Protective effects of oral α-pinene pretreatment against acetic acid-induced colitis in rats: effects on oxidative stress and Nrf2, HO-1, and NQO1 mRNA expression

Background: Colitis is a chronic inflammatory disorder associated with excessive oxidative stress and inflammatory responses. This study aimed to evaluate the protective effects of alpha-pinene pretreatment against acute acetic acid (AA)-induced colitis in rats. Methods: Forty male Wistar rats were randomly assigned into five groups (n = 8): control, AA, α-pinene (75 or 150 mg/kg), and sulfasalazine (100 mg/kg). α-pinene and sulfasalazine were administered orally for 14 consecutive days prior to colitis induction using intrarectal administration of 4% AA. Animals were evaluated 24 h after AA exposure. Colonic damage was assessed by macroscopic colonic injury score and histopathological examination. Oxidative stress markers (MDA, SOD, CAT, GSH), pro-inflammatory cytokines (TNF-α and IL-6), and mRNA expression levels of Nrf2, HO-1, and NQO1 were evaluated. Results: AA significantly increased macroscopic and histopathological colonic injury, MDA, TNF-α, and IL-6, while decreasing SOD, CAT, GSH, and Nrf2, HO-1, and NQO1 mRNA expression (p < 0.05). α-pinene pretreatment significantly reduced colonic injury, MDA, TNF-α, and IL-6, while increasing SOD, CAT, GSH, and Nrf2, HO-1, and NQO1 mRNA expression compared with AA (p < 0.05). Conclusion: α-pinene pretreatment attenuated AA-induced colonic injury, oxidative stress, and inflammation, potentially through enhancement of antioxidant defenses and upregulation of Nrf2, HO-1, and NQO1 mRNA expression. These findings support its potential protective role against acute colitis.