Improvement of the extraction efficiency of d-amygdalin from Armeniacae Semen powder through inactivating emulsin and suppressing the epimerization of d-amygdalin

Armeniacae Semen contains not only amygdalin but also emulsin, which is an enzyme that hydrolyzes amygdalin. This hydrolysis reaction has been a major problem associated with the water extraction of Armeniacae Semen powder. In this study, the emulsin was inactivated by extracting Armeniacae Semen powder at a constant temperature of 90°C. In addition, in order to suppress the epimerization of d-amygdalin, the extraction time was kept to less than 8 min. The use of a 10 mM sodium phosphate buffer (pH 2.3) containing 13.5% acetonitrile as a mobile phase in reversed-phase HPLC was effective in separating and analyzing the d-amygdalin and neoamygdalin. The linearity between the concentrations and detector responses was obtained in the range of 0.05 to 0.5 mM. The detection limits for d-amygdalin and neoamygdalin were approximately 5 μM per amount injected.