Recently, a research group screened a number (37 to be exact) of plant extracts to see what effect they might have on slowing aging and extending life. They say they’ve found the most potent life extension substance ever.
The screening was done by adding these substances to the growth medium of the yeast Saccharomyces cerevisiae, which is the same yeast used to make wine and beer, and which is often used in aging studies. Yeast cells have biochemistry similar to mammalian cells, they age and die similarly to mammalian cells, their lifespans can be increased by calorie restriction, they are cheap experimental animals, and their lifespans are short, all of which make them ideal for aging experiments and especially, screening of a large number of compounds. The paper is “Discovery of plant extracts that greatly delay yeast chronological aging and have different effects on longevity-defining cellular processes”, published in Oncotarget.(1)
An news write-up in Science Alert (2) stated:
“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 fromCimicifuga racemosa, Valeriana officinalis L., Passiflora incarnata L., Ginkgo biloba,and Apium graveolens L.. [My emphases.]
These compounds may be much more potent than the two most widely touted anti-aging drugs, rapamycin and metformin.
What really caught my eye was that the most potent substance they found was an extract of willow bark. This the same source from which aspirin was derived.
Willow bark contains salicin, which when metabolized in the body becomes salicylate, an anti-inflammatory and pain-killing chemical. In the new paper, the potent life-extending willow bark extract contained “>25% salicin”.
The technical name for aspirin is acetyl salicylic acid (ASA). When metabolized, the acetyl group is split off, and the active pain-killing substance, salicylate, is generated. (Aspirin has two modes of action: the anti-platelet (“blood-thinning”) action comes from the acetylation of platelets; the pain-killing mode from salicylate.)
So, we see that there’s a huge point of similarity between aspirin and the willow bark extract that extended lifespan. Of course, there may be other compounds in willow bark besides salicin that are important – we just don’t know at this point. There’s even a possibility that salicin is irrelevant to the extract’s effects, though that seems very unlikely, as I’ll explain.
How much did this extract with >25% salicin extend yeast lifespan? See the following chart.
In the chart, the willow bark extract is PE21, at the bottom. The top, black bar is the control yeast, with no plant extract added to the medium. Willow bark extract extended yeast lifespan by almost 5-fold, making it the most potent life-extending substance yet found, eclipsing metformin and rapamycin.
Importantly, as the chart shows, the yeast were grown in 2% glucose, i.e. were not food restricted. When cells were grown in calorie-restricted conditions — 0.5% glucose — all the extracts were much less or even not at all effective. This shows that a major mode of action of these substances is by mimicking calorie restriction, presumably by activating the same biochemical pathways.
If salicin in willow bark is wholly or partially responsible for its life-extending power, then aspirin could also be one of the most potent life-extending drugs known.
We already know that aspirin extends lifespan in mammals (mice) and in C. elegans (a worm). So the fact that salicin was involved in the present study is unlikely to be a fluke.
Aspirin also extends lifespan in another experimental animal, the cricket.(3) Not only did it extend lifespan, but it was much more potent than metformin in doing so, and showed very few life history trade-offs in life extension. In other words, metformin, while it extends lifespan, also significantly impairs growth and rate of maturity, while aspirin does not.
Unlike the reigning dietary restriction paradigm, low aspirin conformed to a paradigm of “eat more, live longer.” In contrast, metformin-treated females were only ~67 % of the mass of controls. Our results suggest that hormetic agents like metformin may derive significant trade-offs with life extension, whereas health and longevity benefits may be obtained with less cost by agents like aspirin that regulate geroprotective pathways.
How does aspirin increase lifespan? It’s anti-inflammatory, but that just moves the question a step further back. It turns out that aspirin chelates iron, which could account for its anti-inflammatory property.(4)
These results may help to explain the interaction of nonsteroidal anti-inflammatory drugs with free radicals and the anti-inflammatory properties of these agents, inasmuch as accumulating evidence indicates that much of the injury observed during inflammatory disorders may be mediated by oxidative stress frequently induced by iron-dependent reactions.
It follows from this that control of iron may be the proximate mechanism of action of salicin, aspirin, and calorie restriction, or that control of iron operates through the same biochemical pathways to extend life. I discussed this at length in my new book, Dumping Iron.
Aspirin could be one of the most potent anti-aging drugs. We might see more research on it except for the fact that pharmaceutical companies can’t make big profits from it, as it’s dirt cheap and over-the-counter.