Synthesis and biological activity of structurally diverse phthalazine derivatives: A systematic review.

Phthalazine, a structurally and pharmacologically versatile nitrogen-containing heterocycle, has gained more attention from medicinal chemists in the design and synthesis of novel drugs owing to its pharmacological potential. In particular, phthalazine scaffold appeared as a pharmacophoric feature numerous drugs exhibiting pharmacological activities, in particular, antidiabetic, anticancer, antihypertensive, antithrombotic, anti-inflammatory, analgesic, antidepressant and antimicrobial activities. This review presents a summary of updated and detailed information on phthalazine as illustrated in both patented and non-patented literature. The reported literature have described the optimal pharmacological characteristics of phthalazine derivatives and highlighted the applicability of phthalazine, as potent scaffold in drug discovery.

Biodegradable Polymeric Nanocarrier-Based Immunotherapy in Hepatitis Vaccination.

Various commercial vaccines are used for immunization against hepatitis B. However, these immunotherapeutic vaccines require invasive administration, which can induce side effects, and require multiple shots to elicit an immune response, limiting their efficacy. Compared to traditional hepatitis B vaccines, polymer nanoparticles have more advantageous inherent properties as vaccine delivery carriers, providing increased stability of encapsulated antigen, the possibility of single-shot immunotherapy, and the capability of mucosal administration, which allows various routes of vaccination. In this review, we present up-to-date information on the potential of a biodegradable nanoparticle-based delivery system in treating hepatitis B. We also discuss the application of nanoparticles in various vaccines and highlighted strategies for eliciting an appropriate immune response.

Bacterial Peptide Deformylase Inhibition of Tetrazole-Substituted Biaryl Acid Analogs: Synthesis, Biological Evaluations, and Molecular Docking Study.

The synthesis and screening of tetrazole-substituted biaryl acid analogs 7a-l as bacterial peptide deformylase (PDF) enzyme inhibitors is reported. The compounds 7e (IC50 value = 5.50 µM) and 7g (IC50 value = 7.25 µM) showed good PDF inhibition activity. The compounds 7e (MIC range = 10.75-11.66 µg/mL) and 7g (MIC range = 8.91-12.83 µg/mL) also showed potent antibacterial activity when compared with the standard ciprofloxacin (MIC range = 25-50 µg/mL). Thus, the active derivatives were not only potent PDF enzyme inhibitors but also efficient antibacterial agents. In order to gain more insight into the binding mode of the compounds with the PDF enzyme, the most active compounds 7e and 7g, the moderately active compound 7k, and the least active compound 7h were docked against the PDF enzyme of Escherichia coli. The docking study of the most active compounds 7e and 7g against the PDF enzyme exhibited good binding properties. Hence, we believe our synthesized compounds 7a-l could serve as reservoir for bacterial PDF inhibitor development.

Exploring antibiofilm potential of some new imidazole analogs against C. albicans: synthesis, antifungal activity, molecular docking and molecular dynamics studies.

A series of 1, 2, 4, 5-tetrasubstituted imidazole derivatives were synthesized and their antibiofilm potential against Candida albicans was evaluated in vitro. Two of the synthesized derivatives 5e (IC50 = 25 µg/mL) and 5m (IC50 = 6 µg/mL),displayed better antifungal and antibiofilm potential than the standard drug Fluconazole (IC50 = 40 µg/mL) against C. albicans. Based on the in vitro results, we escalated the real time polymerase chain reaction (RT-PCR) analysis to gain knowledge of the enzymes expressed in the generation and maintenance of biofilms and the mechanism of biofilm inhibition by the synthesized analogues. We then investigated the possible interactions of the synthesized compounds in inhibiting agglutinin-like proteins, namely Als3, Als4 and Als6 were prominently down-regulated using in-silico molecular docking analysis against the previously available crystal structure of Als3 and constructed structure of Als4 and Als6 using the SWISS-MODEL server. The stability and energy of the agglutinin-like proteins-ligand complexes were evaluated using molecular dynamics simulations (MDS). According to the 100 ns MDS, all the compounds remained stable, formed a maximum of 3, and on average 2 hydrogen bonds, and Gibb's free energy landscape analysis suggested greater affinity of the compounds 5e and 5m toward Als4 protein.Communicated by Ramaswamy H. Sarma.

Efficient gene transfection to lung cancer cells via Folate-PEI-Sorbitol gene transporter.

