Glycosidation of Cu,Zn-Superoxide Dismutase with End-Group Aminated Dextran. Pharmacological and Pharmacokinetics Properties

Strategies to expand the therapeutic potential of superoxide dismutase by exploiting delivery approaches

The overproduction of free radicals can cause oxidative-stress damage to a range of biomolecules, and thus potentially contribute to several pathologies, from neurodegenerative disorders to cardiovascular diseases and metabolic disorders. Endogenous antioxidant enzymes, such as superoxide dismutase (SOD), play an important role in diminishing oxidative stress. SOD supplementation could therefore be an effective preventive strategy to reduce the risk of free-radical overproduction. However, the efficacy of SOD administration is hampered by its rapid clearance. Several different approaches to improve the bioavailability of SOD have been explored in recent decades. This review intends to describe the rationale that underlie the various approaches and chemical strategies that have led to the most recent advances in SOD delivery. This critical description includes SOD conjugates, SOD loaded into particulate carriers (micelles, liposomes, nanoparticles, microparticles) and the most promising and suitable formulations for oral delivery, with a particular emphasis on reports of preclinical/clinical results. Likely future directions are also considered and reported.

Dextran-Functionalized Quantum Dot Immunoconjugates for Cellular Imaging

Brightly luminescent semiconductor quantum dots (QDs) are ideal materials for cellular imaging and analysis because of their advantageous optical properties and surface area that supports multivalent conjugation of biomolecules. An important design consideration for effective use of these materials is a hydrophilic, biocompatible surface chemistry that provides colloidal stability and minimizes nonspecific interactions with biological molecules and systems. Dextran coatings are able to satisfy these criteria. Despite frequent use of dextran coatings with other nanomaterials (e.g., iron oxide nanoparticles), there has been little development and application of dextran coatings for QDs. In this chapter, we describe methods for the synthesis and characterization of a dextran ligand for QDs, including preparation of an immunoconjugate via tetrameric antibody complexes (TAC). The utility of these immunoconjugates is demonstrated through immunofluorescent labeling and imaging of overexpressed human epidermal growth factor receptor 2 (HER2) on the surface of SK-BR3 breast cancer cells.

Two-step polymer- and liposome-enzyme prodrug therapies for cancer: PDEPT and PELT concepts and future perspectives

Polymer-directed enzyme prodrug therapy (PDEPT) and polymer enzyme liposome therapy (PELT) are two-step therapies developed to provide anticancer drugs site-selective intratumoral accumulation and release. Nanomedicines, such as polymer-drug conjugates and liposomal drugs, accumulate in the tumor site due to extravasation-dependent mechanism (enhanced permeability and retention - EPR - effect), and further need to cross the cellular membrane and release their payload in the intracellular compartment. The subsequent administration of a polymer-enzyme conjugate able to accumulate in the tumor tissue and to trigger the extracellular release of the active drug showed promising preclinical results. The development of polymer-enzyme, polymer-drug conjugates and liposomal drugs had undergone a vast advancement over the past decades. Several examples of enzyme mimics for in vivo therapy can be found in the literature. Moreover, polymer therapeutics often present an enzyme-sensitive mechanism of drug release. These nanomedicines can thus be optimal substrates for PDEPT and this review aims to provide new insights and stimuli toward the future perspectives of this promising combination.

The conjugation of Cu/Zn superoxide dismutase (SOD) to O-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (O-HTCC) enhances its therapeutic potential against radiation-induced oxidative damage

A novel polymer–enzyme conjugate, O-HTCC–SOD, was prepared to improve the therapeutic potential of SOD in vitro and in vivo.

Enzyme therapeutics for systemic detoxification

Life relies on numerous biochemical processes working synergistically and correctly. Certain substances disrupt these processes, inducing living organism into an abnormal state termed intoxication. Managing intoxication usually requires interventions, which is referred as detoxification. Decades of development on detoxification reveals the potential of enzymes as ideal therapeutics and antidotes, because their high substrate specificity and catalytic efficiency are essential for clearing intoxicating substances without adverse effects. However, intrinsic shortcomings of enzymes including low stability and high immunogenicity are major hurdles, which could be overcome by delivering enzymes with specially designed nanocarriers. Extensive investigations on protein delivery indicate three types of enzyme-nanocarrier architectures that show more promise than others for systemic detoxification, including liposome-wrapped enzymes, polymer-enzyme conjugates, and polymer-encapsulated enzymes. This review highlights recent advances in these nano-architectures and discusses their applications in systemic detoxifications. Therapeutic potential of various enzymes as well as associated challenges in achieving effective delivery of therapeutic enzymes will also be discussed.

