RESUMO
Combination-based chemotherapies have been the standard treatment for multiple solid tumors since the 1960s. Combined therapies where both agents have toxicity results in dose-limiting effects. α- tocopherol succinate (TS) is an analogue of vitamin E that exhibits antitumor properties in the absence of toxicity. Hence, its combination with a frontline chemotherapy, doxorubicin (DOX) is an alternative to increase antitumor efficacy. Therefore, the aim of this work was to evaluate the antitumor activity of nanostructed lipid carriers (NLC) loaded with TS and DOX. The NLC-TS-DOX were prepared, characterized and radiolabeled with technetium-99m. Cytotoxicity studies were performed in vitro, using two breast cancer cell lines, MDA-MB-231 and 4T1. Biodistribution and antitumor activity were evaluated in 4T1 tumor-bearing mice. The results showed that NLC-TS-DOX had a small diameter (85â¯nm) and a long blood clearance (T1/2ßâ¯=â¯1107.71â¯min) that consequently resulted in a higher tumor uptake compared to contralateral muscle for up to 48â¯h. Drug combination studies in MDA-MB-231 and 4T1 cells showed a combination index below 0.8 at ED50-90 for both cell lines. Interestingly, a high synergism was found at ED90. Antitumor activity showed a better control of tumor growth for animals treated with NLC-ST-DOX. The small particle size, along with the EPR effect and the controlled release of DOX from the particle, associated with the synergic combination between TS and DOX led to an increase of the antitumor efficacy. Therefore, NLC-TS-DOX can be considered a plausible alternative to improve antitumor efficacy in DOX therapeutic regimens.
Assuntos
Neoplasias da Mama/tratamento farmacológico , Doxorrubicina/uso terapêutico , Portadores de Fármacos/química , Lipídeos/química , Nanopartículas/química , alfa-Tocoferol/análogos & derivados , Animais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/patologia , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Modelos Animais de Doenças , Doxorrubicina/farmacologia , Liberação Controlada de Fármacos , Feminino , Humanos , Camundongos Endogâmicos BALB C , Microscopia de Força Atômica , Tamanho da Partícula , Eletricidade Estática , Distribuição Tecidual , alfa-Tocoferol/farmacologia , alfa-Tocoferol/uso terapêuticoRESUMO
There is a great need for orally active drugs for the treatment of the neglected tropical disease leishmaniasis. Amphiphilic Sb(V) complexes, such as 1:3 Sb-N-octanoyl-N-methylglucamide complex (SbL8), are promising drug candidates. It has been previously reported that SbL8 forms kinetically stabilized nanoassemblies in water and that this simple dispersion exhibits antileishmanial activity when given by oral route to a murine model of visceral leishmaniasis. The main objective of the present work was to interfere in the structural organization of these nanoassemblies so as to investigate their influence on the oral bioavailability of Sb, and ultimately, optimize an oral formulation of SbL8 for the treatment of cutaneous leishmaniasis. The structural organization of SbL8 nanoassemblies was manipulated through addition of propylene glycol (PG) to the aqueous dispersion of SbL8. The presence of 50% (v/v) PG resulted in the loss of hydrophobic microenvironment, as evidenced by fluorescence probing. However, nanostructures were still present, as demonstrated by dynamic light scattering, small-angle X-ray scattering, and atomic force microscopy (AFM). A remarkable property of these nanoassemblies, as revealed by AFM analysis, is the flexibility of their supramolecular organization, which showed changes as a function of the solvent and substrate polarities. The formulation of SbL8 in 1:1 water:PG given orally to mice promoted significantly higher and more sustained serum levels of Sb, when compared to SbL8 in water. The new formulation, when given as repeated doses (200 mg Sb/kg/day) to BALB/c mice infected with Leishmania amazonensis, was significantly more effective in reducing the lesion parasite burden, compared to SbL8 in water, and even, the conventional drug Glucantime(®) given intraperitoneally at the same dose. In conclusion, this work introduces a new concept of polarity-sensitive nanocarrier that was successfully applied to optimize an oral formulation of Sb(V) for treating cutaneous leishmaniasis.
