Comparison of the Salmonella/Microsome Microsuspension Assay with the new Microplate Fluctuation Protocol for Testing the Mutagenicity of Environmental Samples

The objective of this study was to compare the responses of the Salmonella/microsome microsuspension assay with the new microplate fluctuation protocol (MPF) for the evaluation of the mutagenic activity of environmental samples. Organic extracts of total particulate atmospheric air samples, surface waters, and effluents were tested in dose-response experiments. The assays were performed with strain TA98 in the absence and presence of S9 mix. Both protocols produced similar results, despite the fact that the maximum score of the MPF is limited to 48 wells, whereas in the regular plate assay it is possible to count up to 1,500 colonies using an automatic counter. Similar sensitivities based on the lowest dose that resulted in a positive response were obtained for both assays. The MPF procedure is less laborious (e.g., all-liquid format, use of multi-channel pipettors) and allows for automation of the pipetting and dispensing steps, thus, reducing time of the analysis which is particularly important in environmental quality monitoring programs or in effect-directed analysis. The results show that the MPF procedure is a promising tool to test environmental samples for mutagenic activity. Environ. Mol. Mutagen. 51:31-38, 2010. (C) 2009 Wiley-Liss, Inc.

Ruthenium-nitrite complex as pro-drug releases NO in a tissue and enzyme-dependent way

Nitric oxide (NO) plays an important role in the control of the vascular tone and the most often employed NO donors have limitations due to their harmful side-effects. In this context, new NO donors have been prepared, in order to minimize such undesirable effects. cis-[Ru(bpy)(2)(py)NO(2)](PF(6)) (RuBPY) is a new nitrite complex synthesized in our laboratory that releases NO in the presence of the vascular tissue only. In this work the vasorelaxation induced by this NO donor has been studied and compared to that obtained with the well known NO donor SNP. The relaxation induced by RuBPY is concentration-dependent in denuded rat aortas pre-contracted with phenylephrine (EC(50)). This new compound induced relaxation with efficacy similar to that of SNP, although its potency is lower. The time elapsed until maximum relaxation is achieved (E(max) = 240 s) is similar to measured for SNP (210 s). Vascular reactivity experiments demonstrated that aortic relaxation by RuBPY is inhibited by the soluble guanylyl-cyclase inhibitor 1H-[1,2,4] oxadiozolo[4,3-a]quinoxaline-1-one (ODQ 1 mu M). In a similar way, 1 mu M ODQ also reduces NO release from the complex as measured with DAF-2 DA by confocal microscopy. These findings suggest that this new complex RuBPY that has nitrite in its structure releases NO inside the vascular smooth muscle cell. This ruthenium complex releases significant amounts of NO only in the presence of the aortic tissue. Reduction of nitrite to NO is most probably dependent on the soluble guanylyl-cyclase enzyme, since NO release is inhibited by ODQ. (C) 2011 Elsevier Inc. All rights reserved.

In situ gelling hexagonal phases for sustained release of an anti-addiction drug

In this study, fluid precursor formulations for subcutaneous injection and in situ formation of hexagonal phase gels upon water absorption were developed as a strategy to sustain the release of naltrexone, a drug used for treatment of drug addiction. Precursor formulations were obtained by combining BRIJ 97 with propylene glycol (PG, 5-70%, w/w). To study the phase behavior of these formulations, water was added at 10-90% (w/w), and the resulting systems were characterized by polarized light microscopy. Two precursor formulations containing BRIJ:PG at 95:5 (w/w, referred to as BRIJ-95) and at 80:20 (w/w, referred to as BRIJ-80) were chosen. Naltrexone was dissolved at 1% or suspended at 5% (w/w). Precursor formulations were transformed into hexagonal phases when water content exceeded 20%. Water uptake followed second-order kinetics, and after 2-4 h all precursor formulations were transformed into hexagonal phases. Drug release was prolonged by the precursor formulations (compared to a drug solution in PBS), and followed pseudo-first order kinetics regardless of naltrexone concentration. The release from BRIJ-80 was significantly higher than that from BRIJ-95 after 48 h. The relative safety of the precursor formulations was assessed in cultured fibroblasts. Even though BRIJ-95 was more cytotoxic than BRIJ-80, both precursor formulations were significantly less cytotoxic than sodium lauryl sulfate (considered moderate-to-severe irritant) at the same concentration (up to 50 mu g/mL). These results suggest the potential of BRIJ-based precursor formulations for sustained naltrexone release. (C) 2011 Elsevier By. All rights reserved.

