Spectrophotometric determination of clotrimazole in bulk drug and dosage forms

A simple, specific, rapid and sensitive spectrophotometric method has been developed for the assay of clotrimazole, in bulk drug and its pharmaceutical preparations. This method is based on the ion-pair complex reaction of clotrimazole and methyl orange in aqueous methanol, and in the presence of citric acid. The chromogen, being extractable with chloroform, could be measured quantitatively at 422 nm. All variables were studied to optimize the reaction conditions. Regression analysis of beer's plot showed good correlation in a general concentration range of 2-14 mu/ml. The proposed method has been successfully applied for the analysis of the bulk drug and its dosage forms such as powder, vaginal tablets, topical solution and creams. No interference was observed from betamethasone dipropionate (Lotriderm cream) or dexamethasone acetate and azidamphenicol (Baycuten cream) or other common pharmaceutical adjuvants. In addition, this method was also found to be specific for the analysis of clotrimazole in the presence of its hydrolytic products as well as imidazole, as a possible impurity.     

Destabilization of whole skin lipid bio-liposomes induced by skin penetration enhancers and FT-IR/ATR (Fourier transform infrared/attenuated total reflection) analysis of stratum corneum lipids.

Whole skin lipid bio-liposomes (skin bio-liposomes), in size ranging from 2 to 8 microns, were prepared by a reverse phase evaporation technique using rat full thickness skin. Leakage of an encapsulated fluorescence probe, ANTS (delta-amino-1,3,6-naphthalene-trisulfonate), was measured by adding transdermal penetration enhancers (penetrants) into the medium where the skin bio-liposomes were present. Oleylamine induced a fast release of ANTS from the liposomes compared to lauryl-amine which showed a weak action. With these penetrants, the degree of ANTS release from the prepared bio-liposomes was found to correlate well with the results of frequency changes in the CH-asymmetric stretching band near 2920 cm-1 in the rat stratum corneum. The penetrant which caused relatively strong leakage of ANTS induced the significantly large shift of the peak toward the higher wave-numbers due to the perturbation in the structure of lipids of the stratum corneum. The skin bio-liposomes prepared from the rat full thickness skin could be useful in evaluating the penetrants.     

Electrophoretic mobility-assisted identification of proteins by nanoelectrospray capillary electrophoresis/mass spectrometry under methanolic conditions

A novel method for electrophoretic mobility-assisted identifications of proteins, using capillary electrophoresis/mass spectrometry (CE/MS) under methanolic conditions, was developed. The number of functional groups of the enzymatic digest peptides was estimated from a single run CE/MS analysis and utilized as an additional tag for database searching in addition to the mass map of the peptides. The additional amino acid information thus obtained can improve the confidence level of the protein identification. The database searching software algorithm ProFound was modified to accept the tag, based on this new concept. In this study, optimization of the CE/MS conditions for the estimation of basic functional groups was performed as an example. An accurate value of the number of such functional groups was obtained from CE characteristics when methanolic buffer (methanol/formic acid/water = 60:20:20) was used, via an excellent correlation (r = 0.997) between the number of functional groups of the peptides and [MW((2/3))]. The mass spectrometry sensitivity was also improved when using the methanolic buffer in comparison with that obtained using aqueous 1% formic acid buffer. The identification of a protein of Saccharomyces cerevisiae, which was separated by two-dimensional electrophoresis, was performed using the methanolic buffer in combination with sheathless nanoelectrospray CE/MS. A protein spot that had not been identified by MALDI-TOFMS and LC/MS/MS was successfully identified using this new method.     

Synthesis and anti-HIV activity of 3-alkylamido-3-deoxy-betulinic acid derivatives

3-Alkylamido-3-deoxy-betulinic acids were synthesized and evaluated for anti-HIV activity as part of the structure-activity relationship study of the potent anti-HIV agent 3-O-(3',3'-dimethyl)-succinyl-betulinic acid (DSB) (2). 3Alpha-diglycorylamide-3-deoxy-betulinic acid demonstrated relatively potent anti-HIV activity (EC50 0.24 microm, TI 728). However, replacing the ester group at C-3 in 2 and its analogues with an amido group yielded inactive or much less potent compounds against HIV replication, indicating that the ester group at C-3 in 2-4 is essential for potent anti-HIV activity.     

