The Preparation of Curcumin-Loaded Pickering Emulsion Using Gelatin-Chitosan Colloidal Particles as Emulsifier for Possible Application as a Bio-Inspired Cosmetic Formulation.

In the field of preparing cosmetic formulations, recent advances recommend the usage of excipients derived from biocompatible materials. In this context, the present study aimed to prepare and characterize the curcumin-loaded Pickering emulsion for possible applications in cosmetic formulation. The coconut oil which is often the component of skin care formulations is used as the oily phase. Curcumin, which is well known for absorbing solar radiation, is expected to work synergistically with coconut oil towards improving the sun protection factor (SPF) of the formulation. Additionally, curcumin can also protect the intracellular components through its well-known antioxidant mechanisms. The Pickering emulsion of coconut oil into water was prepared using the composite colloidal particles derived from ß-carboxymethyl chitosan (CMC) and Gelatin-A (GA) as the emulsifying agent. The reaction conditions in terms of the weight ratios of CMC and GA, the pH of the reaction medium, the oil volume fraction, and the homogenization speed were optimized to obtain the most stable Pickering emulsion. The obtained systems were physico-chemically characterized by dynamic light scattering, zeta potential, optical microscopy, and rheometric measurements. The final CMC-GA-stabilized emulsion demonstrated an oil droplet size of 100 µm and a SPFspectrophotometric (290-320 nm) value of 8.5 at a curcumin loading of 4 mg/mL. Additionally, the final formulation facilitated the uptake of curcumin into fibroblast (WI26) cells under in vitro conditions. Together, the investigation demonstrates a bio-inspired approach to prepare a curcumin-loaded green Pickering emulsion using biocompatible pharmaceutical grade excipients, which may find utility in cosmetic applications.

Alginate and Chitosan-Based Delivery Systems for Improving the Bioavailability and Therapeutic Efficacy of Curcumin.

One of the major challenges in harnessing the therapeutic benefits of curcumin (an active ingredient from turmeric) is its poor bioavailability due to its short biological half-life. In this regard, nanoformulations have shown tremendous hope for improving the pharmacokinetic and therapeutic behavior of curcumin by altering its biological stability and bioavailability. Biopolymers, especially alginate and chitosan, have received special attention as excipients to prepare nanoformulations of curcumin due to their abundant availability, biocompatibility, and amicability to form different types of self-assembled structures and ease of undergoing chemical modifications. However, there are certain challenges, such as poor water solubility under physiological conditions and heterogeneity with regard to molecular weight and large-scale production of well-preserved nanostructures. Substantial advancement has been achieved towards overcoming these challenges by developing newer derivatives through a chemical modifications approach, and this has ascertained the suitability of alginate and chitosan as excipients for drug delivery systems (DDS). The present minireview briefly discusses curcumin and its limitation as a drug molecule, carbohydrates as DDS, and the recent developments related to the alginate and chitosan-based nanoformulations of curcumin. Special emphasis has been given to highlighting the impact of alginate and chitosan-based nanoformulations in improving the therapeutic efficacy and bioavailability of curcumin.

Post-radiation treatment of 3,3'-diselenodipropionic acid augments cell kill by modulating DNA repair and cell migration pathways in A549 cells.

Aim of the present study was to test whether ionizing radiation (IR) treatment along with 3,3'-diselenodipropionic acid (DSePA), a redox active organodiselenide achieved better tumor control by suppressing the growth and migration of lung cancer cells. The results indicated that post-IR (2 Gy) treatment of DSePA (5 µM) led to a significantly higher cell death as compared to that of DSePA and IR treatments separately. Importantly, combinatorial treatment also showed reduction in the proportion of cancer stem cells and the clonogenic survival of A549 cells. The mechanistic studies indicated that combinatorial treatment although exhibited reductive environment (marked by decrease in ROS and increase of GSH/GSSG) at early time points (2-6 h postradiation), slowed DNA repair, inhibited epithelial-mesenchymal transition (EMT)/cell migration and induced significant level of apoptosis. DSePA mediated suppression of ATM/DNAPKs/p53 (DNA damage response signaling) and Akt/G-CSF (EMT) pathways appeared to be the major mechanism responsible for its radio-modulating activity. Finally, the combined treatment of IR (2 Gy × 4) and DSePA (0.1-0.25 mg/kg body weight daily through oral gavage) showed a significantly higher tumor suppression of the A549 xenograft as compared to that of DSePA and IR treatments separately in the mouse model. In conclusion, post-IR treatment of DSePA augmented cell kill by inhibiting DNA repair and cell migration in A549 cells.