Using Computer-aided Drug Design and Medicinal Chemistry Strategies in the Fight Against Diabetes

The aim of this work is to present a simple, practical and efficient protocol for drug design, in particular Diabetes, which includes selection of the illness, good choice of a target as well as a bioactive ligand and then usage of various computer aided drug design and medicinal chemistry tools to design novel potential drug candidates in different diseases. We have selected the validated target dipeptidyl peptidase IV (DPP-IV), whose inhibition contributes to reduce glucose levels in type 2 diabetes patients. The most active inhibitor with complex X-ray structure reported was initially extracted from the BindingDB database. By using molecular modification strategies widely used in medicinal chemistry, besides current state-of-the-art tools in drug design (including flexible docking, virtual screening, molecular interaction fields, molecular dynamics. ADME and toxicity predictions), we have proposed 4 novel potential DPP-IV inhibitors with drug properties for Diabetes control, which have been supported and validated by all the computational tools used herewith.

Iontophoretic transport of zinc phthalocyanine tetrasulfonic acid as a tool to improve drug topical delivery

Phthalocyanines have been used as systemic photosensitizers because of their high affinity towards tumour tissue, and the high rates of reactive oxygen species produced when they are irradiated during photodynamic therapy. However, the topical administration of these compounds is limited by their large size, poor hydrosolubility and ionic character. This study aimed to investigate the iontophoretic delivery of charged zinc phthalocyanine tetrasulfonic acid (ZnPcS(4)) from a hydrophilic gel to different skin layers by means of in-vitro and in-vivo studies. Six hours of passive administration was insufficient for ZnPcS(4) to cross the stratum corneum (SC) and to reach the epidermis and dermis. No positive effect was reached when anodal iontophoresis was performed, showing that the drug-electrode attraction effect was higher than the electro-osmosis contribution at a pH of 5.5. Cathodal iontophoresis, however, was able to transport significant amounts of the drug to the viable epidermis. In addition, the absence of NaCl in the formulation significantly increased (by five-fold) the amount of ZnPcS(4) that crossed the SC and accumulated in the epidermis and dermis. It was possible to visualize the drug accumulation in the follicle openings and in the epidermis, even after SC removal. In-vivo experiments in rat skin showed that these results were maintained in an in-vivo model, even with only 15 min of iontophoresis. In addition, confocal analysis of the treated skin showed a homogeneous distribution of ZnPcS(4) in the viable epidermis after this short period of cathodal iontophoresis. Anti-Cancer Drugs 22:783-793 (C) 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Stability Testing of Spray- and Spouted Bed-Dried Extracts of Passiflora alata

The aim of this research was to perform a stability testing of spray- and spouted bed-dried extracts of Passiflora alata Dryander (Passion flower) under stress storage conditions. Spouted bed- and spray-dried extracts were characterized by determination of the average particle diameter (dP), apparent moisture content (XP), total flavonoid content (TF), and vitexin content. Smaller and more irregular particles were generated by the spouted bed system due to a higher attrition rate (surface erosion) inside the dryer. The SB dryer resulted in an end product with higher concentration of flavonoids (approximate to 10%) and lower moisture content (1.6%, dry basis) than the spray dryer, even with both dryers working at similar inlet drying air temperature and ratio between the extract feed flow rate to drying air flow rate (Ws/Wg). Samples of the spouted bed- and spray-dried extracts were stored at two different temperatures (34 and 45 degrees C) and two different relative humidities (52 and 63% RH for 34 degrees C; 52 and 60% RH for 45 degrees C) in order to perform the stability testing. The dried extracts were stored for 28 days and were analyzed every 4 days. The flavonoid vitexin served as the marker compound, which was assayed during the storage period. Results revealed shelf lives ranging from 9 to 184 days, depending on the drying process and storage conditions.

The Preparation of Ternary Solid Dispersions of an Herbal Drug via Spray Drying of Liquid Feed

The present study aimed the preparation and characterization of ternary solid dispersions by direct spray drying of a liquid suspension containing curcumin, a solubility enhancer and a drying aid. The experiments followed a Box-Behnken design in order to evaluate the influence of temperature, ratio of curcumin: lipidic carrier, and the collodial silicon dioxide content on the characteristics of the microparticulated solid dispersions. The angle of repose, Hausner factor, Carr index, water activity, and solubility were used to characterize solid dispersions. The results show that water activity, Hausner factor, and Carr index varied in an acceptable range for pharmaceutical purposes. The condition that maximizes solubility was determined using an exploratory design based on a surface response analysis and allowed a 3200-fold increase in curcumin solubility. Ternary solid dispersion showed a 90% curcumin release after 10min during a dissolution test. The results show that the spray drying of a liquid feed is an attractive and promising alternative to obtain enhanced solubility drug ternary solid dispersions.

