A team of Japanese researchers have shown that low concentrations of cetylpyridinium chloride, used in certain mouthwashes, has an antiviral effect on SARS-CoV-2. Their findings were published in the journal Scientific Reports.
SARS-CoV-2 is transmitted via aerosols, which are spread from the oral and nasal cavities. In addition to infecting the cells of the respiratory tract, SARS-CoV-2 is also known to infect the cells of the lining of the mouth and the salivary glands.
Store-bought mouthwashes contain a number of antibiotic and antiviral components, such as cetylpyridinium chloride (CPC), which has been shown to reduce the oral viral load of SARS-CoV-2, chiefly by disrupting the virus’s lipid envelope. While there are other chemicals with similar effects, CPC has the advantage of being tasteless and odourless.
The researchers, led by Professor Kyoko Hida at Hokkaido University, were interested in studying the effects of CPC in Japanese mouthwashes, which typically contain a fraction of the CPC compared to previously tested mouthwashes. They tested the effects of CPC on cell cultures that express trans-membrane protease serine 2 (TMPRSS2), which is required for SARS-CoV-2 entry into the cell.
They found that, within 10 minutes of application, 30–50 µg/mL of CPC inhibited the infectivity and capability for cell entry of SARS-CoV-2. Interestingly, commercially available mouthwashes that contain CPC performed better than CPC alone. They also showed that saliva did not alter the effects of CPC. Testing with the original, alpha, beta and gamma variants of SARS-CoV-2 showed similar effetcts of CPC.
This study shows that low concentrations of CPC in commercial mouthwash suppress the infectivity of four variants of SARS-CoV-2. The authors have already begun assessing the effect on CPC-containing mouthwashes on viral loads in saliva of COVID patients. Future work will also focus on fully understanding the mechanism of effect, as lower concentrations of CPC do not disrupt lipid membranes.
Source: Hokkaido University
