Evaluation of amylose used as a drug delivery carrier

The enzyme-dependent conjugates of indomethacin and amylose (Am-IND) were synthesized at room temperature using N,N′-dicyclohexylcarbodiimide (DCC) as a coupling agent and 4-(N,N′-dimethylamino) pyridine (DMAP) as a catalyst. Their structures were characterized by FTIR and ¹H NMR analyses, and the results indicated that the IND residues were conjugated with amylose backbones through ester bonds. For the conjugate with a lower IND content, the better water absorption property was advantageous for enzymes diffusing into the swollen conjugate, resulting in biodegradation of the conjugates and release of IND. In vitro biodegradation evaluation indicated that the Am-IND conjugates were biodegraded in the simulated media of the intestines. In vitro drug release experiments showed that the Am-IND conjugates exhibited a sustained release behavior in the simulated media of the intestines, while IND was hardly released in the simulated gastric fluid. These features provide a great opportunity to use the conjugates as a prodrug for intestinally targeted and controlled release of IND through oral administration. This study may lead to the development of effective methods for utilizing amylose as a new drug delivery carrier.     

Characterization of physical interaction between Casiopeina III-ia and chitosan. Toward a Cas III-ia drug delivery system

Casiopeínas® are a new generation of anticancer drugs that have shown great in vitro and in vivo antineoplastic activities. Information about interaction drug-excipient, for developing a based-nanoparticle drug delivery system, has not been investigated yet. In order to elucidate if chitosan (CS) modifies the copper complex due to its interaction with Cu²⁺ ion, different studies in aqueous media between CS and Casiopeina III-ia (Cas III-ia) were carried out. CS–Cas III-ia mixtures were characterized by viscosity curves, UV–vis, EPR, and in vivo activity against HeLa cell line. Rheological behavior showed a decrease of viscosity when the drug was present due to diminished electrostatic interactions of charged amine group. UV–vis results illustrate that Cas III-ia is not stable at low pH as a result of interaction with acetic acid. However, when chitosan is present at the acidic solution Cas III-ia is stable. These results are supported by EPR studies. Finally, activity of the drug against HeLa cell line was not modified. Therefore, the present work presents evidence that there is no breaking of copper complex due to interaction between CS and Cas III-ia in acidic media. In addition, Cas III-ia maintains both its stability and effectiveness against cancer cell line.     

Rosin microparticles as drug carriers: Influence of various solvents on the formation of particles and sustained-release of indomethacin

The aim of this study was to formulate a sustained release system for indomethacin (IND) with rosin gum obtained from a pine tree. Rosin microparticles were prepared by a dispersion and dialysis method without the addition of surfactant. In order to investigate the influence of solvents on the formation of colloidal microparitcles, various solvents like ethanol, DMF, DMAc, and acetone were used. The rosin microparticles containing IND were characterized by X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The morphologies of rosin microparticles observed by scanning electron microscopy (SEM) were spherical. The solvents used to dissolve rosin significantly affected the drug content and drug release rate of IND. The release behaviors of IND from the rosin microparticles were dependent on the drug content and size of the particles. Rosin microparticles with a higher drug content and of a larger particle size had a slower drug release rate. Also, the IND release rate from the rosin microparticles could be regulated by the rosin content in the microparticles. From these results, rosin microparticles have the potential of being used as a sustained release system of IND.     

Preparation of chondroitin sulfate nanocapsules for use as carries by the interfacial polymerization method

In this paper, the method of interfacial polymerization in emulsion was employed to fabricate chondroitin sulfate-methacrylate (ChSMA) nanocapsules, in which poor water-soluble drug of indomethacin (IND) could be effectively encapsulated. The morphology and the size distribution of synthesized nanocapsules were characterized by field emission scanning electron microscopy (FESEM) and dynamic light scattering (DLS) techniques. The quantitative drug loading was investigated. The IND/ChSMA noodle-like self-assemblies were observed with the increase of IND feed concentration, and the interactions between IND and ChSMA were illuminated by FT-IR and XRD measurements. The in vitro drug release of IND-loaded nanocapsules and IND/ChSMA self-assemblies were also carried out in simulated body fluid pH 7.4 at 37 °C.     

