Antimicrobial indole alkaloids from Tabernaemontana corymbosa

Area of Science:

• Natural Product Chemistry
• Medicinal Chemistry
• Pharmacognosy

Background:

• Tabernaemontana corymbosa is a plant species known to produce various indole alkaloids.
• Indole alkaloids are a diverse class of natural products with a wide range of biological activities.
• Previous research has identified numerous alkaloids from the Tabernaemontana genus, highlighting its potential as a source of bioactive compounds.

Purpose of the Study:

• To isolate and characterize novel monoterpene indole alkaloids from the stem bark of Tabernaemontana corymbosa.
• To elucidate the structures and absolute configurations of the isolated compounds using advanced analytical techniques.
• To evaluate the antibacterial and antifungal activities of the isolated alkaloids against various pathogenic microorganisms.

Main Methods:

• Isolation of alkaloids from Tabernaemontana corymbosa stem bark using chromatographic techniques.
• Structure elucidation employing extensive spectroscopic methods (NMR, MS) and computational analyses (DP4+ probability, quantum chemical calculations).
• Determination of absolute configurations via Mo₂(OAc)₄-induced electronic circular dichroism (ECD) experiments.

Main Results:

• Four new monoterpene indole alkaloids, named tabernaecorymines B-E (compounds 1-4), were identified.
• Twenty-one known indole alkaloids (compounds 5-25) were also isolated and characterized.
• Several isolated compounds demonstrated significant antibacterial activity against Staphylococcus aureus, Bacillus subtilis, and Streptococcus dysgalactiae, as well as antifungal activity against Candida albicans.

Conclusions:

• The chemical investigation of Tabernaemontana corymbosa led to the discovery of novel monoterpene indole alkaloids.
• The elucidated structures and absolute configurations provide valuable data for understanding alkaloid biosynthesis and structure-activity relationships.
• The identified antibacterial and antifungal activities suggest the potential of these alkaloids as leads for developing new antimicrobial agents.