In vitro Suppression of SARS-CoV-2 Infection by Existing Kampo Formulas and Crude Constituent Drugs Used for Treatment of Common Cold Respiratory Symptoms

Masaki Kakimoto; Toshihito Nomura; Tanuza Nazmul; Hiroki Kitagawa; Keishi Kanno; Keiko Ogawa-Ochiai; Hiroki Ohge; Masanori Ito; Takemasa Sakaguchi

doi:10.3389/fphar.2022.804103

In vitro Suppression of SARS-CoV-2 Infection by Existing Kampo Formulas and Crude Constituent Drugs Used for Treatment of Common Cold Respiratory Symptoms

Front Pharmacol. 2022 Mar 29:13:804103. doi: 10.3389/fphar.2022.804103. eCollection 2022.

Authors

Affiliations

¹ Department of General Internal Medicine, Hiroshima University Hospital, Hiroshima, Japan.
² Department of Infectious Disease, Hiroshima University Hospital, Hiroshima, Japan.
³ Department of Virology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
⁴ Kampo Clinical Center, Department of General Internal Medicine, Hiroshima University Hospital, Hiroshima, Japan.

Abstract

Several traditional Japanese Kampo formulas are known to have inhibitory effects on infections with viruses that cause respiratory symptoms. Although some herbs and their components have been reported to suppress SARS-CoV-2 replication in vitro, it is difficult to compare effective Kampo formulas because of the different methods used in studies. Thus, we carried out in vitro experiments on the suppression of SARS-CoV-2 infection by Kampo formulas and crude drugs used for the common cold to compare their suppressive effects on virus infection. After infecting VeroE6/TMPRSS2 cells with SARS-CoV-2, lysates of the Kampo formulas and crude drugs were added, and after 24 h, the infectious titer in the medium was measured by the TCID₅₀ method. Maoto was the most effective among the Kampo formulas, and Ephedrae herba was the most effective among the constituent crude drugs. However, a comparison of the suppressive effects of Ephedrae herba and Kampo formulas containing Ephedrae herba showed that the suppressive effect on virus infection did not depend on the content of Ephedrae herba. Based on the results, we believe that the use of Maoto among Kampo formulas is suitable as a countermeasure against COVID-19.

Keywords: COVID-19; SARS-CoV-2; anti-viral; crude drug; herbal medicine; kampo medicine.