The Design of Nanostructured Metronidazole-Loaded HPC/Oxide Xerogel Composites: Influence of the Formulation Parameters on In Vitro Characterisation

In this study, oxide and polymer/oxide xerogels with metronidazole were prepared and examined as carriers of drug for the local application to the bone. The nanoporous SiO₂–CaO–P₂O₅ and HPC–SiO₂–CaO–P₂O₅ xerogel materials with different amounts of the polymer [hydroxypropyl cellulose (HPC)] were prepared using the sol–gel technology, and their physicochemical properties were characterised with respect to chemical structure [by Fourier transform infrared spectroscopy (FTIR)], porosity and the specific surface area of solids (BET), crystallinity [by X-ray powder diffraction (XRD)], morphology [by scanning electron microscope (SEM)] and the in vitro release of the metronidazole over time (by UV–vis spectroscopy, in the ultraviolet light region). HPC-modified oxide xerogels as the carriers of drug showed slower release of metronidazole, due to the structure and stronger interactions with drug as compared with the pure oxide xerogel. Kinetic analysis indicated diffusional mechanism of drug release from all xerogel carriers. HPC addition to the oxide material resulted in a decrease in the porosity and improved the bioactive properties of xerogels. Obtained results for xerogel composites suggest that the metronidazole-loaded xerogels could be attractive candidates for local delivery systems particularly to a bone.KEY WORDS: drug delivery systems, nanostructured composites, porous materials     

Permeation Studies of Indomethacin from Different Emulsions for Nasal Delivery and Their Possible Anti-Inflammatory Effects

The purpose of this research was to develop an emulsion formulation of indomethacin (IND) suitable for nasal delivery. IND was incorporated into the oil phases of oil in water (O/W) and water in oil (W/O) emulsions. For this purpose, different emulsifying agents (Tween 80, Span 80 and Brij 58) were used in two emulsion formulations. When the effects of several synthetic membranes (nylon, cellulose, cellulose nitrate) were compared with the sheep nasal mucosa, the cellulose membrane and sheep nasal mucosa showed similar permeation properties for O/W emulsion (P > 0.05). To examine the absorption characteristics of IND, the anti-inflammatory properties of intravenous solution of IND, intranasal O/W emulsions of IND (with or without enhancers) and intranasal solution of IND (IND-Sol) were investigated in rats with carrageenan-induced paw edema. When citric acid was added to the nasal emulsion, the anti-inflammatory activity was similar to that of intravenous solution (P > 0.05). Finally, it was concluded that, intranasal administration of IND emulsion with citric acid may be considered as an alternative to intravenous and per oral administrations of IND to overcome their adverse effects.     

Formation of nanometal particles in the dialdehyde starch matrix

Environmentally friendly method of the preparation of dialdehyde starch (DAS) based composites containing nanosilver (DAS/Ag) and nanogold (DAS/Au) as reducing and protecting agents was developed. UV–vis spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) confirmed formation of about 10 nm ball shaped Ag and Au nanoparticles situated within the polysaccharide template. Thermal properties of the composites were characterized involving differential scanning calorimetry (DSC), whereas molecular weights of polysaccharide chains of the matrix were estimated with the size exclusion chromatography coupled with multiangle laser light scattering and refractometric detectors (HPSEC-MALLS-RI).     

