Hypolipidemic and antioxidant activities of thymoquinone and limonene in atherogenic suspension fed rats

The hypolipidemic and antioxidant actions of thymoquinone (TQ) and limonene (LMN) were investigated by giving 1 ml of 10 mg TQ or 200 mg LMN suspension, by gavage in two equal doses (morning and evening) of 0.5 ml each for 30 days, in rats, fed an atherogenic suspension. These compounds effectively ameliorated all the altered cardiovascular risk parameters via a reduction in HMG-CoA reductase activity, along with an increase in arylesterase activity. The compounds significantly blocked the shift in buoyancy from less atherogenic lb-LDL to highly atherogenic sd-LDL, restoring the percent distribution of LDL-C and apoB into sd-LDL and lb-LDL to near normal levels. These compounds also blocked basal and maximal formation of CD and malondialdehyde, and lengthened the lag times of LDL, sd-LDL and lb-LDL in the order TQ > LMN. Our results strongly suggest an important therapeutic use of test compounds, especially TQ, in the prevention of cardiovascular disease risks parameters.