Decorating graphene oxide/nanogold with dextran-based polymer brushes for the construction of ultrasensitive electrochemical enzyme biosensors

A novel strategy to prepare a water-soluble graphene derivative by attaching dextran polymer brushes.

Protective effect of chemically modified SOD on lipid peroxidation and antioxidant status in diabetic rats

Reactive oxygen species mediated oxidative stress play an important role on the injury of tissue damage and increased attention has been focused on the role of free radicals in diabetes mellitus (DM). In the present study firstly superoxide dismutase (SOD) enzyme was chemically modified with two different polymer and physicochemical properties of these conjugates clearly analyzed. Then, the stability of carboxymethylcellulose-SOD (CMC-SOD) and poly methyl vinyl ether-co-maleic anhydride-SOD (PMVE/MA-SOD) conjugates was investigated against temperature and externally added H2O2. Moreover, we investigated the effect of chemically modified SOD enzyme on lipid peroxidation and antioxidant status in streptozotocin (STZ)-induced diabetic rats. PMVE/MA-SOD conjugate treatment significantly reduced MDA level compared with the control groups, native and CMC-SOD conjugate treated groups in brain, kidney and liver tissue. GSH and SOD enzyme activity in diabetic groups was significantly increased by treatment of CMC-SOD and PMVE/MA-SOD conjugates. The protective effects on degenerative changes in diabetic rats were also further confirmed by histopathological examination. This study provides the preventative activity of SOD-polymer conjugates against complication of oxidative stress in experimentally induced diabetic rats. These results suggest that chemically modified SOD is effective on the oxidative stress-associated disease and offer a therapeutic advantage in clinical use.

Synthesis of amphiphilic diblock copolymers derived from renewable dextran by nitroxide mediated polymerization: towards hierarchically structured honeycomb porous films

A novel dextran-SG1 macro-alkoxyamine was designed to afford amphiphilic linear block copolymers synthesized by nitroxide mediated polymerization toward the formation of hierarchically structured bio-resourced honeycomb films.

Bienzymatic Supramolecular Complex of Catalase Modified with Cyclodextrin-Branched Carboxymethylcellulose and Superoxide Dismutase: Stability and Anti-Inflammatory Properties

A bienzymatic supramolecular assembly of CAT and SOD is reported. CAT was chemically glycosilated with CD branched CMC and then associated with SOD modified with 1-adamantane carboxylic acid. SOD was remarkably resistant to inactivation by H(2)O(2) and its anti-inflammatory activity was 4.5-fold increased after supramolecular association with the modified CAT form. [structure: see text]

Improved pharmacological properties for superoxide dismutase modified with β-cyclodextrin–carboxymethylcellulose polymer

Superoxide dismutase was glycosidated with cyclodextrin-branched carboxymethylcellulose. The modified enzyme contained 1.4 mol polymer per mol protein and retained 87% of the initial activity. The anti-inflammatory activity of superoxide dismutase was 2.2-times increased after conjugation and its plasma half-life time was prolonged from 4.8 min to 7.2 h.

Pharmacokinetics and Stability Properties of Catalase Modified with Water-Soluble Polysaccharides

Bovine liver catalase (EC 1.11.1.6) was chemically modified with mannan, carboxymethylcellulose, and carboxymethylchitin. The enzyme retained about 48-97% of the initial specific activity after glycosidation with the polysaccharides. The prepared neoglycoenzyme was 1.9-5.7 fold more stable against the thermal inactivation processes at 55 degrees C, in comparison with the native counterpart. Also, the modified enzyme was more resistant to proteolytic degradation with trypsin. Pharmacokinetics studies revealed higher plasma half-life time for all the enzyme-polymer preparations, but better results were achieved for the enzyme modified with the anionic macromolecules.