Development and validation of reliable astaxanthin quantification from natural sources

Area of Science:

• Natural Product Chemistry
• Analytical Chemistry
• Biotechnology

Background:

• Natural astaxanthin exists as complex esters and stereoisomers, hindering accurate quantification.
• Existing analytical methods for astaxanthin lack standardization and precision.
• Haematococcus pluvialis is a significant natural source of astaxanthin.

Purpose of the Study:

• To develop a simplified and precise method for astaxanthin quantification.
• To hydrolyze astaxanthin esters and determine free astaxanthin in all diastereomeric forms.
• To standardize astaxanthin measurement in natural sources like H. pluvialis.

Main Methods:

• Development of an enzymolysis-based quantification method using cholesterol esterase.
• Analysis of astaxanthin standards and processed H. pluvialis biomass.
• Comparison with other astaxanthin determination approaches (e.g., acetone conversion, photometry).

Main Results:

• The enzymolysis method demonstrated linear correlation for all-E-astaxanthin standards (1.0–11.2 μg/mL) with CV < 5%.
• Measurement range extended to 30 μg/mL in H. pluvialis extracts, accounting for sample composition.
• High precision achieved for all-E-astaxanthin (CV ≤ 1.1%) and diastereomers (CV < 10%) in dried biomass.
• Developed method showed higher total astaxanthin recovery but lower diastereomer selectivity compared to other methods.
• Photometric methods lost precision at earlier H. pluvialis cell cycle stages compared to chromatography.

Conclusions:

• The enzymolysis method provides a standardized and precise approach for astaxanthin quantification.
• Optimal storage conditions (≤ -20°C, no oxygen, intact cells) minimize astaxanthin degradation.
• The developed method enhances the reliability of astaxanthin analysis from natural sources.