|M.Sc Thesis||Department of Biotechnology and Food Engineering|
|Supervisors:||Prof. Emeritus Cogan Uri|
|Assoc. Prof. Bomzon Arieh|
This investigation focuses on the characterization of the biochemical mechanisms associated with the antioxidative properties of three water extracts of two indigenous medicinal plants in Israel: Pistacia palaestina and Teucrium polium that are considered therapeutically beneficial in treating liver diseases in the Arab folk medicine.
There is considerable evidence that the diseased liver is oxidatively stressed. Thus, we hypothesized that the beneficial action of these plants is related to their antioxidative properties.
The antioxidative potential was evaluated by inhibiting oxidation of β-carotene, by inhibiting iron-induced and AAPH (free radical generator)- induced lipid peroxidation in rat liver homogenates and in human plasma respectively. The results obtained show that these extracts possess antioxidative properties at concentrations above 0.05mg/mL.
The research included studies aimed to assess the biosafety of these extracts in human Hepatic cells. Extracts of P. palaestina fruits and T. polium were not toxic at all tested concentrations. However, leaves and stems extract of P. palaestina showed signs of cytoxicity at concentrations higher than 0.5 mg/mL.
Characterization of the mechanism of the antioxidant action of these extracts was assessed by examining their ability to reduce levels of reactive oxygen species, and to increase the content of the intracellular antioxidant-glutathione (GSH), in HepG2 cells, under both normal and oxidative stress states. The three extracts scavenged superoxide radicals at concentrations above 0.05mg/mL.
In addition, these extracts tended to increase glutathione levels at all tested concentrations (0.001-1 mg/mL), without an increase in oxidized/reduced GSH ratio.
Furthermore, the study demonstrated that under oxidative stress these extracts possessed glutathione-sparing action in that they blocked its oxidation, but did not exhibit cytoprotection properties.
In conclusion, these plant extracts may prove to possess hepatoprotective properties, as they prevent lipid peroxidation, by virtue of being potent scavengers and by possessing glutathione-sparing action.