Effect of Natural Deep Eutectic Solvents and Conventional Solvents on Extraction Yield, Antioxidant Activity, and Toxicity of Peperomia pellucida (L.) Kunth

What if the secret to unlocking a plant's healing power lies not in the plant itself, but in the liquid we use to soak it? For 'Sirih Cina,' that liquid just might be a green chemistry marvel.

For centuries, Peperomia pellucida, known as 'Sirih Cina', has been a quiet workhorse in traditional medicine. But its full therapeutic potential has often been overlooked, partly because the solvent used to extract its bioactive compounds can make or break its biological powers. Now, researchers have put this humble herb under the spotlight, comparing ordinary solvents with a new generation of eco-friendly alternatives called Natural Deep Eutectic Solvents, or NADES.

Using an ultrasonic water bath to coax out the leaf's compounds, the team tested water, methanol, ethanol, ethyl acetate, and a NADES formulation. They measured total flavonoid content (TFC) via a colorimetric assay, antioxidant activity with the DPPH radical scavenging test, and toxicity using the brine shrimp lethality assay. The results were striking: NADES outperformed all conventional solvents, yielding the highest extraction yield (17.39 ± 0.03%) and the strongest antioxidant activity (83.31 ± 0.03% DPPH scavenging).

What's more, NADES extracts were non-toxic to brine shrimp, with an LC50 of 1597.62 µg/mL, far above the toxicity threshold. Interestingly, while NADES ranked third in TFC, the moderate correlation between TFC and antioxidant activity hints that other compounds also play a role. This suggests that NADES is not just a green solvent but a smart one, capable of pulling out a broader spectrum of beneficial molecules.

This study positions NADES as a powerful, safe, and sustainable tool for exploring the medicinal potential of 'Sirih Cina' and similar plants. With its high yield and non-toxic profile, NADES could be the key to unlocking natural therapies that are both effective and environmentally friendly.

Key Points

• NADES gave highest yield (17.39%) and DPPH activity (83.31%).
• NADES extract non-toxic (LC50 = 1597.62 µg/mL) in brine shrimp.
• TFC not sole factor; other compounds affect antioxidant activity.