A practical synthesis of the powerful antitumor agents, mitomycin C and FR900482, remains an elusive goal to this date. These substances may be thought to arise from suitably functionalized benzazocinones as retrosynthetic intermediates. The key to a unified strategy for the synthesis of all mitomycinods is thus a concise, efficient route to a common benzazocenone, which requires appropriate substituents on the aromatic ring as dictated by the specific target molecule. The preparation of medium ring heterocycles of this type is troublesome. The research described herein has been directed toward the development of a practical solution to this problem. We describe the application of our novel ene-like reaction for the construction of benzazocinone intermediates as well as research towards various methods to transform them into suitable intermediates for the total synthesis of mitomycinoids. We also developed an efficient method for construction of properly functionalized aldehydes for our ene-like reaction, as well as the synthesis of an achiral diol which can be desymmetrized for use in an enantiocontrolled synthesis. The information accumulated from these experiments will, undoubtedly, be helpful in completion of the total synthesis of FR900482 and other mitomycinoids, which continues in our laboratories.

The goal of this project is to develop the strategies necessary to synthesize the rubromycin class of natural products. Synthesis of fully functionalized isocoumarin and naphthoquinone moieties of rubromycin and related compounds are reported. The isocoumarin is formed by a modified condensation reaction of diethyl bromomalonate with a substituted phthalaldehydic acid. The naphthoquinone system is assembled from readily available 2-bromo-5,7,8-trimethoxy-1,4-naphthoquinone that is oxygenated in a copper-catalyzed, addition-elimination reaction with methanol to yield the intermediate 2,5,7,8-tetramethoxy-1,4-naphthoquinone, which is also easily converted to the natural products mompain and 2,7-dimethoxy-1,4-naphthoquinone. A model for the spiroketal core of the rubromycins is also discussed. Multiple coupling strategies of the isocoumarin and naphthoquinone fragments are also discussed. This thesis represents the founding work for this project in the Behar group.

The first fullerene-based X-ray contrast agent (CA) has been designed, synthesized, and characterized. The new CA is an externally functionalized derivative of C60 that is conceptually based on contemporary X-ray CA, all of which use iodine as the X-ray attenuating vehicle and are built on the 2,4,6-triiodinated-benzene-ring substructure. Aqueous solutions of the agents are injected intravenously via catheter into patients followed by X-ray imaging. The CA is then eliminated rapidly through the kidneys. A modified Bingel-type reaction (nucleophilic cyclopropanation) was developed in which 6 iodine atoms can be appended to C60 (per addend) to form a cyclopropane ring exclusively across one of the [6,6] double bonds of C60. Each addend contains two 2,4,6-triiodinated-benzene-ring moieties attached to a malonodiamide functionality through a nitrogen in the 5 ring position, with water-solubilizing 1,3-diol-containing serinol-benzamide substituents in the remaining ring positions (1 and 3). When the malonodiamide is reacted with C60 in excess (≥3 molar excess), however, only the fullerene monoadduct forms in good yield, with only small amounts of the diadduct detected. A general method for producing highly water-soluble, non-ionic fullerene materials was simultaneously developed. The synthetic approach also utilizes the new malonodiamide addend methodology to form multiple Bingel adducts with C60 to give C60[C(COSer)2]n (n = 4, 5, 6, Ser = 2-amino-1,3-propanediol). The compound is the most water soluble fullerene material reported to date (>240 mg C 60 mL-1). In addition, the aqueous solubility has no notable pH dependence. Due to the lack of water solubility of the amphiphilic iodinated C 60 monoadduct, the water-solubilization methodology was combined with the iodination methodology to prepare a "hybrid" material that contains both the water-solubilizing groups and the iodine containing groups. The resulting fullerene-based X-ray CA is a fully water-soluble, non-ionic pentaadduct with one hexaiodinated addend containing 8 hydroxy groups and four additional addends each containing 4 hydroxy groups. The new, first generation fullerene-based CA contains 24% iodine by weight. The ideological development of the new CA, the successful (and some of the unsuccessful) synthetic pathways and the spectral characterization of the new products is presented and discussed.

Fullerene (C60) derivatives have been extensively studied for a variety of medical applications, which include neuroprotective agents, HIV-1 protease inhibitors, photosensitizers for photodynamic therapy, MRI contrast agents, and radiopharmaceuticals. The first part of this work is dedicated to the development of a new application of C60 as a slow-release system for the liposome aerosol delivery of lipophilic chemotherapeutics to lung cancer. TaxolRTM (paclitaxel), one of the most active anticancer drugs in clinical use, has shown significant potential for treatment of lung cancer when delivered by the liposome aerosol method. However, rapid clearance of Taxol from the lungs (within 40 minutes after cessation of aerosol delivery) results in its reduced therapeutic efficacy. A C60-Taxol conjugate, a slow-release drug, has been designed and synthesized as a prospective solution to the problem. The conjugate was designed to have no intrinsic activity by modifying 2'-hydroxyl group of Taxol and to release the active drug via enzymatic hydrolysis of a 2'-ester bond. The conjugate synthesis involved the synthesis of Taxol-2'-succinate and a fullerene aminoderivative and then coupling them with EEDQ. Although very stable as a 10% DMSO solution at physiological pH, the C60-Taxol conjugate demonstrated the ability to release Taxol in the presence of bovine plasma with the hydrolysis half-life of about 80 minutes. The conjugate was also shown to form a stable liposome formulation using dilaurylphosphatidylcholine (DLPC), and as a DLPC suspension, demonstrated cytotoxic activity comparable to that of Taxol in human epithelial lung carcinoma A549 cells. With both clinically-relevant kinetics of hydrolysis and significant cytotoxicity in tissue culture, the conjugate holds promise for enhanced therapeutic efficacy of Taxol in vivo. The second part of this work is dedicated to the design and synthesis of C60-based transfection vectors in order to establish a structure-activity relationship (SAR) profile for this class of compounds. Several positively-charged derivatives of C60 were synthesized via Bingel and Prato chemistry and tested for transfection activity in HEK293 cells. Out of the three studied derivatives, only Bingel bisadducts permitted effective gene delivery. The maximum of protein expression was observed after 5 days of incubation which is consistent with the results reported for other known C60-based transfection vectors. The comparison of the structures of fullerene derivatives now known to permit effective gene delivery reveal similar structural features which can guide the design of potential C60-based transfection vectors.

