RESUMO
Callistemon citrinus has terpenes effective in inducing antioxidant enzymes, an important mechanism involved in cancer chemoprevention. This study investigated the chemopreventive efficacy of herbal preparation of C. citrinus leaves against the oxidative stress produced during the colorectal cancer (CRC) in male Wistar rats. The amelioration of toxicity in a model of CRC induced with 1,2-dimethylhydrazine (DMH) was determined by assessing antioxidant enzymes, phase II enzymes activities and lipid peroxidation (LPO) products after 22 weeks of treatment. C. citrinus was administered at a daily oral dose of 250 mg/kg. The activities in proximal, middle and distal colon, liver, kidney and heart were determined. C. citrinus showed a strong antioxidant activity that correlated with the high content of phenolics and terpenoids. DMH treated animals showed a decrease of the enzymes activity in most tissues and the level of reduced glutathione (GSH). Conversely, the levels of lipid peroxidation products were increased. Macroscopic examination revealed the protective effect of C. citrinus in damaged organs caused by DMH. Moreover, histopathological examination of the liver displayed normal structure in the C. citrinus-treated group, unlike the DMH-treated group. C. citrinus supplementation significantly maintained or increased the antioxidant enzyme activities, whereas lipid peroxidation products levels were reduced to values similar to the level of control group. The ability of C. citrinus to induce the antioxidant system reduced the damage of oxidative stress, which makes this plant a good candidate to be used as a prevention agent in treatment of diseases such as colorectal cancer.