OBJECTIVE: The objective of this study is to study the chemoprevention effects of MEMCL against azoxymethane (AOM)-induced colon cancer and to examine the involvement of endogenous antioxidants Materials and methods: Male Sprague-Dawley rats, divided into five groups (n = 7), were injected intraperitoneally once weekly for 2 weeks with 15 mg/kg AOM, except for the normal group (received saline). The animals were then administered orally for 8 weeks with 8% Tween-80 (vehicle; normal group), 8% Tween-80 (vehicle; cancer group) or, 50, 250 or 500 mg/kg MEMC. After treatments, colon samples were collected from each rat for the histopathological analysis, quantification of aberrant crypt foci formed and determination of colon antioxidant levels. MEMC was also subjected to HPLC analysis.

METHODS: A new synthetic compound, 2-(1,1-dimethyl-1H-benzo[e]indol-2-yl)-3-((2-hydroxyphenyl)amino) acrylaldehyde, abbreviated as DBID, was prepared through the reaction of 2-(diformylmethylidene)-1,1- dimethylbenzo[e]indole with 2-aminophenol. The chemical structure of the synthesized compound was characterized by 1H NMR, 13C NMR and APT-NMR spectroscopy and confirmed by elemental analysis (CHN). The compound was screened for the antiproliferation effect against colorectal cancer cell line, HCT 116 and its possible mechanism of action was elucidated. To determine the IC50 value, the MTT assay was used and its apoptosisinducing effect was investigated.

RESULTS: DBID inhibited the proliferation of HCT 116 cells with an IC50 of 9.32 µg/ml and significantly increased the levels of caspase -8, -9 and -3/7 in the treated cells compared to untreated cells. Apoptosis features in HCT 116 cell was detected in treated cells by using the AO/PI staining that confirmed that the cells had undergone remarkable morphological changes in apoptotic bodies. Furthermore, this changes in expression of caspase -8, -9 and -3 were confirmed by gene and protein quantification using RT-PCR and western blot analysis, respectively.