Antibacterial Potential of Gold Nanoparticles Synthesized From Leaf Extract of Syzygium cumini Against Multidrug-Resistant Urinary Tract Pathogens.

BACKGROUND: Urinary tract infection (UTI) is one of the most commonly encountered bacterial infections. Due to the misuse or excessive use of antibiotics, the upsurge of multidrug-resistance cases in UTIs has now become a global threat to public health. Exploring a newer or safer treatment using green synthesized nanoparticles (NPs) is another substitute for eliminating multidrug-resistant pathogens. METHODOLOGY: Leaf extract of Syzygium cumini was used for green synthesis of gold NPs. Synthesis of Syzygium cumini gold nanoparticles (ScAu-NPs) was achieved by optimizing various reaction parameters. These ScAu-NPs were characterized through UV-visible spectroscopy, transmission electron microscope, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction. ScAu-NPs were then processed for antibacterial activity against clinically isolated multidrug-resistant pathogens like Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Acinetobacter baumannii, Staphylococcus aureus, and Enterococcus faecalis. RESULTS: Characterization of NPs revealed that biosynthesized NPs were spherical in shape. FTIR spectroscopy showed the presence of phenolics and aromatic compounds. Biosynthesized NPs exhibit good antibacterial activity with a significant bacterial reduction seen against all bacterial isolates compared to the controls. CONCLUSION: From the results of the present study, the formulation of biosynthesized ScAu-NPs can be utilized in drug development for eliminating infections caused by multidrug-resistant pathogens.

Exploration of Benzo[b]carbazole-6,11-diones as anticancer agents: Synthesis and studies of hTopoIIα inhibition and apoptotic effects.

Two series of (hetero)arylamino-naphthoquinones and benzo-fused carbazolequinones were considered for study with the rationale that related structural motifs are present in numerous drugs, clinical trial agents, natural products and hTopoIIα inhibitors. Total 42 compounds were synthesized by reactions including dehydrogenative CN and Pd-catalyzed CC bond forming transformations. These compounds were screened against numerous cancer cells including highly metastatic one (MCF-7, MDA-MB-231, H-357 and HEK293T), and normal cells (MCF 10A). Some of the active compounds were evaluated for clonogenic cell survival and apoptotic effects in cancer cells (DAPI nuclear staining, Comet assay, Annexin-V-FITC/PI dual staining, flow cytometry, and western blot analysis with relevant proteins). All compounds were tested for hTopoIIα inhibitory activity. The investigated series compounds showed important properties like significant apoptotic antiproliferation in cancer cells with cell cycle arrest at S-phase and downregulation of NF- κß signaling cascade, relatively less cytotoxicity to normal cells, and hTopoIIα inhibition with more efficiency compared to an anticancer drug etoposide.

Light-assisted anticancer photodynamic therapy using porphyrin-doped nanoencapsulates.

Light activatable porphyrinic photosensitizers (PSs) are essential components of anticancer and antimicrobial therapy and diagnostic imaging. However, their biological applications are quite challenging due to the lack of hydrophilicity and biocompatibility. To overcome such drawbacks, photosensitizers can be doped into a biocompatible polymer such as gelatin and further can be used for biomedical applications. Herein, first, a novel A4 type porphyrin PS [5,10,15,20-tetrakis(4-pyridylamidephenyl)porphyrin; TPyAPP] was synthesized via a rational route with good yield. Further, this porphyrin was encapsulated into the gelatin nanoparticles (GNPs) to develop hydrophilic phototherapeutic nanoagents (PTNAs, A4por-GNPs). Notably, the synthesis of such porphyrin-doped GNPs avoids the use of any toxic chemicals or solvents. The nanoprobes have also shown good fluorescence quantum yield demonstrating their applicability in bioimaging. Further, the mechanistic aspects of the anticancer and antimicrobial efficacy of the developed A4por-GNPs were evaluated via singlet oxygen generation studies. Overall, our results indicated porphyrin-doped biodegradable polymeric nanoparticles act as effective phototherapeutic agents against a broad range of cancer cell lines and microbes upon activation by the low-cost LED light.

Co-administration of zinc phthalocyanine and quercetin via hybrid nanoparticles for augmented photodynamic therapy.

