New Carbonic Anhydrase-II Inhibitors from Marine Macro Brown Alga Dictyopteris hoytii Supported by In Silico Studies

In continuation of phytochemical investigations of the methanolic extract of Dictyopteris hoytii, we have obtained twelve compounds (1–12) through column chromatography. Herein, three compounds, namely, dimethyl 2-bromoterepthalate (3), dimethyl 2,6-dibromoterepthalate (4), and (E)-3-(4-(dimethoxymethyl)phenyl) acrylic acid (5) are isolated for the first time as a natural product, while the rest of the compounds (1, 2, 6–12) are known and isolated for the first time from this source. The structures of the isolated compounds were elucidated by advanced spectroscopic 1D and 2D NMR techniques including ¹H, ¹³C, DEPT, HSQC, HMBC, COSY, NEOSY, and HR-MS and comparison with the reported literature. Furthermore, eight compounds (13–20) previously isolated by our group from the same source along with the currently isolated compounds (1–12) were screened against the CA-II enzyme. All compounds, except 6, 8, 14, and 17, were evaluated for in vitro bovine carbonic anhydrase-II (CA-II) inhibitory activity. Eventually, eleven compounds (1, 4, 5, 7, 9, 10, 12, 13, 15, 18, and 19) exhibited significant inhibitory activity against CA-II with IC₅₀ values ranging from 13.4 to 71.6 μM. Additionally, the active molecules were subjected to molecular docking studies to predict the binding behavior of those compounds. It was observed that the compounds exhibit the inhibitory potential by specifically interacting with the ZN ion present in the active site of CA-II. In addition to ZN ion, two residues (His94 and Thr199) play an important role in binding with the compounds that possess a carboxylate group in their structure.     

Secondary Metabolite Profiling,Anti-Inflammatory and Hepatoprotective Activity of Neptunia triquetra (Vahl) Benth

The present study aimed to analyze the phytoconstituents of Neptunia triquetra (Vahl) Benth. Anti-inflammatory and hepatoprotective activities of ethanol (EE), chloroform (CE) and dichloromethane (DCME) of stem extracts were evaluated using in vivo experimental models. The extracts were analyzed for phytoconstituents using GC-HRMS. Anti-inflammatory activity of CE, EE and DCME was accessed using carrageenan-induced paw oedema, cotton pellet-induced granuloma and the carrageenan-induced air-pouch model in Wistar albino rats. The hepatotoxicity-induced animal models were investigated for the biochemical markers in serum (AST, ALT, ALP, GGT, total lipids and total protein) and liver (total protein, total lipids, GSH and wet liver weight). In the in vivo study, animals were divided into different groups (six in each group) for accessing the anti-inflammatory and hepatoprotective activity, respectively. GC-HRMS analysis revealed the presence of 102 compounds, among which 24 were active secondary metabolites. In vivo anti-inflammatory activity of stem extracts was found in the order: indomethacin > chloroform extract (CE) > dichloromethane extract (DCME) > ethanolic extract (EE), and hepatoprotective activity of stem extracts in the order: CE > silymarin > EE > DCME. The results indicate that N. triquetra stem has a higher hepatoprotective effect than silymarin, however the anti-inflammatory response was in accordance with or lower than indomethacin.     

Surface sensitivity of straight long-range surface plasmon waveguides for attenuation-based biosensing

The sensing performance of straight long-range surface plasmon waveguides consisting of a thin gold stripe embedded in Cytop is explored theoretically as a function of the metal stripe cross-sectional dimensions and the length of the sensing channel, and as a function of the sensing medium refractive index. The surface sensitivity and detection limit of such waveguides for attenuation-based biosensing are assessed. We find that changes in coupling efficiency between the sensing waveguide and the access waveguides, and changes in attenuation constant, due to adlayer formation, can contribute additively to the sensing performance. We observed a trade-off between the insertion loss and the change in insertion loss occurring during sensing. Optimum designs leading to compact, sensitive, and cost-effective biosensors are reported.     

Quantum mechanical charge field molecular dynamics simulation of the TiO2+ ion in aqueous solution

Structural and dynamical properties of the TiO(2+) ion in aqueous solution have been investigated by using the new ab initio quantum mechanical charge field (QMCF) molecular dynamics (MD) formalism, which does not require any other potential functions except those for solvent-solvent interactions. Both first and second hydration shell have been treated at Hartree-Fock (HF) quantum mechanical level. A Ti-O bond distance of 1.5 A was observed for the [Ti=O](2+) ion. The first hydration shell of the ion shows a varying coordination number ranging from 5 to 7, five being the dominant one and representing one axial and four equatorial water molecules directly coordinated to Ti, which are located at 2.3 A and 2.1 A, respectively. The flexibility in the coordination number reflects the fast exchange processes, which occur only at the oxo atom, where water ligands are weakly bound through hydrogen bonds. Considering the first shell hydration, the composition of the TiO(2+) hydrate can be characterized as [(H(2)O)(0.7)(H(2)O)(4) (eq)(H(2)O)(ax)](2+). The second shell consists in average of 12 water molecules located at a mean distance of 4.4 A. Several other structural parameters such as radial and angular distribution functions and coordination number distributions were analyzed to fully characterize the hydration structure of the TiO(2+) ion in aqueous solution. For the dynamics of the TiO(2+) ion, different sets of dynamical parameters such as Ti=O, Ti-O(eq), and Ti-O(ax) stretching frequencies and ligands' mean residence times were evaluated. During the simulation time of 15 ps, 3 water exchange processes in the first shell were observed at the oxo atom, corresponding to a mean residence time of 3.6 ps. The ligands' mean residence time for the second shell was determined as 3.5 ps.     

