UK scientists are a step closer to unlocking eternal youth after developing a drug that can prolong the life of some animals.
An experimental substance called 991 has been found to make yeast, worms and flies live 25 per cent longer.
It triggers a protein called AMPK that helps cells conserve and produce energy in times of stress, exercise or fasting. Scientists have long suspected this survival mechanism could also help slow some of the biological changes associated with ageing.
They say the new discovery raises hopes that humans could ‘eventually’ benefit.
Professor Filipe Cabreiro, from the UK's Medical Research Council (MRC), said: 'The field is still a long way from anti-ageing clinical trials in humans. This is because ageing is not technically classified as a disease.
'But improving health in older age would be hugely beneficial from a societal and healthcare perspective, since ageing is a major risk factor for so many diseases, such as heart disease, diabetes, cancer and dementia.
'The ability to make individuals healthier for longer, for instance by pharmacologically targeting energy balance through AMPK, would be a major biomedical breakthrough.'
The experimental drug extended the lifespan of yeast, worms and flies by up to 25 per cent, the study showed
AMPK is often described as the body's 'fuel gauge' because it constantly monitors how much energy is available inside cells.
When energy levels start to fall, AMPK acts like a biological switch, shutting down energy-hungry processes and ramping up mechanisms that generate more fuel.
The enzyme is naturally activated by activities such as exercise, fasting and other forms of physical stress, helping cells adapt when resources are limited.
Scientists have become increasingly interested in AMPK because it influences many of the biological processes linked to ageing, including metabolism, inflammation and cellular repair.
Because the protein sits at the centre of the body's metabolic network, it has also been linked to conditions including obesity, type 2 diabetes, cardiovascular disease and dementia.
Several popular drugs, including the diabetes medication metformin, are known to activate AMPK, which has fuelled interest in whether the pathway could be harnessed to improve health in old age.
However, many of these work indirectly, making it much harder to confirm and interpret biological results in the laboratory and clinic.
The drug, called 991, works by triggering a protein called AMPK that governs energy levels in the body
To overcome this hurdle, the team used the 991 drug to target AMPK directly in fission yeast, nematode worms and fruit flies.
They chose these organisms specifically because they have comparatively short lifespans.
Dr Helena Cochemé, who leads the Redox Metabolism Group at MRC, said: 'The fact that we can extend lifespan in yeast, worms and flies is very exciting.
'Worms and flies in the lab live for around three weeks and three months respectively, ...so we can make progress and discoveries much more rapidly and efficiently than in mammalian systems.
'Our study is the first demonstration that directly targeting AMPK using a drug can have longevity benefits in living organisms.
'If a treatment works successfully in three such distantly related species, then these results give us more confidence that in the longer-term, the effects possibly translate to mammals and eventually perhaps humans.'
Having demonstrated clear longevity benefits in yeast, worms and flies, the scientists are now aiming to see whether the same effects can be replicated in mice.
They say the fact that direct AMPK activators have already shown a good safety profile in trials for metabolic conditions raises hopes that the drugs could one day be used more widely in medicine.
The study, published in the journal Aging Cell, was primarily publicly funded by the MRC, part of UKRI.
The research also involved contributions from scientists at Queen Mary University of London, the Francis Crick Institute and the University of Lyon.