No description available.

Multienzyme systems with cofactor recycling have been immobilized within artificial cells (AC) to carry out certain metabolic functions in living cells. In liver failure there is an increase in systemic ammonia levels and a decrease in the ratio of branched chain (BCAA) to aromatic amino acids (AAA). The multienzyme system consisting of: urease, leucine dehydrogenase (LDH), glucose dehydrogenase (GDH) and immobilized coenzyme (dextran-NAD$ sp+$) is encapsulated in polyterephthalamide microcapsules with amyloglucosidase (AG) adsorbed on the surface: AG-MIC (1% albumin (BSA), Urease, LDH, GDH, dextran-NAD$ sp+$). Such AC may be administered orally where ammonia and urea would be removed while L-leucine, L-valine, L-isoleucine (BCAA) produced from the incorporation of ammonia to the corresponding $ alpha$-keto-acids would diffuse freely across the intestinal tract. Results show that 1 ml of 10% albumin filled AC with a mean diameter of 86.9 $ mu$m can adsorb a maximum of 94.87 mg of AG at PH = 8.0 and T = 37$ sp circ$C.

Chlorpheniramine, a reversible competitive inhibitor at the H1-receptor that has demonstrated potent, long-lasting antihistaminic activity with only mild side-effects, has been a popular choice for the treatment of allergic conditions and is a common component of cold/cough preparations. A number of groups have studied the pharmacokinetics of chlorpheniramine since its development, but results have been conflicting. Moreover, most of the pharmacokinetic studies had only involved analysis of the parent compound and excluded pharmacologically active metabolites. / As part of a new pharmacokinetic study of chlorpheniramine, an enantiomeric method to resolve chlorpheniramine from its N-demethylated metabolites and chlorpheniramine N-oxide was required. The use of high performance liquid chromatography (HPLC) with the amylose tris(3,5-dimethylphenylcarbamate) chiral stationary phase (AD-CSP) failed to resolve the enantiomers of chlorpheniramine and its metabolites. Capillary electrophoresis was used to screen a number of chiral selectors including hydroxypropyl beta-cyclodextrin, sulfated beta-cyclodextrin and carboxymethyl beta-cyclodextrin. The resolution of the enantiomers of chlorpheniramine and its metabolites was achieved using carboxymethyl beta-cyclodextrin obtained from Wacker Chemie, Munich, Germany. Detection limits of chlorpheniramine down to 200 ng/mL were achieved by concentrating samples and using sample stacking methods.

Natural polymers such as polysaccharides have been used as self-assembled matrices for drug delivery. Modified high amylose starch tablets swell to a limit when submerged in water, yielding a hydrogel with quasi-reversible viscoelastic properties. Such tablets display slow-release properties with a near zero-order drug delivery kinetics. Mechanical properties, electron microscopy imaging and swelling behavior have been investigated. Results from the foregoing investigations and from 13C CP/MAS NMR studies, which showed a clear transition from amorphous to crystalline organization upon wetting, were used to propose a model. The latter proposes that the viscoelastic hydrogel is formed due to the propensity of amylopectin and amylose, the two components of starch, to organize into double helices. The so formed pseudo-crosslinks, as water penetrates the dry tablet, explain the shape retention (limited swelling). This model was tested using Curdlan, a beta-1,3-glucan that is known to crystallize as triple helices. Studies on Curdlan tablets demonstrated limited swelling and shape retention, but unsuitable mechanical properties. This supported the model and added a feature that takes into account the heterogeneous nature of starch as an important factor in the obtention of a good viscoelastic hydrogel. / Because hydrophobic drugs are difficult to release by diffusion through matrices of hydrophilic polysaccharides, synthesis of compatibilizers was undertaken. Using a natural hydrophobic polyester: poly([R]-3-hydroxybutyric acid), PHB, possessing a high enthalpy of crystallization, a self-assembly amphiphilic system was created. Diblock copolymers of monomethoxy poly(ethylene glycol), mPEG and PHB were synthesized in a one-step, solvent-free, transesterification reaction. The resulting diblock copolymers were used to form colloidal suspensions of nanoparticles that are potential drug carriers and compatibilizers.

No description available.

No description available.