New indole alkaloids from Alstonia macrophylla

Area of Science:

• Natural Product Chemistry
• Phytochemistry
• Organic Chemistry

Background:

• Alstonia macrophylla is a plant species known for its rich phytochemical profile.
• Indole alkaloids represent a significant class of natural products with diverse biological activities.
• Previous research has indicated the presence of various alkaloids in Alstonia species.

Purpose of the Study:

• To isolate and characterize new indole alkaloids from the leaf extract of Malayan Alstonia macrophylla.
• To contribute to the understanding of the chemical diversity of Alstonia macrophylla.
• To identify novel chemical entities for potential pharmacological investigations.

Main Methods:

• Extraction of secondary metabolites from Alstonia macrophylla leaves.
• Chromatographic techniques for isolation of individual compounds.
• Spectroscopic analyses, including Nuclear Magnetic Resonance (NMR) and Mass Spectrometry (MS), for structure elucidation.

Main Results:

• Isolation and identification of ten new indole alkaloids: alstomaline (1), 10,11-dimethoxynareline (2), alstohentine (3), alstomicine (4), 16-hydroxyalstonisine (5), 16-hydroxyalstonal (6), 16-hydroxy-N(4)-demethylalstophyllal oxindole (7), alstophyllal (8), 6-oxoalstophylline (9), and 6-oxoalstophyllal (10).
• Identification of 21 additional known indole alkaloids from the same plant extract.
• Complete structural determination of the new compounds using comprehensive spectroscopic data.

Conclusions:

• The leaf extract of Malayan Alstonia macrophylla is a rich source of structurally diverse indole alkaloids.
• The discovery of these new compounds expands the known chemical repertoire of the Alstonia genus.
• Further investigation into the biological activities of these novel indole alkaloids is warranted.