Momordica charantia L., known as bitter melon (BM), is a plant that belongs to the family Cucurbitaceae. Aims of this study are to investigate the anti-inflammatory effect of crude BM extract on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced experimental colitis model in rat. It was also aimed to determine the content and bioaccessibility of carotenoids of BM. BM was purchased from local markets in Izmir, Turkey. Fruits of BM were lyophilized, powdered, and used in the experiment. Carotenoids were determined by high-performance liquid chromatography. To determine the bioaccessibility of β-carotene, in vitro digestion was performed. Wistar albino rats were divided into four groups: group A (BM+TNBS), group B (BM), group C (TNBS), and group D (control). BM solution was given 300 mg/(kg·day) for 6 weeks orally. Colitis was induced by 0.25 mL of a solution containing 100 mg/kg 5% (w/v) TNBS in 50% ethanol (w/v) intrarectally after 6 weeks. After sacrification, macroscopic and microscopic evaluations were performed. Myeloperoxidase, cytokines levels (interleukin-17 [IL-17], TNF-alpha, and interleukin-10 [IL-10]) were measured in serum and colonic samples by ELISA test. Institutional Animal Ethics Committee approval was obtained. Total carotenoid content of BM was determined 11.7 mg/g dry weight as β-carotene equivalents. Bioaccessibility of total carotenoids was determined as 2.1% with in vitro digestion. Pretreatment with crude BM extract significantly reduced weight loss, macroscopic, and microscopic colitis damages in colonic samples (P = .000), (P = .015), and (P = .026), respectively. Serum anti-inflammatory cytokine IL-10 increased significantly in both treatment groups (P = .000). BM is a rich source of carotenoids, but the bioaccessibility of its carotenoids is low. This study displays that BM has protective anti-inflammatory effects on TNBS-induced colitis.
Keywords: Momordica charantia; TNBS-induced colitis; anti-inflammatory; carotenoids; colitis; digestion.