Effect of protein hydrolysates from sardinelle (Sardinella aurita) on the oxidative status and blood lipid profile of cholesterol-fed rats Hayet Ben Khaled a , Zohra Ghlissi b , Yassine Chtourou c , Ahmed Hakim b , Naourez Ktari a , Makni Ayadi Fatma d , Ahmed Barkia a , Zouheir Sahnoun b , Moncef Nasri a, ⁎ a Laboratoire de Génie Enzymatique et de Microbiologie, Ecole Nationale d'Ingénieurs de Sfax, B.P. 1173-3038, Université de Sfax, Tunisie b Laboratoire de Pharmacologie, Faculté de Médecine, Sfax, Université de Sfax, Tunisie c Laboratoire de Physiologie Animale, UR 08-73, Faculté des Sciences de Sfax, BP 1171-3000, Sfax, Université de Sfax, Tunisie d Laboratoire de Biochimie, Faculté de Médecine, Sfax, Université de Sfax, Tunisie abstract article info Article history: Received 7 July 2011 Accepted 5 October 2011 Keywords: Sardinelle Protein hydrolysates Cholesterol-enriched diet Hypocholesterolemic This study was designed to test the hypolipidemic properties and antioxidative activities of sardinelle (Sardinella aurita) protein hydrolysates (SPHs) obtained by treatment with crude enzyme preparations from Bacillus pumilus A1(SPHA1), Bacillus mojavensis A21(SPHA21) and crude enzyme extract from sardinelle viscera (SPHEE). Wistar rats were fed during 7 weeks a standard laboratory diet, a cholesterol-enriched diet (1%) or a choles- terol SPH-enriched diet. The hypercholesterolemic diet induced the elevation of total cholesterol (TC), tri- glycerides (TG), and low-density lipoprotein cholesterol (LDL-C). Supplementing cholesterol-enriched diet with SPHs or whole sardinelle protein (WSP) at a concentration of 5% (w/w) increased the serum level of high-density lipoprotein cholesterol (HDL-C) and HDL-C/TC ratio and decreased the serum levels of TC, TG, LDL-C and LDL-C/HDL-C ratio significantly. The thiobarbituric acid-reactive substances (TBARS) level, as an indicator of lipid peroxidation, and the activ- ity of superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) were examined. The hepatic antioxidant enzymes activities were significantly decreased and the malondialdehyde (MDA) level was increased in rats fed a cholesterol-enriched diet compared to those fed a standard diet. The treatment of hypercholesterolemic (HCD) diet rats with SPHs reduced the MDA concentration and increased the antiox- idant enzyme activities. These results suggested that the hypolipidemic effect of SPHs might be due to their abilities to lower serum TC, TG, and LDL-C levels as well as to their antioxidant activities preventing the lipid peroxidation process. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Hyperlipidemia is a major cause of atherosclerosis and atherosclerosis-associated conditions such as coronary heart disease, ischemic cerebrovascular disease, and peripheral vascular disease. A causal relationship between the elevated plasma lipids and the devel- opment of atherosclerotic plaques has been well established. Hyper- lipidemia is an elevation of lipids in the bloodstream and these lipids include fats, fatty acids, cholesterol, cholesterol esters, phospholipids, and triglycerides (Jain, Kathiravan, Somani, & Shishoo, 2007). Oxidative stress is currently suggested as a mechanism underlying hypercholesterolemia (Jiangwei, Zengyong, & Xia, 2011). Free radicals are continually produced in the body as the result of normal metabolic processes and interaction with environmental stimuli. Oxidative stress results from imbalance between the production of free radicals and the effectiveness of the antioxidant defense system (Chenni et al., 2007). Several defense systems have been developed by the cell in order to protect itself against free radicals such as non enzymatic anti- oxidant (ascorbic acid, glutathione) and antioxidant enzymes (super- oxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)) (McEligot, Yang, & Meyskens, 2005). It is crucial to maintain serum cholesterol to an adequate level. Serum cholesterol levels are influenced by diet and cholesterol bio- synthesis, uptake and secretion (Zhang & Beynen, 1993). Several works have reported the importance of dietary proteins and protein hydrolysates in the regulation of cholesterol metabolism. To date, hypocholesterolemic properties have been reported for soy (Sugano et al., 1990) and whey (Zhang & Beynen, 1993). Soy protein hydrolysates were found to exhibit a higher hypocholesterolemic activity than the undigested proteins (Zhong, Liu, Ma, & Shoemaker, 2007). Wergedahl et al. (2004), reported that fish protein hydrolysate (FPH) have a role as a cardioprotective nutrient. In fact, FPH treatment Food Research International 45 (2012) 60–68 ⁎ Corresponding author. Tel.: + 216 96 501 698; fax: + 216 74 275 595. E-mail addresses: mon_nasri@yahoo.fr, moncef.nasri@enis.rnu.tn (M. Nasri). 0963-9969/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2011.10.003 Contents lists available at SciVerse ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres