Qamar Zia

Sol-gel synthesis of thorn-like ZnO nanoparticles endorsing mechanical stirring effect and their antimicrobial activities: Potential role as nano-antibiotics

The effect of mechanical stirring on sol-gel synthesis of thorn-like ZnO nanoparticles (ZnO-NPs) and antimicrobial activities is successfully reported in this study. The in-house synthesized nanoparticles were characterized by XRD, SEM, TEM, FTIR, TGA, DSC and UV-visible spectroscopy. The X-Ray Diffraction analysis revealed the wurtzite crystal lattice for ZnO-NPs with no impurities present. The diametric measurements of the synthesized thorn-like ZnO-NPs (morphology assessed by SEM) were well accounted to be less than 50 nm with the help of TEM. Relative decrease in aspect ratio was observed on increasing the agitation speed. The UV-visible spectroscopy showed the absorption peaks of the ZnO-NPs existed in both UVA and UVB region. A hypsochromic shift in λmax was observed when stirring pace was increased from 500 rpm to 2000 rpm. The FTIR spectroscopy showed the absorption bands of the stretching modes of Zn-O between 500 cm−1 to 525 cm−1. The Thermal analysis studies revealed better stability for ZnO-NPs prepared at 2000 rpm (ZnO-2000 rpm). TGA revealed the weight loss between two main temperatures ranges viz. around (90 °C–120 °C) and (240 °C–280 °C). Finally, the effect of ZnO-NPs prepared at different stirring conditions on the growth of Gram-positive (Bacillus subtilis), Gram-negative (Escherichia coli) bacteria and a fungi (Candida albicans) were examined; which showed good antibacterial as well as antifungal properties. These findings introduce a simple, inexpensive process to synthesize ZnO-NPs using conventional methods without the use of sophisticated equipments and its application as a potent nano-antibiotic.

Development, characterization and efficacy of niosomal diallyl disulfide in treatment of disseminated murine candidiasis

UNLABELLED In the current study, a novel niosome based formulation of diallyl disulfide (DADS) was evaluated for its potential to treat disseminated candidiasis in mouse model. Among various non-ionic surfactants tested, niosome formulation prepared using Span 80 was found to be most efficient in the entrapment of DADS. The DADS loaded niosomes had size dimensions in the range of 140 ± 30 nm with zeta potential of -30.67 ± 4.5. Liver/kidney function tests as well as histopathologic studies suggested that noisome-based DADS formulations are safe at the dose investigated. When administered to Candida albicans infected animals, the DADS bearing niosomal formulation cleared the fungal burden and increased their survival much efficiently than its free form. FROM THE CLINICAL EDITOR In this study, a novel niosomal formulation of the antifungal DADS was utilized in a murine candidiasis model, resulting in more efficient fungal clearance compared to the free formulation.

Characterization of doxorubicin binding site and drug induced alteration in the functionally important structural state of oxyhemoglobin.

Doxorubicin (DOX) binding to hemoglobin (Hb) was studied to investigate the drug induced protein dysfunction. The features of anti-tumor drug doxorubicin infused structural perturbation of human Hb were studied by circular dichroism (CD). The mechanism of DOX-Hb binding was elucidated by steady-state and synchronous fluorescence spectroscopy. The Stern-Volmer analysis indicated that the binding of Hb to DOX is characterized by more than one high affinity binding site with the association constants of the order of 10(5). Hydrophobic probe ANS was employed to elucidate the drug binding site. Binding mode expounded by thermodynamic parameters implied the role of hydrogen bonding, electrostatic and hydrophobic interaction in stabilizing the complex. The molecular distance between donor (Hb) and acceptor (DOX) was calculated according to Försters theory of energy transfer. Fourier transform infrared (FT-IR) spectroscopy provides an insight to the changes occurring in protein on DOX binding. Treatment of Hb with DOX resulted in a dose dependent fragmentation of protein. The quantitative analysis revealed the release of acid soluble amino groups from the photoexcited Hb-DOX mixture. The free radical mediated degradation was suggested by its rescue on mannitol and superoxide dismutase (SOD) appliance. The loss of protein band further corroborates the concentration dependent Hb fragmentation. The molecular modeling complies with the thermodynamic data of forces involved in DOX binding and depicts its interaction in the proximity of oxygen binding pocket of Hb. Thus, this study enriches our understanding of the interaction dynamics of anticancer drugs to the physiologically important protein Hb.

