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Fabrication, Characterization and Biological Fate of Phytochemical Delivery System

Polymethoxyflvones (PMFs) are a group compounds with promising cancer preventing activities and many other health benefits. There's a growing interest in fabricating delivery systems for PMFs as well as other phytochemicals due to their low water solubility. Firstly, we use nanoemulsion delivery system to encapsulate β-carotene. Sonication assisted method was developed to dissolve β-carotene to ensure minimum degradation. Powdered nanoemulsion was obtained after spray dry and freeze dry. Sample obtained after freeze dry showed better physiochemical characteristics. Then we use protein nanoparticle delivery system to encapsulate PMFS. The nanoparticle delivery system was fabricated by mixing the aqueous phase containing β-lactoglobulin with organic phase containing ethanol and tangeretin. Powder was obtained after vacuum evaporation of ethanol followed by freeze-drying. This powder can be easily dispersed into water and have similar property as freshly prepared, suggesting excellent applicability of the system as a convenient powder ingredient. Different delivery systems were made by mixing this powder with stock emulsion to represent various types of diets. These systems were then go through in vitro digestion process. The delivery system contained 4% oil exhibited the highest bioaccessibility of tangeretin due to increased amount of mixed micelle formed after digestion in simulated small intestine. The following permeability determination experiments on Caco-2 cell monolayer model suggested digested sample with higher oil content has higher permeability than PMF that did not go through the digestion process. In order to further study the uptake and internalization of PMFs, a new approach to visualize polymethoxyflavones (PMFs) inside the cell and in mice colon using a fluorescence microscope was developed. 5, 3', 4'-tridemethylnobiletin (THN) was used for further study due to strong fluorescent intensity upon conjugation with DPBA. Fluorescence spectroscopy indicated this conjugate has the maximum excitation wavelength of 490 nm and maximum emission wavelength of 570 nm. Both mass spectroscopy and Raman spectroscopy confirmed the reaction between one or two hydroxyl group on THN and diphenyl boron group on DPBA. This method could easily detect the PMFs in the single suspend cell or in the attached cell. It can also be used to visualize PMFs absorbed by mouse tissue such as colon.
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