RESUMEN
Lipid free-radical oxidation has been studied in vivo in the mitochondrial fractions of the liver of rats fed RoseOx (carnosic acid nutritional supplement) by measuring chemiluminescence. The kinetics of the lipid chemiluminescence in rats fed RoseOx are significantly different from those of the control. The intensity of the chemiluminescence fast flash decreases by 45% (p < 0.01), which indicates a reduction of lipid peroxides. The time between fast and slow flashes increases by 96% (p < 0.05), which indicates a higher content of antioxidants in the lipid membrane. The in vitro experiments in rat liver mitochondrial fraction display more effective antioxidant action of alpha-tocopherol in 1 microM concentration than 1 microM carnosic acid by an increase of the time between fast and slow chemiluminescence flashes (p < 0.01). However, the higher antioxidant activity of 1 microM carnosic acid by a decrease of intensity of the chemiluminescence fast (p < 0.05) and slow (p < 0.05) flashes in comparison with alpha-tocopherol is revealed in these experimental conditions in vitro. Carnosic acid has antioxidant effects on homogeneous oxidation in vitro as well. The chemiluminescence of methyl oleate initiated by 2,2'-azobis(2-methylpropionitrile) decreases by 25% (p < 0.01) in the presence of 13.5 microM carnosic acid. 13.5 microM alpha-tocopherol decreases the methyl oleate chemiluminescence by 45%. A higher antioxidant activity of alpha-tocopherol in comparison with carnosic acid (p < 0.001) is found in this system. These results indicate that RoseOx reduces free-radical-induced lipid peroxidation in vivo. In vitro data show that carnosic acid has direct action as an antioxidant, rather than as a membrane-structure modifier.
Asunto(s)
Antioxidantes/metabolismo , Diterpenos/metabolismo , Mitocondrias Hepáticas/metabolismo , Extractos Vegetales/metabolismo , Abietanos , Animales , Antioxidantes/administración & dosificación , Diterpenos/administración & dosificación , Mediciones Luminiscentes , Extractos Vegetales/administración & dosificación , Ratas , Ratas WistarRESUMEN
The first terpenolignan, brevitaxin [1], has been isolated from the bark of Taxus brevifolia. Identification was carried out using spectral methods, and the regiochemistry and cytotoxicity of 1 are discussed.
Asunto(s)
Antineoplásicos Fitogénicos/aislamiento & purificación , Diterpenos/aislamiento & purificación , Lignanos/aislamiento & purificación , Plantas Medicinales/química , Antineoplásicos Fitogénicos/farmacología , Diterpenos/farmacología , Humanos , Lignanos/farmacología , Espectroscopía de Resonancia Magnética , Células Tumorales CultivadasRESUMEN
Liothyronine and levothyroxine were quantitatively determined in samples of commercial thyroid tablets and bulk powders. Samples were first hydrolyzed using a bacterial protease and then analyzed by high-performance liquid chromatography. Various hydrolysis conditions were investigated. The liothyronine and levothyroxine contents of commercial tablets and bulk powders were found to be approximately 8-11 micrograms and 25-43 micrograms, respectively, per 65 mg of thyroid. The stability of the iodothyronines in thyroid tablets was also investigated.
Asunto(s)
Tiroxina/análisis , Triyodotironina/análisis , Cromatografía Líquida de Alta Presión , Estabilidad de Medicamentos , Hidrólisis , Péptido Hidrolasas , Polvos , ComprimidosRESUMEN
A reverse-phase high-performance liquid chromatographic (HPLC) method for determining sodium levothyroxine in tablet formulations is described. The sodium levothyroxine was extracted from tablets using a mobile phase consisting of 60% acetonitrile and 40% aqueous buffer. After centrifugation 200 microliter of the solution was chromatographed on a 10-micron C18 column. The method gave accurate results when tested against the USP method, by the standard additions method, and by the spiked-placebo method. The method can also be used to determine content uniformity and dissolution of sodium levothyroxine tablets.
Asunto(s)
Tiroxina/análisis , Química Farmacéutica , Cromatografía Líquida de Alta Presión/métodos , Estabilidad de Medicamentos , Solubilidad , Comprimidos/normas , TemperaturaRESUMEN
A procedure for the determination of thyroid (thyroid hormone) in pharmaceutical preparations by titration with 1 mM silver nitrate using an ion-selective electrode was developed and evaluated. Samples were combusted according to the USP procedure and analyzed with a minimum of work-up for iodine content. The results obtained by this method were compared with those obtained by the official methods. The recovery of iodide from spiked placebo samples was investigated. The method is applicable to content uniformity analyses as well as to bulk material and to the analysis of organically bound iodide in other pharmaceutical preparations such as sodium levothyroxine tablets. The method is fast, simple, accurate, applicable to automation, and is suitable for routine quality control use.