Whey Protein Isolate-Encapsulated Astaxanthin Nanoemulsion More Effectively Mitigates Skeletal Muscle Atrophy in Dexamethasone-Induced Mice.

BACKGROUND

Skeletal muscle, as the largest organ in the body and the main protein pool, is crucial for various physiological processes, but atrophy of skeletal muscle can result from glucocorticoids, including dexamethasone, or from aging. Astaxanthin (AST) is a ketocarotenoid with a variety of physiological activities. However, the clinical application of AST is hampered by its strong hydrophobicity, intense off-flavors, and susceptibility to oxidation.

METHODS

In this study, we prepared whey protein isolate (WPI)-encapsulated AST nanoemulsion (WPI-AST, W-A) and investigated its alleviating effects on dexamethasone-induced skeletal muscle atrophy.

RESULTS

The optimal concentration of astaxanthin was determined to be 30 mg/mL with an oil/water ratio of 1:5. The W-A was a typical oil-in-water (O/W) emulsion with a particle size of about 110 nm. The bioaccessibility of astaxanthin was significantly improved, with the off-flavors of astaxanthin effectively masked. After oral administration, the W-A further ameliorated skeletal muscle atrophy by inhibiting skeletal muscle catabolism, promoting skeletal muscle production, and inhibiting mitochondrial autophagy compared with the same dose of WPI and AST. In addition to this, the W-A further improved the glycometabolism of skeletal muscle by reducing the expression of Foxo3 and increasing the expression of PGC-1α.

CONCLUSIONS

In conclusion, the W-A nanoemulsion demonstrated good therapeutic value in alleviating skeletal muscle atrophy.