The volatile oil of Nardostachyos Radix et Rhizoma inhibits the oxidative stress-induced cell injury via reactive oxygen species scavenging and Akt activation in H9c2 cardiomyocyte.

ETHNOPHARMACOLOGICAL RELEVANCE

Nardostachyos Radix et Rhizoma (NRR; the root and rhizome of Nardostachys jatamansi DC.) is a well-known medicinal herb widely used in Chinese, Uyghur and Ayurvedic medicines for the treatment of cardiovascular disorders. The oxidative stress-induced cardiomyocyte loss is the major pathogenesis of heart disorders. Here, the total volatile oil of NRR was isolated, and its function in preventing the cell death of cardiomyocyte was demonstrated.

MATERIALS AND METHODS

The cyto-protective effect of volatile oil of NRR against tBHP-induced H9c2 cardiomyocyte injury was measured by MTT assay. A promoter-report construct (pARE-Luc) containing four repeats of antioxidant response element (ARE) was applied to study the transcriptional activation of ARE. The amounts of phase ΙΙ antioxidant enzymes were analyzed by quantitative real-time polymer chain reaction (qPCR) upon the volatile oil treatment at 30 μg/mL for 24 h. The activation of Akt pathway was analyzed by western blot.

RESULTS

In cultured H9c2 cardiomyocytes, application of NRR volatile oil exhibited strong potency in preventing tBHP-induced cell death and accumulation of intracellular reactive oxygen species (ROS) in a concentration-dependent manner. In addition, the application of NRR volatile oil in cultures stimulated the gene expressions of self-defense antioxidant enzymes, which was mediated by the transcriptional activation of antioxidant response element (ARE). The induced genes were glutathione S-transferase, NAD(P)H quinone oxidoreductase, glutamate-cysteine ligase catalytic and modulatory subunits. In addition, the volatile oil of NRR activated the phosphorylation of Akt in cultured H9c2 cells. The treatment of LY294002, an Akt inhibitor, significantly inhibited the volatile oil-mediated ARE transcriptional activity, as well as the cell protective effect of NRR oil.

CONCLUSION

These results demonstrated that NRR volatile oil prevented the oxidative stress-induced cell death in H9c2 cells by (i) reducing intracellular ROS production, (ii) inducing antioxidant enzymes and (iii) activating Akt phosphorylation.