Red light-activable biotinylated copper(II) complex-functionalized gold nanocomposite (Biotin-Cu@AuNP) towards targeted photodynamic therapy.

We report the synthesis and characterization of red-light activable gold nanoparticle functionalized with biotinylated copper(II) complex of general molecular formula, [Cu(L3)(L6)]-AuNPs (Biotin-Cu@AuNP), where L3 = N-(3-((E)-3,5-di-tert-butyl-2-hydroxybenzylideneamino)-4-hydroxyphenyl)-5-((3aS,4S,6aR)-2-oxo-hexahydro-1H-thieno[3,4-d]imidazol-4-yl)pentanamide, L6 = 5-(1,2-dithiolan-3-yl)-N-(1,10-phenanthrolin-5-yl)pentanamide, which was explored for their photophysical, theoretical and photo-cytotoxic potentials. The nanoconjugate exhibits differential uptake in biotin positive and biotin negative cancer cells as well as normal cells. The nanoconjugate also shows remarkable photodynamic activity against biotin positive A549 (IC50: 13 µg/mL in red light; >150 µg/mL in dark) and HaCaT (IC50: 23 µg/mL in red light; >150 µg/mL in dark) cells under red light (600-720 nm, 30 Jcm-2) irradiation, with significantly high photo-indices (PI>15). The nanoconjugate is less toxic to HEK293T (biotin negative) and HPL1D (normal) cells. Confocal microscopy confirms preferential mitochondrial and partly cytoplasmic localization of Biotin-Cu@AuNP in A549 cells. Several photo-physical and theoretical studies reveal the red light-assisted generation of singlet oxygen (1O2) (Ф (1O2) =0.68) as a reactive oxygen species (ROS) which results in remarkable oxidative stress and mitochondrial membrane damage, leading to caspase 3/7-dependent apoptosis of A549 cells. Overall, the nanocomposite (Biotin-Cu@AuNP) exhibiting red light-assisted targeted photodynamic activity has emerged as the ideal next generation PDT agents.

3,3'-Diselenodipropionic acid immobilised gelatin gel: a biomimic catalytic nitric oxide generating material for topical wound healing application.

Nitric oxide (NO) plays a pivotal role in the wound healing process and promotes the generation of healthy endothelium. In this work, a simple method has been developed for fabricating a diselenide grafted gelatin gel, which reduces NO donors such as S-nitroso-N-acetylpenicillamine (SNAP) by glutathione peroxidase-like mechanism to produce NO. Briefly, the process involved covalently conjugating 3,3'-diselenodipropionic acid (DSePA) with gelatin via carbodiimide coupling. The resulting gelatin-DSePA conjugate (G-Se-Se-G) demonstrated NO production upon incubation with SNAP and glutathione (GSH) with the flux of 4.8 ± 0.6 nmol cm-2 min-1 and 1.6 ± 0.1 nmol cm-2 min-1 at 10 min and 40 min, respectively. The G-Se-Se-G recovered even after 5 days of incubation with the reaction mixture retaining catalytic activity up to 74%. Subsequently, G-Se-Se-G was suspended (5% w/v) in water with lecithin (6% w/w of gelatin) and F127 (3% w/w of gelatin) to prepare gel through temperature dependant gelation method. The fabricated G-Se-Se-G gel exhibited desirable rheological characteristics and excellent mechanical stability under storage conditions and did not cause any significant toxicity in normal human keratinocytes (HaCaT) and fibroblast cells (WI38) up to 50 µg ml-1 of selenium equivalent. Finally, mice studies confirmed that topically applied G-Se-Se-G gel and SNAP promoted faster epithelization and collagen deposition at the wound site. In conclusion, the development of a biomimetic NO generating gel with sustained activity and biocompatibility was achieved.

Diselenide-derivative of 3-pyridinol targets redox enzymes leading to cell cycle deregulation and apoptosis in A549 cells.

