenium triple bond. The isolation and characterization of compounds that contain the four-center Re(μ-X)(μ-PR2)Re cluster (X=halide)

Diphenylphosphine oxidatively adds to the ReRe bonds of Re₂ X ₄(-dppm)₂ (X=Cl or Br; dppm=Ph₂PCH₂PPh₂) and Re₂Cl₄(-dpam)₂ (dpam=Ph₂AsCH₂AsPh₂) to afford the dirhenium(III) complexes Re₂(-X)(-PPh₂)HX ₃(-LL)₂. The dppm complexes have also been prepared from the reactions of Re₂(-O₂CCH₃)X ₄(-dppm)₂ with Ph₂PH, and a similar strategy has been used to prepare Re₂(-Cl)(-PPh₂)HCl₃(-dmpm)₂ (dmpm=Me₂PCH₂PMe₂) from Re₂(-O₂CCH₃)Cl₄(dmpm)₂. Phenylphosphine likewise reacts with Re₂ X ₄(-dppm)₂ to give Re₂(-X)(-PHPh)HX ₃(-dppm)₂. An X-ray crystal structure determination on Re₂(-Cl)(-PPh₂)HCl₃(-dppm)₂ confirms its edge-shared bioctahedral structure. This complex crystallizes in the space group (No. 148) witha=21.699(3) Å, =84.50(4)°,V=10084(5) ų, andZ=6. The structure was refined toR=0.049 (R _w 0.069) for 5770 data withI>3.0(I). The Re-Re distance is 2.5918(7) Å. Oxidation of the bromide complex Re₂(-Br)(-PPh₂)HBr₃(-dppm)₂ with NOPF₆ produces the unusual dirhenium(III, II) cation [Re₂(-H)(-Br)[P(O)Ph₂]Br₂(NO)(-dppm)₂]⁺ which has been structurally characterized as its perrhenate salt, [Re₂(-H)(-Br)[P(O)Ph₂]Br₂(NO)(-dppm)₂]ReO₄ · 2CH₂Cl₂. This complex crystallizes in the space group (No. 2) witha=14.187(7) Å,b=16.419(5) Å,c=16.729(5) Å, =98.76(2)°, =110.11(3)°, =104.66(3)°,V=3414(6) ų,Z=2. The structure was refined toR=0.040 (R _w =0.051) for 5736 data withI>3.0(I). The presence of a phosphorus-bound [P(O)Ph₂]^– ligand, a linear nitrosyl and a bridging hydrido ligand has been confirmed. The Re-Re distance is 2.6273(8) Å.