NARA -- A research group at Nara Medical University in the western Japan city of Kashihara announced on Dec. 13 that experiments on hamsters revealed that saliva containing bitter juice, or tannin, extracted from persimmon meant they are less likely to be infected with COVID-19 or develop severe symptoms.
The group's finding was published in the electronic version of the British journal Scientific Reports on Dec. 8.
The experiment was conducted by a group including immunology professor Toshihiro Ito and Hisakazu Yano, professor of microbiology and infectious diseases. Researchers observed how hamsters, which were administered highly pure persimmon tannin into their oral cavity, and others that weren't, were doing after three days of being infected with the coronavirus.
Hamsters that weren't given an administration had a high viral load in their lungs, and developed pneumonia. Meanwhile, hamsters that were given persimmon tannin had a low viral load in their lungs, and showed no signs of pneumonia.
Furthermore, when the hamsters treated with persimmon tannin and untreated hamsters were put in the same cage as those infected with the COVID-19 virus for 30 minutes, viruses were not detected in the treated hamsters' lungs one week later.
In September 2020, Ito's group confirmed in vitro experiments that persimmon tannin has the effect of reducing the infectivity of the coronavirus in saliva. The group says the experiment on hamsters proved that it is difficult to become infected with the coronavirus or develop serious symptoms if the saliva contains persimmon tannin.
Ito explained, "From the results of the animal model, we can expect to put persimmon tannin to practical use to prevent and treat coronavirus infections. We are currently conducting clinical research on humans."
(Japanese original by Satoshi Kubo, Nara Bureau)