Lung cancer is known to be one of the fatal diseases in the world and is experiencing treatment difficulties. Many treatments have been discovered and implemented, but death rate of patients with lung cancer continues to remain high. Current treatments for cancer such as chemotherapy, immunotherapy, and radiotherapy have shown considerable results, yet they are accompanied by side effects. One effective method for reducing the cytotoxicity of these treatments is via the use of a nanoparticle-mediated siRNA delivery strategy with selective silencing effects and non-viral vectors. In this study, a folate (FA) moiety ligand-conjugated poly(sorbitol-co-PEI)-based gene transporter was designed by combining low-molecular weight polyethyleneimine (LMW PEI) and D-sorbitol with FA to form FPS. Since folate receptors are commonly overexpressed in various cancer cells, folate-conjugated nanoparticles may be more effectively delivered to selective cancer cells. Additionally, siOPA1 was used to induce apoptosis through mitochondrial fusion. The OPA1 protein stability level is important for maintaining normal mitochondrial cristae structure and function, conserving the inner membrane structure, and protecting cells from apoptosis. Consequently, when FPS/siOPA1 was used for lung cancer in-vitro and in-vivo, it improved cell viability and cellular uptake.

Insilico structure based drug design approach to find potential hits in ventilator-associated pneumonia caused by Pseudomonas aeruginosa.

Tetraacyldisaccharide 4'-kinase (LpxK) is the prime enzyme responsible for the biosynthesis of lipid A. LpxK is a key antibacterial drug target, but it is less exploitation in Pseudomonas aeruginosa and other bacterial species limits its therapeutic use. Pseudomonas aeruginosa is responsible for severe infections like pneumonia and urinary tract infections. The precautionary measures of Pseudomonas aeruginosa infections are decisive as it results in extensive drug resistance, systemic bacteremia, and ventilator-associated pneumonia. The current rational approach highlights exploiting the use of computer-aided drug design approaches to counter Pseudomonas aeruginosa specific LpxK. The various approaches used were exploring the metabolic pathway database (Metacyc), drug target validation using DEG, protein modeling, ligand docking, e-pharmacophore assisted virtual screening, physicochemical and Toxicity profile prediction studies, and molecular simulations in spotting out novel potential hits compounds. The virtual hits which have highly ranked in the study were STOCK4S-16119, STOCK1S -60869, STOCK6S -43621, STOCK6S -3328, and STOCKS-39892 which can act as a scaffold for the establishment of new hits against LpxK and can result in control of Pseudomonas aeruginosa infectivity.

Mucoadhesive and pH-sensitive thiolated Eudragit microspheres for oral delivery of Pasteurella multocida antigens containing dermonecrotoxin.

In this study, cysteine was conjugated to the Eudragit to have mucoadhesive and pH-sensitive properties. Pasteurella multocida dermonecrotoxin (PMT) is a major virulence factor as a causative agent of atrophic rhinitis (AR) in swine and, therefore, inactivated P. multocida was used as a candidate vaccine in the current study. PMT-loaded thiolated Eudragit microspheres (TEMS) prepared using W/O/W emulsion-solvent evaporation method were characterized to assess their efficacy in oral vaccination. PMT-loaded TEMS were observed as spherical shapes with smooth surfaces and average particle sizes were 5.2 +/- 0.55 microm. The loading efficiency of PMT in the TEMS was about 75.3%. A significantly higher percentage of PMT from PMT-loaded TEMS was released at pH 7.4 than at pH 1.5. Murine macrophage stimulated with PMT-loaded TEMS facilitated a gradual secretion of tumor necrosis factor-alpha and nitric oxide as immune stimulatory mediators in a time dependent manner, suggesting that the released PMT from PMT-loaded TEMS had immune stimulating activity of AR vaccine in vitro.

Development of novel, biocompatible, polyester amines for microglia-targeting gene delivery.

Recent progress in personalized medicine and gene delivery has created exciting opportunities in therapeutics for central nervous system (CNS) disorders. Despite the interest in gene-based therapies, successful delivery of nucleic acids for treatment of CNS disorders faces major challenges. Here we report the facile synthesis of a novel, biodegradable, microglia-targeting polyester amine (PEA) carrier based on hydrophilic triethylene glycol dimethacrylate (TG) and low-molecular weight polyethylenimine (LMW-PEI). This nanocarrier, TG-branched PEI (TGP), successfully condensed double-stranded DNA into a size smaller than 200 nm. TGP nanoplexes were nontoxic in primary mixed glial cells and showed elevated transfection efficiency compared with PEI-25K and lipofector-EZ. After intrathecal and intracranial administration, PEA nanoplexes delivered genes specifically to microglia in the spinal cord and brain, respectively, proposing TGP as a novel microglia-specific gene delivery nanocarrier. The microglia-specific targeting of the TGP nanocarrier offers a new therapeutic strategy to modulate CNS disorders involving aberrant microglia activation while minimizing off-target side effects.

pH-Responsive Polymers as Gene Carriers.