The photodynamic anticancer activity of a photosensitizer can be further increased by co-administration of a flavonoid. However, this requires that both molecules must be effectively accumulated at the tumor site. Hence, in order to enhance the activity of zinc phthalocyanine (ZnPc, photosensitizer), it was co-encapsulated with quercetin (QC, flavonoid) in lipid polymer hybrid nanoparticles (LPNs) developed using biodegradable & biocompatible materials and prepared using a single-step nanoprecipitation technique. High stability and cellular uptake, sustained release, inherent fluorescence, of ZnPC were observed after encapsulation in the LPNs, which also showed a higher cytotoxic effect in breast carcinoma cells (MCF-7) compared to photodynamic therapy (PDT) alone. In vivo studies in tumor-bearing Sprague Dawley rats demonstrated that the LPNs were able to deliver ZnPc and QC to the tumor site with minimal systemic toxicity and increased antitumor effect. Overall, the photodynamic effect of ZnPc was synergized by QC. This strategy could be highly beneficial for cancer management in the future while nullifying the side effects of chemotherapy.

Tailoring a stable and recyclable nanobiocatalyst by immobilization of surfactant treated Burkholderia cepacia lipase on polyaniline nanofibers for biocatalytic application.

Polyaniline nanofibers were synthesized by the oxidative polymerization of aniline. Surfactant treated lipase from Burkholdaria cepacia was immobilized on these polyaniline nanofibers by adsorption. The activity of immobilized preparation was six times higher than that of free lipase with an enhanced dispersion in organic solvents. Five-level-four-factor central composite design was applied for the optimization of immobilization parameters (viz. reaction time, pH, stirring rate and enzyme-support ratio) which were evaluated on the basis of lipase loading and activity. The thermal stability of the lipase in the nanobioconjugate, demonstrated in terms of the half-life at 80 °C was almost sixteen-fold higher than in the free form. The reusability data revealed the utility of the nanoconjugate for seven consecutive cycles with a slow and gradual decline in the activity. However, the nanoconjugate retained almost 30% of their initial activity after seven cycles of reuse revealing its utility of in industrial applications. The nanoconjugate was used in the kinetic resolution of (RS)-1-(7-(3-chloro-2-hydroxypropoxy)benzofuran-2-yl) ethanone, racemic intermediate of an important ß-blocker (Befunolol), with a high conversion rate of 48.2%, 98% ee-value and enantioselectivity (E) of 188, which signify its importance as a nanobiocatalyst.

E-pharmacophore guided discovery of pyrazolo[1,5-c]quinazolines as dual inhibitors of topoisomerase-I and histone deacetylase.

In the quest to ameliorate the camptothecin (CPT) downsides, we expedite to search for stable non-CPT analogues among 11 motifs of pyrazoloquinazolines reported. E-pharmacophore drug design approach helped filtering out pyrazolo[1,5-c]quinazolines as Topoisomerase I (TopoI) 'interfacial' inhibitors. Three compounds, 3c, 3e, and 3l were shown to be potent non-intercalating inhibitors of TopoI specifically and showed cancer cell-specific cytotoxicity in lung, breast and colon cancer cell lines. The compounds induced cell cycle arrest at S-phase, mitochondrial cell death pathway and modulated oxidative stress in cancer cells. Furthermore, a preliminary study was conducted to explore the feasibility of these compounds to be developed as dual TopoI-HDAC1 (histone deacetylase 1) inhibitors (4a) to combat resistance. Compound 4a was found to possess dual inhibitory capabilities in-vitro. Cytotoxic potential of 4a was found to be significantly higher than parent compound in 2D as well as 3D cancer cell models. Probable binding modes of 4a with TopoI and HDAC1 active sites were examined by molecular modelling.

Cyclic enaminone as new chemotype for selective cyclooxygenase-2 inhibitory, anti-inflammatory, and analgesic activities.

