Effects of aqueous soybean, mistletoe and red clover extracts on activities of adenosine deaminase and xanthine oxidase enzyme.

Soybean (Glycine max), mistletoe (Viscum album) and red clover (Trifolium pratence) have been argued to have anti-cancer effects. In the present study it was aimed to investigate possible effects of these plant extracts on the activities of DNA turn-over enzymes, namely adenosine deaminase (ADA) and xanthine oxidase (XO) in cancerous and non-cancerous gastric and colon tissues. For this aim, 6 cancerous and 6 non-cancerous adjacent human gastric tissues, and 7 cancerous and 7 non-cancerous adjacent colon tissues were obtained by surgical operations. Our results suggest that aqueous soybean, mistletoe and red clover extracts may exhibit anti-tumoral activity by depleting hypoxanthine concentration in the cancer cells through XO activation, which may lead to lowered salvage pathway activity necessary for the cancer cells to proliferate in the cancerous colon tissue. Some foods like soybean, mistletoe and red clover may provide nutritional support to medical cancer therapy through inhibiting and/or activating key enzymes in cancer metabolism (Tab. 4, Ref. 33).

Plasma paraoxonase activity in patients with systemic sclerosis.

BACKGROUND & OBJECTIVE: Systemic sclerosis (SSc) is a connective tissue disease characterized vascular damage and fibrosis. The aim of this study was to investigate the possible relation between systemic sclerosis and paraoxonase which is an antioxidant enzyme on the HDL. METHODS: Twenty nine patients with SSc and 16 healthy subjects (control group) participated in the study. Plasma cholesterol levels, anti-centromere antibody (ACA) levels and paraoxonase (PON) activities were measured. RESULTS: Lower level of high-density lipoprotein (HDL) cholesterol was observed in ACA negative SSc patients than in controls. Paraoxonase activity in ACA positive patients was however found to increase relative to control and ACA negative patient groups. INTERPRETATION & CONCLUSION: Our findings suggested that low HDL level in ACA negative SSc patients might be one of the factors leading to some vascular problems, and increased PON activity in ACA positive SSc group might have some role in the limitation of cutaneous sclerotic process observed in these patients. However, these preliminary findings need to be confirmed with a larger sample.

Effects of cholesterol supplementation on antioxidant enzyme activities in rat hepatic tissues: possible implications of hepatic paraoxonase in atherogenesis.

BACKGROUND AND AIM: The effects of cholesterol supplementation on antioxidant enzyme activities were investigated hepatic tissue taken from Sprague Dawley rats. METHODS AND REULTS: The study involved 14 male Sprague Dawley rats: seven fed a normal laboratory diet and seven a normal diet plus cholesterol (3.6 g/kg/day) for three months, during which blood samples were obtained to measure serum cholesterol levels. At the end of the 3-month period, the livers were surgically removed in order to measure antioxidant enzyme activities (superoxide dismutase, catalase, glutathione peroxidase and paraoxonase-1). At the end of the study period, serum total cholesterol and HDL-cholesterol levels were significantly higher in the cholesterol-fed group than the control group. There were no significant between-group differences in hepatic superoxide dismutase, catalase and glutathione peroxidase activities, but there was a significant decrease in hepatic paraoxonase-1 activity in the cholesterol-fed group. CONCLUSIONS: Cholesterol supplementation significantly decreases paraoxonase-1 activity in rat liver tissue without changing the activities of other antioxidant enzymes. These results suggest that cholesterol significantly suppresses hepatic paraoxonase-1 synthesis. It seems that the decreased paraoxinase-1 activity in the plasma HDL-fraction of atherosclerotic patients is associated with suppressed liver synthesis. A reduction in paraoxonase-1 activity may therefore lead to the more intensive exposure of LDL to oxidant attacks.