M.Tech. / There are over 250 cinnamon species existing worldwide, and amongst them, 2 species Cinnamomum cassia and Cinnamomum zeylanicum, are commonly used all over the world as spices, fragrances in perfumes and as medicines. These two species are distinguished from each other by the presence and absence of certain compounds depending on the origin and distribution of the plant. Nevertheless, all cinnamon species contain essential oils and water soluble components and the composition of these components found in each species depends on the type of species involved. These components are made up of phenyl propanoids, terpenes, flavonoids and saponins. In general, the essential oil component contains the following compounds: cinnamaldehyde as a major constituent with its derivatives cinnamic acid, cinnamyl alcohol, ethyl cinnamate, cinnamyl acetate and 2-methoxy cinnamaldehyde; eugenol; linalool; coumarin; carvone; carvacrol and β-caryophyllene. Most of these compounds are abundantly found in the bark except in the case of eugenol which is found in either leaves or bark depending on the species involved. The other water soluble component is composed of a group of compounds such as tannin, chalcone, catechins and anthocyanidins. These compounds polymerize to form methyl hydroxy chalcone polymers (MHCP) which has been shown to play an important role in lowering blood sugar levels in Type ll diabetic individuals. It is said that MHCP has an ability to promote the phosphorylation process which in turn activates the beta-cells and thereby creating insulin activity that will then convert glucose into glycogen. Besides all health benefits of cinnamon, the plant contains a toxic compound, coumarin which impacts badly on animals resulting in death, and little information on its toxicity to human beings has been documented. Concerns arose about the possible presence of coumarin in these formulations, since these formulations are made from the cinnamon and the plant contains coumarin. This work has investigated the potential toxicity of coumarin from cinnamon powder and cinnamon formulation. The components from both cinnamon samples were extracted using various solvents according to their polarities and these compounds were screened on thin layer chromatography (TLC). The essential oil components were separated by column chromatography, and quantified by using high performance liquid chromatography (HPLC), all components (essential oil and water soluble) were identified by HPLC, and finally the characterization of the essential oil components was done with infrared (IR) and nuclear magnetic resonance (NMR) whereas those of the water soluble were characterized by using liquid chromatography coupled to a mass spectrometer (LC-MS).

In this dissertation, the mechanisms of nanosuspension stabilization via polymer adsorption on nanoparticle surface were investigated. As the electrokinetic behavior and colloidal stability depend on the surface characteristics, altering the surface adsorbed polymers affords the different surface properties of nanoparticles and leads to the insight on the mechanism of nanoparticle stabilization. Drug nanosuspensions were prepared by wet milling of drug with water as medium and polymers as stabilizers. Block copolymers were evaluated based on varying the hydrophobic and hydrophilic amounts, polymer concentration, and polymer affinity differences onto the nanoparticle surface. Specifically, block copolymers of ethylene oxide (EO) and propylene oxide (PO) with different EO chain lengths were used to modify the nanoparticle surface and investigate the mechanisms of stabilization by varying the ratio of hydrophobic (PO) and hydrophilic (EO) units. It was hypothesized that the PO chain of block copolymers adsorb at the solid-solution interface and the EO chain provides steric hindrance preventing aggregation. Block copolymer adsorption layer thicknesses were experimentally determined with adsorption layer thicknesses increasing from 4.7 to 9.5 nm as the number of EO increase from 26 to 133 monomer units. Nanoparticle aggregation occurred with insufficient polymer monolayer coverage and electrokinetic zeta potential greater than -20 mV. The amount of block copolymers on the surface of nanoparticles was quantified and the affinity of polymer adsorption increased as the copolymer hydrophobic units increased. The amount adsorbed and affinity provides a qualitative ranking of the affinities between a specific polymer and nanoparticle substrate to provide a method in determining the mechanism of stabilization, where specific functional groups for adsorption could be selected for maximum nanoparticle stability. A molecular modeling was conducted to visualize and support the mathematical model and the proposed mechanism of block copolymer adsorption onto a nanoparticle surface. The time lapse molecular modeling of a block copolymer in an aqueous media showed the hydrophobic units adsorbing onto the nanoparticle surface with the hydrophilic units projecting into the aqueous media. For the first time in pharmaceutical research, a systematic series of studies were conducted to elucidate the mechanisms of adsorption with both surface charge and polymer affinity analyses. A series of studies evaluating the adsorption properties polymer stabilizers provided useful information on how a block copolymer comprised of both hydrophilic and hydrophobic domains adsorbs onto an active pharmaceutical ingredient. A systematic set of experimental techniques were presented with novel analysis tools and predictors to construct stable nanoparticle formulations.