The fountain of youth might only exist as a mythical concept, but that's not stopping scientists from trying to find its molecular equivalent. Right now, there are huge levels of interest in drugs such as rapamycin and metformin, for example, thanks to their impressive life-extending and disease-fighting properties.

But a new study suggests that the anti-ageing effects of these medications might have now been outdone: certain plant extracts have been found to contain the most effective anti-ageing molecules ever seen.

In conjunction with Quebec-based biotech company Idunn Technologies, a team from Concordia University in Canada has conducted more than 10,000 trials screening for plant extracts that could increase the chronological lifespan of yeast.

While you might not think it, yeast is one of the most common organisms studied in longevity research, due to similarities in the ways that yeast and humans age at the cellular level.

"In total, we found six new groups of molecules that decelerate the chronological ageing of yeast," said biologist Vladimir Titorenko from Concordia University.

As the authors report in Oncotarget, one of these compounds – a specific extract of willow bark (Salix alba) – is the most potent longevity-extending pharmacological intervention ever described in scientific literature. In testing, the willow bark extract increased the average chronological lifespan of yeast by 475 percent and the maximum chronological lifespan by 369 percent.

If these findings can be replicated in something other than yeast, it's a major discovery, outperforming the anti-ageing effects of both rapamycin and metformin. And in addition to slowing ageing, the compounds may also have beneficial effects on cellular processes when it comes to preventing related diseases, such as cancer, the researchers say. The other extracts come from Cimicifuga racemosa, Valeriana officinalis L., Passiflora incarnata L., Ginkgo biloba, and Apium graveolens L..

"Rather than focus on curing the individual disease, interventions on the molecular processes of ageing can simultaneously delay the onset and progression of most age-related disorders," said Idunn Technologies founder, Éric Simard. "This kind of intervention is predicted to have a much larger effect on healthy ageing and life expectancy than can be attained by treating individual diseases."

The researchers say they'll be furthering their study of the molecular compounds, with Idunn Technologies collaborating with four other universities on six separate research programs. The goal is to study the plant extracts in an animal model of ageing, in addition to two cancer models. We can't wait to hear the results.