Assuntos
Antimônio/uso terapêutico , Antiprotozoários/uso terapêutico , Portadores de Fármacos/química , Leishmaniose Cutânea/tratamento farmacológico , Nanopartículas/química , Administração Oral , Animais , Antimônio/sangue , Antimônio/farmacocinética , Antiprotozoários/química , Antiprotozoários/farmacocinética , Modelos Animais de Doenças , Feminino , Interações Hidrofóbicas e Hidrofílicas , Meglumina/uso terapêutico , Antimoniato de Meglumina , Camundongos Endogâmicos BALB C , Microscopia de Força Atômica , Nanopartículas/ultraestrutura , Compostos Organometálicos/uso terapêutico , Espalhamento a Baixo Ângulo , Solventes , Resultado do Tratamento , Difração de Raios XRESUMO
Paclitaxel (PTX) is widely used as a first-line treatment for patients with metastatic breast cancer; however, its poor water solubility represents a major challenge for parenteral administration. The encapsulation of the PTX in drug-delivery systems with high affinity for tumor sites could improve the uptake and increase its therapeutic efficacy. In this work, long-circulating and pH-sensitive PEG-coated (SpHL-PTX) and PEG-folate-coated liposomes containing PTX (SpHL-FT-PTX) were prepared, and the physicochemical properties and in vitro cytotoxic activity were evaluated. Both formulations presented adequate physicochemical properties, including a mean diameter smaller than 200 nm, zeta potential values near the neutral range, and an encapsulation percentage higher than 93%. Moreover, SpHL-FT-PTX showed a good stability after storage for 100 days at 4 °C. The viability studies on breast cancer cell lines (MDA-MB-231 and MCF-7) demonstrated cytotoxic activity more pronounced for SpHL-FT-PTX than for SpHL-PTX or free drug for both tumor cell lines. This activity was reduced to a rate comparable to SpHL-PTX when the cells were previously treated with folic acid in order to saturate the receptors. In contrast, in the normal cell line (L929), cell viability was decreased only by free or liposomal PTX in the highest concentrations. A significantly higher selectivity index was obtained after SpHL-FT-PTX treatment compared to SpHL-PTX and free PTX. Therefore, the results of the present work suggest that SpHL-FT-PTX can be a promising formulation for the treatment of metastatic breast cancer.
Assuntos
Neoplasias da Mama/tratamento farmacológico , Lipídeos/administração & dosagem , Lipossomos , Paclitaxel/uso terapêutico , HumanosRESUMO
This study investigated the anti-viral effects of the polyphenolic compounds Quercetin and Kaempherol on the release of HTLV-1 from the surface of MT-2 cells. Atomic force microscopy (AFM) was used to scan the surface of the MT-2 cells. MT-2 cells were fixed with 100% methanol on round glass lamina or cleaved mica and dried under UV light and laminar flow. The images were captured on a Multimode equipment monitored by a NanoScope IIId controller from Veeco Instruments Inc operated in tapping mode and equipped with phase-imaging hardware. The images demonstrated viral budding structures 131 ± 57 nm in size, indicating profuse viral budding. Interestingly, cell-free viruses and budding structures visualized on the surface of cells were less common when MT-2 was incubated with Quercetin, and no particles were seen on the surface of cells incubated with Kaempherol. In summary, these data indicate that HTLV-1 is budding constantly from the MT-2 cell surface and that polyphenolic compounds were able to reduce this viral release. Biological samples were analyzed with crude cell preparations just after cultivation in the presence of Quercetin and Kaempherol, showing that the AFM technique is a rapid and powerful tool for analysis of antiviral activity of new biological compounds.
Assuntos
Antivirais/farmacologia , Vírus Linfotrópico T Tipo 1 Humano/efeitos dos fármacos , Quempferóis/farmacologia , Quercetina/farmacologia , Linfócitos T/ultraestrutura , Linfócitos T/virologia , Liberação de Vírus/efeitos dos fármacos , Microscopia de Força AtômicaRESUMO
Complement activation is an important step in the acceleration of liposome clearance. The anaphylatoxins released following complement activation may motivate a wide variety of physiologic changes. We performed physicochemical characterization and in vitro studies of the interaction of complement system with both noncirculating and long-circulating pH-sensitive and nonpH-sensitive liposomes. The liposomes were characterized by diameter, zeta potential, and atomic force microscopy (AFM). The study of liposome interactions with complement system was conducted using hemolytic assay in rat serum. All liposomes presented a similar mean diameter (between 99.8 and 124.3 nm). The zeta potential was negative in all liposome preparations, except in liposomes modified with aminopoly (ethyleneglycol) 2000-distearoylphosphatidylethanolamine (aPEG(2000)-DSPE), which presented positive zeta potential. Atomic force microscopy images showed that non-long-circulating pH-sensitive liposomes are prone to vesicles aggregation. Non-pH-sensitive liposomes complement system activates, while pH-sensitive liposomes showed to be poor complement activators in rat serum.
Assuntos
Ativação do Complemento , Proteínas do Sistema Complemento/química , Lipossomos/química , Animais , Colesterol/química , Proteínas Inativadoras do Complemento/química , Sistemas de Liberação de Medicamentos , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Lipídeos/química , Masculino , Membranas/química , Microscopia de Força Atômica , Fosfatidilcolinas/química , Ratos , Ratos WistarRESUMO
The development of solid lipid nanoparticles (SLN) containing all-trans retinoic acid (RA) is an interesting approach to topical treatment of acne. SLN has potential for controlled release and follicular penetration, which can reduce adverse effects in comparison with conventional formulations. However, the encapsulation efficiency (EE) of RA in SLN is usually low, unless a high surfactant/lipid ratio is used. The aim of this work was to develop SLN with high EE using a low surfactant/lipid ratio. Different formulations of RA-loaded SLN were prepared using glyceryl behenate as lipid matrix. The particle size, EE, zeta potential and differential scanning calorimetry (DSC) were investigated. High EE in SLN was obtained with addition of amines. These results indicate that the utilization of amines is an interesting approach to improve the EE of RA in SLN using a low surfactant/lipid ratio.