Abstract
BackgroundAzoxymethane (AOM) is a potent carcinogenic agent commonly used to induce colon cancer in rats; the cytotoxicity of AOM is considered to mediate oxidative stress. This study investigated the chemopreventive effect of three natural extracts [pomegranate peel extract (PomPE), papaya peel extract (PapPE) and seaweed extract (SE)] against AOM-induced oxidative stress and carcinogenesis in rat colon.MethodsEighty Sprague–Dawley rats (aged 4 weeks) were randomly divided into 8 groups (10 rats/group). Control group was fed a basal diet; AOM-treated group was fed a basal diet and received AOM intraperitonial injections for two weeks at a dose of 15 mg/kg bodyweight, whereas the other six groups were received oral supplementation of PomPE, PapPE or SE, in the presence or absence of AOM injection. All animals were continuously fed ad-libitum until aged 16 weeks, then all rats were sacrificed and the colon tissues were examined microscopically for pathological changes and aberrant crypt foci (ACF) development, genotoxicity (induced micronuclei (MN) cells enumeration), and glutathione and lipid peroxidation.ResultsOur results showed that AOM-induced ACF development and pathological changes in the colonic mucosal tissues, increased bone marrow MN cells and oxidative stress (glutathione depletion, lipid peroxidation) in rat colonic cells. The concomitant treatment of AOM with PomPE, PapPE or SE significantly ameliorated the cytotoxic effects of AOM.ConclusionsThe results of this study provide in-vivo evidence that PomPE, PapPE and SE reduced the AOM-induced colon cancer in rats, through their potent anti-oxidant activities.
Highlights
Azoxymethane (AOM) is a potent carcinogenic agent commonly used to induce colon cancer in rats; the cytotoxicity of AOM is considered to mediate oxidative stress
Determination of total phenol and flavonoid contents Total phenol content of pomegranate peel extract (PomPE), papaya peel extract (PapPE) and seaweed extract (SE) extracts was determined with the Folin-Ciocalteu reagent, where different volumes of the three natural extracts were added to 2.50 ml of Folin-Ciocalteu phenol reagent and 750 μl of Na2CO3 (7.5%, w/v) [16]
The phytochemical analysis of the biomaterials showed the presence of various quantities of polyphenols and flavonoids, and it was observed that PapPE showed the highest contents of polyphenols, SE contained the highest flavonoids as compared to others (Table 1)
Summary
Azoxymethane (AOM) is a potent carcinogenic agent commonly used to induce colon cancer in rats; the cytotoxicity of AOM is considered to mediate oxidative stress. This study investigated the chemopreventive effect of three natural extracts [pomegranate peel extract (PomPE), papaya peel extract (PapPE) and seaweed extract (SE)] against AOM-induced oxidative stress and carcinogenesis in rat colon. Cancer is considered as a leading cause of death worldwide accounting for 7.6 million death in the year 2005, the rate of colorectal cancer (CRC) has increased dramatically as compared to other types of cancers. This increase was attributed to environmental insults that synergize with genetics for the epidemic of CRC worldwide [5]. Azoxymethane (AOM) induces colon cancer in experimental animals; in a mechanism that is mediated by glutathione (GSH) depletion and impairing total antioxidant capacity in colonic cells of rats [8,9]
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