Pterostilbene reduces fat buildup in cultured mouse muscle cells

In a laboratory dish, the Shinshu University team led by Associate Professor Takakazu Mitani exposed cultured C2C12 mouse skeletal muscle cells to food-derived compounds. Pterostilbene, a molecule found in blueberries, grapes and other berries, produced the strongest reduction in intracellular fat buildup while the cells continued to grow and differentiate normally, the team reported in Food Bioscience.

The target is fat stored inside muscle cells, known as ectopic lipid accumulation. Unlike subcutaneous fat—the fat beneath the skin—these intracellular droplets can interfere with normal muscle function and reduce the body’s ability to use glucose and fatty acids efficiently. The resulting loss of metabolic flexibility, meaning the ability to shift between fuels, is linked to insulin resistance.

The experiments suggest that pterostilbene does not prevent fatty acids from entering muscle cells. Instead, treated cells released more extracellular glycerol, a key sign of fat breakdown, while showing increased expression of genes involved in fatty acid oxidation. That points to greater intracellular lipolysis and lipid catabolism rather than reduced fatty-acid entry into the cells.

The researchers then traced the effect to PPARδ, or peroxisome proliferator-activated receptor delta, a signaling protein involved in fatty acid oxidation. Most experimental drugs designed to stimulate it bind directly to the receptor. Pterostilbene worked differently: the experiments indicate that it prevented PPARδ from being degraded through the ubiquitin–proteasome pathway, leaving more of the protein available to activate genes involved in lipid metabolism.

Concretely, the immediate result is a research lead for functional foods, nutritional supplements and future drug development—not a therapy people can use today. The work was done in cultured mouse cells, and the researchers say animal studies must still test efficacy, safety and target selectivity before the mechanism can be translated into a practical nutritional or pharmaceutical application.