A New Sulfur Molecule Could Change How We Think About Muscle Aging

Your muscles have their own repair system.

When muscle is damaged or stressed, one of the signals involved in starting that repair process is a protein called HGF, or hepatocyte growth factor. HGF helps activate satellite cells, the stem-like cells that can help repair and regenerate skeletal muscle. It does this by attaching to a receptor called c-Met on the surface of those cells.

A simple way to think about it is:

HGF sends the repair message. c-Met receives it. Satellite cells respond.

Researchers have been interested in what happens when that communication system becomes less effective with age.

And a new study suggests an unusual sulfur-containing molecule might help protect that message and even make it easier for the cell to receive.

The molecule is called lipoic acid trisulfide, or LASSS. In a July 2026 Scientific Reports study, researchers found that exposing HGF to LASSS changed the way HGF behaved in laboratory experiments. The treated HGF bound more strongly to c-Met and became more resistant to a type of chemical damage that can interfere with HGF function.

The researchers have nicknamed this enhanced form “Super HGF.”

That sounds dramatic. The underlying science is actually more interesting.

First, what happens to HGF as muscle ages?

Proteins in the body are constantly exposed to chemical stress.

One modification researchers are studying is called nitration. You can think of nitration as a small piece of chemical damage that alters specific parts of a protein and can change how well that protein works.

This research group previously found that HGF becomes increasingly nitrated in aging rat muscle. Two spots on HGF, known as Y198 and Y250, appear to be particularly important because they sit in regions involved in binding to c-Met. When those sites were nitrated in laboratory experiments, HGF became worse at binding its receptor and activating muscle satellite cells.

In plain language, the repair message was still there, but damage to the message made it harder for the cell to hear it.

That is potentially relevant to muscle aging because satellite cells help maintain and regenerate muscle. But there is an important distinction here: this specific HGF nitration mechanism has primarily been demonstrated in animal and laboratory research. It has not been established as a major cause of sarcopenia in humans.

So the researchers asked a more targeted question:

Could they protect HGF from that damage?

Enter LASSS

LASSS is a small molecule containing a chain of three sulfur atoms.

And despite the similar name, it is not the same thing as the alpha-lipoic acid, or ALA, found in supplements.

Regular lipoic acid contains two linked sulfur atoms. LASSS contains three. That seemingly small structural difference appears to change what the molecule can do. In the study, ordinary lipoic acid did not reproduce LASSS’s effects on HGF.

At first, researchers were interested in LASSS because sulfur-containing molecules can participate in antioxidant and redox chemistry.

But then they found something they were not expecting.

LASSS did more than protect HGF

When HGF was mixed with a high concentration of LASSS, the HGF subsequently produced more than twice the c-Met binding signal of untreated HGF in the researchers' receptor-binding assay.

In other words, LASSS did not simply stop HGF from getting damaged.

It appeared to make HGF better at interacting with its receptor.

The researchers then washed away the free LASSS and repeated the experiment.

The effect remained.

That is important because it suggests LASSS may have actually changed HGF itself rather than simply surrounding the protein and temporarily protecting it.

The researchers suspect LASSS may alter some of the sulfur-containing bonds inside HGF, causing a small structural change that helps HGF interact with c-Met. But they have not yet directly demonstrated exactly which bonds are changing, so this remains a proposed mechanism.

This is where the “Super HGF” nickname comes from.

It is not a newly discovered hormone. It is essentially HGF that behaved differently after being exposed to LASSS: it bound its receptor more strongly and was harder to damage through nitration.

Did that stronger signal actually do anything to muscle cells?

The researchers next tested satellite cells isolated from male rats.

Normally, their cell system requires around 5 ng/mL of HGF to produce maximal satellite-cell activation.

But HGF that had been treated with LASSS produced a similar maximal activation response at just 1 ng/mL.

That does not mean muscle grew five times faster.

It means that in this specific cell experiment, a lower concentration of LASSS-treated HGF could produce the same type of satellite-cell activation that normally required more untreated HGF.

So now the researchers had two connected findings:

LASSS-treated HGF bound the receptor more strongly.

