Inula viscosa phenolic extract suppresses colon cancer cell proliferation and ulcerative colitis by modulating oxidative stress biomarkers

Inula viscosa is a perennial herbaceous plant native to the Mediterranean Basin, which is used topically for the treatment of various diseases in folk medicine. This study aimed to evaluate the in vivo intestinal anti-inflammatory activity of the ethanolic extract of I. viscosa (EEIV) and to test its effect on a colorectal cancer cell line. EEIV was administered to rats orally and daily at 100 and 200 mg/kg body weight for 7 days, and then colitis was induced by intrarectal instillation of 2 ml of 4% (v/v) acetic acid (AA) solution. At the end of the experiment, clinical examinations of the rats were conducted by evaluating macroscopic and histological signs of colonic tissues and measuring erythrocyte sedimentation rate (ESR) and the levels of C-reactive protein, fibrinogen, myeloperoxidase (MPO), malondialdehyde (MDA) and nitric oxide (NO). Using MTS assay, the antiproliferative effect of EEIV against human colon carcinoma HT29 cells and cytotoxicity on nondifferentiated Caco-2 cell line was evaluated. EEIV significantly decreased the ESR and fibrinogen levels as compared to control colitic rats (P < 0.001). It also significantly decreased the NO, MDA, and MPO levels in the colon tissue compared with the untreated colitic group (P < 0.001). These results were confirmed by macroscopic and histological examination, which showed significant protection against AA-induced ulcerative colitis. Furthermore, EEIV at a concentration of 369.88 μg/ml did not show cytotoxicity on confluent Caco-2 cells, with significant inhibition of colorectal cancer cell (HT29) growth (EC50 = 62.39 μg/ml). These results demonstrate that EEIV plays a potential role as a pharmacological tool in the management of inflammatory bowel disease and prevention of colorectal cancer.