Green extraction of poplar type propolis: ultrasonic extraction parameters and optimization via response surface methodology

What if the key to unlocking propolis's powerful compounds lies in a simple, green recipe—citric acid and a splash of propanediol? Scientists have found the perfect conditions to do just that.

Propolis, the bee's 'superglue,' is a treasure trove of bioactive compounds, but extracting them often demands harsh chemicals and energy. This study turned to a greener alternative: natural deep eutectic solvents (NADES), specifically a mix of citric acid and 1,2-propanediol (1:4). The goal was to optimize ultrasonic extraction of poplar-type propolis, making the process efficient and eco-friendly.

Using response surface methodology (RSM) with a Box-Behnken design, researchers identified the sweet spot: a solvent-to-solid ratio of 30 mL/g, 39 minutes of ultrasonication, and 65°C. These conditions yielded impressive results—total phenolic content (TPC) of 290.35 mg/g, total flavones and flavonols (TFC) of 89.48 mg/g, and radical scavenging activity (RSA) of 31.89%.

Gas chromatography-mass spectrometry (GC-MS) revealed a high relative content of valuable compounds, including pinocembrin, chrysin, galangin, and phenethyl caffeate (CAPE). These are known for their antioxidant and anti-inflammatory properties, making the extract a promising candidate for cosmetics, nutraceuticals, and pharmaceuticals.

This research not only maps out optimal extraction parameters but also paves the way for sustainable, high-value propolis products—proving that green chemistry can be both effective and economically viable.

Key Points

• NADES (citric acid:1,2-propanediol 1:4) used for green extraction.
• Optimal conditions: 30 mL/g, 39 min, 65°C.
• High TPC (290.35 mg/g) and valuable compounds found.