Abstract:

Objective: To study the respective processes for the extraction and purification of total polyphenols from Elaeagnus angustifolia seeds. Methods: Mixtures of methanol and water at different volume ratios were used to extract total polyphenols from Elaeagnus angustifolia seeds, and 40% aqueous methanol solution was selected. Reflux extraction presented higher both yield and purity of total polyphenol extract when compared to ultrasonic extraction and shaking extraction. Subsequently, orthogonal array design method was used to optimize the process for the reflux extraction of total polyphenols using 40% aqueous methanol solution. In the final section of this study, the purification of the crude total polyphenol extract from Elaeagnus angustifolia seeds was investigated by macroporous resin adsorption or ionic precipitation. Results: The optimal extraction process of total polyphenols from Elaeagnus angustifolia seeds was based on the use of 30-fold volume of 40% aqueous methanol solution to extract the material three times for 1 h each time, followed by vacuum condensation. Macroporous resin adsorption was found more suitable for the purification of the crude total polyphenol extract from Elaeagnus angustifolia seeds than ionic precipitation. An optimal purification was achieved through the steps of adsorption of the target products onto AB-8 resin, washing with distilled water until no saccharides could be detected in the eluate, elution with 2-fold bed volume of 40% aqueous methanol solution, harvesting of eluate fractions, condensation and drying. The preparation of total polyphenols from Elaeagnus angustifolia seeds was performed in triplicate, and an average value of product purity of 52.17% was obtained. Conclusion: The preparation method integrating the above optimized extraction and purification processes has the benefits of good repeatability and stability..

Key words: Elaeagnus angustifolia seeds, total polyphenols, extraction, purification, macroporous adsorption resin