The cyclic enaminone moiety has been identified as a new scaffold for selective inhibition of cyclooxygenase-2 with anti-inflammatory and analgesic activities. The designed cyclic enaminones have been synthesized conveniently through the development of a new catalyst-free methodology and evaluated for cyclooxygenase (COX-1 and COX-2) inhibitory activities. Three compounds 7d, 8, and 9 predominantly inhibited COX-2 with selectivity index of 74.09, 19.45 and 108.68, respectively, and were assessed for in vivo anti-inflammatory activity in carrageenan induced rat paw edema assay. The anti-inflammatory activity of 7d was comparable to that of celecoxib at a dose of 12.5 mg/kg. However, the compounds 8 and 9 were more/equally effective as anti-inflammatory agent compared to celecoxib at the doses of 12.5 mg/kg and 25 mg/kg and also exhibited anti-inflammatory activity comparable to that of diclofenac. The therapeutic potential of the most active compound 9 was further assessed by performing in vivo thermal and mechanical hyperalgesia tests using various models that revealed its analgesic activity. The in vivo non-ulcerogenicity of 9 revealed the gastrointestinal safety as compared to the non-selective COX inhibitor indomethacin. The in vitro antioxidant activity and in vivo experiments on heart rate and blood pressure provided the cardiovascular safety profile of 9. The molecular docking studies rationalize the COX-2 selectivity of the newly found anti-inflammatory compounds 7d, 8, and 9.

Paclitaxel-encapsulated core-shell nanoparticle of cetyl alcohol for active targeted delivery through oral route.

Aim: Paclitaxel (PTX) has no clinically available oral formulations. Cetyl alcohol is metabolized by alcohol dehydrogenase and aldehyde dehydrogenase that are overexpressed in cancer cells. So, PTX-encapsulated core-shell nanoparticle of cetyl alcohol (PaxSLN) could target the cancer cells through oral route. Materials & methods: PaxSLN was synthesized using microemulsion template. Efficiency of PaxSLN was evaluated by ALDEFLUOR™, multicellular tumor spheroid formation inhibition assays and CT26 colorectal carcinoma animal model. Pharmacokinetics and biodistribution studies were done in Sprague Dawley rats. Results: PTX was encapsulated at the core of approximately 78 nm PaxSLN. PaxSLN targeted aldehyde dehydrogenase overexpressing cells. Its oral bioavailability was approximately 95% and chemotherapeutic efficacy was better than Taxol® and nab-PTX. Conclusion: A novel oral nanoformulation of PTX was developed.

Tailoring a robust and recyclable nanobiocatalyst by immobilization of Pseudomonas fluorescens lipase on carbon nanofiber and its application in synthesis of enantiopure carboetomidate analogue.

Pseudomonas fluorescens lipase (PFL) was covalently immobilized on carbon nanofiber (CNF) using 1­ethyl­3­[3­dimethylaminopropyl] carbodiimide (EDC)/N­hydroxysuccinimide (NHS). Surface functionalization of carbon nanofiber augments dispersibility as well as efficiency of covalent immobilization. Crucial parameters for immobilization such as pH, enzyme-support ratio, reaction time and mixing rate were optimized using one factor at a time (OFAT) approach. The nanobiocatalyst prepared under optimized conditions demonstrated a ten-fold increase in enzyme activity and the advantage of high thermal stability (up to 85 °C) along with 10 cycles of reusability. Subsequently practical application of the nanobiocatalyst was explored in the kinetic resolution of racemic 1­phenylethanol into (S)­1­phenylethanol [C = 49.1%, eep = 99.5%, ees = 98.5% and E value = 151.4] followed by Mitsunobu reaction with a substituted pyrrole, giving an enantiopure (R)-carboetomidate analogue (yield = 83%).

Facile development of biodegradable polymer-based nanotheranostics: Hydrophobic photosensitizers delivery, fluorescence imaging and photodynamic therapy.

