Preparation of shikonin by hydrolyzing ester derivatives using basic anion ion exchange resin as solid catalyst

An efficient catalytic hydrolysis approach was developed to prepare shikonin from its ester derivatives with anion exchange resins as solid catalyst. The performance of seven anion exchange resins including D290, D296, D261, D280, 201×7, D301-G and D301-R has been evaluated. The research results indicate that D290 resin is the most appropriate for preparation of shikonin. The reaction conditions such as reaction temperature, reaction time, catalyst amount and catalyst reuse have been studied. The maximum yield of shikonin reached 93.74 ± 2.99% under optimal conditions of hydrolysis temperature 20 °C, hydrolysis and desorption time both 30 min and resin amount 10% (w/v). HPLC chromatograms of samples, obtained after the new catalytic process, demonstrated that conversion of shikonin ester derivatives into shikonin performed well.