Valorization of Pterospartum tridentatum (Carqueja) Stems: Influence of Extraction Methods on Phenolic Composition, Antioxidant Capacity, and Functional Bioactivity

While everyone has been staring at the flowers, the stems of this Iberian medicinal plant have been quietly hiding a treasure trove of antioxidants. Could the 'waste' be the real gold?

Carqueja, a shrub cherished in Iberian kitchens and traditional medicine, has long been studied for its showy flowers. But the stems—which make up a huge chunk of the plant—have been largely ignored. A new study set out to change that, asking whether these stems could be a powerhouse of bioactive compounds.

Researchers tested four extraction methods: plain water, hydroethanolic mixtures, ultrasound, and pressurized liquid. They then measured everything from yield and protein to phenolic composition, antioxidant power, antimicrobial clout, and even toxicity on human cell lines. The result? Thirty-seven phenolic compounds were tentatively identified, mostly flavonoid and isoflavonoid glycosides, with genistein derivatives leading the charge.

While extraction yields varied, the phenolic profiles were surprisingly consistent across methods. Ultrasound and pressurized liquid extracts boasted slightly higher antioxidant activity. Antimicrobial effects were modest—only mild inhibition against Staphylococcus epidermidis and Malassezia furfur—but cytotoxicity was low, meaning the extracts are gentle on human cells.

This study flips the script: stems, once overlooked, are a promising, underutilized biomass source. They're rich in phenolics, antioxidant-ready, and safe in lab tests. Maybe it's time to give carqueja stems their moment in the spotlight.

Key Points

• 3
• 7