Photodynamic therapy (PDT) is reported to be a promising technique to eradicate various cancers. As most of the photosensitizers (PSs) are hydrophobic in nature, thus, the effective delivery of PSs at the targeted site is the main hurdle associated with PDT. Zinc phthalocyanine and Zinc naphthalocyanine are reported as good PSs, however, highly hydrophobic characteristics restrict their use for clinical applications. To circumvent this limitation here we developed the advanced polymer-based nano-delivery system having polyethylene glycol (PEG) coated polymeric core with ~90% PS encapsulation. The PEG coating was responsible for the stabilization of probe in the physiological environment and storage conditions. The developed theranostic probes showed efficient in vitro fluorescence and singlet oxygen quantum yields upon irradiation with 620-750 nm (30 mW/cm2) light. The clathrin-mediated endocytosis (CME) based mechanism of cellular internalization was evaluated. The fluorescence of treated MCF-7 cells showed the ability of the probes as imaging agents. Moreover, up to 65% cell inhibition showed their cytotoxic efficiency. Further, comparatively higher tumor-accumulation of PSs without significant hepato/nephro-toxicity shown in vivo experimentation using breast tumor-bearing female Sprague Dawley (SD) rats suggested the featured passive targeting ability of preparations and clinically safe to be used. The study explored the exceptional delivery system for hydrophobic PSs with commendable theranostic applications.

Self-Assembled Gold Nanoparticle-Lipid Nanocomposites for On-Demand Delivery, Tumor Accumulation, and Combined Photothermal-Photodynamic Therapy.

In this study, a distinct photoamenable nanoparticle-based drug delivery system was developed for highly efficient targeted on-demand delivery, fluorescence imaging, and therapy by incorporating zinc phthalocyanine (ZnPc) and gold nanoparticles (AuNPs) into liposomes. The hyperthermia, produced by AuNPs under LED light irradiation, enhanced the liquidity of liposomal membrane and promoted the instantaneous release of ZnPc from the carriers realizing the concept of on-demand release. In addition, the local hyperthermia also resulted in thermal damage of cancer cells along with photodynamic effect and achieved a synergetic effect of photodynamic and photothermal therapy. The developed probes showed a high breast cancer carcinoma cells (MCF-7 cell line) inhibition up to 86.7% under red light irradiation. Further, in vivo experiments suggested the high tumor accumulation as well as the antitumor effect in breast tumor-bearing female Sprague-Dawley (SD) rats. The outcomes demonstrate the capability of these probes as a novel drug delivery system to codeliver therapeutic agents with photothermal agents and will have an enormous potential for future diagnosis and therapy.

Porphyrin Functionalized Gelatin Nanoparticle-Based Biodegradable Phototheranostics: Potential Tools for Antimicrobial Photodynamic Therapy.

Photomedicine-based antimicrobial therapy has emerged as an alternative treatment for antibiotic-resistant microbial infections. Although various photosensitizers (PSs) have been reported as efficient antimicrobial agents, their efficient delivery to the specific target area requires further investigation. In the current study, development of a biodegradable phototheranostic nanoagent (PTNA) by incorporation of a PS (trans-AB-porphyrin) and gelatin nanomatrix is described. The antimicrobial efficacy of the PTNA against Gram-positive bacteria, Gram-negative bacteria, and yeast strains, along with other properties including hydrophilicity, biocompatibility, and targeting ability, is evaluated. Unlike the commonly used membrane permeabilizing chemicals that are toxic, the delivery vehicle gelatin used in this study is biocompatible and biodegradable. Here, the method offers a sustainable synthesis of gelatin-based stable formulation of nanotheranostic agents with high loading (>85%). The study revealed that the reactive oxygen species (ROS), generated in situ by the PTNAs, are primarily responsible for microbial cell death. The developed PTNAs described herein featured "nano size (<200 nm), have high fluorescence and singlet oxygen quantum yields, retain photophysical properties of PS after incorporation into the gelatin matrix, could be activated by a cost-effective light irradiation, and have efficient antimicrobial photodynamic activity." This antimicrobial photodynamic therapy using the newly synthesized phototheranostic nanoagent has manifested its competence, therapeutic modality of general acceptance, and wide-spectrum antimicrobial action.

Facile immobilization of Pseudomonas fluorescens lipase on polyaniline nanofibers (PANFs-PFL): A route to develop robust nanobiocatalyst.

