PROTECTIVE EFFECT OF MANDARIN (CITRUS RETICULATA) PEEL EXTRACT ON POTASSIUM DICHROMATE INDUCED HEPATOTOXICITY AND NEPHROTOXICITY IN RATS Samir AE Bashandy 1 , Abeer Salama 1 , Abdel-Hameed M. Fayed 1 , Enayat A. Omara 2 , Sayed A. El-Toumy 3 and Josline Y. Salib 3 . 1 Department of Pharmacology, Medical Division, National Research Centre, 33 EL Bohouth St. (former EL Tahir St.), Dokki, Cairo , Egypt. P.O.12622. 2 Department of Pathology, Medical Division, National Research Centre, 33 EL Bohouth St. (former EL Tahir St.), Dokki, Cairo , Egypt. P.O.12622. 3 Chemistry of Tannins Department, National Research Centre, Dokki, Cairo, Egypt. 33 EL Bohouth St. (former EL Tahir St.), Dokki, Cairo , Egypt. P.O.12622. Abstract The present study evaluate the ability of water extract of mandarin (Citrus reticulata) peel to mitigate the hepatorenal toxicity of potassium dichromate (K 2 Cr 2 O 7 ). Both doses of peel extract (200mg/Kg & 400mg/Kg) and K 2 Cr 2 O 7 (15mg/Kg) were orally administered to rats for eight weeks. Treatment of rats with mandarin peel extract along with K2Cr2O7 led to a decrease in the activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma- glutamyl transferase (GGT) as well as reduction in the levels of creatinine, urea and uric acid. Moreover, the treatment with peel extract of mandarin relieved oxidative stress manifested by a decrease of malondialdehyde (MDA) levels with a significant elevation of antioxidant capacity (TAC), hepatorenal contents of superoxide dismutase (SOD) and reduced glutathione (GSH). The treatment with extract of mandarin peel displayed anti-inflammatory property as concluded from its lowering effect of serum tumor necrosis factor-alpha (TNF-) level. Finally, the peel extract minimized the pathological changes in liver and kidney evoked by K 2 Cr 2 O 7 and the immune-histochemical study revealed that mandarin peel extract minimized the increase of hepatorenal activity of P53 compared to K 2 Cr 2 O 7 group. The peel extract of mandarin can efficiently alleviate the hepaorenal toxicity of K 2 Cr 2 O 7 via its antioxidant and anti-inflammatory properties. Key words: Mandarin peel extract, potassium dichromate, hepatotoxicity, nephrotoxicity, rats. Introduction Chromium (Cr) is a heavy metal familiar in the environment and contaminates environmental systems since it is vastly used in diverse industrial processes (Bagchi et al., 2002). Chromium compounds are used in paints, tanning of leather, manufacture of magnetic tape and as catalyst for hydrocarbons production (Sreeram and Ramasami, 2003; Weckhuysen and Schoonheydt, 1999). During metabolism of chromium, it is transformed to reactive chromium intermediates that produce reactive oxygen species (ROS) (O’Brien et al., 2001). ROS can give rise to tissues injury, damage of cellular components and oxidative stress (Valko et al., 2006; Yam-Canul et al., 2008). On the other hand, chromium exists in different states, being hexavalent chromium [Cr (VI)] and trivalent chromium [Cr (III)] the most stable forms. Cr (III) is predominantly present in the environment and in salts used as micronutrients and dietary supplements (Pechova and Pavlata, 2007). Cr (VI) salts such as potassium dichromate and chromic acid are widely used in leather, chrome-plating, and dye-producing industries (Bagashi et al., 2002). Exposure to Cr (VI)-containing compounds is known to be toxic, mutagenic, and carcinogenic to human beings and diverse animals, leading to serious damage to the kidney, liver (Fathima and Priyanka, 2017) and other vital organs (Shrivastava et al., 2002, Nudler et al., 2002). The scientist recommended in the use of natural Plant Archives Vol. 20 Supplement 1, 2020 pp. 2231-2242 e-ISSN:2581-6063 (online), ISSN:0972-5210