Garcinol loaded vitamin E TPGS emulsified PLGA nanoparticles: preparation, physicochemical characterization, in vitro and in vivo studies

Garcinol (GAR) is a naturally occurring polyisoprenylated phenolic compound. It has been recently investigated for its biological activities such as antioxidant, anti-inflammatory, anti ulcer, and antiproliferative effect on a wide range of human cancer cell lines. Though the outcomes are very promising, its extreme insolubility in water remains the main obstacle for its clinical application. Herein we report the formulation of GAR entrapped PLGA nanoparticles by nanoprecipitation method using vitamin E TPGS as an emulsifier. The nanoparticles were characterized for size, surface morphology, surface charge, encapsulation efficiency and in vitro drug release kinetics. The MTT assay depicted a high amount of cytotoxicity of GAR-NPs in B16F10, HepG2 and KB cells. A considerable amount of cell apoptosis was observed in B16f10 and KB cell lines. In vivo cellular uptake of fluorescent NPs on B16F10 cells was also investigated. Finally the GAR loaded NPs were radiolabeled with technetium-99m with >95% labeling efficiency and administered to B16F10 melanoma tumor bearing mice to investigate the in vivo deposition at the tumor site by biodistribution and scintigraphic imaging study. In vitro cellular uptake studies and biological evaluation confirm the efficacy of the formulation for cancer treatmen

Tricarbonyl 99mTc(I) and Re(I)–thiosemicarbazone complexes: synthesis, characterization and biological evaluation for targeting bacterial infection

Methyl, ethyl and phenyl nitrofuryl thiosemicarbazone ligands (1, 2 and 3 respectively) were radiolabeled with freshly prepared aqueous solution of a fac[99mTc(CO)3(H2O)3]+ precursor. The radiochemical yield was around 98% as determined by thin layer chromatography and HPLC. The complexes exhibited substantial stability. The corresponding Re(I) complexes were prepared from a Re(CO)5Br precursor to understand the coordination behavior of the ligands against a tricarbonyl rhenium(I) precursor. The rhenium(I) complexes were characterized by means of IR, NMR and mass spectroscopic studies as well as by X-ray crystallography, and correlated with the technetium complexes by means of HPLC studies. Electrochemical reduction of monomeric Re(CO)3-complexes of nitrofuryl ethyl thiosemicarbazone was also studied using cyclic voltammetry. Biodistribution studies of 99mTc(CO)3-labeled thiosemicarbazones in rats intramuscularly infected with S. aureus exhibited substantial in vivo stability of the complex and moderate accumulation at the site of focal infectio

Synthesis, Characterization, and Biological Evaluation of 99mTc(CO)3-Labeled Peptides for Potential Use as Tumor Targeted Radiopharmaceuticals

During the past decade, several peptides containing Arg-Gly-Asp sequence have been conjugated with different chelating agents for labeling with various radionuclides for the diagnosis of tumor development. In this study, we report the synthesis of two tetrapeptides (Asp-Gly-Arg-His and Asp-Gly-Arg-Cys) and one hexapeptide [Asp-Gly-Arg-D-Tyr-Lys-His] by changing the amino acid sequence of the Arg-Gly-Asp motif. Peptide synthesis was initiated from aspartic acid. Aspartic acid placed at C-terminal end of the peptide chain can be conjugated with different drug molecules facilitating their transport to the site of action. The peptides were synthesized in excellent yield and labeled using freshly prepared [99mTc(CO)3(H2O)3]+ intermediate. A complexation yield of over 97% was achieved under mild conditions even at low ligand concentrations of 10�2 M. Radiolabeled peptides were characterized by HPLC and were found to be substantially stable in saline, in His solution as well as in rat serum and tissue (kidney, liver) homogenates. Internalization studies using Ehrlich ascites carcinoma cell line showed rapid and significant internalization (30–35% at 30 min of incubation attaining maximum value of about 40–60% after 2–4 h incubation). A good percentage of quick internalization was also observed in avb3-receptor-positive B16F10 mouse melanoma cell line (14–16% after 30 min of incubation and 25–30% after 2–4 h incubation). Imaging and biodistribution studies were performed in Swiss albino mice bearing Ehrlich ascites tumor in right thigh. Radiolabeled peptides exhibited fast blood clearance and rapid elimination through the urinary systems. 99mTc(CO)3-tetra-Pep2 exhibited remarkable localization at tumor site (1.15%, 1.17%, and 1.37% ID/g at 2, 4, and 6 h p.i., respectively) which could be due to slow clearance of the radiolabeled peptide from blood in comparison with the other two radiolabeled peptides. However, 99mTc(CO)3-hexa-Pep exhibited the highest tumor to muscle and tumor to blood ratios among the three. The preliminary results with these amino acid–based peptides are encouraging enough to carry out further experiments for targeting tumor

