Six new alkaloids from Melodinus henryi.

Area of Science:

• Natural Product Chemistry
• Organic Chemistry
• Pharmacognosy

Background:

• Melodinus species are a source of bioactive alkaloids.
• Bisindole and quinolinic alkaloids possess diverse pharmacological properties.
• Structural elucidation of complex natural products remains a challenge.

Purpose of the Study:

• To isolate and characterize new alkaloids from Melodinus henryi.
• To determine the structures and absolute configurations of novel compounds.
• To advance the understanding of alkaloid diversity in the Melodinus genus.

Main Methods:

• Isolation of alkaloids using chromatographic techniques.
• Structure elucidation via extensive spectroscopic analyses (2D NMR, HRESIMS).
• Determination of absolute configuration using ECD exciton chirality method.

Main Results:

• Six new alkaloids, melodinhenines A-F (1-6), were successfully isolated.
• Melodinhenines A and B represent novel eburnan-vindolinine-type bisindole alkaloids.
• Melodinhenines C-F are new quinolinic melodinus alkaloids.
• The absolute configurations of compounds 1 and 2 were determined.

Conclusions:

• The study expands the known chemical diversity of Melodinus alkaloids.
• This is the first report determining the absolute configuration of eburnan-vindolinine-type bisindole alkaloids using ECD.
• The findings provide a basis for further investigation into the biological activities of these novel compounds.