Inducible nitric oxide synthase downregulation and cellular antioxidant enzyme enhancing potential of oleanolic acid from Isodon wightii (Bentham) H. Hara against lipopolysaccharide-induced liver damage in bagg albino strain C mice

Background: Isodon wightii (Bentham) H. Hara is an aromatic medicinal herb belongs to Lamiaceae which has been considered as a prolific source of diterpenoids with diverse structural and medicinal values. Objective: The objective of the study is to evaluate in vivo anti-inflammatory activity of oleanolic acid from I. wightii against lipopolysaccharide-induced liver inflammation in Bagg albino strain C mice. Materials and Methods: Fractions were obtained using silica gel 60–120 mesh column chromatography, and structural elucidation was done using spectroscopic studies. Hepatoprotection, inducible nitric oxide synthase (iNOS) gene downregulation and the levels of cellular antioxidant enzymes with their respective gene expression were analyzed using reverse transcriptase-polymerase chain reaction (RT-PCR). Results: White amorphous powder (58 mg) was isolated from petroleum ether extract (15 g) eluted with petroleum ether: ethyl acetate mixture (90.5:9.5), and structure has been elucidated as oleanolic acid. 50 μg of oleanolic acid showed effective hepatoprotection and multiple fold increase in the level of antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, and glutathione S-transferase. RT-PCR analysis revealed that oleanolic acid had a remarkable effect on iNOS downregulation and antioxidant genes upregulation at 50 μg concentration. Conclusion: The present study proves that oleanolic acid possesses liver protecting activity with a positive effect on increased antioxidant enzymes production. The triterpenoid acid and oleanolic acid could be a suitable natural source for preparing hepatoprotective tonics.