Galangin and Piperine Attenuate Bleomycin-Induced Pulmonary Fibrosis by Modulating Oxidative Stress and MPO-Mediated Inflammation

Abstract

Aims: To evaluate and compare the protective efficacy of galangin and piperine—individually and in combination—against bleomycin-induced pulmonary fibrosis in C57BL/6 mice, with emphasis on oxidative and nitrosative stress modulation and histopathological recovery. The study focused on changes in antioxidant enzymes (SOD, CAT, GSH), oxidative stress markers (MDA, nitrite, MPO), and microscopic alterations in lung architecture. Study Design:  Controlled, randomised, experimental animal study with seven parallel groups. Place and Duration of Study: Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science, Hyderabad, India; 21-day experimental period conducted under IAEC approval. Methodology: Fifty male C57BL/6 mice (6–7 weeks old) were assigned to seven groups (n = 6–8): (1) Control; (2) Bleomycin (BLM, 1.5 U/kg, oropharyngeal, day 0); (3) Galangin (GA, 5 mg/kg/day, p.o.); (4) Piperine (PIP, 50 mg/kg/day, p.o.); (5) BLM + GA; (6) BLM + PIP; (7) BLM + GA (2.5 mg/kg) + PIP (25 mg/kg). On day 21, lungs were harvested for biochemical assays of SOD, CAT, GSH, MDA, nitrite, and MPO, and for histopathological analysis using H&E and Masson’s trichrome staining. Statistical analysis was performed using one-way ANOVA followed by Tukey’s post-hoc test (P < 0.05). Results: BLM administration significantly reduced antioxidant enzyme activities (SOD, CAT, GSH) and elevated MDA, nitrite, and MPO levels (P < 0.05), indicating oxidative and nitrosative stress. Treatment with galangin or piperine restored antioxidant status and reduced oxidative biomarkers, while their combination showed the most pronounced effect (P < 0.05). Histopathologically, BLM-treated lungs exhibited severe alveolar destruction, oedema, inflammatory infiltration, and collagen deposition. These lesions were markedly ameliorated by galangin and piperine treatment, with the combination group demonstrating near-normal alveolar structure, minimal congestion, and reduced fibrotic changes. Conclusion: Galangin and piperine protect against bleomycin-induced pulmonary fibrosis by attenuating oxidative and nitrosative stress, reducing MPO-mediated inflammation, and preserving normal lung histoarchitecture. Their combination produced synergistic antioxidant and histological protection, underscoring their potential as natural, multi-targeted therapeutic agents against pulmonary fibrosis.