Preparation,characterization, and in vitro efficacy of O-carboxymethyl chitosan conjugate of melphalan

A series of melphalan-O-carboxymethyl chitosan (Mel-OCM-chitosan) conjugates with different spacers were prepared and structurally characterized. All conjugates showed satisfactory water-solubility (160-217 times of Mel solubility). In vitro drug release behaviors by both chemical and enzymatic hydrolysis were investigated. The prodrugs released Mel rapidly within papain and lysosomal enzymes of about 40–75%, while released only about 4–5% in buffer and plasma, which suggested that the conjugates have good plasma stability and the hydrolysis in both papain and lysosomes occurs mostly via enzymolysis. It was found that the spacers have important effect on the drug content, water solubility, drug release properties and cytotoxicity of Mel-OCM-chitosan conjugates. Cytotoxicity studies by MTT assay demonstrated that these conjugates had 52–70% of cytotoxicity against RPMI8226 cells in vitro as compared with free Mel, indicating the conjugates did not lose anti-cancer activity of Mel. Overall these studies indicated Mel-OCM-chitosan conjugates as potential prodrugs for cancer treatment.     

Fabrication of novel combinatorial drug encapsulated micelles for enhanced tumor targeting in intestinal cancer in mouse model

Hindrance to successful therapy of colon cancer is generally characterized with reduced potency of a single drug at the active site of cancer, poor drug release, and most importantly, potential toxic side effects of the drug resulting in cytotoxicity. Therefore, we investigated combinatorial drug micelles which are a potent combination of twin anticancer drugs (indomethacin and piroxicam, IND+PIR mc) for successful therapeutics of colon cancer. The novel combinatorial micelles showed improved drug encapsulation efficiency, an in vitro burst release of the dual drugs, increased cytocompatibility and increased efficacy in tumor reduction (weight and volume) than in single drug micelles (IND mc or PIR mc). The improved IND+PIR MC were to have small size 150.36 ± 15.13 nm (to avoid being taken up by liver, lungs or kidney or to sediment) with poly dispersity index (PDI) value at 0.24 ± 0.01. The PDI values suggest homogenous distribution. Encapsulation efficiency of IND+PIR mc was calculated at 86%. IND+PR mc had improved biocompatibility as demonstrated by CRL-1459™ (normal colon) cell line than IND mc or PIR mc individually. The in vivo studies in mice model clearly depict that subcutaneous tumor weight reduced by almost 75% and volume reduced drastically by 55% on administration of IND+PIR mc than IND mc or PIR mc. Furthermore, fewer side effects were found with IND+PIR mc. To conclude, IND+PIR mc may be a potential anticancer strategy to be explored more in the future.     

Release of indomethacin from pH-sensitive pullulan acetate microsphere

We studied the pH-sensitive indomethacin (IND) delivery system using pullulan. Hydrophobic pullulan acetate was prepared by chemical modification of hydrophilic pullulan and pullulan acetate microsphere was made by a solvent evaporation method. The size of microspheres was below 5 μm, and the drug loading efficiencies of microspheres were approximately 78 and 65% at the initial amount of drug 40 and 80 mg, respectively. The microsphere showed pH-sensitive swelling behavior in PBS buffer. After 15 hrs, the swelling of the microsphere at pH 7.4 was approximately 20 times greater than that at pH1.2. The pH of the medium significantly influenced on thein vitro release rate. The released amount of drug at pH 7.2 was approximately 90 times greater than that at pH 1.2. The shape of microspheres at pH 1.2 were maintained sphere forms, but at pH 7.4 were disintegrated. The pH-sensitive IND release pattern was due both to the pH-sensitive diffusion of IND from the microspheres and to the release of the drug from the surface which underwent disintegration after swelling, due to the chemical composition of the microspheres and the pH of the release media.     

