Effect of Enzyme‐Treated Asparagus Extract on brain function

Abstract

Enzyme‐Treated Asparagus Extract (ETAS) is an anti‐stress functional material which is made from asparagus native to Hokkaido, Japan. It shows a variety of anti‐stress effects including heat shock protein 70 (HSP70)‐inducing activity. Several investigations were conducted to evaluate the anti‐stress effects of ETAS in in vitro and in vivo studies and in a clinical trial.In the in vitro study, when NG108‐15 neuronal cells were treated with ETAS, it upregulated the expressions of cytoprotective and anti‐apoptotic mRNAs such as HSP70, heme oxygenase‐1, growth differentiation factor 15, and neuronal apoptosis inhibitor protein 2. In the in vivo experiment, a senescence‐accelerated prone mouse (SAMP8) which shows early deficits of learning and memory, was supplemented with ETAS. When a contextual fear conditioning test was conducted, the ratio of freezing responses of SAMP8 mice treated with ETAS increased significantly compared to that of SAMP8 mice without ETAS.A randomized, double‐blind, placebo‐controlled, cross‐over study was also carried out. Healthy volunteers (n=25) received ETAS (150 mg/day) or placebo, each of 28 days, with a 14‐day wash‐out. The subjects took the mental arithmetic (the Uchida‐Kraepelin test) for psychological test. After the mental arithmetic test, stress markers were measured using blood and saliva collected, and profile of mood states (POMS) was performed. The intake of ETAS inhibited the elevation of noradrenaline in blood and enhanced s‐IgA level in saliva. Furthermore, the number of answers and correct answers in the mental arithmetic test increased significantly.In conclusion, it was demonstrated that ETAS has neuroprotective effects and ability to maintain homeostasis against psychological stress, suggesting that ETAS may have beneficial effects in brain function.