Abstract

This study was carried out to investigate the oxidative stress status of colorectal cells of rats exposed to Cycas circinalis leaf powder and the ethanol extract separately. Seven (07) groups of five (5) rats each were used for this study. Group 1 rats were maintained on normal rat feed without cycas leaf powder or the extract (control), group 2 rats were exposed to the leaf powder tainted feed (5% w/w) continuously for six weeks. Group 3 rats were placed on normal feed but administered ethanol extract of cycas leaf (10 mg/kg body weight) while groups 4,5,6 and 7 were exposed to the extract at a dose of 30,50,80 and 100 mg/kg body weight respectively once a week for 6 weeks by gavage. At the end of the treatment period each rat was sacrificed and the colon excised and sections obtained for histological examination and biochemical assessment of colon homogenate supernatant for oxidative stress indices. Results showed that there were significant (p≤0.05) decreases in the total protein level as well as superoxide dismutase, catalase and gluthatione peroxidase activities but an increase in malondialdehyde level in the colon homogenate supernatant of rats placed on the powder tainted feed and the ethanol extract treated ones when compared to the control. Histopathological examination of stained colon sections revealed that cycas powder and the extract at 80 and 100 mg/kg body weight caused ultrastructural changes in the colon amongst which are inflammation, reduced number of globlet cells with nuclear polarization and nuclear atypia which are early events in the onset of colorectal cancer. The results suggest that the leaf powder and the ethanolic extract of C.circinalis at higher doses are capable of inducing oxidative stress and early ultrastructural changes in colorectal cells, the later extent being indices of early events in colorectal carcinogenesis.

Keywords: Cycas circinalis; Ethanolic extract; Oxidative stress;Colorectal cancer