Molecular docking and experimental investigation of new indole derivative cyclooxygenase inhibitor to probe its binding mechanism with bovine serum albumin

The indole derivative 2-(5-methoxy-2-methyl-1H-indol-3-yl)-N'-[(E)-(3-nitrophenyl) methylidene]acetohydrazide (IND) was synthesized for its therapeutic potential to inhibit cyclooxygenase (COX)-II. Binding if IND to bovine serum albumin (BSA) was investigated was because most drugs bind to serum albumin in-vivo. Fluorescence, UV–vis spectrophotometry and molecular modeling methodologies were employed for studying the interaction mechanism. The intrinsic fluorescence of BSA was quenched by BSA and the quenching mechanism involved was static quenching. The binding constants between IND and BSA at the three studied temperatures (298, 301 and 306 K) were 1.09 × 10⁵, 4.36 × 10⁴ and 1.23 × 10⁴ L mol⁻¹ respectively. The most likely site for binding IND to BSA was Site I (subdomain IIA). The analysis of thermodynamic parameter revealed the involvement of hydrogen bonding and van der Waals forces in the IND-BSA interaction. Synchronous fluorescence spectroscopic (SFS) and UV–vis spectrophotometric studies suggested conformational change in BSA molecule post interaction to IND. Molecular docking and the experimental results corroborated one another. The study can prove as an insight for future IND drug development.     

Synthesis and characterization of folate conjugated chitosan and cellular uptake of its nanoparticles in HT-29 cells

Folate–chitosan (FA–CS) conjugates synthesized by coupling FA with CS render new and improved functions because the original properties of CS are maintained and the targeting ligand of FA is incorporated. In this work, FA–CS conjugates were synthesized based on chemical linking of carboxylic group of FA with amino group of CS as confirmed by Fourier transform spectroscopy (FTIR) and nuclear magnetic resonance (¹H NMR). FA–CS conjugates displayed less crystal nature when compared to CS. The FA–CS nanoparticles (NPs) were prepared by crosslinking FA–CS conjugates with sodium tripolyphosphate (STPP). Positively charged FA–CS nanoparticles were spherical in shape with a particle size of about 100 nm. Cellular uptake of CS or FA–CS nanoparticles was assayed by fluorescent microscopy using calcein as fluorescent marker in colon cancer cells (HT-29). The FA–CS nanoparticles exhibited improved uptake of HT-29 and could become a potential targeted drug delivery system for colorectal cancer.     

Impact of Cross-linking and Drying Method on Drug Delivery Performance of Casein–Pectin Microparticles

Pectin is a heteropolysaccharide which has been investigated for the development of colon-specific drug delivery systems. Polymers have been associated with pectin to reduce its aqueous solubility and improve the performance of drug delivery systems. Pectin–casein interaction is widely known in food research, but it has not been fully considered by pharmaceutical scientists. Thus, this study investigated the potential of casein–pectin microparticles as a drug delivery system and clarified the impact of cross-linking and drying methods on the in vitro release of indomethacin (IND) or acetaminophen (PCT) from microparticles. Microparticles were prepared by coacervation and dried by spray or spouted bed methods. Drug recovery, in vitro drug release, size, morphology, and the thermal and diffractometric properties of dried microparticles were determined. Spray-dried non-cross-linked microparticles were able to prolong IND release, and pectin was still degraded by pectinolytic enzymes. On the other hand, glutaraldehyde cross-linking prevented the enzymatic breakdown of pectin without improving IND release. Spouted bed drying reduced IND recovery from all microparticles when compared with spray drying, thus the successful spouted bed drying of microparticles depends on the chemical characteristics of both the drug and the polymer. Release data from PCT microparticles suggested that the microparticle formulation should be improved to bring about a more efficient delivery of water-soluble drugs. In conclusion, casein–pectin microparticles show great potential as a drug delivery system because casein reduces the water solubility of pectin. The drying method and cross-linking process had significant effects on the in vitro performance of these microparticles.     

