A sulfur based molecule may give aging muscles a second wind. Scientists in Japan have identified a compound that appears to protect and even boost a protein critical for repairing damaged muscle tissue. The discovery could eventually lead to new ways to slow muscle loss and preserve strength as people grow older.
A key repair protein gets damaged with age
Researchers at Kyushu University in Fukuoka focused on hepatocyte growth factor, or HGF. This protein normally sits inactive in the structural network around muscle fibers. When muscle tissue is injured or mechanically stimulated, HGF is released. It then binds to receptors on satellite cells, the stem cells that maintain and repair skeletal muscle. That signal wakes the satellite cells up, allowing them to multiply, mature, and rebuild damaged fibers.
But aging disrupts this system. The team previously discovered that HGF can undergo a chemical change called nitration. A nitro group attaches to two spots on the protein, Y198 and Y250, which are in the same region HGF uses to connect with its receptor. After nitration, HGF can no longer bind effectively. The researchers compare the damaged protein to a rusted key that no longer fits its lock. This loss of function may be one reason older adults experience muscle wasting and reduced regeneration.
Testing sulfur based antioxidants
Led by Professor Ryuichi Tatsumi, the scientists wondered if a strong antioxidant could protect HGF from nitration or compensate for the damage. They tested two trisulfide compounds, molecules with three sulfur atoms linked in a chain: glutathione trisulfide (GSSSG) and lipoic acid trisulfide (LASSS). Both are known for their ability to participate in redox reactions.
Early experiments showed that both GSSSG and LASSS reduced nitration at the Y198 and Y250 sites on HGF. But neither compound fully restored the protein's ability to bind to its receptor. So the researchers increased the molar ratio of HGF to trisulfide from 1:4000 to 1:8000.
At that higher concentration, LASSS did something unexpected. It not only protected HGF but also created a stronger signal. The treated HGF activated satellite cells more powerfully than normal, undamaged HGF. The compound appeared to supercharge the repair protein rather than just shield it.
Why this matters for aging muscles
Skeletal muscle often begins to deteriorate relatively early in the aging process. Over time, this leads to loss of strength, increased scarring, fat buildup within muscle tissue, and a decline in fast twitch fibers, which support rapid and powerful movements. The results were published on July 24, 2026, in Scientific Reports.
Tatsumi noted that HGF is not necessarily missing as people age. Rather, it becomes chemically altered after it is made. A compound that protects HGF or compensates for the functional loss could help maintain the body's natural repair system. The discovery opens a new avenue for developing treatments that preserve muscle strength and mobility in older adults.