The aim of present study was to understand the mechanism of action of 2,2'-diselenobis(3-pyridinol) or DISPOL in human lung cancer (A549) cells. A549 cells were treated with 10 µM (∼IC50) of DISPOL for varying time points to corelate the intracellular redox changes with its cytotoxic effect. The results indicated that DISPOL treatment led to a time dependant decrease in the basal level of reactive oxygen species (ROS). Additionally, DISPOL treatment elevated the ratio of reduced (GSH) and oxidised (GSSG) glutathione by upregulating gamma-glutamylcysteine ligase (γ-GCL) involved in GSH biosynthesis and inhibiting the activities of redox enzymes responsible for GSH utilization and recycling, such as glutathione-S-transferase (GST) and glutathione reductase (GR). Molecular docking analysis suggests putative interactions of DISPOL with GST and GR which could account for its inhibitory effect on these enzymes. Further, DISPOL induced reductive environment preceded G1 arrest and apoptosis as evidenced by decreased expression of cell cycle genes (Cyclin D1 and Cyclin E1) and elevation of p21 and apoptotic markers (cleaved caspase 3 and cleaved PARP). The combinatorial experiments involving DISPOL and redox modulatory agents such as N-acetylcysteine (NAC) and buthionine sulfoximine (BSO) indeed confirmed the role of reductive stress in DISPOL-induced cell death. Finally, Lipinski's rule suggests attributes of drug likeness in DISPOL. Taken together, DISPOL exhibits a novel mechanism of reductive stress-mediated cell death in A549 cells that warrants future exploration as anticancer agent.

Gelatin-lecithin-F127 gel mediated self-assembly of curcumin vesicles for enhanced wound healing.

Curcumin, a principal component of Curcuma longa, has a long history of being used topically for wound healing. However, poor aqueous solubility of curcumin leads to poor topical absorption. Recently, gelatin based gel has been reported to overcome this issue. However, the release of curcumin from gelatin gel in the bioavailable or easily absorbable form is still a challenge. The present study reports the development of a composite gel prepared from gelatin, F127 and lecithin using temperature dependant gelation and loading of curcumin within it. Notably, the composite gel facilitated the release of curcumin entrapped within vesicles of ~400 nm size. Further, the composite gel exhibited increase in the storage modulus or gel strength, stability, pore size and hydrophobicity as compared to only gelatin gel. Finally, wound healing assay in murine model indicated that curcumin delivered through composite gel showed a significantly faster healing as compared to that delivered through organic solvent. This was also validated by histopathological and biochemical analysis showing better epithelization and collagen synthesis in the group dressed with curcumin containing composite gel. In conclusion, composite gel facilitated the release of bioavailable or easily absorbable curcumin which in turn enhanced the wound healing.

Highly stable spherical shaped and blue photoluminescent cyclodextrin-coated tellurium nanocomposites prepared by in situ generated solvated electrons: a rapid green method and mechanistic and anticancer studies.

Highly stable blue photoluminescent tellurium nanocomposites (Te NCs) coated with a molecular assembly of α-cyclodextrin (α-CD) have been prepared by using in situ generated solvated electrons (esol-) in the reaction media. The methodology used is rapid and green as the preparation of colloids was over in a matter of a few seconds and no hazardous agents (reducing or stabilizing) were used. Furthermore, fine control over the size of Te NCs has been demonstrated by simply varying the absorbed irradiation dose. As a matter of fact, the anisotropic property exhibited by tellurium makes it difficult to control the phase and morphology of its nanomaterials. However, unlike the majority of the previous reports, Te NCs formed by the current approach were amorphous and spherical shaped. Another interesting aspect of this work is the cyan-blue photoluminescence (PL) exhibited by the NCs. Systematic photophysical investigations indicated bandgap radiative decay as the origin of photoluminescence. A compositional analysis indicated the presence of Te(0) along with tellurium oxides (TeOx). TGA studies revealed the formation of a dense coating (∼55%) of α-CD molecules on the NCs. Pulse radiolysis-based studies evidenced the formation of Te-based transients by the solvated electron-induced reaction. Importantly, no interference of α-CD was observed in the kinetics of the transient species. Remarkable concentration-dependent killing was observed only in the case of cancerous cells, while no such trend was seen in normal healthy cells. This is a significant observation that can be utilized to achieve differential toxicity of Te nanomaterials in tumor versus normal cells.

Balancing loading, cellular uptake, and toxicity of gelatin-pluronic nanocomposite for drug delivery: Influence of HLB of pluronic.

