Curcumin, Hormesis and the Nervous System

Abstract

Curcumin is a polyphenol compound extracted from the rhizome of Curcuma longa Linn (family Zingiberaceae) commonly used as a spice to color and flavor food. Several preclinical studies have suggested beneficial roles for curcumin as an adjuvant therapy in free radical-based diseases, mainly neurodegenerative disorders. Indeed, curcumin belongs to the family of hormetins and the enhancement of the cell stress response, mainly the heme oxygenase-1 system, is actually considered the common denominator for this dual response. However, evidence-based medicine has clearly demonstrated the lack of any therapeutic effect of curcumin to contrast the onset or progression of neurodegeneration and related diseases. Finally, the curcumin safety profile imposes a careful analysis of the risk/benefit balance prior to proposing chronic supplementation with curcumin.

Keywords: antioxidants; heme oxygenase; hormesis; vitagenes.

Figure 1

Neuroprotective effects of curcumin on neuro-inflammaging. Neuro-inflammaging is characterized by a down regulation of vitagene system (Hsp 70, γ-GCS, HO-1, Trx and Sirt1) and Nfr2 activity with the consequent upregulation of NF-κB activation. The increased NF-κB activation, also trough Tool Like Receptors 4 (TLR4), induces, in turn, raised proinflammatory factors, such as TNFα, IL1b, IL6, COX2 and iNOS. The disequilibrium between anti-(IL10) and pro-inflammatory molecules leads to increased inflammation, and a vicious circle is established that supports neuro-inflammaging. The neuroprotective curcumin inducing upregulation of vitagene system and Nrf2 could be able to inhibit the NF-κB activation and then break the vicious circle, ending the progression of the neurodegenerative disease.

Figure 2

The chemical structure of curcumin and its derivates.