D-carvone attenuates LPS-induced acute lung injury via TLR4/NF-κB and Nrf2/HO-1 signaling pathways in rats

Acute lung injury (ALI) is a severe respiratory disorder associated with high morbidity and mortality. Lipopolysaccharide (LPS) is widely used to induce ALI in animal models. D-carvone, a natural monoterpene, has been reported to possess anti-inflammatory and antioxidant properties. This study aimed to investigate the protective effects of D-carvone on LPS-induced ALI in rats. Thirty-six male rats were randomly divided into six groups (n = 6): control, D-carvone (10 mg/kg and 20 mg/kg p.o.), LPS (10 mg/kg E. coli lipopolysaccharide i.p.), and LPS + D-carvone (LPS with either 10 or 20 mg/kg D-carvone). D-carvone was administered orally once daily for 10 days. On day 10, sepsis was induced with LPS administration, and samples were collected after 6 h under deep anesthesia. LPS administration caused significant lung injury, as evidenced by increased histopathological scores, upregulation of pro-inflammatory markers (TLR4, IL-1β, TNF-α), and oxidative stress (increased MDA, decreased GSH and SOD). Treatment with D-carvone at both doses significantly attenuated these changes. D-carvone downregulated pro-inflammatory markers, upregulated anti-inflammatory (NRF2) and anti-apoptotic (Bcl-2) proteins, and reduced the levels of pro-inflammatory cytokines (IL-1β, TNF-α, IL-8) in lung tissues. In conclusion, D-carvone protects against LPS-induced ALI in rats, possibly through its anti-inflammatory and antioxidant properties. These findings suggest that D-carvone could be a potential therapeutic candidate for preventing and treating ALI.