Anti-MDR Effects of Quercetin and its Nanoemulsion in Multidrug-Resistant Human Leukemia Cells.

BACKGROUND: Quercetin has potential against the Multidrug Resistance (MDR) phenotype, but with low bioavailability. The increase in the bioavailability can be obtained with nanostructures. OBJECTIVE: To analyze the effects of quercetin and its nanoemulsion on MDR and non-MDR cells. METHODS: We used high-pressure homogenization for nanoemulsion production; Trypan Blue for cytostatic/cytotoxicity assays; Epifluorescence microscope (with specific probes) for apoptosis and DNA damage; Real-Time PCR for gene expression; AutoDock Vina for docking and Flow Cytometry for efflux analysis. Quercetin exerted antiproliferative impact, induced apoptosis, necrosis and DNA damage on cells. RESULTS: Quercetin combined with vincristine showed an effect similar to verapamil (an ABCB1 inhibitor), and docking showed that it binds to ABCB1 in a similar region. Quercetin was also capable of altering ABCB1 gene expression. Quercetin in nanoemulsion maintained the cytotoxic and cytostatic effects of quercetin, which may increase bioavailability. Besides, the unloaded nanoemulsion was able to inhibit per se the efflux activity of ABCB1, demonstrating pharmacological action of this structure. CONCLUSION: Quercetin may be considered as a prospective drug to overcome resistance in cancer cells and its nanoemulsion can be an alternative for in vivo application.

Physical and chemical stability of ß-carotene nanoemulsions during storage and thermal process.

Nanotechnology has become an option for the encapsulation of compounds, such as carotenoids. However, for the incorporation in to food, it is necessary to develop nanometric systems that are stable under the different conditions to which the food is submitted during its production, transport, and storage. Thus, with the intent to develop a stable nanoemulsion formulation for food application, the physical and chemical stability of ß-carotene nanoemulsions after thermal treatments and storage under different conditions, were investigated in this work. The ß-carotene nanoemulsions were formulated with corn oil, by applying high-pressure homogenization, with an average size in the 300 nm range, which is within the appropriate scale for industrial preparations, such as foods and cosmetics. The nanoemulsion droplets had negative charge (more than -25 mV) and monodisperse profile. The sample were pasteurized, sterilized, and stored at 4, 25, and 37 °C in the presence and absence of light for up to 90 days. Following the heat treatments and storage, the nanoemulsions showed no evidence of physical destabilization, retaining 70-80% of the carotenoid after the pasteurization and sterilization processes, and 70% when stored at 4 °C without light, respectively. Overall, our findings provide new information about the physical and chemical stability of ß-carotene nanoemulsions during traditional thermal processes and environmental conditions.

Coumestrol/hydroxypropyl-ß-cyclodextrin association incorporated in hydroxypropyl methylcellulose hydrogel exhibits wound healing effect: in vitro and in vivo study.

Several beneficial effects on the skin have been reported for coumestrol (COU), such as protection against photoaging and improvement of skin elasticity and thickness in postmenopausal women. However no reports on the effect of COU on wound healing were found. Nevertheless, COU has low aqueous solubility, which is a crucial limitation for biological tests. The present study was designed as a two-step experiment to evaluate the wound healing effect of COU. First, we used fibroblasts and the experimental in vitro artificial wound model, scratch assay, to compare the effects of COU free, dissolved in dimethyl sulfoxide (DMSO) or Dulbecco's modified Eagle's medium (DMEM), or associated with hydroxypropyl-ß-cyclodextrin (HPßCD). The 50 µM (66.1%) and 10 µM (56.3%) COU/HPßCD association induced cell proliferation and migration in inflicted wounds. Subsequently, the in vivo wound healing experimental model (Wistar rats) revealed that COU/HPßCD incorporated into hypromellose (HPMC) hydrogel had similar efficacy in wound healing in comparison to the positive control (Dersani®), with the advantage that 50% wound healing was achieved within a shorter period. In summary, the results successfully demonstrated, for the first time, the wound healing effect of COU/HPßCD incorporated into HPMC hydrogel and describe the feasibility of the biological tests with the use of HPßCD instead DMSO.

Effects of the compounds resveratrol, rutin, quercetin, and quercetin nanoemulsion on oxaliplatin-induced hepatotoxicity and neurotoxicity in mice.