Green synthesis of silver nanoparticles using cellulose extracted from an aquatic weed; water hyacinth

As part of the desire to save the environment through “green” chemistry practices, we herein report an environmentally benign synthesis of silver nanoparticles (Ag-NPs) using cellulose extracted from an environmentally problematic aquatic weed, water hyacinth (WH), as both reducing and capping agent in an aqueous medium. By varying the pH of the solution and reaction time, the temporal evolutions of the optical and morphological properties of the as-synthesised Ag-NPs were investigated. The as-synthesised cellulose capped silver nanoparticles (C–Ag-NPs) were characterised using Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The maximum surface plasmon resonance (SPR) peak decreased as the pH increased indicating that an increase in the pH of the solution favoured the formation of smaller particles. In addition, instantaneous change in the colour of the solution from colourless to brown within 5 min at pH 11 showed that the rate of reduction is faster at this pH compared to those at lower pH. The TEM micrographs showed that the materials are small, highly monodispersed and spherical in shape. The average particle mean diameters were calculated to be 5.69 ± 5.89 nm, 4.53 ± 1.36 nm and 2.68 ± 0.69 nm nm at pH 4, 8 and 11 respectively. The HRTEM confirmed the crystallinity of the material while the FTIR spectra confirmed the capping of the as-synthesised Ag-NPs by the cellulose. It has been shown therefore that based on this synthetic method, this aquatic plant can be used to the advantage of mankind.     

Potential of a white-rot fungus Pleurotus eryngii F032 for degradation and transformation of fluorene

The white-rot fungus Pleurotus eryngii F032 showed the capability to degrade a three fused-ring aromatic hydrocarbons fluorene. The elimination of fluorene through sorption was also investigated. Enzyme production is accompanied by an increase in biomass of P. eryngii F032 during degradation process. The fungus totally degraded fluorine within 23 d at 10-mg l⁻¹ solution. Fluorene degradation was affected with initial fluorene concentrations. The highest enzyme activity was shown by laccase in the 10-mg l⁻¹ culture after 30 d of incubation (1620 U l⁻¹). Few activities of enzymes were observed in the fungal cell at the varying concentration of fluorene. Three metabolic were detected and separated in ethylacetate extract, after isolated by column chromatography. The metabolites, 9-fluorenone, phthalic acid, and benzoic acid were identified using UV–vis spectrophotometer and gas chromatography–mass spectrometry (GC–MS). The results show the presence of a complex mechanism for the regulation of fluorene-degrading enzymes.     

Proniosomal Oral Tablets for Controlled Delivery and Enhanced Pharmacokinetic Properties of Acemetacin

Free-flowing proniosomal powders of acemetacin (AC) were prepared using the slurry method and maltodextrin as carrier. Positively charged proniosomes composed of 70:20:10 of Span 60/cholesterol (Chol)/stearylamine (SA), respectively, were successively compressed into tablets using direct compression method. The tablets were characterized for weight variability, friability, hardness, drug content uniformity, and dissolution properties. The in vivo evaluation of the prepared proniosomes (powder or tablet forms) after oral administration was investigated by the determination of AC and its active metabolite indomethacin (IND) in the blood of albino rabbits. Results indicated that the increase of Chol from 10% to 20% markedly reduced the efflux of the drug. Further Chol addition from 30% to 50% led to increased AC release rates. The proniosome tablets of AC showed greater hardness and disintegration time and less friability than AC plain tablets. The dissolution of proniosomal tablets indicated a lower drug release percentage compared to powdered proniosomes and AC plain tablets. The mean pharmacokinetic parameters of AC and IND from different formulations indicated increased t_1/2 and area under the curve (AUC) of both AC and IND for proniosomal tablets compared with both proniosomal powders and AC plain tablets. This study suggested the formulation of AC proniosomal powder into tablets to control and extend its pharmacologic effects.KEY WORDS: acemetacin, proniosomes, sustained-release tablet, pharmacokinetics     

New dinuclear copper(II) and zinc(II) complexes for the investigation of sugar–metal ion interactions

