en پژوهشي Research Article Excretory-secretory products (ESP) play an important role in the host biochemical defense by means of activities of detoxifying and antioxidant enzymes. The aim of this study was to evaluate praziquantel (PZQ) effects by detection of glutathione S- transferase (GST) and superoxide dismutase (SOD) enzymes activities in ESP samples of Fasciola spp. Fasciola gigantica and Fasciola hepatica adult parasites were collected and cultured within buffer media for 4 h at 37°C. Treated (with 50, 100 and 150 mg PZQ) and control ESP samples for each species were collected and centrifuged. The supernatants were stored at -20 ° C. SOD and GST enzymes activities of ESP samples were estimated photometrically. To determine the statistically-significant difference between ESP of treated and control samples, t-test was conducted. ESP protein bands were detected by gel electrophoresis (SDS-PAGE). SOD enzyme activities level in treated F.hepatica and F. gigantica ESP samples were determined as 0.26, 0.29, 0.76 and 1.73, 1.60, 1.43 U/ml respectively. SOD activities level in control samples were detected 1.31 and 1.35 U/ml. GST activities level in treated F.hepatica and F. gigantica ESP samples were calculated 9.4, 3.1, 23.96 and 435.4, 333.3, 720.9 U/ml. GST activities levels in control samples were detected 43.8 and 134.4 U/ml respectively. Statistical analysis revealed the significant decrease of GST and SOD enzyme activities in treated ESP samples of Fasciola hepatica , and significant increase of GST enzyme activity in treated ESP samples of F. gigantic a in comparison to the control samples ( p < 0.05). There was also no difference between SDS-PAGE results of treated and control samples. Based on the results of present work, PZQ has decreasing effect on the ESP enzymatic activities of Fasciola hepatica and increasing effect on F. gigantica enzyme activities. In other words, F. hepatica has less capability to protect against xenobiotics and free radicals than F.gigatica does. 9 0 http://ijpt.iums.ac.ir/browse.php?a_code=A-10-100-281&slc_lang=en&sid=1 Ali Farahnak 1003194753284600955 1003194753284600955 No Tehran University of Medical Sciences, Tehran, Iran Taghi Golmohamdi 1003194753284600956 1003194753284600956 No Tehran University of Medical Sciences, Tehran, Iran Mohamad Reza Eshraghian 1003194753284600957 1003194753284600957 No