And:

Less of that HGF was needed to activate muscle satellite cells in culture.

That made the mechanism much more interesting.

LASSS also made HGF harder to damage

There was another part of the story.

After LASSS was mixed with HGF and then washed away, the HGF became more resistant to subsequent nitration, particularly around the Y198 site.

This matters because it suggests LASSS may have two related effects:

1. Make HGF better at communicating with its receptor.

2. Make HGF more resistant to a form of chemical damage that can weaken that communication.

That is different from simply saying LASSS is an antioxidant.

Another sulfur-containing molecule, glutathione trisulfide or GSSSG, could also protect HGF from nitration while it was present in the reaction. But it did not produce LASSS's persistent increase in receptor binding after the free molecule was removed.

That is one reason researchers think LASSS may be interacting with HGF in a more specific way.

Then they tried it in mice

The researchers wanted to know whether anything similar could happen in a living animal.

They gave male mice LASSS in their drinking water for three days and then stopped the LASSS. The mice subsequently underwent five days of tail suspension, which unloads the hind legs and is commonly used to model rapid muscle disuse.

Muscle unloading increased HGF nitration.

But in the mice that had received LASSS beforehand, that increase was largely prevented. A comparison group given GSSSG did not show the same protection.

That is the first hint that the phenomenon might extend beyond a test tube.

But this part of the study was extremely preliminary.

There were only three mice per group according to the study methods, all were male, and the researchers measured HGF nitration rather than outcomes people actually care about, such as muscle mass, strength, mobility, or recovery.

They also did not measure how much LASSS entered the bloodstream or muscle, whether LASSS reached muscle intact, or exactly how it was metabolized.

So we cannot say that LASSS “preserved muscle” in mice.

We can say that LASSS pretreatment prevented the increase in HGF nitration produced by muscle disuse in this small mouse experiment.

Why muscle-aging researchers might care

Age-related muscle loss is much more complicated than any one protein.

Sarcopenia involves changes in muscle fibers, nerves, hormones, inflammation, mitochondrial function, protein turnover, activity levels, nutrition, and many other processes.

HGF nitration is therefore unlikely to be the explanation for muscle aging.

But this study raises a more interesting therapeutic idea.

Instead of simply giving the body more of a signaling molecule, what if you could make an existing repair signal work better and remain functional for longer?

That is essentially what researchers are exploring here.

If LASSS really can modify HGF so that it binds its receptor more effectively and resists age-related chemical damage, that could eventually become one strategy for maintaining muscle regeneration during aging or periods of prolonged inactivity. The authors specifically point to conditions such as sarcopenia, frailty, and disuse atrophy as areas worth investigating.

But “worth investigating” is doing a lot of work in that sentence.

And no, this is not a reason to take more alpha-lipoic acid

This distinction is especially important for supplement users.

LASSS is not alpha-lipoic acid.

Regular lipoic acid was tested in the experiments and did not produce the same enhancement of HGF.

There are also currently no human trials showing that LASSS can preserve muscle, prevent sarcopenia, improve strength, or enhance muscle recovery.

There is no established human dose.

There is no evidence from this study that taking an ALA supplement will create “Super HGF.”

And we do not yet know whether LASSS itself will ultimately prove safe or useful as a drug or supplement.

The takeaway

The exciting part of this study is not that scientists discovered a new muscle-building supplement.

It is that they may have discovered a new way to manipulate one of the body's existing muscle-repair signals.

The basic idea is surprisingly simple:

HGF helps tell muscle stem cells to repair.

Chemical damage can make that signal harder for cells to receive.

LASSS appears to change HGF so it binds its receptor more strongly and becomes harder to damage.

And in one very small mouse experiment, oral LASSS pretreatment also prevented the increase in HGF nitration caused by muscle disuse.

That is an intriguing biological mechanism.

It is also a very long way from showing that LASSS can keep human muscles stronger with age.

For now, “Super HGF” is a laboratory finding worth following, not a supplement strategy worth acting on.

This article is for educational purposes and is not medical advice. The research described is preclinical and has not been tested as a treatment in humans.