We have studied the binding interactions of biologically important carbohydrates (d-glucose, d-xylose and d-mannose) with the newly synthesized five-coordinate dinuclear copper(II) complex, [Cu₂(hpnbpda)(μ-OAc)] (1) and zinc(II) complex, [Zn₂(hpnbpda)(μ-OAc)] (2) [H₃hpnbpda = N,N′-bis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine-N,N′-diacetic acid] in aqueous alkaline solution. The complexes 1 and 2 are fully characterized both in solid and solution using different analytical techniques. A geometrical optimization was made of the ligand H₃hpnbpda and the complexes 1 and 2 by molecular mechanics (MM+) method in order to establish the stable conformations. All carbohydrates bind to the metal complexes in a 1:1 molar ratio. The binding events have been investigated by a combined approach of FTIR, UV–vis and ¹³C NMR spectroscopic techniques. UV–vis spectra indicate a significant blue shift of the absorption maximum of complex 1 during carbohydrate coordination highlighting the sugar binding ability of complex 1. The apparent binding constants of the substrate-bound copper(II) complexes have been determined from the UV–vis titration experiments. The binding ability and mode of binding of these sugar substrates with complex 2 are indicated by their characteristic coordination induced shift (CIS) values in ¹³C NMR spectra for carbon atoms C1, C2, and C3 of sugar substrates.     

Study of potential binding of biologically important sugars with a dinuclear cobalt(II) complex

The investigation of the sugar–metal ion interactions remains one of the main objectives of carbohydrate coordination chemistry because the interactions between metal ions and carbohydrates are involved in many biochemical processes. The potential binding interaction between a five-coordinate dinuclear cobalt(II) complex, Na₂[Co₂(tcdc)(μ-OAc)] (1) [Na₅tcdc = Sodium-N,N,N′,N′-tetrakis(sodium carboxylate methyl)-2,6-diaminocresolate] and biologically important sugar substrates (d-glucose, d-xylose, and d-mannose) has been studied. In alkaline media, the complex 1 shows an excellent chelating ability toward these sugar substrates. A combined approach of FTIR and UV–vis spectroscopic investigations shows that the complex forms a 1:1 complex/substrate-bound product. UV–vis spectra indicate a significant blue-shift of the absorption maximum of metal complex during carbohydrate coordination highlighting the sugar binding ability of complex 1. The apparent binding constants of the substrate-bound cobalt(II) complexes have been determined from the UV–vis titration experiments.     

DDA-Based Simulation of UV?Cvis Extinction Spectra of Ag Nanorods Synthesized Through Seed-Mediated Growth Process

Present investigation demonstrates a very simple seed-mediated route for the synthesis of silver nanorods in aqueous solution. Central to the concept of seed-mediated growth of nanoparticles is that small nanoparticle seeds serve as nucleation centres to grow nanoparticles to a desired size and shape. Hydroxypropyl methyl cellulose (HPMC) has been used as soft template for one-dimensional growth of silver particles. Morphological, structural and spectral changes that are associated with the seed-mediated growth of the nanoparticles in presence of HPMC are characterized using UV–vis and HR-TEM spectroscopic study. Simulation of UV–vis extinction spectra of our synthesized silver nanorods has been carried out using discrete dipole approximation methodology. The broad red-shifted longitudinal extinction band of green-coloured silver sol has been explained, due to the presence of silver nanorods of different aspect ratios.     

A radioimmuno—chromatographic scanning method for the analysis of testosterone conjugates in urine and serum

A method for the analysis of testosterone (and 5α-dihydrotestosterone) conjugates in human serum and urine samples is described. The samples were brought to pH 1 and extracted with a diethyl ether—methanol mixture. After evaporation the residues were run in a thin-layer chromatography system, individual samples' paths were cut into 1-cm long pieces and eluted with methanol. The methanol was evaporated and the residue subjected to acid hydrolysis. The released steroid was extracted by diethyl ether and measured by radioimmunoassay. The methodology described represents a new approach to the qualitative and quantitative study of steroid conjugates in serum and urine, and can easily be applied to the study of steroid conjugates in other biological material.