Features of isolation of enalapril from biological material

Objective. The aim is to study the isolation of enalapril from biological material.

Materials and methods. ((Z)-but-2-enedioic acid;(2S)-1-[(2S)-2-[[(2S)-1-ethoxy-1-oxo-4-phenylbutan-2-yl] amino] propanoyl] pyrrolidine-2-carboxylic acid) was selected as the analyte (enalapril as maleate). Extraction in the infusion mode was used as an isolation method. Column chromatography of normal pressure, TLC, spectrophotometry and HPLC are considered as methods of purification and analysis.

Results. The most comprehensive enalapril isolation in the form of maleate can be carried out from the biomatrix by methanol infusion in combination with acetone (6:4). According to the results obtained it is necessary to double (0.5 hours) the infusion of the proposed extracting mixture to isolate the analyte, and the amount of this mixture should be in relation to the amount of biomatrix as 10 to 5 or more. As an option for eliminating endogenous impurities, we recommend distribution chromatography of enalapril maleate (column (15×1 cm) of the Silasorb S-8 sorbent, dispersion 0.015 mm, isopropanol-water mobile phase (9:1)). Reliable confirmation of the analyte identity was provided by chromatographic (TLC, HPLC) and spectral (UV spectrophotometry) methods. Data on the amount of enalapril maleate in the biomatrix were obtained by the spectrophotometric method (medium - ethanol, the registration point of the signal intensity is 219 nm).

Conclusion. Quite small (up to 1.5%) fluctuations in the degree of extraction of enalapril maleate were revealed at a level of its presence in the biomatrix of 0.02-0.4%. Isolation of analyte by infusion with methanol in combination with acetone (6:4), a well-grounded optimal isolation mode and the recommended purification option make it possible to fix the recovery (83.64-85.12%) ± (3.30-4.46) enalapril from a model matrix (liver).

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