Transdermal permeation of tetracaine hydrochloride by lecithin microemulsion: in vivo

In vivo transdermal permeation of tetracaine hydrochloride encapsulated in lecithin water-in-oil and oil-in-water microemulsion was studied. The effect of the composition of the lecithin microemulsion on analgesic response of tetracaine hydrochloride was evaluated on Wistar rats by tail flick method. To find out the toxicity of lecithin/n-propanol/isopropyl myristate/water/tetracaine hydrochloride microemulsion histopathological and irritation response were measured in Swiss mice. Time course studies were also conducted for the biochemical response of microemulsion by measuring catalase, glutathione and lipid peroxidation levels of the treated mice skin. The analgesic response was found to be dependent on the drug concentration and composition of the systems. The histopathological, irritation and biochemical findings reveal that lecithin/n-propanol/isopropyl myristate/water/tetracaine hydrochloride microemulsion is a safe carrier for transdermal drug delivery systems. Confocal laser scanning microscopy observation indicated that sweat gland and hair follicle also provided the path for transdermal permeation of lecithin/n-propanol/isopropyl myristate/water microemulsion.     

Asymmetric total syntheses of spisulosine, its diastereo- and regio-isomers

Starting from palmityl alcohol, divergent stereoselective syntheses of spisulosine and its diastereo- and regio-isomers have been achieved. In the Sharpless asymmetric dihydroxylation-based approach, the key step is the synthesis of monoprotected diol, whereas Miyashita’s boron-directed C-2 regioselective azidolysis of enantiomerically pure epoxy alcohol is the vital step in the Sharpless asymmetric epoxidation-based route. The latter approach involves the first protecting-group-free synthesis of spisulosine.     

Alkali metal (Na and K)-mediated supramolecular assembly of oxovanadium(V) complexes: Synthesis and structural characterization

The syntheses and characterization of alkali metal complexes [{VO₂L}M(H₂O}_n] (1 and 2) [M = Na⁺ (1), K⁺ (2)] of anionic cis-dioxovanadium(V) species (LVO₂⁻) of the Schiff base 2-hydroxybenzoylhydrazone of 2-hydroxybenzaldehyde have been reported. The number of coordinated water molecules in [{VO₂L}M(H₂O}_n] decreases as the charge density of the alkali metal ion decreases (n = 5 for Na⁺ and 1 for K⁺). These compounds represented M⁺-mediated supramolecular assembly [{VO₂L}M(H₂O}_n]_∝ with an infinite polymeric structure containing an alternating array of cis-dioxo vanadium(V), [VO₂L]⁻, units and aquated metal ion centres, as confirmed by X-ray crystallographic investigation of both. All the compounds are characterized by elemental analysis, IR, UV–Vis and NMR spectroscopy.     

Influence of Aprotic Solvents on the Transmission of Anomalous Substituent Effects on 13C NMR Chemical Shifts at the Carboxyl Carbon (δco) in Meta-Substituted Benzoic Acids: A Strong Evidence for π-Polarization Mechanism

Anomalous (reverse) substituent-induced ¹³C nuclear magnetic resonance chemical shifts at the carboxyl carbon (δ_co) in meta-substituted benzoic acids have been studied for 11 substituents having varying electronic effects in 4 aprotic (nonhydroxylic) solvents of varying polarity by employing different dual substituent parameter models. The regression results for apolar aprotic solvents provide a strong evidence for through space π-polarization mode of transmission of reverse meta-substituent effects on the carboxyl carbon in benzoic acids. The results for dipolar aprotic solvents indicate significant specific solvation of π-polarized forms of the acids. The study showed further that an apolar aprotic solvent has a distinct preference over a dipolar aprotic one for investigating intrinsic substituent effects on chemical shifts in aromatic molecules.     

Photoionization Bands of Cyanogen: Multi-Mode Vibronic Coupling and Renner-Teller Effects

Multi-mode vibronic coupling in the , , and electronic states of Cyanogen radical cation (C N ) is investigated with the aid of ab initio quantum chemistry and first principles quantum dynamics methods. The electronic degenerate states of Π symmetry of C N undergo Renner-Teller (RT) splitting along degenerate vibrational modes of π symmetry. The RT split components form symmetry allowed conical intersections with those from nearby RT split states or with non-degenerate electronic states of Σ symmetry. A parameterized vibronic Hamiltonian is constructed using standard vibronic coupling theory in a diabatic electronic basis and symmetry rules. The parameters of the Hamiltonian are derived from ab initio calculated adiabatic electronic energies. The vibronic spectrum is calculated, assigned and compared with the available experimental data. The impact of various electronic coupling on the vibronic structure of the spectrum is discussed.