Aim. The aim of the study was to evaluate the efficacy, safety and possible mechanism of action of potassium humate loaded with selenium Objectives. The objectives of the study were to evaluate the possible in vitro cytotoxic effect of potassium humate loaded with selenium (Phse) on the growth of primary cell cultures (lymphocytes), to evaluate the in vitro antioxidant activity of Phse, to evaluate the in vitro effect of Phse on CR3 expression using mixed leukocytes, to evaluate the anti-inflammatory properties of Phse using the carrageenan-induced paw oedema rat model and finally to evaluate the effect of Phse on acute phase proteins in the rat model Methods. For the cytotoxicity effects on lymphocytes, the MTT assay was used where lymphocytes were isolated and divided in to two groups, one group was stimulated with PHA and the other not, then the cells were treated with different concentrations of the test compounds. The evaluation of the antioxidant activity was done using the ORAC and DCFH-DA assays with the DCFH-DA assay also done using the HepG2 cell line. The expression of CR3 by mixed leukocytes was quantified by flow cytometry. The evaluation of the anti-inflammatory properties of Phse was done using the carrageenan-induced paw oedema rat model. The rats were randomly assigned to six groups, the negative control, positive control, experimental group 1, 2, 3 and sham group. A once daily dose by gavage for five consecutive days of their respective treatment was administered. Prior to the assay the rats were dosed according to the experimental group to which they were assigned. On the fifth day of the experiment, 50 µl of λ- Carrageenan was injected subplanter into the right hind paw of the rats and 50 µl of saline into the left hindpaw. The right hind paw volume of each rat was measured hourly from the time of injection for seven consecutive hours with a water displacement plethysmometer. At the end of the 7 hours the rats were anaesthetised and approximately 5 ml of blood was collected via cardiac puncture. The blood was centrifuged, the plasma removed and frozen at -80°C until assayed. For evaluating the effects of the test compounds on acute phase proteins ELISA was used according to the manufacturer’s protocols. Results. None of the test compounds were toxic to lymphocytes but rather caused cell proliferation. The test compounds demonstrated no antioxidant activity, with Phse showing pro-oxidant activity. All the test compounds inhibited the expression of CR3 significantly with selenium free Ph being the most potent inhibitor. Ph reduced the carrageenan induced paw oedema volumes in a similar manner to indomethacin and Phse had an insignificant effect. Ph decreased SP slightly but the results were not statistically significant whereas Se and Phse had no effect. All the test compounds statistically significantly decreased plasma CRP levels with Se showing the greatest effect. Conclusion. Phse is safe but not more effective than Ph as an anti-inflammatory agent. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Pharmacology / unrestricted