Green Extraction Strategies and Bioactivity of Rheum cordatum Losinsk: Antioxidant, Antimicrobial, and Molecular Docking Insights

What if the greenest extraction method also yields the most powerful bioactive compounds? A new study on the roots of Rheum cordatum suggests that supercritical CO2 might be the unsung hero of natural product chemistry.

Forget harsh solvents and high heat—green extraction is the new frontier, and Rheum cordatum, a plant with medicinal promise, is at the center of it. Researchers compared three eco-friendly techniques: ultrasound-assisted extraction (UAE), subcritical ethanol (Sbc-EtOH), and supercritical CO2 (ScCO2). They wanted to see which method pulls out the most phenolic compounds while keeping their antioxidant and antimicrobial powers intact.

The results were striking. ScCO2 extraction outperformed the others, capturing most of the 53 phenolic compounds identified by LC-MS/MS—often exclusively or in the highest amounts. Interestingly, lower pressure (100 bar) yielded more phenolics than higher pressure (400 bar). And the ScCO2 extracts boasted the strongest antioxidant activity.

But that's not all. The ScCO2-100 extract, produced at 100 bar, showed potent antimicrobial effects against four bacterial strains, including Staphylococcus aureus and Escherichia coli, with minimum inhibitory concentrations (MICs) from 31.25 to 250 µg/mL. Key compounds like gallic acid and catechin were present, and molecular docking suggested epicatechin binds well to several disease-related proteins, with docking scores as low as −9.479 kcal/mol.

This study highlights that green extraction isn't just environmentally friendly—it's scientifically superior. By fine-tuning pressure and solvent, we can unlock nature's pharmacy without leaving a heavy footprint.

Key Points

• ScCO2 extraction yielded the most phenolic compounds.
• Lower pressure (100 bar) increased phenolic yield.
• ScCO2-100 showed strong antimicrobial activity (MIC 31.25–250 µg/mL).