RESUMEN
Biguanides (i.e. metformin, phenformin and buformin) are antidiabetic drugs with potential antitumor effects. Herein, a polycationic polymer, N,N'-bis(cystamine)acrylamide-buformin (CBA-Bu), containing multiple biodegradable disulphide bonds and buformin-mimicking side chains was synthesised. CBA-Bu was equipped with high efficiency and safety profile for gene delivery, meanwhile exhibiting potential antitumor efficacy. As a gene vector, CBA-Bu was able to condense plasmid DNA (pDNA) into nano-sized (<200 nm), positively-charged (>30 mV) uniform polyplexes that were well resistant to heparin and DNase I. Due to the reduction responsiveness of the disulphide bonds, CBA-Bu/pDNA polyplexes could release the loaded pDNA in the presence of dithiothreitol, and induce extremely low cytotoxicity in NIH/3T3 and U87 MG cells. The transfection results showed that CBA-Bu had a cellular uptake efficiency comparable to 25 kDa PEI, while a significantly higher gene expression level. Additionally, CBA-Bu had a lower IC50 value than its non-biguanide counterpart in two cancer cell lines. Furthermore, CBA-Bu could activate AMPK and inhibit mTOR pathways in U87 MG cells, a mechanism involved in the antitumor effect of biguanides. Taken together, CBA-Bu represented an advanced gene vector combining desirable gene delivery capability with potential antitumor activity, which was promising to achieve enhanced therapeutic efficacy in antitumor gene therapy.
Asunto(s)
Buformina/química , Buformina/farmacología , Terapia Genética/métodos , Neoplasias/terapia , Poliaminas/química , Poliaminas/farmacología , Proteínas Quinasas Activadas por AMP/efectos de los fármacos , Animales , Buformina/administración & dosificación , Línea Celular Tumoral , Técnicas de Transferencia de Gen , Vectores Genéticos , Humanos , Concentración 50 Inhibidora , Ratones , Células 3T3 NIH , Nanopartículas , Plásmidos , Poliaminas/administración & dosificaciónRESUMEN
BACKGROUND: The formation and accumulation of advanced glycation end products (AGE) in various tissues are known to be involved in the aging process and complications of long-term diabetes. Aminoguanidine as AGE inhibitors was first studied, and metformin as biguanide compounds have been reported to react with reactive dicarbonyl precursors such as methylglyoxal. METHODS: We studied the effects of the biguanides of buformin and metformin on AGE formation by the methods of specific fluorescence, and enzyme-linked immunosorbent assay and a Western blot analysis using the anti-AGE antibody after incubating BSA or RNase with methylglyoxal. RESULTS: Buformin is a more potent inhibitor of AGE formation than metformin, and suggests that the amino group of buformin trap the carbonyl group of methylglyoxal to suppress formation of AGE. CONCLUSION: In addition to that of metformin, buformin may be clinically useful to prevent diabetic complications.
Asunto(s)
Buformina/química , Productos Finales de Glicación Avanzada/síntesis química , Metformina/química , Piruvaldehído/química , Animales , Bovinos , Ensayo de Inmunoadsorción Enzimática , Productos Finales de Glicación Avanzada/análisis , Guanidinas/química , Ribonucleasas/química , Ribonucleasas/farmacología , Albúmina Sérica Bovina/química , Factores de TiempoRESUMEN
A sensitive and rapid high-performance liquid chromatographic assay is developed and validated for the determination of buformin in plasma. After addition of metformin as the internal standard, the analytes were deproteinated with acetonitrile, washed with dichloromethane, and the resulting supernatant injected. Chromatography was performed at ambient temperature by pumping a mobile phase of 0.03 m diammonium hydrogen phosphate buffer (pH 7, 250 mL) in methanol (750 mL) at a fl ow rate of 1 mL/min through a silica column. Buformin and metformin were detected at 236 nm, and eluted 9.8 and 15.4 min, respectively. No endogenous substances were found to interfere. Calibration curves were linear over the concentration range of 20-2000 ng/mL. The limit of quantitation was 20 ng/mL. The intra- and inter-day relative standard deviation (RSD) was 8.3%, or less, and the accuracy was within 10.1% of the relative error (RE). The method is suitable in pharmacokinetic investigation of buformin.
Asunto(s)
Buformina/sangre , Cromatografía Líquida de Alta Presión/métodos , Metformina/sangre , Animales , Antipsicóticos/sangre , Buformina/química , Calibración , Hipoglucemiantes/sangre , Masculino , Metformina/química , Metformina/farmacología , Ratas , Ratas Sprague-Dawley , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Espectrofotometría Ultravioleta/métodosRESUMEN
Spherical microparticles based on methacrylic acid-methyl methacrylate copolymer have been developed. The method chosen for the preparation of such microparticles was suspension radical copolymerization of acrylic comonomers in the presence of the ethyleneglycol dimethacrylate as crosslinking agent. The microparticles obtained were characterised by inverse size exclusion chromatography, scanning electron microscopy, swelling degree and exchange capacity. The porous volume of the microspheres ranged from 0.086 ml/g for the microparticles produced by a methacrylic acid/methyl methacrylate ratio of 1/3 and a 10% degree of crosslinking, to 8.57 ml/g for the microparticles produced by a methacrylic acid/methyl methacrylate ratio of 3/1 and 2% degree of crosslinking (in 0.1 N NaCl in phosphate buffer pH 7.4). Also the pore diameter of the swollen microparticles ranged from a few to 120 A. Buformin tosylate - a classical hypoglycaemic drug - was included in the polymer network of the microparticles during the polymerization process. Due to the water solubility of the drug and its low solubility in the organic phase, the entrapment yield did not exceed 15%. However the amount of encapsulated drug as well as the drug released from the microparticles, was dependent on the methacrylic acid/methyl methacrylate ratio, the degree of crosslinking and solvent/comonomers ratio.