Upcycling Black Garlic Peels into Multifunctional Cosmeceutical Extracts: Antioxidants and UV-Shielding via Antimicrobial Natural Deep Eutectic Solvents

What if your kitchen scraps could become the next skincare breakthrough? Black garlic peels, often tossed aside, hide a wealth of bioactive compounds—and scientists have found a green way to unlock them.

Black garlic peels are more than just waste—they're a treasure trove of bioactives waiting to be tapped. This study turns these underutilized by-products into multifunctional extracts for green cosmetics, using natural deep eutectic solvents (NaDES) as a sustainable extraction method.

After screening four eutectic mixtures, the choline chloride–lactic acid (ChCl:LA) system emerged as the star performer, delivering the highest extraction efficiency. The optimized extract boasted a remarkable total phenolic content of 5216.61 µg GAE/mL and strong antioxidant activity, confirmed by DPPH and FRAP assays, capturing both free and bound phenolic fractions.

But here's the twist: the antimicrobial activity came entirely from the solvent itself, not the garlic compounds. The NaDES showed broad-spectrum efficacy against C. albicans, P. aeruginosa, and S. aureus. When incorporated into emulsions with UV filters, the extract didn't boost SPF or UVA-PF directly, but a photochemiluminescence (PCL) analysis revealed it synergized with organic filters, enhancing the formulation's biological antioxidant shield.

This pioneering work highlights the upcycling potential of black garlic peels, proposing NaDES extracts as multifunctional, antioxidant, and antimicrobial ingredients for next-generation cosmeceuticals.

Key Points

• ChCl:LA NaDES yields highest extraction efficiency from black garlic peels
• Extract rich in phenolics (5216.61 µg GAE/mL) with strong antioxidant activity
• Antimicrobial effect solely from solvent; synergizes with organic UV filters