ترکیبات زیست فعال، پتانسیل آنتی اکسیدانی و فعالیت حفاظت کبدی خیار دریایی (Holothuria atra) در برابر مسمومیت تیواستامید در موش های صحرایی Bioactive compounds, antioxidant potential, and hepatoprotective activity of sea cucumber (Holothuria atra) against thioacetamide intoxication in rats

Introduction The sea cucumber (Holothuria) is a marine invertebrate of the phylum Echinoderm and the class Holothuroidea found on the sea floor worldwide [1]. There are more than 1000 species of sea cucumber, and approximately 20 are edible. Sea cucumber is a delicacy food in China and Asian countries. In addition to their good flavor, sea cucumbers are commonly used to treat wounds, eczema, arthritis, hypertension, and impotence [2,3]. The sea cucumber is a healthy food because it contains different physiologically active substances, including vitamins (A, C, B1, B2, and B3), trace elements (calcium, iron, magnesium, and zinc), polysaccharides (chondroitin sulfate), and saponin glycosides [4]. Furthermore, some bioactive compounds extracted from holothurians have been reported to have anti-inflammatory [5], antitumor [6], and fungicidal[7] activities. Most studies on the sea cucumber of the Red Sea (H. atra) have been taxonomic [8–۱۰]. Oxidative stress is known to play an important role in liver injury [11]. Recent interest in food phenolics has increased owing to their roles as antioxidants and scavengers of reactive oxygen species and free radicals and their implied role in the prevention  of many pathologic diseases, such as heart and liver diseases [12]. Alternatively, phenolic compounds have been found to increase endogenous defense mechanisms, stimulate the antioxidant response element that regulates the gene expression of enzymes involved in phase II metabolism of xenobiotics and antioxidant defense, and exhibit inhibitory effects on membrane lipid peroxidation [13]. The present study was undertaken to identify the bioactive phenolic compounds in the H. atra body wall mixed extract and to evaluate its hepatoprotective potential against thioacetamide (TAA)-induced liver fibrosis in rats. The aim of the study was extended to determine the antioxidant efficacy of the extract in cell-free systems. Materials and methods Sample collection and preparation Sea cucumbers (H. atra) caught from the Red Sea (Hurghada) were kindly provided by Dr. Mohamed Zaki (Laboratory of Marine Biochemistry, National Institute of Oceanography and Fisheries, Suez and Aqaba Gulfs branch). The animals were transported to our laboratory in an ice box containing ice cubes and a few pinches of table salt. The animals were immediately washed under running tap water and cut open, and all visceral organs were removed. The animals were rinsed thoroughly of any internal organs or body fluids, and then the body walls of the animals were stored at 20C until processing. Preparation of sea cucumber mixed (organic/aqueous) extract The adopted extraction technique was previously described by Haug et al. [14], with slight modifications. The body walls of the animals were cut into small parts, finely ground in a blender, and then poured in Petri dishes. The Petri dishes were precisely weighed and placed in an oven at 70C for 18 to 20 h until no change in weight was recorded. The dried samples were blended further with a pestle until a fine powder was produced. The weight of the fine powder was suspended in 10 vol of a mixture of acetonitrile and 0.1% trifluoroacetic acid at a proportion of 60:40 (v/v) and stirred continuously in the dark for 24 h using a magnetic stirrer. The extract was centrifuged at 3000 rpm for 20 min and the supernatant was aspirated into a dry flask and kept at 4C. The extraction was repeated twice on the residue and the supernatants were combined. The mixed extract was kept at 4C for 24 h until the organic solvent was completely evaporated and then freeze-dried at 50C for 36 h.