Novel sesterterpenes from Leucosceptrum canum of nepalese origin

Two novel sesterterpenoids, leucosesterterpenone (1) and leucosesterlactone (2), with novel skeleta were isolated from the hexane extract of the medicinal plant, Leucosceptrum canum. Their structures were established by the analysis of NMR data and the single-crystal X-ray diffraction of compound 1. Compounds 1 and 2 were found to exhibit activity against prolylendopeptidase (PEP).     

Conjugate additions of o-iodoanilines and methyl anthranilates to acetylenic sulfones. A new route to quinolones including first syntheses of two alkaloids from the medicinal herb Ruta chalepensis

A novel synthesis of 2-substituted 4-quinolones was developed on the basis of the conjugate additions of appropriately ortho-substituted anilines to acetylenic sulfones followed by intramolecular acylation of the corresponding sulfone-stabilized anions. Conjugate additions of variously substituted anilines to alkyl-substituted acetylenic sulfones generally proceeded slowly and in poor yield, especially when the aniline contained an electron-withdrawing substituent such as an ester group. In some cases, the reactions were enhanced by the presence of DMAP and the use of an excess of the sulfone in aqueous DMF. N-Formylanilines proved superior to free anilines. The products were either vinyl or allyl sulfones, depending on the conditions and the structure of the reactants. The acetylenic sulfone exists in equilibrium with its allenic and propargylic isomers under base-catalyzed conditions. Therefore, any of the three unsaturated sulfones can serve as the starting material for the conjugate additions. o-Iodoanilines proved superior to methyl anthranilate derivatives and underwent conjugate additions smoothly. The products were subjected to palladium-catalyzed carbonylation in methanol, and the resulting methyl esters were cyclized by treatment with strong bases such as LiHMDS or LiTMP, followed by reductive desulfonylation with aluminum amalgam. The resulting 2-substituted 4-quinolones included the naturally occurring medicinal compounds 1 and 2 and the O-methyl derivative 3.     

Recovery and regularization of initial temperature distribution in a two-layer cylinder with perfect thermal contact at the interface

We investigate the inverse problem associated with the heat equation involving recovery of initial temperature distribution in a two-layer cylinder with perfect thermal contact at the interface. The heat equation is solved backward in time to obtain a relationship between the final temperature distribution and the initial temperature profile. An integral representation for the problem is found, from which a formula for initial temperature is derived using Picard’s criterion and the singular system of the associated operators. The known final temperature profile can be used to recover the initial temperature distribution from the formula derived in this paper. A robust method to regularize the outcome by introducing a small parameter in the governing equation is also presented. It is demonstrated with the help of a numerical example that the hyperbolic model gives better results as compared to the parabolic heat conduction model.     

Novasomes as Nano-Vesicular Carriers to Enhance Topical Delivery of Fluconazole: A New Approach to Treat Fungal Infections

The occurrence of fungal infections has increased over the past two decades. It is observed that superficial fungal infections are treated by conventional dosage forms, which are incapable of treating deep infections due to the barrier activity possessed by the stratum corneum of the skin. This is why the need for a topical preparation with advanced penetration techniques has arisen. This research aimed to encapsulate fluconazole (FLZ) in a novasome in order to improve the topical delivery. The novasomes were prepared using the ethanol injection technique and characterized for percent entrapment efficiency (EE), particle size (PS), zeta potential (ZP), drug release, Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and antifungal activity. The FN7 formulation with 94.45% EE, 110 nm PS and −24 ZP proved to be the best formulation. The FN7 formulation showed a 96% release of FLZ in 8 h. FTIR showed the compatibility of FLZ with excipients and DSC studies confirmed the thermal stability of FLZ in the developed formulation. The FN7 formulation showed superior inhibition of the growth of Candida albicans compared to the FLZ suspension using a resazurin reduction assay, suggesting high efficacy in inhibiting fungal growth.     

Investigation and Biological Assessment of Rumex vesicarius L. Extract: Characterization of the Chemical Components and Antioxidant,Antimicrobial, Cytotoxic,and Anti-Dengue Vector Activity

The objective of this study was to assess the biological potency and chemical composition of Rumex vesicarius aboveground parts using GC–MS. In this approach, 44 components were investigated, comprising 99.99% of the total volatile compounds. The major components were classified as fatty acids and lipids (51.36%), oxygenated hydrocarbons (33.59%), amines (7.35%), carbohydrates (6.06%), steroids (1.21%), and alkaloids (0.42%). The major components were interpreted as 1,3-dihydroxypropan-2-yl oleate (oxygenated hydrocarbons, 18.96%), ethyl 2-hydroxycyclohexane-1-carboxylate (ester of fatty acid, 17.56%), and 2-propyltetrahydro-2H-pyran-3-ol (oxygenated hydrocarbons, 11.18%). The DPPH antioxidant activity of the extracted components of R. vesicarius verified that the shoot extract was the most potent with IC₅₀ = 28.89 mg/L, with the percentages of radical scavenging activity at 74.28% ± 3.51%. The extracted plant, on the other hand, showed substantial antibacterial activity against the diverse bacterial species, namely, Salmonella typhi (23.46 ± 1.69), Bacillus cereus (22.91 ± 0.96), E. coli (21.07 ± 0.80), and Staphylococcus aureus (17.83 ± 0.67). In addition, the extracted plant was in vitro assessed as a considerable anticancer agent on HepG2 cells, in which MTT, cell proliferation cycle, and DNA fragmentation assessments were applied on culture and treated cells. The larvicidal efficacy of the extracted plant was also evaluated against Aedes aegypti, the dengue disease vector. As a result, we may infer that R. vesicarius extract increased cytocompatibility and cell migratory capabilities, and that it may be effective in mosquito control without causing harm.     

Synthesis, characterization, and fluorescence behavior of twisted and planar B2N2-quaterphenyl analogues

A series of planar and twisted heteroaromatic quaterphenyl analogues containing BN ring linkages has been synthesized using primarily difunctional Lewis acidic diborabiphenyl moieties as molecular cores. Crystal structure analyses indicated the presence of large twist angles between adjacent aromatic rings in 1 and 3, which were also observed to possess nonfluorescent behavior due to a lack of molecular rigidity and insufficient B=N character in the excited state. In contrast, the incorporation of one or two bridging ethylene groups between the adjacent rings (installed via an ethynyl cycloisomerization) was found to afford planar phenanthrene or pyrene moieties, which resulted in weak fluorescence behavior (Phi F = 0.02-0.16) for the n-Bu and Ph derivatives 5-12. Emission colors ranged from green (lambda em = 521 nm) to red (lambda em = 630 nm) and depended primarily on the conformation (2,2'- vs 4,4'-), the extent of chromophore conjugation (phenanthrene vs pyrene), and the type of exocyclic substituent present (n-Bu vs Ph). Communication between the two phenanthrene or pyrene moieties was observed in some cases, which was characterized by bathochromically shifted emission bands relative to that of monomeric phenanthrene or pyrene species. Unique excited-state dimer (excimer) fluorescence was observed for the 2,2'-isomer 8, which was characterized by broad, low-energy emission bands bathochromically shifted from that of the corresponding monomer.     

Structural characterization of molybdenum(V) species in aqueous HCl solutions

Mo(V) aqua-chloro complexes in hydrochloric acid solutions have been studied by means of Mo K- and L2,3-edge X-ray absorption and Raman spectroscopic methods. The solid compounds (HPPh3)2[MoOCl5] (1), 6[MoOCl4(H2O)]-.10(pyH)+.4Cl- (2), and (pyH)2[Mo2O4Cl4(trans-OH2)2] (3) were used for structural comparisons. The compound 2 crystallizes in the orthorhombic space group Pmma (no. 51) with a=21.398(3), b=8.057(4), c=13.330(4) A, and Z=4. In 0.2 M solutions of MoCl5 in 7.4-9.4 M HCl the mononuclear [MoOCl4(OH2)]- complex dominates with the bond distances Mo=O 1.66(2) A, Mo-Cl 2.38(2) A, and Mo-OH2 2.30(2) A. Its Raman band at 994 cm-1 for the Mo=O symmetric stretching vibration is closer to that of 2 (988 cm-1) than of 1 (969 cm-1). The Mo K-edge EXAFS spectrum for 0.2 M MoCl5 in 1.7 M HCl solution reveals a dinuclear [Mo2O4Cl6-n(OH2)n]n-4 (n=2, 3) complex with a double oxygen bridge and the average distances Mo=O 1.67(2) A, Mo-(mu-O) 1.93(2) A, Mo-Cl 2.47(3) A, Mo-Mo 2.56(2) A, and a short Mo-OH2 distance of 2.15(2) A, which implies that at least one of the aqua ligands is in equatorial position relative to the two axial Mo=O bonds. This position differs from the Mo-OH2 configuration exclusively trans to the M=O groups of the isomeric (with n=2) dinuclear complex in 3. The difference in the ligand field is also reflected in their L2,3-edge XANES spectra. For 0.2 M MoCl5 solutions in intermediate HCl concentrations (3.7-6.3 M) the Raman bands at 802 cm-1 (Mo-O-Mo) and 738 cm-1 (Mo-(mu-O)2-Mo) verify three coexisting classes of Mo(V) complexes: mononuclear complexes together with dinuclear mono-oxo (e.g., [Mo2O3Cl6(H2O)2]2-) and dioxo bridged species, even though principal component analysis (PCA) of the corresponding series of EXAFS spectra only could distinguish two major components. By fitting linear combinations of the appropriate EXAFS oscillation components, dioxo-bridged dinuclear complexes were found to dominate at HCl concentrations相似文献   

Parametric analysis of four wave mixing in DWDM systems

The developments made over the years in WDM (Wavelength Division Multiplexing), on one side, produced compensation of increasing traffic and channel capacity, but on other side, pertinently caused WDM systems to undergo different linear and non-linear effects thereby degrading the performance as such. To overcome linear effects is relatively convenient and manageable, however, the non-linear effects including four wave mixing (FWM) is not only difficult to eliminate but also highly incompatible from system point of view. In this research, valid parameters which lead to generation and enhancement of FWM, are discussed, simulated and based on exhaustive sets of obtained results, a detailed analysis has been carried out to reduce the FWM. The simulated results obtained by exploiting nine important parameters using Optisys simulator, divulge very incisive information for the removal of nonlinear effects in WDM. The authors are reasonably confident to extend their results as a contribution in the subject area.