mPEG-carboxymethyl astaxanthin monoester: A novel hydrophilic astaxanthin with increased water solubility and bioavailability

To develop hydrophilic astaxanthin with significantly enhanced water solubility, an optimized one-step synthesis method was developed by heating free astaxanthin (F-Asta) and mPEG-carboxymethyl (mPEG-CM) in dichloromethane (27 degrees C) with two catalysts, yielding 61.38 +/- 2.16% of mPEG-carboxymethyl astaxanthin monoester (mPC-Asta) in 12 h mPC-Asta showed a characteristic wavelength absorption at 441 nm with high dispersibility (206 mg mL(-1)) in water. The particle size of mPC-Asta nanomicelles was in the range of 10-30 nm. Experiments on storage stability indicated best maintenance of mPC-Asta nanomicelles at 4 degrees C, pH 5, in the dark and in the presence of nitrogen. The AUC(0-t) of Asta in the serum of mice after gavage of mPC-Asta nanomicelles was 9.05 +/- 0.69 h mu g.mL(-1), which was significantly higher (four-fold) than that of F-Asta. The results show that mPC-Asta greatly enhances water solubility and bioavailability of astaxanthin.

Automated summary

The optimized one-step synthesis method significantly enhances the water solubility and bioavailability of astaxanthin with the formation of mPC-Asta. The experiments show that mPC-Asta nanomicelles have good stability under specific storage conditions.