A century-old antiseptic made from coal tar and used to treat wounds and sleeping sickness in World War I Australian soldiers has been found to help the body fight off viral infections, including the common cold.
Acriflavine antiseptic is a brown or orange powder that is mixed with water to wash out wounds and treat abrasions.
In World War I and World War II it was used to treat everything from open wounds and bladder infections to gonorrhoea. It was also used to kill the parasite that causes sleeping sickness. But it has never been clear how it worked – until now.
Molecular biologists Michael Gantier and Genevieve Pepin from Melbourne's Hudson Institute of Medical Research have established that the antiseptic attaches to the DNA of the patient, which sparks the body's immune system into action.
Acriflavine was also found to bind to bacterial DNA, slowing the spread of bacteria and allowing the body's immune system to gain the upper hand.
The findings, published in the journal Nucleic Acids Research, reveal the healing power of the antiseptic to be far greater than realised.
As well as fighting the common cold and influenza, it could be useful in containing the spread of viral outbreaks including SARS, Zika and Ebola.
And because the overlooked antiseptic works by supercharging the body's immune system, it could also prove a valuable treatment option for antibiotic-resistant superbugs, which have been forecast to kill 10 million people by 2050.
"While we have published on its impact on viruses, it is most likely that this is applicable to bacterial infections as well," Dr Gantier said.
To establish how the antiseptic works, the team led by Dr Pepin studied its effect on colds.
They found that if cells were treated with the antiseptic two days before exposure to the common cold, then the virus was not able to replicate as quickly, while the immune response was faster.
"In a patient, that would mean that if you were to encounter the virus, you wouldn't feel as sick and you would clear the infection quicker," Dr Gantier said.
He said the antiseptic could prove a preventative tool for vulnerable members of the community including the young, elderly and healthcare workers.
While further trials with viruses need to be undertaken, early indications suggest acriflavine can protect against influenza –including new strains that develop as the virus mutates.
Identified as an antiseptic by German scientists in 1912, acriflavine is still used in some poorer countries, although the past 50 years have largely seen it replaced by penicillin.
"It is extremely cheap, which is why it is still used in poorer countries," Dr Gantier said. "It is also easy to move around because you don't have to worry about temperature or humidity."