Self-assembled amphotericin B-loaded polyglutamic acid nanoparticles: preparation, characterization and in vitro potential against Candida albicans

In the present study, we developed a self-assembled biodegradable polyglutamic acid (PGA)-based formulation of amphotericin B (AmB) and evaluated its in vitro antifungal potential against Candida albicans. The AmB-loaded PGA nanoparticles were prepared in-house and had a mean size dimension of around 98±2 nm with a zeta potential of −35.2±7.3 mV. Spectroscopic studies revealed that the drug predominantly acquires an aggregated form inside the formulation with an aggregation ratio above 2. The PGA-based AmB formulation was shown to be highly stable in phosphate-buffered saline as well as in serum (only 10%–20% of the drug was released after 10 days). The AmB–PGA nanoparticles were less toxic to red blood cells (<15% lysis at an AmB concentration of 100 μg/mL after 24 hours) when compared with Fungizone®, a commercial antifungal product. An MTT assay showed that the viability of mammalian cells (KB and RAW 264.7) was negligibly affected at AmB concentrations as high as 200 μg/mL. Histopathological examination of mouse kidney revealed no signs of tissue necrosis. The AmB–PGA formulation showed potent antimicrobial activity similar to that of Fungizone against C. albicans. Interestingly, AmB-bearing PGA nanoparticles were found to inhibit biofilm formation to a considerable extent. In summary, AmB–PGA nanoparticles showed highly attenuated toxicity when compared with Fungizone, while retaining equivalent active antifungal properties. This study indicates that the AmB–PGA preparation could be a promising treatment for various fungal infections.

Chemotherapeutic potential of curcumin-bearing microcells against hepatocellular carcinoma in model animals

Curcumin (diferuloylmethane) is found in large quantities in the roots of Curcuma longa. It possesses strong antioxidant and anti-inflammatory properties, and inhibits chemically-induced carcinogenesis in the skin, forestomach, colon, and liver. Unfortunately, the poor bioavailability and hydrophobicity of curcumin pose a major hurdle to its use as a potent anticancer agent. To circumvent some of these problems, we developed a novel, dual-core microcell formulation of curcumin. The encapsulation of curcumin in microcells increases its solubility and bioavailability, and facilitates slow release kinetics over extended periods. Besides being safe, these formulations do not bear any toxicity constraints, as revealed by in vitro and in vivo studies. Histopathological analysis revealed that curcumin-bearing microcells helped in regression of hepatocellular carcinoma and the maintenance of cellular architecture in liver tissue. Free curcumin had a very mild effect on cancer suppression. Empty (sham) microcells and microparticles failed to inhibit cancer cells. The novel curcumin formulation was found to suppress hepatocellular carcinoma efficiently in Swiss albino mice.

Molecular mechanisms of drug photodegradation and photosensitization.

Drug-induced photosensitivity of the skin is drawing increasing attention. In past few decades, photosensitivity has been reported with an array of drugs, and is now recognized as a noteworthy medical problem by clinicians, regulatory authorities and pharmaceutical industry. The photosensitivity is of two types i.e., phototoxicity and photoallergy. Phototoxic disorders have a high incidence, whereas photoallergic reactions are much less frequent in human population. Several hundred substances, chemicals, or drugs may invoke phototoxic and photoallergic reactions. In order to avoid photosensitive reactions, it is essential to understand the mechanism behind the photosensitizing properties of such substances before these drugs are introduced in clinical settings. Photosensitization is inter-related to photochemical reaction, through the knowledge of which the photosensitivity of a drug can be anticipated. This review highlights the current research status on photosensitizing drugs and its correlation to phototoxicity. Different mechanisms of photodegradation of photolabile drugs have also been discussed.