In this study, pluronic stabilized gelatin nanocomposite of varying hydrophilic-lipophilic balance (HLB) were synthesized to study the effect of surface hydrophobicity on their cellular uptake and in turn the delivery of a model hydrophobic bioactive compound, curcumin (CUR). Notably, the variation in HLB from 22 to 8 did not cause much change in morphology (~spherical) and surface charge (~ -6.5 mV) while marginally reducing the size of nanocomposite from 165 ± 097 nm to 134 ± 074 nm. On contrary, nanocomposites exhibited a very significant increase in their numbers, hydrophobicity as well as CUR loading with decreasing HLB values (22-8) of pluronic. Further, the cellular uptake of CUR through pluronic-gelatin nanocomposites was studied in human lung carcinoma (A549) cells. The results indicated that cellular uptake of CUR through nanocomposites followed the order HLB 22 > HLB 18 > HLB 15 > HLB 8. This was also reflected in terms of the decrease in cytotoxicity of CUR through nanocomposite of HLB 8 as compared to that of HLB 22. Interestingly, bare nanocomposite of HLB 8 showed significantly higher cytotoxicity as compared to that of HLB 22. Together these results suggested that although higher hydrophobicity of the gelatin-pluronic nanocomposite facilitated higher entrapment of CUR, the carrier per se became toxic due to its hydrophobic interaction with lipid bilayer of plasma membrane. Thus, HLB parameter is very important in designing hybrid nanocomposite systems involving protein and pluronic to ensure both bio-compatibility of the carrier and the optimum cellular delivery of the pay load.

Iron(III) Complex-Functionalized Gold Nanocomposite as a Strategic Tool for Targeted Photochemotherapy in Red Light.

Iron(III)-phenolate/carboxylate complexes exhibiting photoredox chemistry and photoactivated reactive oxygen species (ROS) generation at their ligand-to-metal charge-transfer (LMCT) bands have emerged as potential strategic tools for photoactivated chemotherapy. Herein, the synthesis, in-depth characterization, photochemical assays, and remarkable red light-induced photocytotoxicities in adenocarcinomic human immortalized human keratinocytes (HaCaT) and alveolar basal epithelial (A549) cells of iron(III)-phenolate/carboxylate complex of molecular formula, [Fe(L1)(L2)] (1), where L1 is bis(3,5 di-tert-butyl-2-hydroxybenzyl)glycine and L2 is 5-(1,2-dithiolan-3-yl)-N-(1,10-phenanthroline-5-yl)pentanamide, and the gold nanocomposite functionalized with complex 1 (1-AuNPs) are reported. There was a significant red shift in the UV-visible absorption band on functionalization of complex 1 to the gold nanoparticles (λmax: 573 nm, 1; λmax: 660 nm, 1-AuNPs), rendering the nanocomposite an ideal candidate for photochemotherapeutic applications. The notable findings in our present studies are (i) the remarkable cytotoxicity of the nanocomposite (1-AuNPs) to A549 (IC50: 0.006 µM) and HaCaT (IC50: 0.0075 µM) cells in red light (600-720 nm, 30 J/cm2) while almost nontoxic (IC50 > 500 µg/mL, 0.053 µM) in the dark, (ii) the nontoxicity of 1-AuNPs to normal human diploid fibroblasts (WI-38) or human peripheral lung epithelial (HPL1D) cells (IC50 > 500 µg/mL, 0.053 µM) both in the dark and red light signifying the target-specific anticancer activity of the nanocomposite, (iii) localization of 1-AuNPs in mitochondria and partly nucleus, (iv) remarkable red light-induced generation of reactive oxygen species (ROS: 1O2, •OH) in vitro, (v) disruption of the mitochondrial membrane due to enhanced oxidative stress, and (vi) caspase 3/7-dependent apoptosis. A similar cytotoxic profile of complex 1 was another key finding of our studies. Overall, our current investigations show a new red light-absorbing iron(III)-phenolate/carboxylate complex-functionalized gold nanocomposite (1-AuNPs) as the emerging next-generation iron-based photochemotherapeutic agent for targeted cancer treatment modality.

Redox reactions of organoselenium compounds: Implication in their biological activity.