Despite the immense potential of non-viral delivery system in gene therapy its application has been impaired greatly by various impediments having contrasting traits. Therefore it is an absolute necessity to develop some non-viral vectors which are endowed with special characteristics to act differently in intracellular as well as extracellular compartments to surmount these inter-conflicting hurdles. Such smart polymers should serve some specific purposes by adjusting their structural or functional traits under the influence of stimuli such as temperature, light, salt concentration or pH. Among all these stimuli-responsive polymers pH-responsive polymers have attracted major attention and great impetus has been directed towards utilizing the subtle yet significant change in pH value within the cellular compartments. This review is intended to provide a comprehensive account of the development of pH-responsive polymeric vectors based on their structural features and consequent functional attributes to achieve efficient transfection. The underlying modes of actions relating to structure and differential pH environment have also been discussed in this review.

Biodegradable nano-polymeric system for efficient Akt1 siRNA delivery.

Biodegradable nano-polymeric carrier composed of polycaprolactone (PCL) and polyethylenimine (PEI) (BNPP) was successfully synthesized for the delivery of sh/siRNA in lung cancer cells. BNPP efficiently and safely delivered siRNA in lung cancer cells. BNPP-delivered Akt1 siRNA silenced Akt1 protein, and reduced the cancer cell survival, proliferation, malignancy and metastasis.

Folate conjugated poly(ester amine) for lung cancer therapy.

Folate conjugated poly(ester amine) (PEA) was prepared by reaction of folic acid with PEAs based on polycaprolactone (PCL) and low molecular weight polyethylenimine (LMW-PEI) with PEG as a linker. This novel gene carrier showed excellent physicochemical properties and relatively low cytotoxicity compared with PEI 25K. It showed excellent transfection efficiency through folate receptor mediated endocytosis.

Insights of tankyrases: A novel target for drug discovery.

Tankyrases are the group of enzymes belonging to a class of Poly (ADP-ribose) polymerase (PARP) recently named ADP-ribosyltransferase (ARTD). The two isoforms of tankyrase i.e. tankyrase1 (TNKS1) and tankyrase2 (TNKS2) were abundantly expressed in various biological functions in telomere regulation, Wnt/ß-catenin signaling pathway, viral replication, endogenous hormone regulation, glucose transport, cherubism disease, erectile dysfunction, and apoptosis. The structural analysis, mechanistic information, in vitro and in vivo studies led identification and development of several classes of tankyrase inhibitors under clinical phases. In the nutshell, this review will drive future research on tankyrase as it enlighten the structural and functional features of TNKS 1 and TNKS 2, different classes of inhibitors with their structure-activity relationship studies, molecular modeling studies, as well as past, current and future perspective of the different class of tankyrase inhibitors.

Efficient gene delivery with osmotically active and hyperbranched poly(ester amine)s.

Degradable and hyperbranched poly (ester amine)s (PEAs) were successfully synthesized by Michael addition reaction between hydrophilic glycerol triacrylate (GTA) and low-molecular-weight polyethylenimine (LMW-PEI) and evaluated as nonviral gene carriers. PEAs effectively condensed DNA with particle sizes below 200 nm and suitable surface charges (15-45 mV), suitable for intracellular delivery. PEAs degraded in a controlled fashion showing half-lives of more than 12 days and were essentially nontoxic in three different cell lines. Elevated transfection levels by luciferase assay revealed the superiority of PEAs over PEI 25K and Lipofectamine. PEAs synthesized using 1:4 mol ratio of GTA to PEI [GTA/PEI-1.2(1:4)] showed highest transfection efficiency in HepG2 cells. PEAs showed significant gene expression in vitro as well as in vivo through aerosol administration. Reduction in packed cell volume (PCV) of cells when treated with polyplexes supported the hyperosmotic effect of PEAs. Effect of bafilomycin A1 on transfection efficiency of PEAs on 293T cells indicated its endosomal buffering capacity. High transfection efficiency was attributed to the synergism from hyperosmotic glycerol backbone in the PEAs and endosomal buffering capacity of PEI amine groups. Therefore, this convergence of osmotically active biodegradable PEAs suggests their potential as a safe and efficient gene delivery vector.