Rheological, mechanical and mucoadhesive properties of thermoresponsive, bioadhesive binary mixtures composed of poloxamer 407 and carbopol 974P designed as platforms for implantable drug delivery systems for use in the oral cavity

This study described the formulation and characterisation of the viscoelastic, mechanical and mucoadhesive properties of thermoresponsive, binary polymeric systems composed of poloxamer (P407) and poly(acrylic acid, C974P) that were designed for use as a drug delivery platform within the oral cavity. Monopolymeric and binary polymeric formulations were prepared containing 10, 15 and 20% (w/w) poloxamer (407) and 0.10-0.25% (w/w) poly(acrylic acid, 934P). The flow theological and viscoelastic properties of the formulations were determined using controlled stress and oscillatory rheometry, respectively, the latter as a function of temperature. The mechanical and mucoadhesive properties (namely the force required to break the bond between the formulation and a pre-hydrated mucin disc) were determined using compression and tensile analysis, respectively. Binary systems composed of 10% (w/w) P407 and C934P were elastoviscous, were easily deformed under stress and did not exhibit mucoadhesion. Formulations containing 15 or 20% (w/w) Pluronic P407 and C934P exhibited a sol-gel temperature T(sol/gel), were viscoelastic and offered high elasticity and resistance to deformation at 37 degrees C. Conversely these formulations were elastoviscous and easily deformed at temperatures below the sol-gel transition temperature. The sol-gel transition temperatures of systems containing 15% (w/w) P407 were unaffected by the presence of C934P; however, increasing the concentration of C934P decreased the T(sol/gel) in formulations containing 20%(w/w) P407. Rheological synergy between P407 and C934P at 37 degrees C was observed and was accredited to secondary interactions between these polymers, in addition to hydrophobic interactions between P407 micelles. Importantly, formulations composed of 20% (w/w) P407 and C934P exhibited pronounced mucoadhesive properties. The ease of administration (below the T(sol/gel)) in conjunction with the viscoelastic (notably high elasticity) and mucoadhesive properties (at body temperature) render the formulations composed of 20% (w/w) P407 and C934P as potentially useful platforms for mucoadhesive, controlled topical drug delivery within the oral cavity. (c) 2009 Published by Elsevier B.V.

Candida albicans and Candida tropicalis in Oral Candidosis: Quantitative Analysis, Exoenzyme Activity, and Antifungal Drug Sensitivity

Candida albicans and C. tropicalis obtained from whole saliva of patients presenting signs of oral candidosis were assayed for quantification of colony forming units, exoenzyme activity (phospholipase and proteinase) and antifungal drug sensitivity (amphotericin B, fluconazole and itraconazole) by the reference method of the Clinical and Laboratory Standards Institute. The number of colony forming units per milliliter varied according to the Candida species involved and whether a single or mixed infection was present. Proteinase activity was observed in both C. albicans and C. tropicalis, but phospholipase activity was noted only in C. albicans. In vitro resistance to antifungals was verified in both species, but C. tropicalis appears to be more resistant to the tested antifungals than C. albicans.

Computer-aided Drug Design of Novel PLA(2) Inhibitor Candidates for Treatment of Snakebite

Phospholipases A(2) (PLA(2)) are enzymes commonly found in snake venoms from Viperidae and Elaphidae families, which are major components thereof. Many plants are used in traditional medicine its active agents against various effects induced by snakebite. This article presents the PLA(2) BthTX-I structure prediction based on homology modeling. In addition, we have performed virtual screening in a large database yielding a set of potential bioactive inhibitors. A flexible docking program was used to investigate the interactions between the receptor and the new ligands. We have performed molecular interaction fields (MIFs) calculations with the phospholipase model. Results confirm the important role of Lys49 for binding ligands and suggest three additional residues as well. We have proposed a theoretically nontoxic, drug-like, and potential novel BthTX-I inhibitor. These calculations have been used to guide the design of novel phospholipase inhibitors as potential lead compounds that may be optimized for future treatment of snakebite victims as well as other human diseases in which PLA(2) enzymes are involved.

Computer-aided drug design and ADMET predictions for identification and evaluation of novel potential farnesyltransferase inhibitors in cancer therapy

We have used various computational methodologies including molecular dynamics, density functional theory, virtual screening, ADMET predictions and molecular interaction field studies to design and analyze four novel potential inhibitors of farnesyltransferase (FTase). Evaluation of two proposals regarding their drug potential as well as lead compounds have indicated them as novel promising FTase inhibitors, with theoretically interesting pharmacotherapeutic profiles, when Compared to the very active and most cited FTase inhibitors that have activity data reported, which are launched drugs or compounds in clinical tests. One of our two proposals appears to be a more promising drug candidate and FTase inhibitor, but both derivative molecules indicate potentially very good pharmacotherapeutic profiles in comparison with Tipifarnib and Lonafarnib, two reference pharmaceuticals. Two other proposals have been selected with virtual screening approaches and investigated by LIS, which suggest novel and alternatives scaffolds to design future potential FTase inhibitors. Such compounds can be explored as promising molecules to initiate a research protocol in order to discover novel anticancer drug candidates targeting farnesyltransferase, in the fight against cancer. (C) 2009 Elsevier Inc. All rights reserved.

