Intestinal absorption enhancement properties of indigenous aloe leaf gel polysaccharides.
Many drugs, including therapeutic proteins are administered almost exclusively by means of the parenteral route (e.g. intravenous injection) because of their poor absorption from the gastrointestinal tract after oral administration. However, the parenteral route is associated with many disadvantages such as pain and infections. A suitable absorption enhancer that could effectively improve the absorption of poorly absorbable drugs from the gastrointestinal tract would contribute to the development of an oral drug delivery system for these drugs.
The aim of this study is to investigate the effect of leaf gels, precipitated polysaccharides and whole leaf extracts derived from selected indigenous aloe species, on the in vitro transport of a model compound across Caco-2 intestinal epithelial cell monolayers and pig intestinal tissue.
Specific objectives include:
· To collect, fillet, process and freeze dry the pulp and whole leaves from three selected indigenous aloe species (Aloe marlothii, Aloe ferox and Aloe speciosa),
· To extract the polysaccharide component from each of the aloe leaf pulp fractions by means of a solvent precipitation technique,
· To fingerprint the phytoconstituents of each aloe extract by means of Nuclear Magnetic Resonance (NMR) spectroscopy to identify specific marker molecules typical of aloes,
· To evaluate the effect of each plant component on the transepithelial electrical resistance (TEER) of Caco-2 cell monolayers in order to determine their ability to open tight junctions between adjacent epithelial cells,
· To evaluate the effect of each plant component on the transport of fluorescence isothiocyanate dextran (FITC-dextran, MW = 10 000 Da) across Caco-2 cell monolayers and pig intestines in vitro using Sweetana-Grass diffusion chambers.
Principal supervisor: Prof JH Hamman
Co-supervisors: Prof AM Viljoen