Aim: To verify the involvement of free radicals in tumor progression and to investigate the effects of an ethanolic extract of Ruta Chalepensis L. and of rutin in blood of patients with colon cancer.
Materials and methods: Leaves of Ruta Chalepensis L. were collected in the area around Catania (Italy). For the preparation of the ethanol extract of leaves, an exhaustive extraction of 100 g of the drug was carried out in Soxhlet with 800 ml of 95% ethanol. Fifty-six patients with colorectal cancer were randomly selected for this study; among these, 34 were affected by an early stage (T1 N0 M0 according to scale), while 22 were affected by an advanced stage (T4, N1-2, M0) of cancer. Data obtained from these patients were compared with those of a control group consisting of 20 healthy subjects. Plasma of each sample was used for determining non-proteic antioxidant capacity, thiol groups, lipid hydroperoxides and nitrite/nitrate levels, evaluated by spectrophotometric tests. In addition, percentage of haemolysis was evaluated incubating (for 2 hours at 37 degrees C) erythrocyte suspension with a free radical donor (50 mM 2,2'-azobis-amidino propane chloridrate), in the presence or absence of ethanolic extract of Ruta Chalepensis L. (250 microg/ml) or rutin (1 mM).
Results: Non-proteic antioxidant capacity was significantly lower in cancerous patients than in healthy subjects (p < 0.001). This decrease was stage-related. In fact, non-proteic antioxidant capacity resulted lower in advanced than in early colorectal cancer (p < 0.001). The same significant stage-related decrease was observed in plasma thiol groups (p < 0.001). Coherently with the decrease in non-proteic antioxidant capacity and thiol groups, higher levels of lipid hydroperoxides and nitrite/nitrate were observed in patients with colorectal cancer with respect to healthy subjects (p < 0.001) and the increase in these markers of oxidative stress was related to the cancer stadiation. Neoplastic patients also showed an increased percentage of oxidative hemolysis respect to controls and the haemolytic damage was correlated with the stage of colon cancer. Both the extract of Ruta Chalepensis L. and rutin were able to protect erythrocytes from oxidative stress induced by the free radical donor, but the extract of Ruta Chalepensis L. was more effective than rutin. This protective effect was significant only in erythrocytes from patients with early colorectal group, whereas no significant modification was induced by Ruta Chalepensis L. or rutin in red blood cells from advanced colorectal cancer patients exposed to the same experimental conditions.
Conclusion: Oxidative stress correlates with colon cancer stadiation and both the extract of Ruta chalepensis and rutin are able to protect red blood cells from radical-induced damage. However, their effects are significant in early stages of cancer. So these natural antioxidants might be usefull to prevent carcinogenesis and/or tumor progression.