Antioxidant activity of organoselenium compounds belonging to different classes i.e. functionalized aliphatic, aromatic and cyclic selenoethers, are compared on the basis of their ability to scavenge reactive oxygen species like hydroxyl and peroxyl radicals and to exhibit glutathione peroxidase (GPx) like catalytic activity. The comparative analysis has revealed that the antioxidant activity of the organoselenium compounds show direct correlation with the energy of the highest occupied molecular orbital (HOMO) and neighboring group participation that stabilizes the reaction intermediate. Finally, structural features responsible for improving the rate of reaction of organoselenium compounds with free radical/molecular oxidants have been discussed on the basis of the compounds screened at our institute.

Electrostatically bound lanreotide peptide - gold nanoparticle conjugates for enhanced uptake in SSTR2-positive cancer cells.

Lanreotide peptide (LP) has high affinity to somatostatin receptors like SSTR2 and is commonly used in the treatment of neuro-endocrine tumors. The main objective of this study is to target gold nanoparticles (AuNPs) towards SSTR2-positive cancer cells using lanreotide peptide (LP) as the targeting agent for enhanced tumor uptake and antitumor activity. pH mediated changes in the surface potential of LP and AuNP is used to prepare electrostatically bound AuNP-LP complexes. AuNP-LP complex formation was demonstrated by UV-Visible spectroscopy, surface potential, dynamic light scattering (DLS), small angle X-ray scattering and HR-TEM. Confocal microscopy and flow cytometric studies show that AuNP-LP complex has higher cellular uptake in SSTR2 expressed cancer cells (MCF-7 and AR42J) than in CHO cells. The enhanced cellular uptake of LP coated AuNPs lead to ~1.5 to 2-fold GSH depletion and enhanced ROS generation in MCF-7 cells. The preferential cytotoxicity of the AuNP-LP complex towards MCF-7 and AR42J cells, as revealed by MTT assay, is consistent with the increased cellular uptake. Our studies demonstrate that LP coated AuNP can be used as an effective platform to selectively target SSTR2 positive cancer cells for combination therapy approaches involving gold nanoparticles.

Preparation of a size selective nanocomposite through temperature assisted co-assembly of gelatin and pluronic F127 for passive targeting of doxorubicin.

The preparation of a water dispersible and pH responsive gelatin-F127 nanocomposite using a thermal relaxation approach is reported. The results indicated that physical properties (size and surface charge) of the gelatin-F127 nanoparticle can be tuned by varying the F127 to gelatin weight ratio. The heating (60 °C) of a saline solution (pH 7.4) containing 0.5% (w/v) of gelatin and 20% (w/w of gelatin) of F127 followed by gradual cooling at room temperature yielded nanoparticles of desired size (160 ± 40 nm), viscosity (1.36 ± cP) and surface charge (-6.47 ± 0.7 mV). The drug delivery application of nanocarriers was investigated using doxorubicin hydrochloride (Dox) as a model drug. These nanocarriers showed high encapsulation efficiency of Dox (85%), a sustained release profile, and substantial cellular internalization. Additionally, Dox loaded nanocarriers (G-Dox) exhibited prolonged residence in blood as evidenced by their longer circulation time as compared to plain Dox. Moreover, G-Dox exhibited a higher availability of the drug in plasma as compared to nonspecific organs such as the heart, liver and kidneys, highlighting its significance in reducing drug associated side effects. Finally, the enhanced toxicity of G-Dox to a WEHI-164 (fibrosarcoma) tumor model as compared to that of plain Dox under an identical dosage of 6 mg per kg body weight (IP) confirmed its potential for chemotherapy application.

Tuning the pharmacokinetics and efficacy of irinotecan (IRI) loaded gelatin nanoparticles through folate conjugation.

Gelatin based nanocarriers have major limitation of shorter circulation half-life (t1/2). Present study addressed this issue by conjugating gelatin with folate followed by nanoprecipitation in presence of polysorbate 80 to form folate attached gelatin nanoparticles (GNP-F). The folic acid was conjugated with gelatin through the formation of amide linkage with a maximum conjugation yield of ~69%. Cryo-SEM analysis indicated that unconjugated gelatin nanoparticles (GNP) and GNP-F were spherical of nearly identical size of ~200 nm. The irinotecan (IRI)-loading efficiency estimated for IRI-GNP and IRI-GNP-F was 6.6 ± 0.42% and 11.2 ± 0.73% respectively and both formulations showed faster release of IRI at acidic pH (~5) than at physiological pH (~7). Further IRI-GNP-F demonstrated significantly higher cytotoxicity in folate receptor (FR)-positive HeLa cells than the unconjugated IRI-GNP nanoparticles confirming active targeting. Subsequently the antitumor activity of above formulations in FR-positive fibrosarcoma (syngeneic) tumor-bearing mice followed the order of IRI-GNP-F > IRI-GNP > free IRI. The pharmacokinetic evaluation of IRI-GNP and IRI-GNP-F revealed that encapsulation of IRI within GNP without folate improved its plasma maximum concentration (Cmax). However, folate conjugation of GNP remarkably improved the t1/2 of IRI. Taken together, folate as a targeting ligand modulates the pharmacokinetic property of IRI loaded GNP to favor active verses passive targeting.

