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A broad range of fundamental free radical reactions, including hydrogen and halogen atom transfer, radical deoxygenations, radical cyclization reactions, radical additions to C=C and C=N double bonds utilizing β-cyclodextrin-ionic liquid(mono-6-(1-methyl-3-imidazolium) - 6 - deoxy - β -cyclodextrin tosylate (MIM-β-CDOTs) based molecular reactors/alternative media at room temperature are investigated. The reactions proceeded smoothly in moderate to excellent yield at ambient temperature, with noticable improvements in enantioselectivity observed in several key transformations. © 2011 Bentham Science Publishers.


Zhang S.,VTPChem PTy Ltd. | Chen J.,VTPChem PTy Ltd. | Perchyonok V.T.,VTPChem PTy Ltd.
Current Organic Chemistry | Year: 2011

Reactions of epoxides with tetrasubstitute ammonium halides in the presence of β-cyclodextrins or polyHIPE in aqueous media afforded vicinal halohydrins in excellent yields via regioselective ring opening of the unsymmetric epoxides. © 2011 Bentham Science Publishers Ltd.


Perchyonok V.T.,VTPCHEM Pty. Ltd.
Letters in Organic Chemistry | Year: 2011

The paper highlights an efficient methodology based on consecutive radical reaction for the preparation of cyclonucleoside derivatives. The reactions were performed in organic and aqueous media, using common and efficient free radical hydrogen donors in the range of innovative and conventional initiation conditions to afford good to excellent yields of corresponding cyclonucleosides. The mechanistic aspects of the transformations are also addressed. © 2011 Bentham Science Publishers Ltd.


Perchyonok V.T.,VTPCHEM Pty. Ltd.
Letters in Organic Chemistry | Year: 2011

Floricil (60-100nm, activated)-based Batch Molecular Reactors have been assembled and used in a variety of conventional synthetically useful free radical transformations (Hydrogen Transfer Reactions, Radical Cascade Reactions and Addition to C=C and C=N bonds). Reactions proceeded smoothly in all cases in good to excellent yields at ambient temperature in aqueous and organic media. The advantages of newly assembled setup are ease of setup, recyclability of the solid media, flexibility and scope of the transformations to be performed and ease of scale-up of methodology. © 2011 Bentham Science Publishers Ltd.


β-cyclodextrin based Batch, Flow-Through and "Teabag" Prototype Molecular Reactors have been assembled and used in variety of conventional synthetically useful free radical transformations (Hydrogen Transfer Reactions, Radical Cascade Reactions and Mn(OAc)3 mediated cascade/oxidation reactions. Reactions proceeded smoothly in all cases in good to excellent yields at ambient temperature in aqueous and organic media. The advantages of newly assembled setup are ease of setup, recyclability of the β-cyclodextrin media, flexibility and scope of the transformations to be performed and ease of scale-up of methodology. © 2011 Bentham Science Publishers.


Zhang S.,East China University of Science and Technology | Chen J.,East China University of Science and Technology | Lykakis I.N.,University of Crete | Perchyonok V.T.,VTPCHEM PTY LTD
Current Organic Synthesis | Year: 2010

Increasing emphasis has been placed on producing synthetic organic compounds faster and more efficiently than can be produced using conventional methodology. It is often observed that tried and true methods for performing synthesis, work-up, and purification on individual or low number of reactions do not scale up well even to a modest level of parallel synthesis. As a result, novel methodologies or parallel and combinatorial chemical synthesis continues be developed at a rapid pace. In general, the specific structure of the target molecule(s) guides the selection of the synthetic methodology (e.g., solid or solution phase) used in given reaction sequence. The phrase "Streamline Organic Synthesis" has been coined as descriptor for methodology that lends itself to efficient application to parallel organic synthesis. The advantages of the past few years in microreactors have demonstrated the miniaturizing of chemistry that significant advantage with respect to cost, safety, throughput, kinetics and scale-up. The use of chemical microreactors for broad spectrum of important chemical transformation has illustrated the utility and benefits for both chemical discovery and development of novel and unique applications. The main objective of this tutorial review article is to bring together two important topics of synthetic free radical chemistry and its applications and advancements to "Streamline Organic Synthesis" on the interface of conventional and alternative materials, such as polymer supported reagents/reactants, use of ultraporous materials (PolyHIPEs) as well as continuous microflow systems of natural zeolite and commercial man-made microreactors. © 2010 Bentham Science Publishers Ltd.


PubMed | VTPCHEM PTY LTD
Type: Journal Article | Journal: Current drug delivery | Year: 2011

A novel approach in target specific molecular prototype drug delivery system concerns the attempt to employ radical affording substances (RAS) or radical quenching substances (RQS) as prodrugs able to produce irreversible damage on the desired target and therefore to stimulate cellular apoptosis. However, radical species generated can react quickly within the chemical environment prior to reaching its proper site of action. In this short communication, we report our investigations towards developing two alternative novel, simple, flexible and effective drug delivery systems that provide optimal dosage of drugs precisely where and when needed and therefore achieve and sustain a complex delivery profile. We have demonstrated the application of two effective molecular prototype delivery systems able to harness free radical reactivity within the laboratory where biological processes can be studied and controlled, leading to the prevention of disease and the development of new treatments for disease states mediated by free radicals.


