Extraction of hydroxy safflower yellow A and anhydroxysafflor yellow B from safflower florets using natural deep eutectic solvents: Optimization, biological activity and molecular docking

What if the secret to greener agrochemicals was hiding in cotton waste? Scientists just used natural deep eutectic solvents to unlock it—with a 7-fold boost in yield.

Cotton byproducts are usually discarded. But a new study shows they're a goldmine of bioactive compounds—if you know how to extract them. The trick? Natural deep eutectic solvents, or NADES, a greener alternative to harsh conventional solvents.

Researchers tested nine NADES formulations. One stood out: proline-citric acid (Pro-CA). It pulled out 2.2 times more phenolics and 4.8 times more gossypol than ethanol. After optimization, the gossypol yield jumped to 7 times that of ethanol. The team also isolated 21 gossypol derivatives, including two novel ones.

Bioactivity tests were striking. Several gossypols outperformed carbendazim against four fungal pathogens. Others showed nematicidal activity against root-knot nematodes, with LC50 values as low as 16.29 mg/L. And against a common insect pest, they beat azadirachtin, a commercial botanical insecticide.

Structure-activity analysis revealed why: quinone groups and hydroxyls drive antifungal power, while lactone rings boost insecticidal effects. This work turns cotton waste into a platform for sustainable, multifunctional agrochemicals.

Key Points

• Pro-CA NADES outperforms ethanol: 4.8× gossypol yield.
• Optimized extraction boosts gossypol yield 7-fold vs ethanol.
• 21 gossypol derivatives isolated; several beat commercial controls.