Oxaliplatin (OXA) is a platinum compound widely used in the treatment of some solid tumors, especially colorectal cancer. Despite its usefulness, oxaliplatin-associated neurotoxicity represents the main dose-limiting factor of this drug, and until now, there is no suitable treatment. Chemotherapy with oxaliplatin also increases the rate of developing hepatic damages with inflammatory activity, termed chemotherapy-associated steatohepatitis (CASH). In the present study, we aimed to compare the effects of a series of antioxidant compounds on simultaneous development of oxaliplatin-induced hepato- and neurotoxicity in mice. Mice BALB/c were treated with oxaliplatin for 6 weeks, 10 mg/kg, intraperitoneally, resulting in mechanical allodynia and hepatic steatosis. We administered the following antioxidant compounds--rutin (RT) (20 mg/kg), resveratrol (RVS) (100 mg/kg), quercetin (QT) (20 mg/kg), and quercetin nanoemulsion (NQT) (20 mg/kg)--daily by gavage to BALB/c, and N-acetylcysteine (NAC) was used as positive control. Treatments with RSV, RUT, or NQT were able to prevent mechanical allodynia when compared to the OXA group, and this effect was associated with decreased c-Fos immunopositivity in the lumbar spinal cord. Regarding the effects on steatohepatitis, RVS, QT, and NQT almost completely reversed the mean liver weight increase induced by OXA. In accordance with these previous data, histological evaluation indicated attenuation of all features of hepatic steatosis evaluated in RSV, RUT, QT, and NQT groups. These compounds were able to reduce the immunopositivity for the apoptosis marker caspase-3. On the other hand, only QT and NQT treatments were able to reduce neutrophil migration measured by myeloperoxidase (MPO) activity. These results suggest that the compounds tested, RSV, RUT, QT, and NQT, would be useful for the clinical treatment of neuro- and hepatoxicity induced by oxaliplatin.

Poly(ethylene glycol) hydroxystearate-based nanosized emulsions: effect of surfactant concentration on their formation and ability to solubilize quercetin.

Quercetin is a natural compound that has shown several biological activities. However, it displays poor water solubility and, therefore, low bioavailability. In this study, oil-in-water nanosized emulsions were obtained by the hot solvent diffusion method, using castor oil as oily phase and poly(ethylene glycol) (660)-12-hydroxystearate (PEG 660-stearate) and lecithin as surfactants. The effect of the PEG 660-stearate concentration on the droplet size of the nanosized emulsions and on the ability of these systems to load quercetin was investigated. Dynamic light scattering (DLS), transmission electron microscopy (TEM), cryo-TEM, and small-angle X-ray scattering (SAXS) were used to characterize the systems. We have demonstrated that a critical concentration of PEG 660-stearate (2.5 wt%) was needed to obtain colloidal dispersions displaying microemulsion characteristics. This colloidal dispersion, that was not optically birefringent, was constituted by a monodisperse population of 20 nm-large droplets, and exhibited excellent stability. Besides, this system was able to solubilize five times more quercetin than nanoemulsions prepared using 0.25 wt% PEG 660-stearate. SAXS results suggest that the spherical droplets have a core-shell structure. With regard to the hot solvent diffusion method, both diffusion of the solvent towards the aqueous phase and increase of the temperature above the phase inversion temperature (PIT) of PEG 660-stearate appeared to be required for obtaining clear and isotropic colloidal dispersions.

Anti-inflammatory effect of quercetin-loaded microemulsion in the airways allergic inflammatory model in mice.

Quercetin is a plant-derived flavonoid widely known by its anti-oxidant and anti-inflammatory properties, but its oral bioavailability is very poor and this becomes difficult to assess its therapeutic potential. Here we have compared the anti-inflammatory effect of quercetin-loaded microemulsion (QU-ME) and quercetin suspension (QU-SP) in an experimental model of airways allergic inflammation. Mice received daily oral doses of QU-ME (3 or 10mg/kg; in an oil-in-water microemulsion content 0.02:0.2:1 of lecithin:castor oil:Solutol HS15((R))), QU-SP [10mg/kg, in carboxymethylcellulose (CMC) 0.5% in water] or vehicle from the 18th to the 22nd day after the first immunization with ovalbumin (OVA). Dexamethasone was used as positive control drug. Every parameter was evaluated in the 22nd day (24h after the second OVA-challenge). We have also tried to assess by HPLC-MS a quercetin metabolite in the blood of rats treated with QU-SP or QU-ME. QU-ME was better orally absorbed when compared with QU-SP. Furthermore, oral administration of QU-SP failed to interfere with leukocyte recruitment, while QU-ME inhibited in a dose-dependent way, the eosinophil recruitment to the bronchoalveolar lavage fluid (BALF). QU-ME also significantly reduced both IL-5 and IL-4 levels, but failed to interfere with CCL11, IFN-gamma and LTB(4) levels. In addition, QU-ME oral treatment inhibited the nuclear transcription factor kappa B (NF-kappaB) activation, P-selectin expression and the mucus production in the lung. The present results show that QU-ME exhibits pronounced anti-inflammatory properties in a murine model of airways allergic inflammation and suggest that it might present therapeutic potential for the airways inflammatory diseases management.