By EMI HIRATA/ Staff Writer
September 17, 2020 at 17:19 JST
Persimmons dry in the sun at a farm in Koshu, Yamanashi Prefecture, in November 2018. (Asahi Shimbun file photo)
KASHIHARA, Nara Prefecture--Tannins in persimmons are highly effective against the novel coronavirus, researchers at Nara Medical University here have discovered.
The research team, announcing its findings on Sept. 15, said it is accepting applications from companies to jointly research and develop food products using the tannin such as candies and lemon soda to combat the virus.
“We want to work with companies that can quickly release products to the world by conducting further research with us,” said Hiroshi Hosoi, president of the university.
The tannin content needs to be higher than that in an unprocessed persimmon to be effective, the team explained in its announcement.
“I think the public is more familiar with persimmon tannin since it comes from nature,” said Toshihiro Ito, a professor of immunology at the university and a member of the team. “We want to make our findings beneficial to as many people as possible by determining the best content of the tannin through experiments.”
No clinical trials in humans have been conducted yet to confirm the findings.
Persimmon tannin is contained in the fruit and used in preservatives and dyeing. The team, which also includes Hisakazu Yano, a professor of microbiology and infectious diseases at the university, conducted an experiment on the tannin’s effectiveness against the novel coronavirus.
In the experiment, the researchers prepared solutions that recreated the environment inside the human mouth and body by using saliva and other materials.
They then added the virus into one group of solutions and a mixture of the virus and the tannin into another group of solutions for comparison.
The team said the “active” virus count was reduced to less than one ten-thousandth in solutions that contain the tannin, showing that it is effective against the virus.
But the tannin can no longer render the virus ineffective when the content of the tannin is diluted to a certain level, according to the team.
Ito, who has studied the antibacterial actions of persimmon tannin, said it can be assumed that the tannin sticks to the surface of the coronavirus and prevents it from entering cells inside the mouth and throat.
Persimmon tannin has also been reported to be effective against the flu and the norovirus, according to Ito.
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