Antibacterial and antioxidant activities of Chlorella vulgaris and Scenedesmus incrassatulus using natural deep eutectic solvent under microwave assisted by ultrasound

What if the green slime in your pond could fight bacteria and oxidation better than harsh chemical solvents? A new study just proved it can—using a surprisingly eco-friendly recipe.

Microalgae are tiny factories of natural medicine, but the usual way to unlock their treasures relies on volatile organic solvents—chemicals that are effective yet environmentally nasty. Researchers in Morocco asked a bold question: could natural deep eutectic solvents (DES)—green, renewable mixtures—do the job better? They tested four DES systems made from choline chloride paired with glycerol, citric acid, urea, or glucose, and compared them against ethanol, methanol, and water.

The results are striking. The citric acid-based DES, called SIDES2, extracted 4.98 mg/g of total phenolic content—far above the 3.27 mg/g achieved by ethanol. But extraction was just the beginning. The same DES extracts also showed superior antioxidant activity in DPPH, CAT, and FRAP assays, and stronger antibacterial effects against four bacterial strains, including both Gram-negative and Gram-positive species like E. coli and S. aureus.

This isn't just a lab curiosity. By replacing toxic solvents with renewable DES, we can make the production of bioactive compounds from microalgae cleaner and potentially more effective. The study offers a concrete path toward sustainable 'green chemistry'—where the best extractor isn't the harshest chemical, but the smartest, most natural blend.

Key Points

• Citric acid DES extracted 4.98 mg/g phenolics vs ethanol's 3.27.
• DES outperformed conventional solvents in antioxidant and antibacterial tests.
• Renewable DES offers eco-friendly alternative to toxic volatile solvents.