Five biflavonoids from Calycopteris floribunda (Combretaceae)

Area of Science:

• Natural Product Chemistry
• Phytochemistry
• Organic Chemistry

Background:

• Calycopteris floribunda is a plant source of bioactive compounds.
• Biflavonoids are a class of natural products with diverse biological activities.
• Understanding the chemical diversity of plant secondary metabolites is crucial for drug discovery.

Purpose of the Study:

• To isolate and elucidate the structures of novel biflavonoids from Calycopteris floribunda.
• To compare the spectroscopic and chiroptical properties of new compounds with known biflavonoids.
• To characterize new derivatives and epimers within the calycopterone and calyflorenone skeletons.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy for structural determination.
• Mass Spectrometry (MS) for molecular weight and fragmentation analysis.
• Circular Dichroism (CD) and optical rotation ([alpha]20D) for chiroptical property assessment.

Main Results:

• Five biflavonoids, including 6"-demethoxyneocalycopterone (1), calyflorenone C (2), 6"-epi-calyflorenone B (3), 6"-epi-calyflorenone C (4), and calyflorenone D (5), were identified.
• Compound 1 is a novel calycopterone derivative.
• Compounds 2-5 possess a calyflorenone skeleton, with 3 and 4 identified as epimers.
• Detailed NMR and MS data were obtained for all isolated compounds.

Conclusions:

• The study successfully identified and characterized five biflavonoids from Calycopteris floribunda.
• The findings expand the known chemical diversity of biflavonoids from this plant species.
• The structural and property comparisons provide valuable data for future research on biflavonoid structure-activity relationships.