Is boiled food spice curcumin still biologically active? An experimental exploration

BACKGROUND: As the major active component of turmeric (Curcuma longa), curcumin is widely used as a spice and food coloring agent, and also possesses multiple biological activities and therapeutic potential for neurodegenerative diseases. To answer the paradox between curcumin’s biological activities and poor systemic bioavailability, we proposed that degradation products of curcumin may make important contributions to its biological activities, which needs to be verified. In addition, curcumin is usually heated or boiled used as a spice, it is necessary to explore whether boiled curcumin, which degrades readily, is still biologically active. METHODS: Thus, in the present study we investigated the protective effects of curcumin and boiled curcumin mixture on H2O2-induced oxidative damage in PC12 cells, a widely used model for neurons. RESULTS: Results showed that in spite of high degradation rates, boiled curcumin mixture still possessed similar protective activities like parent curcumin, and could effectively rescue PC12 cells against H2O2-induced damage, via decreasing production of reactive oxygen species and malondialdehyde, reducing caspase-3 and caspase-9 activities. Moreover, curcumin’s degradation products including ferulic acid, vanillin and vanillic acid could also improve PC12 cells survival rate. CONCLUSION: Our findings indicated that boiled curcumin mixtures still possessed protective activity for PC12 cells, and supported the contribution of degradation products to biological activities of curcumin.