Beneficial effect of Bidens pilosa L. (Asteraceae) in a rat model of colitis.

Background Bidens pilosa (BP) possessed anti-inflammatory, antioxidant, and immunomodulatory activities. Its beneficial effects on intestinal inflammation and oxidative stress in 2,4,6 trinitrobenzene sulfonic acid (TNBS) induced colitis in Wistar rats was evaluated. Methods Thirty female Wistar rats weighing 180-200 g were distributed into six groups (n = 5): non-colitic, untreated colitic and colitic rats treated graded doses of methanol extract of BP (50-400 mg/kg). Colitis was induced in rats by intracolonic instillation of 0.2 mL of 40 mg/mL TNBS. BP was administered two days pre-colitis induction and treatments continued until seven days post-colitis induction. A day after the last treatment, rats were euthanized, colon removed aseptically and response to treatment assessed. Phytochemical composition of BP was determined using the GC-MS. Results BP significantly reduced macroscopic colonic damage score, weight/length ratio, colonic lipid peroxidation level, leukocytes infiltration, and TNF-α level in comparison to untreated colitic rats (p ≤ 0.008). Similarly, treatment with 200 and 400 mg/kg BP prevented depletion of colonic glutathione level than other treatment groups (p ≤ 0.0002). Histological findings revealed that treatment with 400 mg/kg BP significantly preserved the mucosal epithelial layer. It also prevented ulceration and sloughing of the mucosal layers and reduced infiltration of inflammatory cells compared to other treatment groups. Among the 16 compounds identified were oleic acid (6.2%) and n-hexadecanoic acid (2.0%) with antioxidant anti-inflammatory activities. Conclusions The beneficial effects of BP in rat colitis might be related to the reduction of leucocytes infiltration, inhibition of oxidative stress and pro-inflammatory cytokines.