Isolation and Characterization of Amygdalin from Apricot Seeds

The dried seeds of P. armeniaca L. (1.0 kg) were extracted three times with EtOH (1 L × 3 h) under reflux. After concentrating under reduced pressure, the EtOH extract (89.7 g) was suspended in distilled water and partitioned with n-hexane, CH₂Cl₂, EtOAc, and n-butanol to yield an n-hexane extract (50 g), a CH₂Cl₂ extract (8.8 g), an EtOAc extract (9.6 g), an n-butanol extract (6.5 g), and a water layer. The n-butanol extract was chromatographed with column chromatography (CC) on silica gel using stepwise eluent of CH₂Cl₂–acetone (gradient 10:1–1:1, v/v) and then CH₂Cl₂–MeOH–H₂O (gradient 6:1:0.1–1:1:0, v/v) to obtain 6 fractions (A–F). Compound 1 (35 mg) was isolated from fraction F (177.5 mg) by reserved phase C18 (RP-18) CC using MeOH–H₂O (3:1, v/v) as an eluent, followed by preparative high-performance liquid chromatography (HPLC) with an isocratic mixture solvent, 60% MeOH in H₂O, at 5 mL/min for 60 min. The nuclear magnetic resonance (NMR) spectra of compound 1 (¹H and ¹³C) were conducted using a 500 MHz NMR spectrometer (JEOL, JNM-ECA 500) with tetramethylsilane (TMS) as an internal standard. NMR solvent DMSO-d₆ was purchased from Sigma-Aldrich (MO, USA). The structure of compound 1 was confirmed as amygdalin using spectroscopic analysis of the NMR data and by comparison with other studies [24 (link),25 ] (Table S1, Figures S1 and S2).