Development and Physical Characterization of Chloramphenicol Loaded Biodegradable Nanoparticles for Prolonged Release

The objectives of our study were to prepare a biodegradable nanoparticulate system of chloramphenicol (CHL) and to evaluate its ability to prolong in vitro release of CHL compared to free drug suspension (FDS). CHL-loaded polylactide-co-glycolide nanoparticles (CHL-PLGA-NPs) were prepared by an emulsion/solvent evaporation method using ethyl acetate and polyvinyl alcohol. CHL-PLGA-NPs were characterized by particle size, zeta potential, infrared spectra, drug entrapment efficiency and in vitro release kinetics measurement. Sonication was done with an ultrasound pulse sonicator at 70 W, 30 kHz for 60 s to produce stable NPs of mean size range from 277 nm to 433 nm. Drug to polymer ratio (D : P) was selected as formulation variable and significantly influenced entrapment efficiency (�30% to 66%) and release (p < 0.05). Entrapment of CHL in biodegradable NPs significantly prolonged drug release compared to FDS and thus implies potential antibiotic delivery system for ocular application

Chloramphenicol-Incorporated Poly Lactide-co-Glycolide (PLGA) Nanoparticles: Formulation, Characterization, Technetium-99m Labeling and Biodistribution Studies

Chloramphenicol-loaded (CHL) poly-D,L-lactic-co-glycolic acid (PLGA) nanoparticles (NPs) were prepared by emulsification solvent evaporation technique either by using polyvinyl alcohol (PVA) as emulsion stabilizer or polysorbate- 80 (PS-80) as surfactant and characterised by transmission electron microscopy, zeta-potential measurements. The NPs were radiolabeled with technetium-99m (99mTc) by stannous reduction method. Labeling conditions were optimised to achieve high-labeling efficiency, in vitro and in vivo (serum) stability. The labeled complexes also showed very low transchelation as determined by DTPA challenge test. Biodistribution studies of 99mTc-labeled complexes were performed after intravenous administration in mice. The CHL-loaded PLGA NPs coated with PS-80 exhibited relatively high brain uptake with comparatively low accumulation in bone marrow to that of free drug and CHL-loaded PLGA NPs (PVA, used as emulsion stabilizer) at 24 h post injection time period. This indicates the usefulness of the above delivery system for prolonged use of the antibiotic

Exploring the Potential of 99mTc(CO)3-Labeled Triazolyl Peptides for Tumor Diagnosis

