AMELIORATIVE EFFECTS OF APIGENIN ON DEXTRAN SULPHATE SODIUM-INDUCED ULCERATIVE COLITIS AND HEPATOTOXICITY IN MALE AND FEMALE BALB/c MICE

Abstract

Ulcerative colitis (UC), a multifactorial inflammatory bowel disorder, is on the increase globally and a major risk factor for colorectal cancer. Existing drugs for treatment of UC have adverse effects, hence current research is focused on compounds with anti-inflammatory and antioxidant properties as alternatives. Apigenin (4’,5,7-trihydroxyflavone), a natural flavone, possesses anti-inflammatory properties, however, there is dearth of information on its effects on UC. This study was designed to assess the effects of apigenin on dextran sulphate sodium (DSS)-induced UC and hepatotoxicity in both male and female Balb/c mice.

Acclimatised male (n=32; 22-26 g) and female (n=32; 19-23 g) mice were divided into four groups (n=8). Group I [Control 0.5mL/kg 1.5% v/v DMSO)], Group II (10 mg/kg Apigenin), Group III (5% w/v DSS) and Group IV (10 mg/kg Apigenin + 5% w/v DSS). The body weights of mice were measured daily. Apigenin was orally administered for 10 days whereas DSS was given for seven days. They were sacrificed after overnight fasting. Colon and liver were excised, weighed and used for biochemical analysis. Colon lengths were measured. Antioxidant indices; Lipid Peroxidation (LPO), hydrogen peroxide concentration (H2O2), Superoxide dismutase (SOD), Catalase, reduced Glutathione (GSH) and inflammatory indices; Nitric Oxide (NO) and myeloperoxidase were determined spectrophotometrically. Cytochrome P450 isoform (CYP3A4), P-glycoprotein, inducible Nitric Oxide Synthase (iNOS) and cyclooxygenase-2 expressions were determined by immunohistochemistry. Histological examinations of colon and liver were carried out. Data were analysed using Two-way ANOVA at α0.05.

Administration of DSS significantly reduced body weight (-2.83±0.39 vs 0.90±0.43 g) and colon length (7.33±0.33 vs 10.08±0.39 cm) in male mice compared to control. The DSS-treated male group had significantly higher colonic NO (0.66±0.08 vs 0.41±0.06 µmol/mg), myeloperoxidase (3.65±0.36 vs 1.14±0.13 U/mg), LPO (11.09±1.08 vs 6.92±1.32 nmol/mg) and H2O2 (0.13± 0.01 vs 0.085±0.01 mmol/mg) but lower catalase (0.93± 0.20 vs 1.57±0.18 U/µg) compared to the female. Hepatic LPO and H2O2 significantly increased in the female by 68.6 and 85.6%, respectively compared to male. In the colon, apigenin pretreatment increased SOD in the female by 51.3% and GSH in male (738.0%) and female (336.9%). Apigenin reduced LPO in male by 51.4%, and H2O2 in male and female by 52.5 and 48.1%, respectively. Catalase reduced in the male (0.46± 0.07 vs 1.07± 0.15 U/µg) while NO (0.57± 0.06 vs 0.37±0.03 µmol/mg) and myeloperoxidase (2.76±0.20 vs 1.15± 0.11 U/µg) increased compared to the female. In the liver, apigenin increased GSH in male by 206.0% and decreased LPO in female by 48.0%. Histology of the colon showed that apigenin reduced mucosal inflammation, neutrophilic infiltration and epithelial erosion. The CYP3A4, iNOS and cyclooxygenase-2 expressions were significantly repressed in both sexes and organs while P-glycoprotein was moderately expressed compared to the DSS-treated group.

Dextran sulphate sodium increased inflammation and oxidative stress in male and female mice compared to control. Apigenin attenuated dextran sulphate-induced ulcerative colitis and hepatotoxicity in the male mice better than in the female.