Epoxide-derived mixed-mode chromatographic stationary phases for separation of active substances in fixed-dose combination drugs.

A method for the preparation of novel mixed-mode reversed-phase/strong cation exchange stationary phase for the separation of fixed-dose combination drugs has been developed. An epoxysilane bonded silica prepared by vapor phase deposition was used as a starting material to produce diol, octadecyl, sulfonate, and mixed octadecyl/sulfonate groups bonded silica phases. The chemical structure and surface coverage of the functional groups on these synthesized phases were confirmed by fourier-transform infrared and solid-state 13 C NMR spectroscopy and elemental analysis. Alkylbenzene homologs, basic drugs, nucleobases and alkylaniline homologs were used as probes to demonstrate the reversed-phase, ion exchange, hydrophilic interaction and mixed-mode retention behaviors of these stationary phases. The octadecyl/sulfonate bonded silica exhibits pronounced mixed-mode retention behavior and superior retentivity and selectivity for alkylaniline homologs. The mixed-mode retention is affected by either ionic or solvent strength in the mobile phase, permiting optimization of a separation by fine tuning these parameters. The mixed-mode stationary phase was applied to separate two fixed-dose combination drugs: compound reserpine tablets and compound methoxyphenamine capsules. The results show that simultaneous separation of multiple substances in the compound dosage can be achieved on the mixed-mode phase, which makes multi-cycles of analysis for multiple components obsolete.

Simultaneous analysis of hydrochlorothiazide, triamterene and reserpine in rat plasma by high performance liquid chromatography and tandem solid-phase extraction.

A tandem solid-phase extraction method (SPE) of connecting two different cartridges (C(18) and MCX) in series was developed as the extraction procedure in this article, which provided better extraction yields (>86%) for all analytes and more appropriate sample purification from endogenous interference materials compared with a single cartridge. Analyte separation was achieved on a C(18) reversed-phase column at the wavelength of 265 nm by high-performance liquid chromatography (HPLC). The method was validated in terms of extraction yield, precision and accuracy. These assays gave mean accuracy values higher than 89% with RSD values that were always less than 3.8%. The method has been successfully applied to plasma samples from rats after oral administration of target compounds.

Comparative effects of Rauwolfia vomitoria and chlorpromazine on locomotor behaviour and anxiety in mice.

AIM OF THE STUDY: Since remedies for mental disorders have been sought through both orthodox and traditional medicine this study compared the effects of the antipsychotic, chlorpromazine (Cpz), the herb Rauwolfia vomitoria (RV) and its alkaloid reserpine (Res) in mice. MATERIALS AND METHODS: Ninety male CD-1 strain of mice (75-80 days old; 30-34 g body weight) were divided into 3 major groups and each consisting 5 subgroups (n=6). Cpz (0.0, 0.25, 1.0, 2.0 and 4.0 mg/kg, i.p.), was administered 30 min before testing. RV (0.0, 0.25, 1.0, 2.0 and 4.0 mg/kg, i.p.) and Res (0.0, 0.1, 0.4, 0.8, 1.6 mg/kg, i.p.) were administered 24 h before testing. The open field test was used to assess locomotor and exploratory behaviour, acceleratory rotarod for motor coordination, light/dark box for anxiety. RESULTS: CPZ dose-dependently decreased locomotor and exploration behaviour and impaired motor coordination (p<0.01). RV also decreased locomotor behaviour at 4.0 mg/kg (p<0.5) but did not alter exploration and motor coordination. Res however, decreased locomotion and exploration and impaired motor coordination 0.8 and 1.6 mg/kg (p<0.05). In the light/dark box, CPZ increased anxiety related behaviour at 1.0, 2.0 mg/kg (p<0.05) whereas RV dose-dependently decreased anxiety from 1.0 to 4.0 mg/kg (p<0.01). Res, unlike RV, dose-dependently increased anxiety related behaviour from 0.4 to 1.6 mg/kg. CONCLUSION: Root bark extract from Rauwolfia vomitoria produced better behavioural effects with less distortion in motor coordination when compared to chlorpromazine and so has a great potential as an alternative antipsychotic agent compared to chlorpromazine. Since Res did not produce same effects as RV, the effect of RV may not be due solely to Res as claimed.

Isoreserpine promotes beta-catenin degradation via Siah-1 up-regulation in HCT116 colon cancer cells.

Aberrant accumulation of intracellular beta-catenin in intestinal epithelial cells is a frequent early event during the development of colon cancer. To identify small molecules that decrease the level of intracellular beta-catenin, we performed cell-based chemical screening using genetically engineered HEK293 reporter cells to detect compounds that inhibit TOPFlash reporter activity, which was stimulated by Wnt3a-conditioned medium. We found that isoreserpine promoted the degradation of intracellular beta-catenin by up-regulation of Siah-1 in HEK293 and HCT116 colon cancer cells. Moreover, isoreserpine repressed the expression of beta-catenin/T-cell factor (TCF)-dependent genes, such as cyclin D1 and c-myc, resulting in the suppression of HCT116 cell proliferation. Our findings suggest that isoreserpine can potentially be used as a chemotherapeutic agent against colon cancer.