Secoiridoids and xanthones in the genus Centaurium

Area of Science:

• Phytochemistry
• Natural Products Chemistry
• Organic Chemistry

Background:

• Secoiridoid glucosides are a significant class of plant metabolites.
• Centaurium species are known sources of bitter compounds.
• Understanding the chemical diversity of iridoids is crucial for drug discovery.

Purpose of the Study:

• To isolate and characterize new secoiridoid glucosides from Centaurium littorale.
• To elucidate the structures of these novel compounds using spectroscopic methods.
• To investigate the chemical relationship and bitterness profile of the isolated compounds.

Main Methods:

• Preparative column chromatography for isolation.
• Thin-layer chromatography (TLC) for chemical interrelation analysis.
• Spectroscopic techniques including NMR (1H, 13C), UV, and IR for structure elucidation.

Main Results:

• Isolation and characterization of two new acyl secoiridoid glucosides, decentapicrins A and B.
• Detection and preparation of a third new compound, decentapicrin C.
• Elucidation of structures (Ic, Id, Ie) revealing novel single acylation at C(3)-OH and C(4)-OH of the glucose moiety.
• Demonstration of chemical interrelation and acyl migration under alkaline conditions.
• Decentapicrins A, B, and C exhibit weak bitterness compared to known bitter principles.

Conclusions:

• The study expands the known chemical diversity of secoiridoid glucosides.
• The novel acylation pattern represents a new finding in iridoid chemistry.
• The weak bitterness of the new compounds differentiates them from related bitter constituents.