Mita Chatterjee Debnath

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 (99m)Tc-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.

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.

Tryptamine-gallic acid hybrid prevents non-steroidal anti-inflammatory drug-induced gastropathy: correction of mitochondrial dysfunction and inhibition of apoptosis in gastric mucosal cells.

Background: Non-steroidal anti-inflammatory drugs (NSAIDs) induce gastropathy by promoting mitochondrial pathology, oxidative stress, and apoptosis in gastric mucosal cells. Results: We have synthesized SEGA (3a), a tryptamine-gallic acid hybrid, which prevents NSAID-induced gastropathy by preventing mitochondrial oxidative stress, dysfunction, and apoptosis. Conclusion: SEGA (3a) bears an immense therapeutic potential against NSAID-induced gastropathy. Significance: This novel molecule is a significant addition in the discovery of gastroprotective drugs. We have investigated the gastroprotective effect of SEGA (3a), a newly synthesized tryptamine-gallic acid hybrid molecule against non-steroidal anti-inflammatory drug (NSAID)-induced gastropathy with mechanistic details. SEGA (3a) prevents indomethacin (NSAID)-induced mitochondrial oxidative stress (MOS) and dysfunctions in gastric mucosal cells, which play a pathogenic role in inducing gastropathy. SEGA (3a) offers this mitoprotective effect by scavenging of mitochondrial superoxide anion (O2̇̄) and intramitochondrial free iron released as a result of MOS. SEGA (3a) in vivo blocks indomethacin-mediated MOS, as is evident from the inhibition of indomethacin-induced mitochondrial protein carbonyl formation, lipid peroxidation, and thiol depletion. SEGA (3a) corrects indomethacin-mediated mitochondrial dysfunction in vivo by restoring defective electron transport chain function, collapse of transmembrane potential, and loss of dehydrogenase activity. SEGA (3a) not only corrects mitochondrial dysfunction but also inhibits the activation of the mitochondrial pathway of apoptosis by indomethacin. SEGA (3a) inhibits indomethacin-induced down-regulation of bcl-2 and up-regulation of bax genes in gastric mucosa. SEGA (3a) also inhibits indometacin-induced activation of caspase-9 and caspase-3 in gastric mucosa. Besides the gastroprotective effect against NSAID, SEGA (3a) also expedites the healing of already damaged gastric mucosa. Radiolabeled (99mTc-labeled SEGA (3a)) tracer studies confirm that SEGA (3a) enters into mitochondria of gastric mucosal cell in vivo, and it is quite stable in serum. Thus, SEGA (3a) bears an immense potential to be a novel gastroprotective agent against NSAID-induced gastropathy.

Pulmonary Delivery of Voriconazole Loaded Nanoparticles Providing a Prolonged Drug Level in Lungs: A Promise for Treating Fungal Infection.

Current therapies are insufficient to prevent recurrent fungal infection especially in the lower part of the lung. A careful and systematic understanding of the properties of nanoparticles plays a significant role in the design, development, optimization, and in vivo performances of the nanoparticles. In the present study, PLGA nanoparticles containing the antifungal drug voriconazole was prepared and two best formulations were selected for further characterization and in vivo studies. The nanoparticles and the free drug were radiolabeled with technetium-99m with 90% labeling efficiency, and the radiolabeled particles were administered to investigate the effect on their blood clearance, biodistribution, and in vivo gamma imaging. In vivo deposition of the drug in the lobes of the lung was studied by LC-MS/MS study. The particles were found to be spherical and had an average hydrodynamic diameter of 300 nm with a smooth surface. The radiolabeled particles and the free drug were found to accumulate in various major organs. Drug accumulation was more pronounced in the lung in the case of administration of the nanoparticles than that of the free drug. The free drug was found to be excreted more rapidly than the nanoparticle containing drug following the inhalation route as assessed by gamma scintigraphy study. Thus, the study reveals that pulmonary administration of nanoparticles containing voriconazole could be a better therapeutic choice even as compared to the iv route of administration of the free drug and/or the drug loaded nanoparticles.

