Joint research teams consisting of Associate professor Takeshi Kawahara (Institute of Agriculture, Academic Assembly School of Science and Technology, Shinshu University) and Yomeishu Manufacturing Co., Ltd. revealed a persisting suppressive effect of a hot water extract of kuromoji (Kuromoji extract) on influenza virus.

Vaccines and anti-influenza drugs are effective in preventing influenza viral infection; however, the development of a new antiviral drug with a different mechanism of action is needed because the virus undergoes significant antigenic variation and there is an emergence of several drug resistant strains. Materials derived from natural products have been reported to suppress viral infection by various mechanisms that include direct inactivation of viruses and suppression of their growth in the target cells.

Although it had been suggested that the kuromoji extract has a similar function, its specific mechanism had not been clarified and research had not been conducted on the sustainability of its inhibitory effect. This study suggests that the extract has a sustainable suppressive effect on influenza viral infection in the target cells.

Influenza virus infects the target cells quickly after contact. Therefore, antiviral drugs that prevent the target cells from getting infected are desired. It was found that kuromoji extract shows such a preventive effect.

It is desired to further clarify the action of kuromoji extract on influenza virus in the future that includes isolation of its active ingredients, clarification of the relationship between the concentration of the extract, time of its action in the body, and molecular mechanism that explains its antiviral effects.

The results of this research were published in the Japanese medical journal: “Japanese Pharmacology & Therapeutics” (Vol. 47, No. 8, August 29, 2019).

Sustained influenza virus growth inhibitory effect of Kuromoji hot water extract
Takeshi Kawahara 1), Bunichiro Ashibe 1,2), Shigeru Matsumi 2), Tetsuya Maruyama 2)
1) Faculty of Agriculture, Shinshu University, 2) Product Development Center, Yomeishu Co., Ltd.
Jpn Pharmacol Ther, 2019, 47 (8) 1197-204.