Researchers from the Institute of Molecular Virology, Ulm University Medical Centre, Technische Universitaet Dresden, and CogniVerde GmbH examined green tea, chokeberry juice, and pomegranate juice as a potential to kill SARS-CoV-2.

They found that these substances were able to prevent the spread of infection in cells in vitro.

For the study, the researchers mixed the herbal substances with the viruses -- including vaccinia virus, influenza A virus, adenovirus type 5, and SARS-CoV-2 -- incubated them at room temperature, and determined infectivity.

The team observed that chokeberry juice decreased infectivity almost 3,000 times compared to a control with only a buffer. In comparison, the elderberry juice, pomegranate juice, and green tea reduced infectivity by about ten times.

The team also tested the swine flu virus (IAV) and SARS-CoV-2 and their interaction with herbal substances. They found the four herbal essences inactivated more than 99 per cent of IAV after 5 minutes.

An increase in incubation time to 20 minutes increased the activity only marginally, indicating the antiviral activity is rapid.

The researchers noted in their study that chokeberry juice inactivated about 97 per cent of SARS-CoV-2 after 5 minutes, while green tea and pomegranate juice inactivated about 80 per cent of the virus. Elderberry juice had no effect on SARS-CoV-2. The naked AdV 5, used as a control, was resistant to all except chokeberry juice.

The researchers also mentioned that SARS-CoV-2 was more resistant than other pathogens, although chokeberry juice was quite useful, with pomegranate juice and green tea also reducing virus amounts.

The authors suggested that continued gargling and rinsing the mouth with juices and teas followed by swallowing could be an effective preventive strategy for SARS-CoV-2, particularly for people at high risk of infection healthcare workers, and the elderly.

The study was published on the preprint server bioRxiv*.