In recent years the authors have reported on 99mTc(CO)3-labeled peptides that serve as carriers for biomolecules or radiopharmaceuticals to the tumors. In continuation of that work they report the synthesis of a pentapeptide (Met-Phe-Phe-Gly-His; pep-1), a hexapeptide (Met-Phe-Phe-Asp-Gly-His; pep-2), and a tetrapeptide (Asp-Gly- Arg-His; pep-3) and the attachment of 3-amino-1,2,4-triazole to the b carboxylic function of the aspartic acid unit of pep-2 and pep-3. The pharmacophores were radiolabeled in high yields with [99mTc(CO)3(H2O)3]+ metal aqua ion, characterized for their stability in serum and saline, as well as in His solution, and found to be substantially stable. B16F10 cell line binding studies showed favorable uptake and internalization. In vivo behavior of the radiolabeled triazolyl peptides was assessed in mice bearing induced tumor. The 99mTc(CO)3- triazolyl pep-3 demonstrated rapid urinary clearance and comparatively better tumor uptake. Imaging studies showed visualization of the tumor using 99mTc(CO)3-triazolyl pep-3, but due to high abdominal background, low delineation occurred. Based on the results further experiments will be carried out for targeting tumor with triazolyl peptide

99mTc-Labeling of Ciprofloxacin and Nitrofuryl Thiosemicarbazone Using Fac-[99mTc(CO)3(H2O)3] Core: Evaluation of Their Efficacy as Infection Imaging Agents

The aim of this study was to radiolabel ciprofloxacin (Cip) and nitrofuryl thiosemicarbazone (NFT) with the fac-[99mTc(CO)3(H2O)3]+ core and to evaluate the ability of the radiopharmaceuticals as tracers in detecting sites of infection. Cip and NFT were radiolabeled with the fac-[99mTc(CO)3(H2O)3]+ core and characterized by RHPLC. The stabilities of the preparations were evaluated in saline and rat serum. In vitro binding studies of the radiopharmaceuticals with S. aureus were performed. Biodistribution studies were conducted at different time points after injecting (i.v.) the radiopharmaceuticals in rats (intramuscularly infected with S. aureus) as well as in rats with sterile inflammation. To assess the infection targeting capacity of 99mTc-tricarbonyl ciprofloxacin and nitrofuryl thiosemicarbazone, 99mTc(V)O-Cip and 99mTc(V)O-NFT were used as control. Scintigraphic imaging studies of tricarbonyl compounds and 99mTc(V)O-Cip were performed at 4 h after injection. The radiochemical purities of 99mTc(CO)3-Cip and 99mTc(CO)3-NFT were between 97–98% as determined by thin layer chromatography (TLRC) and RHPLC; no further purification is necessary before injection. The radiopharmaceuticals exhibited substantial stability when incubated in isotonic saline and serum up to 24 h. Biodistribution studies showed maximum uptake in the infected rat thigh muscle at 4 h post injection and washing out at slower rate from the infected site than the oxo technetium chelate. The mean ratios of uptake in infected/non–infected thighs were 3.87 : 1, 3.41 : 1 and 3.17 : 1 for 99mTc(CO)3-Cip, 99mTc(CO)3-NFT and 99mTc(V)O-Cip respectively. During scintigraphic studies, infection sites appeared quite distinctly with 99mTc(CO)3-Cip and 99mTc(CO)3-NFT, comparable to the behaviour with 99mTc(V)O-Cip. These results encouraged us for further development of infection imaging radiopharmaceuticals based on the 99mTc-tricarbonyl core

Lipid-based nanocarrier efficiently delivers highly water soluble drug across the blood–brain barrier into brain

Delivering highly water soluble drugs across blood–brain barrier (BBB) is a crucial challenge for the formulation scientists. A successful therapeutic intervention by developing a suitable drug delivery system may revolutionize treatment across BBB. Efforts were given here to unravel the capability of a newly developed fatty acid combination (stearic acid:oleic acid:palmitic acid = 8.08:4.13:1) (ML) as fundamental component of nanocarrier to deliver highly water soluble zidovudine (AZT) as a model drug into brain across BBB. A comparison was made with an experimentally developed standard phospholipid-based nanocarrier containing AZT. Both the formulations had nanosize spherical unilamellar vesicular structure with highly negative zeta potential along with sustained drug release profiles. Gamma scintigraphic images showed both the radiolabeled formulations successfully crossed BBB, but longer retention in brain was observed for ML-based formulation (MGF) as compared to soya lecithin (SL)-based drug carrier (SYF). Plasma and brain pharmacokinetic data showed less clearance, prolonged residence time, more bioavailability and sustained release of AZT from MGF in rats compared to those data of the rats treated with SYF/AZT suspension. Thus, ML may be utilized to successfully develop drug nanocarrier to deliver drug into brain across BBB, in a sustained manner for a prolong period of time and may provide an effective therapeutic strategy for many diseases of brain. Further, many anti-HIV drugs cannot cross BBB sufficiently. Hence, the developed formulation may be a suitable option to carry those drugs into brain for better therapeutic management of HIV