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-[(99m)Tc(CO)(3)(H(2)O)(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-[(99m)Tc(CO)(3)(H(2)O)(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 (99m)Tc-tricarbonyl ciprofloxacin and nitrofuryl thiosemicarbazone, (99m)Tc(v)O-Cip and (99m)Tc(v)O-NFT were used as control. Scintigraphic imaging studies of tricarbonyl compounds and (99m)Tc(v)O-Cip were performed at 4 h after injection. The radiochemical purities of (99m)Tc(CO)(3)-Cip and (99m)Tc(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 (99m)Tc(CO)(3)-Cip, (99m)Tc(CO)(3)-NFT and (99m)Tc(v)O-Cip respectively. During scintigraphic studies, infection sites appeared quite distinctly with (99m)Tc(CO)(3)-Cip and (99m)Tc(CO)(3)-NFT, comparable to the behaviour with (99m)Tc(v)O-Cip. These results encouraged us for further development of infection imaging radiopharmaceuticals based on the (99m)Tc-tricarbonyl core.

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 αvβ3‐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.

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 treatment.

Synthesis and evaluation of technetium-99m-labeled bioreductive pharmacophores conjugated with amino acids and peptides for tumor imaging.

Development of molecular imaging agents to target tumor has become a major trend in nuclear medicine. With the aim to develop new potential 99mTc‐radiopharmaceuticals for targeting tumor, we have synthesized 5‐nitroimidazolyl amino acids and RGD‐coupled 2‐nitroimidazoles. Technetium‐99m radiolabeling with high radiochemical purity (>90%) was achieved for all the compounds. The radiolabeled complexes exhibited substantial in vitro stability in saline, serum, and histidine solution (10−2 m). Cell binding studies in EAC and B16F10 cell lines also revealed rapid and comparatively high cellular internalization. Among all the compounds studied, the binding of 99mTc(CO)3‐5 to B16F10 cells was moderately inhibited by the competitive peptide c[RGDfV], suggesting specificity of the radioligand toward αvβ3 receptor. However, no significant displacement of bound radioligand was observed when the binding of the 99mTc‐labeled complexes to above cells was challenged with excess competitive peptide. Fluorescent microscopy study provided direct evidence of intracellular localization of 5(6)‐carboxyfluorescein‐labeled 2‐nitroimidazolyl‐RGD‐peptide in αvβ3‐positive B16F10 mouse melanoma cell line. The ligands caused only 8–13% of hemolysis toward rat erythrocytes at concentrations as high as 100 μm. Imaging and biodistribution studies were performed in Swiss albino mice bearing induced tumor. 99mTc‐1 and 99mTc(CO)3‐5 demonstrated a very favorable in vivo profile. Selective uptake and retention in tumor with encouraging tumor/muscle and tumor/blood ratio and significant cellular uptake of fluorescence‐labeled‐2‐nitroimidazolyl RGD indicate the great potentiality of the pharmacophore for further evaluation as potential molecular imaging agent in cancer diagnosis.

Lipid nanocarrier-based transport of docetaxel across the blood brain barrier

Successful treatment of brain cancer remains a formidable challenge in neuroscience research due to sub-therapeutic permeation of conventional chemotherapeutics across the blood–brain barrier (BBB). By optimizing various conditions and process parameters, we developed a phospholipid based nanosize carrier (NL) encapsulating docetaxel (DTX) and investigated its BBB crossing potential, both qualitatively and quantitatively, in vivo. The optimized NLs had a nanosize below 100 nm, smooth surface with intact lamellarity, 7.8% drug loading and a sustained drug release profile in vitro. Pharmacokinetic and biodistribution data showed an enhanced residence time of the drug in blood and efficient permeation of the drug from the DTX loaded NL through the BBB, as compared to free DTX. The technetium-99m labeled NL effectively crossed the BBB and accumulated in the brain tissue in a time dependant manner compared to technetium-99m labeled DTX. NL may provide a promising platform for an improved management of brain cancer.

Preparation and evaluation of [166Ho] holmium-dimethyl diethylenetriaminepentaaceticacid (DMDTPA) as potential radiopharmaceutical for endovascular radiation therapy (EVRT)

Holmium-166 with its favorable radiation characteristics could be used in endovascular radionuclide therapy (EVRT) technique in liquid filled low-pressure balloon angioplasty. 166Ho-dimethyl di ethylene triamine penta acetic acid (DMDTPA) was prepared and its biodistribution carried out to evaluate its suitability as an EVRT formulation. DMDTPA was synthesized, characterized and was complexed with 166Ho. The complex was stable at 37 degrees C in human serum environment and at room temperature for 48 h. Biodistribution studies in mice revealed rapid renal clearance (approximately 90% of the injected dose in 30 min p.i.) with insignificant retention in any of the major organs including bone. The studies show that 166Ho-DMDTPA is a good formulation which can be explored as an EVRT source.