Sugar alcohol-based polymeric gene carriers: Synthesis, properties and gene therapy applications.

Advances in the field of nanomedicine have led to the development of various gene carriers with desirable cellular responses. However, unfavorable stability and physicochemical properties have hindered their applications in vivo. Therefore, multifunctional, smart nanocarriers with unique properties to overcome such drawbacks are needed. Among them, sugar alcohol-based nanoparticle with abundant surface chemistry, numerous hydroxyl groups, acceptable biocompatibility and biodegradable property are considered as the recent additions to the growing list of non-viral vectors. In this review, we present some of the major advances in our laboratory in developing sugar-based polymers as non-viral gene delivery vectors to treat various diseases. We also discuss some of the open questions in this field. STATEMENT OF SIGNIFICANCE: Recently, the development of sugar alcohol-based polymers conjugated with polyethylenimine (PEI) has attracted tremendous interest as gene delivery vectors. First, the natural backbone of polymers with their numerous hydroxyl groups display a wide range of hyperosmotic properties and can thereby enhance the cellular uptake of genetic materials via receptor-mediated endocytosis. Second, conjugation of a PEI backbone with sugar alcohols via Michael addition contributes to buffering capacity and thereby the proton sponge effect. Last, sugar alcohol based gene delivery systems improves therapeutic efficacy both in vitro and in vivo.

Molecular docking, pharmacophore based virtual screening and molecular dynamics studies towards the identification of potential leads for the management of H. pylori.

The enzyme pantothenate synthetase panC is one of the potential new antimicrobial drug targets, but it is poorly characterized in H. pylori. H. pylori infection can cause gastric cancer and the management of H. pylori infection is crucial in various gastric ulcers and gastric cancer. The current study describes the use of innovative drug discovery and design approaches like comparative metabolic pathway analysis (Metacyc), exploration of database of essential genes (DEG), homology modelling, pharmacophore based virtual screening, ADMET studies and molecular dynamics simulations in identifying potential lead compounds for the H. pylori specific panC. The top ranked virtual hits STOCK1N-60270, STOCK1N-63040, STOCK1N-44424 and STOCK1N-63231 can act as templates for synthesis of new H. pylori inhibitors and they hold a promise in the management of gastric cancers caused by H. pylori.

Biodegradable poly(ester amine) based on glycerol dimethacrylate and polyethylenimine as a gene carrier.

BACKGROUND: Polyethylenimine (PEI) vectors are widely used in gene delivery because of their high transfection efficiency owing to a unique proton sponge effect. An increase in molecular weight increases transfection efficiency, but simultaneously results in increased toxicity. Therefore, the design and synthesis of new degradable gene delivery carriers having high transfection efficiencies and reduced cytotoxicity are necessary. METHODS: In the present study degradable poly(ester amines) (PEAs) based on glycerol dimethacrylate (GDM) and low molecular weight branched polyethylenimine (LMW-PEI) were synthesized in anhydrous methanol at 60 degrees C following Michael addition reaction. The transfection efficiencies of the synthesized PEA/DNA complexes were evaluated using three different cell lines (HeLa, HepG2 and 293T cells) in vitro. RESULTS: PEAs with zeta potential in the range of 30-55 mV (at physiological pH) condensed plasmid DNA into nanosized particles (<150 nm) suitable for intracellular delivery. The PEAs degraded in a controlled fashion (t(1/2) of approximately 9-10 days). Compared with PEI 25K, the PEAs showed significantly lower cytotoxicity in three different cells. The PEAs demonstrated much higher transfection efficiency compared to conventional PEI 25K and Lipofectamine. The PEA synthesized using a 1 : 4 mole ratio of GDM to PEI [GDM/PEI-1.2 (1:4)] showed the highest transfection efficiency in HepG2 cells. Significantly higher pEGFP-N(2) reporter gene expression in 293T cells was achieved using these PEAs. The hyperosmotic effect of PEAs was demonstrated by the reduction in packed cell volume (PCV). The GDM/PEI-1.2 (1:4) showed comparable reduction in PCV with respect to glycerol in 293T cells. The effect of bafilomycin A(1) on transfection efficiency of PEAs on 293T cells indicated its endosomal buffering capacity. CONCLUSIONS: We hypothesized that the higher transfection efficiency of PEAs was the synergistic effect arising from hyperosmotic glycerol and endosomal buffering capacity of PEAs resulting from the presence of a glycerol backbone and PEI amine groups, respectively.