Assessment of the percutaneous penetration of cisplatin: The effect of monoolein and the drug skin penetration pathway

It was intended to examine the in vitro penetration of cisplatin (CIS) through porcine skin in the presence of different concentrations of monoolein (MO) as well as to verify the main barrier for CIS skin penetration. In vitro skin penetration of CIS was studied from propylene glycol (PG) solutions containing 0%, 5%, 10%, and 20% of MO using Franz-type diffusion cell and porcine ear skin. Pretreatment experiments with MO and experiments with skin without stratum corneum (SC) were also carried out. Skin penetration studies of CIS showed that the presence of MO doubled the drug permeation through the intact skin. However, permeation studies through the skin without SC caused only a small enhancement of CIS permeation compared to intact skin. Moreover, pretreatment of skin with MO formulations did not show any significant increase in the flux of the drug. In conclusion, MO did not act as a real penetration enhancer for CIS, but it increased the drug partition to the receptor solution improving CIS transdermal permeation. The absence of improvement in drug permeation by MO pretreatment and by the removal of SC indicates that the SC is not the main barrier for the permeation of the metal coordination compound. (c) 2009 Elsevier B.V. All rights reserved.

Amphotericin B in poly(lactic-co-glycolic acid) (PLGA) and dimercaptosuccinic acid (DMSA) nanoparticles against paracoccidioidomycosis

The present study reports on the preparation and testing of a desoxycholate amphotericin B (D-AMB) sustained delivery system based on poly(lactic-co-glycolic acid) (PLGA) and dimercaptosuccinic acid (DMSA) polymeric blends (Nano-D-AMB) aimed at reducing the number of AMB administrations required to treat mycosis. BALB/c mice were infected with the yeast Paracoccidioides brasiliensis intravenously to mimic the chronic form of paracoccidioidomycosis. At 30 days post-infection, the animals were treated with Nano-D-AMB [6 mg/kg of encapsulated D-AMB, intraperitoneally (ip), interval of 72 h] or D-AMB (2 mg/kg, ip, interval of 24 h). Drug efficacy was investigated by the fungal burden recovery from tissues. Toxicity was assessed by renal and hepatic biochemical parameters, physical appearance of the animals and haematological investigation. The control groups used were non-infected and the infected mice mock treated with PBS. Nano-D-AMB presented results comparable to free D-AMB, with a marked antifungal efficacy. The Nano-D-AMB-treated group presented lower loss of body weight and absence of stress sign (piloerection and hypotrichosis) observed after D-AMB treatment. No renal [blood urea nitrogen (BUN), creatinine] or hepatic (pyruvic and oxalacetic glutamic transaminases) biochemical abnormalities were found. The micronucleus assay showed no significant differences in both the micronucleus frequency and percentage of polychromatic erythrocytes for Nano-D-AMB, indicating the absence of genotoxicity and cytotoxic effects. The D-AMB-coated PLGA-DMSA nanoparticle showed antifungal efficacy, fewer undesirable effects and a favourable extended dosing interval. Nano-D-AMB comprises an AMB formulation able to lessen the number of drug administrations. Further studies would elucidate whether Nano-D-AMB would be useful to treat systemic fungal infections such as paracoccidioidomycosis, candidiasis, aspergillosis and cryptococcosis.

Analysis of Liquid Crystalline Nanoparticles by Small Angle X-Ray Diffraction: Evaluation of Drug and Pharmaceutical Additives Influence on the Internal Structure

The goal of this work was to study the liquid crystalline structure of a nanodispersion delivery system intended to be used in photodynamic therapy after loading with photosensitizers (PSs) and additives such as preservatives and thickening polymers. Polarized light microscopy and light scattering were performed on a standard nanodispersion in order to determine the anisotropy of the liquid crystalline structure and the mean diameter of the nanoparticles, respectively. Small angle X-ray diffraction (SAXRD) was used to verify the influence of drug loading and additives on the liquid crystalline structure of the nanodispersions. The samples, before and after the addition of PSs and additives, were stable over 90 days, as verified by dynamic light scattering. SAXRD revealed that despite the alteration observed in some of the samples analyzed in the presence of photosensitizing drugs and additives, the hexagonal phase still remained in the crystalline phase. (C) 2011 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 100: 2849-2857, 2011