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.

MAIN METHODS: Male Sprague-Dawley rats were fed with either normal diet or high-fat diet for 8weeks. Firstly, OB rats were divided into (1) OB and (2) OB+R (100mg/kg, p.o, 28days). Then, OB rats were subjected to MI (ISO, 85mg/kg, s.c, 2days) and divided into three groups: (1) OB+MI, (2) OB+MI+R and (3) OB+MI+enalapril for another 4weeks.

KEY FINDINGS: Roselle ameliorated OB and OB+MI's cardiac systolic dysfunction and reduced cardiac hypertrophy and fibrosis. The increased oxidative markers and decreased antioxidant enzymes in OB and OB+MI groups were all attenuated by roselle.