Estudo químico em alcaloides de Hippeastrum reginae (L.) Herb. (Amaryllidaceae)

Abstract

Objectives: The main objective of the present work was to carry out a chemical study on alkaloids of the species Hippeastrum reginae, promoting the isolation and characterization of these compounds. Methods: The plant was separated in bulbs and leaves for the extraction with methanol. After this step, the acid-base extraction and then the partition with solvents of different polarities were made to obtain the fractions enriched in alkaloids. The enriched fractions were initially analyzed by gas chromatography coupled to mass spectrometry (GC/MS) and then fractionated by chromatographic techniques such as Sephadex exclusion column, column chromatography and preparative thin layer chromatography. For the isolation of some alkaloids, high performance liquid chromatography (HPLC) and for the identification of the nuclear magnetic resonance (NMR) technique were used. Results: The CG/MS analyze of the extracts evidenced the presence of 11 alkaloids, of which four had no fragmentation pattern compatible with the alkaloid library, and may be unpublished in the literature. Eighteen alkaloids of Amaryllidaceae were isolated, most of them belonging to the homolycorine class. Of these compounds, six new alkaloids of Amaryllidaceae were identified, four of which were fully elucidated (2--methoxy-7-hydroxyhomolycorine, 2--7-dihydroxyhomolycorine, 2-- methoxyhomolycorine and 2-α-hydroxyalbomaculine), while Two (7-hydroxyhomolycorine and N-oxide albomaculine) analyzes were performed for 1H-NMR and high resolution masses. Conclusion: The H. reginae plant had a high alkaloid content and 18 compounds were isolated. Albomaculine and 2--7- dimethoxyhomolycorine alkaloids were the most abundant in GC / MS analysis. Six alkaloids not found in the literature were identified in this work and show a great potential for the discovery of new active compounds.