Poly(beta-amino ester) as a carrier for si/shRNA delivery in lung cancer cells.

Efficient delivery of small interfering RNA (siRNA) or small hairpin RNA (shRNA) is a critical concern in RNA interference (RNAi) studies. In the present study, we evaluated biodegradable poly(beta-amino ester) (PAE) carrier composed of low molecular weight polyethylenimine and poly(ethylene glycol) for si/shRNA delivery in lung cancer cells. PAE carrier successfully delivered EGFP (enhanced green fluorescence protein) siRNA (siGFP) and silenced EGFP expression. The silencing achieved with PAE carrier was found to be nearly 1.5 times superior and safer than standard PEI25K. Also, our PAE carrier exhibited superior Akt1 shRNA delivery (shAkt) and thereby silenced oncoprotein Akt1 efficiently. PAE-shAkt mediated Akt1 knock-down hindered cancer cell growth in Akt1 specific manner. Superior shAkt delivery and low cytotoxicity of PAE carrier promoted Akt1 knock-down specific apoptosis, while low delivery efficiency and high cytotoxicity of PEI25K carrier mainly exhibited undesirable necrosis. Moreover, basic cancer properties like cell proliferation, malignancy and metastasis were reduced more efficiently using PAE-shAkt system. These findings demonstrated the potential of PAE as an alternative to PEI25K in si/shRNA-based RNAi studies.

Sugar-based gene delivery systems: Current knowledge and new perspectives.

Carbohydrates, one of the most abundant natural compounds and key participants in many biological processes, are relevant in medical and industrial fields. In comparison with synthetic polymers, carbohydrates are biocompatible and have intrinsic targeting properties, enabling them to interact with cell-surface receptors. Among the different carbohydrates, polysaccharides are naturally occurring biological molecules with tremendous potential for biomedical applications. The physicochemical properties of these polysaccharide based nanoparticles, such as excellent biocompatibility, surface charge to interact with nucleic acids, low toxicity and cost effectiveness make them superior carriers for nanomedicine. In addition to variety of physicochemical properties, polysaccharides allow the great ease of chemical modification which enables the preparation of wide range of nanoparticles. In this review, we present the state-of-the-art information on the potential of polysaccharides-based polymers as non-viral gene delivery vectors in treating various diseases. Then, we discuss the chemical modification and structure/property relationship of carbohydrates.

Targeted Delivery of siRNA Therapeutics using Ligand Mediated Biodegradable Polymeric Nanocarriers.

BACKGROUND: Cancer poses a major public health issue, is linked with high mortality rates across the world, and shows a strong interplay between genetic and environmental factors. To date, common therapeutics, including chemotherapy, immunotherapy, and radiotherapy, have made significant contributions to cancer treatment, although diverse obstacles for achieving the permanent "magic bullet" cure have remained. Recently, various anticancer therapeutic agents designed to overcome the limitations of these conventional cancer treatments have received considerable attention. One of these promising and novel agents is the siRNA delivery system; however, poor cellular uptake and altered siRNA stability in physiological environments have limited its use in clinical trials. Therefore, developing the ideal siRNA delivery system with low cytotoxicity, improved siRNA stability in the body's circulation, and prevention of its rapid clearance from bodily fluids, is rapidly emerging as an innovative therapeutic strategy to combat cancer. Moreover, active targeting using ligand moieties which bind to over-expressed receptors on the surface of cancer cells would enhance the therapeutic efficiency of siRNA. CONCLUSION: In this review, we provide 1) an overview of the non-viral carrier associated with siRNA delivery for cancer treatment, and 2) a description of the five major cancer-targeting ligands.

Enhanced anticancer effect of conjugated linoleic acid by conjugation with Pluronic F127 on MCF-7 breast cancer cells.

This study is designed to evaluate whether conjugated linoleic acid-coupled Pluronic F127 (Plu-CLA) enhances anticancer efficacy in MCF-7 breast cancer cells when compared to conjugated linoleic acid (CLA) itself. CLA was simply coupled to Pluronic F127 through ester linkage between carboxyl group of CLA and hydroxyl one of Pluronic at melting state without solvent or catalyst. Plu-CLA significantly enhanced apoptosis with increasing concentration compared with CLA itself. Moreover, it was found that p53, p21, and Bax were up-regulated, whereas Bcl-2 and procaspase 9 were down-regulated with increasing concentration of Plu-CLA. These results were attributed to the sensitization activity of Pluronic F127.