Novel Drug Delivery Systems for Antifungal Compounds

Development of new approaches for treatment of invasive fungal infections encompasses new delivery systems for approved and investigational compounds. Novel delivery systems consisting of cyclodextrins (CDs), cochleates, nanoparticles, and long-circulating (“stealth”) liposomes modulate the pharmacokinetics of existing drugs, and may also be useful to enhance the delivery of antifungal agents to sites of infection. Among several promising new drug-delivery systems, liposomes represent an advanced technology for site-directed delivery of active molecules. Research on liposome technology has progressed from conventional vesicles (“first-generation liposomes”) to “second-generation liposomes,” in which long-circulating liposomes are obtained by modifying the surface of liposomes using several molecules, such as glycolipids, sialic acid, or synthetic polymer poly-(ethylene glycol) (PEG), resulting in prolonged reticulo-endothelial system uptake and serum half-life, thus increasing the therapeutic efficacy of drugs. At present, several formulations for amphotericin B are in clinical use for fungal infections in Europe and the United States. Nanoformulations have also been applied as drug delivery systems (DDSs), with great success. Finally, progress in the design of DDSs has led to the development of carriers targeted to specific tissues and cells. Efforts are now going on to improve their stability in the biological environment, to mediate the biodistribution of active compounds, and to improve drug loading, targeting, transport, release, and interaction with biological barriers. This chapter discusses the state of the art in the field of DDSs, used for control of systemic fungal infections.

Novel biodegradable poly(gamma-glutamic acid)–amphotericin B complexes show promise as improved amphotericin B formulations

Commercially available amphotericin B (AmB) formulations are limited by cytotoxicities, lower efficacies, shelf-life related issues and high production costs. In this study, AmB complexes based on poly(gamma-glutamic acid) (PGGA) were prepared and evaluated for their efficacies against AmB-deoxycholate (Fungizone®) and liposomal AmB (AmBisome®). Physical characterizations showed that AmB/PGGA complexes are nanoscopic (20-40 nm) with a negative zeta potential (-45.5 to -51.0 mV), water-soluble, stable in solution (up to 4 weeks, at 4 °C and 25 °C), and have a high drug loading (up to 35% w/w). In vitro, AmB/PGGA complexes exhibited a more favorable cytotoxicity profile than Fungizone® but comparable to AmBisome®, with respect to the hemolytic activity and the modulation of pro-inflammatory cytokines (TNF-α and IL-1ß). In-vivo, AmB/PGGA complexes were significantly more efficacious than both Fungizone® and AmBisome® against experimental murine candidiasis. These results provide strong evidence that AmB/PGGA complexes display better efficacy and safety features than the currently approved AmB products.

Efficacy of Cell Wall-Deficient Spheroplasts Against Experimental Murine Listeriosis

Various strategies adapted to develop an efficient vaccine against foodborne pathogen, Listeria monocytogenes, have met with little success. Spheroplasts (bacterial cell devoid of cell wall) are likely to undergo membrane–membrane fusion, leading to the delivery of their content to the cytosol of antigen‐presenting cells, thus facilitating MHC class I antigen processing and presentation. In this study, we evaluated the prophylactic potential of Listeria spheroplast‐based vaccine against experimental murine listeriosis in comparison with heat‐killed Listeria (HKL) and archaeosome‐entrapped Listeria whole‐cell protein (LWCP). Compared with HKL, the spheroplast‐based vaccine was found to evoke better Th1 response as exhibited by the presence of type 1 cytokines in the host (interferon‐γ and IL‐12) and a high IgG2a/IgG1 ratio. Robust lympho‐proliferative efficacy was apparent in both spheroplast‐immunized and archaeosome‐entrapped LWCP‐immunized groups. The upregulation of costimulatory and effector memory markers upon immunization with spheroplasts was found to be at par with that evoked by archaeosome‐entrapped LWCP‐immunized group. Central memory response in gated CD8+ T cell was much higher in spheroplast‐immunized animals when compared with archaeosome‐entrapped LWCP group. The data presented here clearly demonstrate that spheroplasts evoked a robust immune response and offer better prophylactic potential against L. monocytogenes.

Vaccine potential of plasma bead-based dual antigen delivery system against experimental murine candidiasis

The development of prophylactic anti-candidal vaccine comprising the Candida albicans cytosolic proteins (Cp) as antigen and plasma beads (PB) prepared from plasma as sustained delivery system, is described. The immune-prophylactic potential of various PBs-based dual antigen delivery systems, co-entrapping Cp pre-entrapped in PLGA microspheres were tested in the murine model. Induction of cell mediated immunity was measured by assaying DTH and NO production as well as in vitro proliferation of lymphocytes derived from the immunized animals. Expression of surface markers on APCs (CD80, CD86) and T-cells (CD4+, CD8+) was also evaluated. Humoral immune response was studied by measuring circulating anti-Cp antibodies and their subclasses. When the prophylactic efficacy of the vaccines was tested in mice challenged with virulent C. albicans, the PB-based formulation (PB-PLGA-Cp vaccine) was found to be most effective in the generation of desirable immune response, in terms of suppression of fungal load and facilitating the survival of the immunized animals.