Influence of drawing and heat treatment on surface free energies of polyethylene terephthalate fibers

The surface free energies of polyethylene terepthalate fibers with different draw ratios were experimentally determined by contact angle measurements inn-alkane/water systems. The dispersive component of the surface free energy increased with increasing draw ratio, whereas the nondispersive one remained almost constant. After heat treatment, the dispersive surface free energy increased, but was reduced above 140°C. The nondispersive component increased by heat treatment at 190°C. The increases in the density and birefringence of the fibres due to the drawing and heat treatment suggested that the increase in the dispersive surface free energy was caused by the increase in the atomic density at the fiber surface due to drawing and heat treatment. ESCA results indicated that the increment in the nondispersive surface free energy due to heat treatment was caused by the addition of functional groups to the fiber surface due to heat treatment.     

Determination of dispersive and nondispersive components of the surface free energy of glass fibers

The dispersive component _s ^d of the surface free energy of glass fibers and its interaction energy with alkanes, benzene, 1-nitropropane, ethyleneglycol, glycerol, formamide, and water were quantitatively determined by the tensiometric method within two liquids. The values of nondispersive interaction energy I _SL ^p were found to be a linear function of the square root of the nondispersive component of the surface free energy of liquids. This suggests that the nondispersive interaction energy may be represented by the geometric mean of the nondispersive component of the surface free energy of a solid and a liquid. The slope gave the nondispersive component _s ^p of the surface free energy. The _s ^p values are 33 and 14 mJ/m² for the untreated and aminosilane-treated fibers, respectively, suggesting that organophilic character has developed on the surface after aminosilane treatment. The _s ^p value was almost similar after the treatment, probably because of the polar characteristics of amino groups.     

Application of centrifugal counter-current chromatography to the separation of macrolide antibiotic analogues. I. Selection of solvent systems based on solubility and partition coefficient investigations

As the first part of our studies on counter-current chromatography, the methodology for selecting suitable solvent systems was established based on detailed investigations of solubility and partition coefficients (log K) of macrolide antibiotic analogues. The solubility of two important macrolides, ascomycin and FK-506, was measured in a series of common solvents, where their polarities were ranked with dielectric constants. The partition coefficients of the two macrolides were compared in various binary, ternary, quaternary solvent systems. Hexane-tert.-butyl methyl ether-methanol-water system was selected based on suitable log K of solutes and hydrogen-bonding properties of solvents. In the further optimisation of composition proportions in the multicomponent solvent system, hexane-tert.-butyl methyl ether-methanol-water (1:3:6:5) showed the best solvent selectivity by giving the most prominent difference of partition coefficient (delta log K) between ascomycin and FK-506. With this solvent system, a baseline preparative separation of these two very closely related 23-membered macrolide antibiotics was successfully achieved by employing the newly introduced Quattro counter-current chromatograph.     

Group separation of trivalent actinides and lanthanides by tertiary pyridine-type anion-exchange resin embedded in silica beads

The separation of trivalent actinides and lanthanides was studied by using newly developed tertiary pyridine-type anion-exchange resin embedded in silica beads. Chromatographic elution experiments were carried out by using a packed column of the new resin and methanol-hydrochloric acid solution as an effluent. We confirmed that the actinides were eluted well from the elution bands of lanthanides. Actinides and lanthanides were eluted according to the reverse order of their atomic number.     

手性5-l-(艹孟)氧基丁内酯并[3,4-d]-3-取代基-异(口恶)唑啉类化合物的合成

研究了手性元5-(R)-(l-(艹孟)氧基)-2(5H)-呋喃酮与取代苯甲醛肟以次氯酸钙作为氧化剂进行的区域选择性原位1,3-偶极环加成反应,同步生成两个新的手性中心,得到了一系列光学纯丁内酯并[3,4-d]-3-取代基-异(口恶)唑啉类化合物;应用波谱学手段及X射线单晶衍射法确证了产物的绝对构型,并对产物的核磁共振氢谱规律性加以总结.     

Study of a mathematical model of metal ion complexes in solvent sublation

Separation of metal ion complex, [(C(12)H(8)N(2))(3)Fe(2+)], with surfactant sodium dodecylphrate (DLS) complex from aqueous phase was carried out by solvent sublation, which obeys first-order kinetics. On the base of the complete transport mechanisms, the Langmuir adsorption, and the ion complex equilibrium in the aqueous phase, a mathematical model for the [(C(12)H(8)N(2))(3)Fe(2+)]-surfactant ion complex is obtained with the aid of the Mathematic 4.0 program, 4th Runge-Kutta method, and the Matlab programs. The effects of many parameters, such as K(a), K(l), K(ow), d(i), V(o), V(w), and Q(a), on solvent sublation are investigated. Furthermore, the simulation showed that the model is substantiated for experiments on the solvent sublation of the complex.