Evaluation of 99mTc(I)-tricarbonyl complexes of fluoroquinolones for targeting bacterial infection

The aim of this study was to develop 99mTc(CO)3-labeled fluoroquinolones as novel SPECT radiopharmaceuticals for imaging bacterial infection. Fluoroquinolones, e.g., ofloxacin (OFX), levofloxacin (LVX), lomefloxacin (LMX) and norfloxacin (NFX) were labeled with a fac-[99mTc(CO)3(H2O)3]+ precursor. The radiochemical purity of the radiopharmaceuticals exceeded 97% as determined by thin layer chromatography and HPLC. No further purification was necessary before injection. The Re(CO)3 complex of one of the fluoroquinolones (levofloxacin) was synthesized using [Re(CO)3(H2O)3]OTf and Re(CO)5Br precursors in separate experiments and characterized by IR, NMR and mass spectroscopic analysis. These studies revealed the formation of a single species in which the piperazinyl nitrogen and the –COOH group attached to the benzoxazine ring system of quinolone were involved in co-ordination to the Re(CO)3 core. The HPLC elution pattern and retention time of the Re(CO)3-LVX complex were comparable to those of the corresponding 99mTc(CO)3-complex proving their similarity. When incubated in isotonic saline and serum up to 24 h 99mTc(CO)3-labeled fluoroquinolones exhibited good in vitro stability. Biodistribution studies performed at different time points on rats intramuscularly infected with S. aureus as well as on rats with sterile inflammation revealed a higher uptake in the infected area than the turpentine induced inflamed area. The uptake in infected thigh was significant with 99mTc(CO)3-OFX followed by 99mTc(CO)3-LVX. The mean ratios of the uptake in infected/non-infected thighs were 4.75 and 4.27 at 8 h and 24 h, respectively, for 99mTc(CO)3-OFX and 4.42 and 4.18 at 24 h and 8 h, respectively, for 99mTc(CO)3-LVX. The above abscess to muscle ratios were higher than reported for 99mTc-ciprofloxacin and other 99mTc-labeled fluoroquinolones. Scintigraphy studies also showed a significant uptake in the infectious lesions suggesting that 99mTc(CO)3-fluoroquinolones might be useful as diagnostic agents for targeted delivery in bacterial infection

Preparation, Characterization, and Biodistribution of Letrozole Loaded PLGA Nanoparticles in Ehrlich Ascites Tumor Bearing Mice

Letrozole (LTZ) incorporated PLGA nanoparticles were prepared by solvent displacement technique and characterized by transmission electron microscopy, poly-dispersity index and zeta potential measurement. Radiolabeling of free LTZ and LTZ-loaded PLGA NPs was performed with technetium-99m with high labeling efficiency. The labeled complex showed good in vitro stability as verified by DTPA challenge test. The labeled complexes also showed significant in vivo stability when incubated in rat serum for 24 h. Biodistribution studies of 99mTc-labeled complexes were performed after intravenous administration in normal mice and Ehrlich Ascites tumor bearing mice. Compared to free LTZ, LTZ-loaded PLGA NPs exhibited significantly lower uptake by the organs of RES. The tumor concentration of LTZ-loaded PLGA NPs was 4.65 times higher than that of free LTZ at 4 h post-injection. This study indicates the capability of PLGA nanopartcles in enhancing the tumor uptake of letrozole