Passive and Active Drug Targeting: Role of Nanocarriers in Rational Design of Anticancer Formulations.

BACKGROUND: Cancer is the major public health problem in developing countries. The treatment of cancer requires a multimodal approach and chemotherapy is one of them. Chemotherapeutic drug is administered to cancer patients in the form of a formulation which is prepared by mixing an active ingredient (drug) with the excipient. The role of excipient in a formulation is to regulate the release, bio-distribution, and selectivity of drug within the body. METHODS: In this context, selectivity of an anticancer formulation is achieved through two mechanisms like passive and active targeting. The passive targeting of a formulation is generally through enhanced permeation retention (EPR) effect which is dictated by physical properties of the carrier such as shape and size. On the contrary, active targeting means surface functionalization of excipient with target-specific ligands and/or receptors to increase its selectivity. RESULTS: Over the past several decades, remarkable progress has been made in the development and application of an engineered excipient or carrier to treat cancer more effectively. Especially nanoparticulate systems composed of metal/liposomes/polymeric material/proteins have received significant attention in the rational design of anticancer drug formulations; for example, therapeutic agents have been integrated with nanoparticles of optimal sizes, shapes and surface properties to improve their solubility, circulation half-life, and bio-distribution. In this review article, recent literature is included to discuss the role of physicochemical properties of excipients in achieving tumour targeting through passive and active approaches. CONCLUSION: The selection of an excipient/carrier and targeting ligand plays a very important role in rational design and development of anticancer drug formulations.

Supramolecular Nanorods of (N-Methylpyridyl) Porphyrin With Captisol: Effective Photosensitizer for Anti-bacterial and Anti-tumor Activities.

Porphyrins, especially the 5,10,15,20-tetrakis(4-N-methylpyridyl) porphyrin (TMPyP), are well-accepted as photosensitizers due to strong absorption from visible to near-infrared region, good singlet oxygen quantum yields as well as chemical versatility, all of which can be further modulated through planned supramolecular strategies. In this study, we report the construction of supramolecular nanorods of TMPyP dye/drug with captisol [sulfobutylether-ß-cyclodextrin (SBE7ßCD)] macrocycle through host-guest interaction. The availability of four cationic N-methylpyridyl groups favors multiple binding interaction with the captisol host, building an extended supramolecular assembly of captisol and TMPyP. In addition to the spectroscopic characterizations for the assembly formation, the same has been pictured in SEM and FM images as nanorods of ~10 µm in length or more. Complexation of TMPyP has brought out beneficial features over the uncomplexed TMPyP dye; enhanced singlet oxygen yield, improved photostability, and better photosensitizing effect, all supportive of efficient photodynamic therapy activity. The Captisol:TMPyP complex displayed enhanced antibacterial activity toward E. coli under white light irradiation as compared to TMPyP alone. Cell viability studies performed in lung carcinoma A549 cells with light irradiation documented increased cytotoxicity of the complex toward the cancer cells whereas reduced dark toxicity is observed toward normal CHO cells. All these synergistic effects of supramolecular nanorods of Captisol-TMPyP complex make the system an effective photosensitizer and a superior antibacterial and antitumor agent.

Clinical scale synthesis of intrinsically radiolabeled and cyclic RGD peptide functionalized 198Au nanoparticles for targeted cancer therapy.

