Acute and sub-acute oral toxicity studies of standardized extract of Nasturtium officinale in Wistar rats.

Nasturtium officinale (watercress) is a perennial dicotyledonous plant, rich in vitamins, minerals and chemical compounds. The leaves of this plant, which contain glucosinolate, are used for its diuretic and hypoglycemic effects. The purpose of the study was to investigate the safety of the standardized extract of Nasturtium officinale (SENO) with phenylethyl glucosinolate 5.0 mg/ml-1, using acute and sub-acute oral dosage in Wistar rats. High-Performance Liquid Chromatography (HPLC) analyzed the chemical composition, from aerial parts of watercress. In the acute toxicity study, dose estimated was LD50 in the range of 2000-5000 mg/kg, signs of mortality and toxicity on female rats were observed for 14 days, after single doses of 2000 and 5000 mg/kg. In the sub-acute study, female and male rats, age 10 weeks, were supplemented at doses of 250, 500 and 1000 mg/kg for 28 days. On the 29th day, rats were fasted, anesthetized, euthanized, then their blood used for hematological and biochemical evaluation. No significant changes in general behavior were reported regarding the acute study, while the sub-acute study demonstrated no toxicity of the hematopoietic and biochemical systems. The results showed that SENO at dosage up to 5000 mg/kg in acute study was safe, and NOAEL (no-observed-adverse-effect levels) in the sub-acute, was up to 1000 mg/kg.

Troglitazone increases the resistance of low density lipoprotein to oxidation in healthy volunteers.

The oxidative modification of low density lipoprotein is of importance in atherogenesis. Antioxidant supplementation has been shown, in published work, to increase low density lipoprotein resistance to oxidation in both healthy subjects and diabetic subjects; in animal studies a contemporary reduction in atherogenesis has been demonstrated. Troglitazone is a novel oral antidiabetic drug which has similarities in structure with vitamin E. The present study assessed the effect of troglitazone 400 mg twice daily for 2 weeks on the resistance of low density lipoprotein to oxidation in healthy male subjects. Ten subjects received troglitazone and ten received placebo in a randomised, placebo-controlled, parallel-group design. The lag phase (a measure of the resistance of low density lipoprotein to oxidation) was determined by measurement of fluorescence development during copper-catalysed oxidative modification of low density lipoprotein. The lag phase was increased by 27 % (p < 0.001) at week 1 and by 24% (p < 0.001) at week 2 in the troglitazone treated group compared with the placebo group. A number of variables known to influence the resistance of low density lipoprotein to oxidation were measured. They included macronutrient consumption, plasma and lipoprotein lipid profile, alpha-tocopherol, beta-carotene levels in low density lipoprotein, low density lipoprotein particle size, mono and polyunsaturated fatty acid content of low density lipoprotein and pre-formed low density lipoprotein hydroperoxide levels in low density lipoprotein. Troglitazone was associated with a significant reduction in the amount of pre-formed low density lipoprotein lipid hydroperoxides. At weeks 1 and 2, the low density lipoprotein hydroperoxide content was 17% (p < 0.05) and 18% (p < 0.05) lower in the troglitazone group compared to placebo, respectively. In summary the increase in lag phase duration in the troglitazone group appeared to be due to the compound's activity as an antioxidant and to its ability to reduce the amount of preformed low density lipoprotein lipid hydroperoxides. This antioxidant activity could provide considerable benefit to diabetic patients where atherosclerosis accounts for the majority of total mortality.