Phytochemical Content, Antioxidant and Antimicrobial Potential of Althaea officinalis L. Extracts Prepared by “Green” Classical and Natural Deep Eutectic Solvents

Marshmallow isn't just for s'mores—its extracts might be nature's own medicine cabinet, packing a punch against bacteria. But the secret isn't in the sugar; it's in the green chemistry used to unlock it.

Marshmallow (Althaea officinalis L.) has long been a staple in food and pharma, thanks to its rich cocktail of bioactive compounds. But how we extract those treasures matters—and scientists are turning to greener solvents to do it. In this study, researchers compared classic hydroethanolic extracts with natural deep eutectic solvents (NADES) from the plant's leaves, flowers, and roots, using chromatography and spectrophotometry to dissect their chemistry. The results were impressive: HPLC-MS revealed 35 secondary metabolites, mostly hydroxycinnamic acid derivatives and flavonoid glycosides. Meanwhile, GC-MS spotted ten free amino acids, seven organic acids, and various sugars, with concentrations varying by plant part. Ethanolic extracts boasted the highest total phenolic content (up to 176 mg GAE/L), while flower extracts led in antioxidant power (DPPH up to 89 µmol TE/L). When tested against microbes, NADES1 extracts showed significant antibacterial activity, with inhibition zones up to ~34 mm, but NADES2 extracts were largely inactive. Antifungal effects were negligible across the board. The takeaway? Green solvents can unlock potent bioactivity, but not all are created equal—and the plant's chemistry is a delicate, organ-specific dance.

Key Points

• 35 secondary metabolites found, mainly hydroxycinnamic acid derivatives and flavonoid glycosides.
• Ethanolic extracts: highest phenolics (176 mg GAE/L); flowers: strongest antioxidant (DPPH 89 µmol TE/L).
• NADES1 extracts showed antibacterial zones up to ~34 mm; antifungal activity negligible.