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Uncovering Bioactive Compounds in Propolis Extracts Prior to Isolation Through NMR Chemometric Analysis.
Maria-Ioanna Stavropoulou1, Antigoni Cheilari1, Konstantia Graikou1
1Laboratory of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece.
Molecules (Basel, Switzerland)
|May 27, 2026
Summary
Researchers used NMR-HetCA to rapidly identify bioactive compounds in Greek propolis, revealing caffeic acid derivatives as potent inhibitors of DPPH free radicals and collagenase, aiding quality control.
Area of Science:
- Natural Product Chemistry
- Analytical Chemistry
- Pharmacognosy
Background:
- Propolis, a bee product, possesses antimicrobial, antioxidant, and anti-inflammatory properties.
- Standardizing propolis products requires identifying key bioactive constituents and their activities.
- Greek propolis (PR09), rich in phenolics and flavonoids, was selected for investigation.
Purpose of the Study:
- To identify bioactive compounds in Greek propolis using advanced NMR techniques.
- To evaluate the antioxidant (DPPH inhibition) and anti-collagenase activities of propolis constituents.
- To demonstrate the utility of NMR-HetCA in accelerating the analysis of complex natural product extracts.
Main Methods:
- Extraction and fractionation of Greek propolis using Fast Centrifugal Partition Chromatography (FCPC).
- Evaluation of DPPH radical scavenging and collagenase inhibitory activities of fractions.
- Nuclear Magnetic Resonance HeteroCovariance Approach (NMR-HetCA) and Statistical Total Correlation Spectroscopy (STOCSY) for metabolite identification.
- Bioassays of isolated compounds to confirm NMR-based predictions.
Main Results:
- NMR-HetCA identified 26 secondary metabolites, including diterpenes, flavonoids, and caffeic acid esters.
- Caffeic acid derivatives showed the highest inhibition of DPPH free radicals and collagenase.
- Galangin, 3-O-methyl galangin, and pinocembrin contributed to antioxidant and collagenase inhibitory activities.
- Caffeic acid phenethyl ether exhibited significant DPPH inhibition (92.54%) and notable collagenase inhibition.
Conclusions:
- NMR-HetCA is an effective tool for rapid identification of bioactive compounds in propolis extracts.
- This method accelerates the evaluation of propolis samples, reducing the need for laborious isolation.
- The study highlights specific compounds responsible for the antioxidant and anti-collagenase properties of the investigated propolis.
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