Reduced conductivity and enhancement of Debye orientational polarization in lanthanum doped cobalt ferrite nanoparticles

In this work we have investigated the conductivity and dielectric properties of CoLa_xFe_2−xO₄ (x=0.0, 0.03, 0.05, and 0.07) nanoparticles synthesized by chemical co-precipitation route. X-ray diffraction analysis confirms the inverse spinal structure of nanoparticles with slight increase in the lattice constant as La concentration increases. Transmission electron microscopy shows spherical nanoparticles with sizes of ∼20 nm. Impedance spectroscopy of the samples was performed in the frequency range 20 Hz-2 MHz at room temperature. The resistance of the grains and grain boundaries was found to increase with lanthanum concentration while the AC conductivity of the samples was observed to decrease with increasing La concentration. Dipolar orientational polarization was found to play an important role in determining dielectric properties of the samples.     

Numerical treatment for nonlinear Brusselator chemical model

Nowadays, numerical models have great importance in every field of science, especially for solving the nonlinear differential equations, partial differential equations, biochemical reactions, etc. The total time evolution of the reactant species which interacts with other species is simulated by the Runge-Kutta of order four (RK4) and by Non-Standard finite difference (NSFD) method. A NSFD model has been constructed for the biochemical reaction problem and numerical experiments are performed for different values of discretization parameter h. The results are compared with the well-known numerical scheme, i.e. RK4. The developed scheme NSFD gives better results than RK4.     

Sol–gel synthesis of tetragonal ZrO2 nanoparticles stabilized by crystallite size and oxygen vacancies

In this letter, we present a facile route to produce metastable tetragonal zirconia (ZrO₂) nanoparticles via pH-controlled precipitation of dilute zirconyl nitrate dihydrate [ZrO(NO₃)₂·2H₂O] solution in liquid NH₃ under ambient conditions and calcination at 500 °C for 2 h. The phase pure tetragonal ZrO₂ nanoparticles are obtained at pH 9. The effect of pH on metastable phase stabilization in precipitated ZrO₂ nanoparticles is demonstrated with the help of XRD, SEM/EDX, and X-ray photoelectron spectroscopy techniques. The stability of tetragonal ZrO₂ phase is attributed to the smaller crystallite size and greater oxygen deficiency in phase-pure tetragonal ZrO₂.     

Experimental and numerical analysis of steam jet pump

Steam jet pump is the best choice for pumping radioactive and hazardous liquids because it has no moving parts and so no maintenance. However, the physics involved is highly complicated because of the mass, momentum and energy transfer between the phases involved. In this study the characteristics of SJP are studied both experimentally and numerically to pump water using saturated steam. In the experimental study the static pressure, temperature along the length of the steam jet pump and the steam and water flow rates are recorded. The three dimensional numerical study is carried out using the Eulerian two-phase flow model of Fluent 6.3 software and the direct-contact condensation model developed previously. The experimental and CFD results, of axial static pressure and temperature, match closely with each other. The mass ratio and suction lift are calculated from experimental data and it is observed that the mass ratio varies from 10 to 62 and the maximum value of suction lift is 2.12 m under the conditions of the experiment.     

A validated high‐performance thin‐layer chromatography method for the identification and simultaneous quantification of six markers from Platanus orientalis and their cytotoxic profiles against skin cancer cell lines

Betulinic acid ( 1 ), betulinic acid‐3‐acetate ( 2 ), 3‐acetylbetulinaldehyde ( 3 ), oleanolic acid‐3‐acetate ( 4 ), 3‐β‐hydroxy‐28,19‐β‐olenolide ( 5 ), and β‐sitosterol ( 6 ) were isolated from Platanus orientalis and a high‐performance thin‐layer chromatography method was developed for their simultaneous quantification. The markers were first derivatized on the chromatogram with ceric ammonium sulfate and then high‐performance thin‐layer chromatography densitometry was carried out. Chromatographic separation of these markers was carried out on silica gel 60 plates using a ternary solvent system n‐hexane/toluene/acetone (6:3.5:1 v/v/v) as a mobile phase. For marker 1 , a deuterium (D₂) lamp and wavelength of 420 nm was used. A tungsten (W) lamp was used for markers 2 and 3 at 550 nm and for 4 – 6 at 500 nm. The method was validated for accuracy, precision, LOD, and LOQ. All calibration curves showed a good linear relationship (r > 0.9919). The precision evaluated by an intra‐ and interday study showed RSDs < 2.51% and accuracy validation recovery between 95.54 and 99.33% with RSDs < 1.55%. The successful application of the validated method showed 1 as the most abundant component (4.63%) and 5 (0.017%) the least. The markers displayed a significant cytotoxic effect against human keratinocyte, mouse melanoma, and human skin epithelial carcinoma cancer cells by using a 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay.