薬理と治療

Abstract

Recently, a report was published that extract of the health food natto prevents infection by viruses such as severe acute respiratory syndrome coronavirus 2（SARS-CoV-2）and bovine herpes virus 1（BHV-1）, and we sought to elucidate the actual antiviral action of this extract. In this study, we assumed that Nattokinase（NK）was the actual factor responsible for the major degradation activity in natto extract. For this purpose, NK contained in natto was first purified from the culture medium of Bacillus subtilis natto. When this purified NK was used to act on recombinant SARS-CoV-2 spike protein in vitro, we proved that the viral protein was hydrolyzed by electrophoresis and Western Blot method using anti-SARS-CoV-2 spike protein antibody. It was also found that recombinant SARS-CoV-2 mutant strain S1 RBD（N501Y）was degraded. On the other hand, NK lost its viral degrading effect after heat treatment（HI-NK）at 100℃ for 10 min. Even in the presence of the serine protease inhibitor AEBSF, its degradation was specifically inhibited. Viral HA, which is involved in influenza virus infection, was also degraded similarly by NK, and its degradation was inhibited by HI-NK treatment. From these findings, it was inferred that NK has antiviral activity to prevent not only novel coronaviruses but also influenza virus infection. （Jpn Pharmacol Ther 2022；50：781‒7）