Anti-diarrhea and anti-oxidant properties of Magnolol

Purpose: To provide an experimental basis for the anti-diarrheal and anti-oxidant properties of the bark extract of Magnolia officinalis Rehd. et Wils., a Chinese traditional herb called magnolol. Methods: The effects of magnolol on castor oil-induced diarrhea, small intestinal transit (SIT) in mice were investigated. Additionally, the antioxidant activity of magnolol was assessed in mice by the following parameters: glutathione (GSH), total antioxidant capacity (T-AOC), antioxidant enzyme activities and their gene expression level. Results: Compared with diarrhea model control group, magnolol (25, 50, or 100 mg/kg body weight) showed significant (p < 0.05) inhibitory activity against castor oil-induced diarrhea in mice. Administration of magnolol (25, 50, and 100 mg/kg) also lowered neostigmine-induced SIT acceleration to 60.34 ± 5.17, 59.61 ± 7.66, and 54.12 ± 7.27 %, respectively, as against 70.1 ± 6.89 % for neostigmine control group. In vivo antioxidant assay results showed that mice treated with magnolol exhibited significantly (p < 0.001) higher activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities in blood, compared to control. Similarly, magnolol proups showed significantly higher CAT and SOD and T-AOC activities (p < 0.01) than control in liver tissues. The 100 mg/kg magnolol group had significantly higher liver GSH content than normal control group (1.01 vs. 0.79 mg/mg protein). At 25 and 50 mg/kg doses, magnolol significantly enhanced gene expression levels of CAT (p < 0.01) in liver. Conclusion: Findings from this study indicate that magnolol possesses anti-diarrheal activity and is probably one of the main anti-diarrhea ingredients of Cortex Magnoliae Officinalis. Magnolol modulation of the activity and gene expression of antioxidant enzymes may therefore exert beneficial effects in antioxidant defense.