Herein, we demonstrate the immobilization of Pseudomonas fluorescens lipase (PFL) on polyaniline nanofibers (PANFs) via physical adsorption. Polyaniline nanofibers (PANFs) were synthesized by the oxidative polymerization of aniline. The developed robust nanobiocatalyst (PANFs-PFL) exhibited eight times higher activity than free PFL. In addition, immobilization of lipase on PANFs imparted operational stability of the nanobioconjugate. The various reaction parameters for immobilization (viz. reaction time, pH, stirring rate and enzyme-support ratio) were optimized using statistical design in terms of lipase activity and loading. Furthermore, facile separation, enhanced reusability (upto 6 cycles) and thermostability (upto 75 °C) were additional advantages of the nanobioconjugate. The catalytic prowess of nanobioconjugate was examined in the kinetic resolution of (RS)-N-(4-(3-chloro-2-hydroxypropoxy)phenyl)acetamide and (RS)-1-(1-naphthyl) ethanol in comparison to free PFL. PANFs-PFL demonstrated 49.9% and 48.1% conversion for (RS)-N-(4-(3-chloro-2-hydroxypropoxy)phenyl)acetamide and (RS)-1-(1-naphthyl) ethanol, respectively which signified its importance as a nanobiocatalyst.

Anticancer activity of dihydropyrazolo[1,5-c]quinazolines against rat C6 glioma cells via inhibition of topoisomerase II.

The design and synthesis of dihydropyrazolo[1,5-c]quinazolines (1a-h) as human topoisomerase II (TopoII) catalytic inhibitors are reported. The compounds were investigated for their antiproliferative activity against the C6 rat glial cell line. Two compounds, 1b and 1h, were found to be potent cytotoxic agents against glioma cells and exerted selective TopoII inhibitory activity. Furthermore, the compounds induced alterations in reactive oxygen species levels as measured by DCFDA assay and were found to induce cell cycle arrest at the G1 phase at lower concentrations and profound apoptosis at higher concentrations. The interaction of selected investigational molecules with TopoII was further corroborated by molecular modeling.

Development of Gelatin Nanoparticle-Based Biodegradable Phototheranostic Agents: Advanced System to Treat Infectious Diseases.

Rose bengal (RB)-conjugated and -entrapped gelatin nanoparticle (GNP)-based biodegradable nanophototheranostic (Bd-NPT) agents have been developed for the efficient antimicrobial photodynamic therapy. The study reveals that the use of gelatin nanoparticles could bypass the chemicals such as potassium iodide, EDTA, calcium chloride and polymyxin nonapeptide for the penetration of drug into the cell membrane to achieve antimicrobial activity. We demonstrated that the singlet oxygen generated by the biodegradable gelatin nanoparticles (BdGNPs) could damage the microbial cell membrane and the cell dies. The key features of the successive development of this work include the environmentally benign amidation of RB with GNPs, which was so far unexplored, and the entrapment of RB into the gelatin nanoparticles (GNP). The RB-GNP exhibited potent and broad-spectrum antimicrobial activity and could be useful in treating multi-drug-resistant microbial infections.

Esterase-Mediated Highly Fluorescent Gold Nanoclusters and Their Use in Ultrasensitive Detection of Mercury: Synthetic and Mechanistic Aspects.

The fast, accurate, and ultrasensitive detection of toxic mercury in real water samples is still challenging without the use of expensive sophisticated instruments. Herein, highly fluorescent gold nanoclusters (AuNCs) were synthesized using a newer protein templet, esterase (EST). The EST-AuNCs consisted of ∼25 Au atoms in the nanocluster having ∼2 nm size. EST-AuNCs were found to be highly stable in aqueous buffer with a wide range of pH (pH 4-12) and were also stable in powdered form. The fluorescence quantum yield of EST-AuNCs in deionized water was 6.2% which had increased to 7.8% upon the addition of 1 M NaCl (an increase of 23%). The EST-AuNCs selectively sense the toxic Hg2+ ions with higher sensitivity (limit of detection; 0.88 nM) with the linear range 1-30 nM. The test strips for rapid sensing of Hg2+ in real water samples were developed on the polymeric surface. The validation of sensing ability of EST-AuNCs suggested 94-98% recovery with linearity. Moreover, because of the widely reported applications of EST, the developed EST-AuNCs could also be used for another sensing, catalytic, and biomedical applications.

Exploration of the expeditious potential of Pseudomonas fluorescens lipase in the kinetic resolution of racemic intermediates and its validation through molecular docking.

