THE EFFICIENCY OF USING MILK THISTLE (Silybum marianum) FOR ADJUSTING THE INTENSITY OF OXIDATIVE PROCESSES IN CARP IN THE CONDITIONS OF LEAD CONTAMINATION

Purpose. To determine the effect of milk thistle on the intensity of oxidative processes in carp under the conditions of experimental toxic contamination with lead. Methodology. Experimental works were conducted in laboratory conditions. The object of the study was age-1+ carp, which were divided into three groups of 12?15 fish in each. Carp of the group 1 (intact), which received 3% starch paste through a probe, were used as a control. Carp of the group 2 were kept during a month in water, in which lead salts (PbNO3) were introduced at quantities corresponding to 10 maximum allowable levels calculated as metal ions. Carp of the group 3 during a month were kept in the same environment of dissolved lead salts and received 3% starch paste through a probe together with ground seeds of milk thistle (Silybum marianum) at a quantity of 80 mg/kg of fish body weight. We examined the effect of milk thistle on lipid peroxidation (LPO) and enzyme activity of antioxidant defense system (ADS) in carp organism under conditions of lead contamination. TBA-active products were assessed baed on the content of products which reacted with 2-thiobarbituric acid (malondialdehyde). The level of oxidative damage to lipids was also evaluated based on the content of accumulated lipid hydroperoxide. Superoxide dismutase (SOD) activity was determined in the reaction of quercetine oxidation. Catalase activity was assessed in the reaction with ammonium molybdate. Numeric data were processed by biometric method of variation nonparametric analysis using Microsoft Excel and Statistica 6.0. Differences between the values were considered statistically significant: p <0.05; 0.01 and 0.001. Findings. Toxic contamination with heavy metals in conjunction with the physiological stress are the most significant factors, which stimulate the peroxidation and oxidative disorders in the body. This fact was proved in the study using the salts of lead that increased the intensity of the accumulation of intermediate and final products of lipid peroxidation on the background of the decreased activity of antioxidant enzymes. In particular, in liver, kidneys and muscles the content of TBA-active products significantly increased by 26, 24 and 45%, while that of lipid hydroperoxides by 72, 43 and 124%. At the same time the activity of SOD in liver and kidneys of carp significantly decreased by 21 and 55%, respectively. At the same time, the catalase activity decreased to 1.75±0.16 mmol/min?mg of protein (P <0.05) in fish liver and to 0.41±0.04 mmol/min?mg of protein (P<0.05) in kidneys. It was found that the introduction of milk thistle to the experimental group of carp resulted in significant increase in the activity of SOD and catalase in the studied fish tissues that reduced the intensity of lipid peroxidation in their body. Originality. For the first time the work shows the effectiveness of milk thistle for correcting the intensity of oxidative processes in carp in the conditions of experimental contamination with lead salts. Practical value. The use of milk thistle, an efficient, safe and cost-effective way to protect fish organism from toxic effects of human-induced pollution, will allow neutralizing the negative impact of these factors by activating the antioxidant defense system of their organism.