Carnosic acid protects starvation-induced SH-SY5Y cell death through Erk1/2 and Akt pathways, autophagy, and FoxO3a.

Carnosic acid (CA) is recognized as a unique neuroprotective compound in the herb rosemary, since it induces expression of antioxidant enzymes including heme oxygenase-1 (HO-1), γ-glutamylcysteine synthase (γ-GCS), and glutathione S-transferase (GST) via activation of nuclear factor erythroid 2-related factor 2 (Nrf2), which is a nuclear transcription factor. In this study, we examined the cytoprotective effects of CA against starvation. We found that CA protected starvation-induced SH-SY5Y cell death by activating Akt and extracellular signal-regulated kinase 1/2 (Erk1/2). Interestingly, CA induced moderate autophagy and dephosphorylation of a transcriptional factor, the forkhead box protein O3a (FoxO3a). These effects of CA play an important role in cytoprotection.