Combination Effects of Curcumin and Aqueous Extract of Lignosus rhinocerotis Mycelium on Neurite Outgrowth Stimulation Activity in PC-12 Cells

Abstract

Neurotrophic factors are necessary for neuronal navigation to form viable neuronal networks. These factors are high molecular weight polypeptides that cannot cross the blood brain-barrier. Therefore, small molecules from mushrooms and plants are utilized to maintain neuronal function or up-regulate neurotrophic factors. The present study investigated whether a combination of Lignosus rhinocerotis mycelium aqueous extract and curcumin was more effective than L. rhinocerotis mycelium or curcumin alone in the stimulation of neurite outgrowth of PC-12 cells. The maximum neurite extension for L. rhinocerotis and curcumin was at 21.1% at 20 μg/mL and 29.5% at 10 μg/mL, respectively. Combining 20 μg/mL of L. rhinocerotis with one μg/mL curcumin gave 27.2% neurite extension. This combination was preferred because high concentrations of curcumin were toxic to cells. In the combination, 20 μg/mL of L. rhinocerotis enhanced neurite outgrowth activity at a lower dosage of curcumin at one μg/mL, and produced a comparable percentage of neurite outgrowth stimulation activity to L. rhinocerotis and curcumin alone in PC-12 cells.