PubMed | East China University of Science and Technology, VTPCHEM PTY Ltd and University of the Western Cape
Type: Journal Article | Journal: Journal of functional biomaterials | Year: 2014

IPNs are unique alloys of cross-linked polymers in which at least one network is synthesized and/or cross-linked in the presence of the other. IPNs are also known as entanglements of polymer networks that are ideally held together only by permanent topological interactions. The objectives of this study are to evaluate novel chitosan-based functional drug delivery systems that can be successfully incorporated into dual action bioactive tooth restorative materials. These materials should be capable of inducing an improved wound healing prototype. The novel hydrogels will be investigated with respect to the antioxidant capacity of conventional antioxidants, such as resveratrol, b-carotene and propolis, as a designer drug delivery system, with the use of SEM imaging for the characterization of the surfaces, bio-adhesive property, antioxidant capacity, free radical defence, antioxidant, active ingredient stability and reactive features of novel materials. The additional benefit of the site-specific functional restorative material for use in dressings to deliver antibiotics to wound sites can provide tissue compatibility and reduced interference with wound healing. The materials were tested using an effective in vitro free radical generation model as functional additive prototypes for further development of dual function restorative wound healing materials. We quantified the effects of functional designer biomaterials on the dentin bond strength of a composite and evaluated the bio-adhesive capacity of the materials in the two separate in vitro systems. The added benefits of the chitosan/vitamin C/cyclodextrin (CD) host:guest complex-treated hydrogels involved a positive influence on the tetracycline release, increased dentin bond strength, as well as a demonstrated in vitro built-in free radical defence mechanism and, therefore, acting as a proof of concept for functional multi-dimensional restorative wound healing materials with a built-in free radical defence mechanism. Based on our results, we can conclude that the CD:chitosan-antioxidant-containing hydrogels are a suitable carrier for tetracycline to be slow-released. Within the limitations of the study design, chitosan-based hydrogels are suitable materials for functional restorative and wound healing applications in vitro. Cytotoxicity data are currently being evaluated in our laboratory.


PubMed | VTPCHEM PTY LTD
Type: Journal Article | Journal: Current drug delivery | Year: 2013

In this study we developed and evaluated a prototype of an effective occlusive mucoadhesive system for prophylaxis and/or treatment of oral mucositis based on chitosan and gelatine models together with nystatin as a prophylactic agent incorporated into the formulation and investigated drug release in-vitro. Results of in vitro studies showed that chitosan and gelatine based gels posses properties that makes them excellent candidates for treatment of oral mucositis. These properties include not only the palliative effects of an occlusive dressing but also the potential for delivering therapeutic compounds with chitosan gels providing drug concentrations above their minimum inhibition concentration and extending the retention time in the oral cavity due to their bioadhesive properties. Chitosan also offers an advantage over suspensions because of its inherent antimicrobial properties. The performance of gelatin-based gels highlights the novel, non-toxic, in situ forming gelatine based hydrogel. The results of in vitro drug release experiments demonstrated that all the hydrogel showed sustained release properties.


PubMed | Griffith University, East China University of Science and Technology, VTPCHEM PTY LTD. and University of the Western Cape
Type: Journal Article | Journal: Journal of functional biomaterials | Year: 2014

Healing is a specic biological process related to the general phenomenon of growth and tissue regeneration and is a process generally affected by several systemic conditions or as detrimental side-effects of chemotherapy- and radiotherapy-induced inflammation of the oral mucosa. The objectives of this study is to evaluate the novel chitosan based functional drug delivery systems, which can be successfully incorporated into dual action bioactive restorative materials, capable of inducing in vitro improved wound healing prototype and containing an antibiotic, such as nystatin, krill oil as an antioxidant and hydroxyapatite as a molecular bone scaffold, which is naturally present in bone and is reported to be successfully used in promoting bone integration when implanted as well as promoting healing. The hydrogels were prepared using a protocol as previously reported by us. The physico-chemical features, including surface morphology (SEM), release behaviors, stability of the therapeutic agent-antioxidant-chitosan, were measured and compared to the earlier reported chitosan-antioxidant containing hydrogels. Structural investigations of the reactive surface of the hydrogel are reported. Release of nystatin was investigated for all newly prepared hydrogels. Bio-adhesive studies were performed in order to assess the suitability of these designer materials. Free radical defense capacity of the biomaterials was evaluated using established in vitro model. The bio-adhesive capacity of the materials in the in vitro system was tested and quantified. It was found that the favorable synergistic effect of free radical built-in defense mechanism of the new functional materials increased sustainable bio-adhesion and therefore acted as a functional multi-dimensional restorative material with potential application in wound healing in vitro.

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