A profoundly time-efficient chemoenzymatic method for the synthesis of (S)-3-(4-chlorophenoxy)propan-1,2-diol and (S)-1-chloro-3-(2,5-dichlorophenoxy)propan-2-ol, two important pharmaceutical intermediates, was successfully developed using Pseudomonas fluorescens lipase (PFL). Kinetic resolution was successfully achieved using vinyl acetate as acylating agent, toluene/hexane as solvent, and reaction temperature of 30°C giving high enantioselectivity and conversion. Under optimized condition, PFL demonstrated 50.2% conversion, enantiomeric excess of 95.0%, enantioselectivity (E = 153) in an optimum time of 1 hour and 50.3% conversion, enantiomeric excess of 95.2%, enantioselectivity (E = 161) in an optimum time of 3 hours, for the two racemic alcohols, respectively. Docking of the R- and S-enantiomers of the intermediates demonstrated stronger H-bond interaction between the hydroxyl group of the R-enantiomer and the key binding residues of the catalytic site of the lipase, while the S-enantiomer demonstrated lesser interaction. Thus, docking study complemented the experimental outcome that PFL preferentially acylated the R form of the intermediates. The present study demonstrates a cost-effective and expeditious biocatalytic process that can be applied in the enantiopure synthesis of pharmaceutical intermediates and drugs.

Design, Sustainable Synthesis, and Programmed Reactions of Templated N-Heteroaryl-Fused Vinyl Sultams.

A de novo design and synthesis of N-heteroaryl-fused vinyl sultams as templates for programming chemical reactions on vinyl sultam periphery or (hetero)aryl ring is described. The key features include rational designing and sustainable synthesis of the template, customized reactions of vinyl sultams at C═C bond or involving N-S bond cleavage, and reactions on the periphery of the heteroaryl ring for late-stage diversification. The simple, easy access to the template coupled with opportunities for the synthesis of diversely functionalized heterocyles from a single template constitutes a rare study in contemporary organic synthesis.

Development of nanobiocatalysts through the immobilization of Pseudomonas fluorescens lipase for applications in efficient kinetic resolution of racemic compounds.

The present work reports covalent immobilization of Pseudomonas fluorescens lipase (PFL) on functionalized multiwalled carbon nanotubes (MWCNTs) as a nanobiocatalyst (NBC). This nanobiocatalyst facilitates efficient kinetic resolution of (RS)-1-phenylethanol into (S)-1-phenylethanol [C=49.7%, eep=99.5%, ees=98.1% and E value=191.4]. The immobilized preparation (MWCNTs-PFL) showed ten-fold increase in activity, thermal stability upto 80 °C and recyclability (8 cycles). MWCNTs-PFL nanobioconjugate demonstrated better stability and enhanced activity compared to covalently immobilized PFL on other matrices (silver nanoparticles, gold nanoparticles and chitosan beads) used for the study. A statistical design [response surface methodology (RSM)] employed for the optimization of enzyme immobilization parameters made this study statistically more significant. Overall, the newly developed nanobiocatalyst has applications towards the kinetic resolution of racemic compounds.

Scaffold-Hopping of Aurones: 2-Arylideneimidazo[1,2-a]pyridinones as Topoisomerase IIα-Inhibiting Anticancer Agents.

Scaffold-hopping of bioactive natural product aurones has been studied for the first time. 2-Arylideneimidazo[1,2-a]pyridinones as potential topoisomerase IIα (hTopoIIα)-targeting anticancer compounds were considered. A multifunctional activator, polyphosphoric acid, enabled to realize a cascade reaction of 2-aminopyridine with 2,3-epoxyesters toward synthesis of 2-arylideneimidazo[1,2-a]pyridinones. Most of the compounds exhibited hTopoIIα-selective poison activity with efficiency more than etoposide and DNA-binding property, while not interacting with hTopo I. The compounds showed pronounced antiproliferative activities in nanomolar range with relatively poor toxicity to normal cells, inhibition of invasiveness, and apoptotic effect. The activities for inhibition of tubulin assembly, CDK1 and pCDK1, were also observed. Interestingly, the hTopoIIα inhibitory (in vitro and ex vivo studies) and antiproliferative activities of representative potent compounds were found to be manifold higher compared to corresponding parent aurones bearing alike substitutions, indicating the importance of such scaffold-hopping strategy in medicinal chemistry research.