INTRODUCTION: The emerging concept of intrinsically radiolabeled nanoparticles has the potential to transform the preclinical and clinical studies by improving the in vivo stability and demonstrating minimal alteration in the inherent pharmacokinetics of the nanoparticles. In this paper, a simple and efficient single-step method for clinical scale synthesis of intrinsically radiolabeled 198Au nanoparticles conjugated with cyclic arginine-glycine-aspartate peptide (198AuNP-RGD) is reported for potential use in targeted cancer therapy. METHODS: Large radioactive doses (>37 GBq) of 198AuNP-RGD were synthesized by reaction of 198Au-HAuCl4 with cyclic RGD peptide. The synthesized nanoparticles were characterized by various analytical techniques. In vitro cell binding studies were carried out in B16F10 (murine melanoma) cell line. Biodistribution studies were carried out in melanoma tumor bearing C57BL/6 mice to demonstrate the tumor targeting ability of 198AuNP-RGD. The therapeutic efficacy of 198AuNP-RGD was evaluated by carrying out systematic tumor regression studies in melanoma tumor bearing mice after intravenous administration of the radioactive doses. RESULTS: Well dispersed and biocompatible nanoparticles (~12.5 nm diameter) could be synthesized with excellent radiochemical and colloidal stability. In vitro studies exhibited the cell binding affinity and specificity of 198AuNP-RGD towards melanoma cell line. A high uptake of 8.7 ±â€¯2.1%ID/g in the tumor was observed within 4 h post-injection (p.i.). Significant decrease in tumor uptake of 198AuNP-RGD (2.9 ±â€¯0.8%ID/g) at 4 h p.i. on co-injection of a blocking dose of the peptide suggested that tumor localization of the intrinsically radiolabeled nanoparticles was receptor mediated. Administration of 37.0 MBq of 198AuNP-RGD resulted in significant regression of tumor growth with no apparent body weight loss over a period of 15 d. CONCLUSIONS: Overall, these promising results demonstrate the suitability of 198AuNP-RGD as an advanced functional nanoplatform for targeted cancer therapy.

Toxicological safety evaluation of 3,3'-diselenodipropionic acid (DSePA), a pharmacologically important derivative of selenocystine.

Diselenodipropionic acid (DSePA), a pharmacologically important derivative of selenocystine was evaluated for acute toxicity, mutagenic safety and metabolic stability. The estimated median oral lethal dose (LD50) cut-off of DSePA in mice and rat models was ∼200 mg/kg and ∼25 mg/kg respectively, which is considerably higher than the reported oral LD50 dose of its parent compound. Subsequently DSePA treatment in absence and presence of rat liver S9 fraction was found to be non-mutagenic at the tested doses up to 1 mM in rifampicin resistance assay and up to 6 mM in Ames test. In vitro degradation studies indicated that DSePA was more stable in S9 fraction of human compared to rat. The kinetic parameters Km and Vmax of DSePA degradation estimated using rat S9 fraction was 9.81 µM and 1.06 nmol/ml/min respectively. Further, DSePA treatment (1-50 µM) with or without rat S9 fraction did not induce any toxicity in human intestinal epithelial cells (Int 407) while showing comparable bioactivity of glutathione peroxidase (GPx) level. In conclusion, superior metabolic stability of DSePA in human S9 fraction with a concomitant lack of mutagenic effects suggests that it may be a suitable derivative of selenocytine for future biological studies.

Toxicity and Antigenotoxic Effect of Hispolon Derivatives: Role of Structure in Modulating Cellular Redox State and Thioredoxin Reductase.

Hispolon (HS), a bioactive polyphenol, and its derivatives such as hispolon monomethyl ether (HME), hispolon pyrazole (HP), and hispolon monomethyl ether pyrazole (HMEP) were evaluated for comparative toxicity and antigenotoxic effects. The stability of HS derivatives in biological matrices followed the order HS < HP ≈ HME < HMEP. The cytotoxicity analysis of HS derivatives indicated that HP and HMEP were less toxic than HS and HME, respectively, in both normal and tumor cell types. The mechanisms of toxicity of HS and HME involved inhibition of thioredoxin reductase (TrxR) and/or induction of reductive stress. From the enzyme kinetic and docking studies, it was established that HS and HME interacted with the NADPH-binding domain of TrxR through electrostatic and hydrophobic bonds, resulting in inhibition of the catalytic activity. Subsequently, treatment with HS, HP, and HMEP at a nontoxic concentration of 10 µM in Chinese Hamster Ovary (CHO) cells showed significant protection against radiation (4 Gy)-induced DNA damage as assessed by micronuclei and γ-H2AX assays. In conclusion, the above results suggested the importance of phenolic and diketo groups in controlling the stability and toxicity of HS derivatives. The pyrazole derivatives, HP and HMEP, may gain significance in the development of functional foods.