ABSTRACT

Styrax camporum Pohl, a typical species from the Brazilian cerrado, commonly known as “benjoeiro”, is used to treat gastroduodenal diseases. In previous studies carried out by our research group, hydroalcoholic extract of S. camporum stems (SCHE) exhibited antigenotoxic and antiproliferative effects. For a comparative analysis of the chemopreventive effect of SCHE, the aim of this study was to investigate the influence of SCHE against carcinogen 1,2-dimethylhydrazine (DMH)-induced DNA damage and pre-neoplastic lesions in Wistar rat colon. Animals were treated orally with SCHE at 250, 500 or 1000 mg/kg body weight in conjunction with a subcutaneous injection of DMH. DNA damage was assessed using the comet assay while tpre-neoplastic lesions by aberrant crypt foci (ACF) assay. The following hepatic oxidative stress markers were determined including activities of catalase (CAT) and glutathione S-transferase (GST) as well as levels of reduced glutathione (GSH) and malondialdehyde (MDA). Treatment with SCHE was not genotoxic or carcinogenic at the highest dose tested (1000 mg/kg b.w.). The extract effectively inhibited DNA damage and pre-neoplastic lesions induced by DMH administration at all concentrations tested. Measurement of CAT, and GST activities and levels of GSH showed that SCHE did not reduce oxidative processes. In contrast, treatment with SCHE (1000 mg/kg b.w.) decreased liver MDA levels. Taken together, these findings suggested the chemopreventive effect attributed to SCHE in colon carcinogenesis, may be related to its capacity to inhibit DNA damage as well as an antioxidant action associated with its chemical constituents egonol and homoegonol.

摘要

Styrax camporum Pohl是巴西塞拉多的典型物种，俗称“benjoeiro”，用于治疗胃十二指肠疾病。在我们研究小组之前进行的研究中，香樟的水醇提取物茎（SCHE）表现出抗原毒性和抗增殖作用。为了比较 SCHE 的化学预防作用，本研究的目的是调查 SCHE 对 Wistar 大鼠结肠中致癌物质 1,2-二甲基肼 (DMH) 诱导的 DNA 损伤和肿瘤前病变的影响。动物以 250、500 或 1000 mg/kg 体重的 SCHE 口服治疗，同时皮下注射 DMH。使用彗星试验评估 DNA 损伤，而通过异常隐窝病灶 (ACF) 试验评估肿瘤前病变。确定了以下肝脏氧化应激标志物，包括过氧化氢酶 (CAT) 和谷胱甘肽 S-转移酶 (GST) 的活性以及还原型谷胱甘肽 (GSH) 和丙二醛 (MDA) 的水平。在最高测试剂量（1000 mg/kg b. w.)。在所有测试浓度下，该提取物均能有效抑制由 DMH 给药引起的 DNA 损伤和肿瘤前病变。CAT、GST 活性和 GSH 水平的测量表明 SCHE 不会减少氧化过程。相比之下，用 SCHE（1000 毫克/千克体重）治疗降低了肝脏 MDA 水平。总之，这些发现表明 SCHE 在结肠癌发生中的化学预防作用，可能与其抑制 DNA 损伤的能力以及与其化学成分 egonol 和 homoegonol 相关的抗氧化作用有关。用 SCHE（1000 毫克/千克体重）治疗可降低肝脏 MDA 水平。总之，这些发现表明 SCHE 在结肠癌发生中的化学预防作用，可能与其抑制 DNA 损伤的能力以及与其化学成分 egonol 和 homoegonol 相关的抗氧化作用有关。用 SCHE（1000 毫克/千克体重）治疗可降低肝脏 MDA 水平。总之，这些发现表明 SCHE 在结肠癌发生中的化学预防作用，可能与其抑制 DNA 损伤的能力以及与其化学成分 egonol 和 homoegonol 相关的抗氧化作用有关。