Natural deep eutectic solvent (NADES)-aided extraction of bioactive compounds from cotton byproducts for agricultural applications: Extraction optimization, structural identification, and bioactivity evaluation

Cotton waste just got a second life: scientists turned leftover plant material into a green goldmine of natural pesticides using eco-friendly solvents called NADES.

In a world hungry for sustainable solutions, researchers have found a way to turn cotton byproducts—often discarded agricultural waste—into powerful natural agrochemicals. The secret weapon? Natural deep eutectic solvents, or NADES, a family of green solvents that mimic nature's own chemistry. Among nine formulations tested, a proline-citric acid mix (Pro-CA) stood out, extracting 2.2 times more phenolics and 4.8 times more gossypol than traditional ethanol extraction.

But extraction was just the beginning. The Pro-CA extracts showed remarkable antifungal, nematicidal, and insecticidal activities, even outperforming synthetic controls. The key driver? Gossypol content, which correlated strongly with all three bioactivities. By optimizing extraction conditions—35.93 mL/g liquid-solid ratio, 61.42°C, and 90.69 minutes—researchers achieved a stunning 7-fold increase in gossypol yield compared to ethanol.

Delving deeper, the team isolated 21 gossypol derivatives, including 2 novel analogs. Several of these compounds outperformed commercial pesticides: gossypols 1, 2, 3, 5, 8, and 9 beat carbendazim against four fungal pathogens, while gossypols 1–4 showed insecticidal power stronger than azadirachtin. Even more intriguing, structure-activity relationships revealed that quinone and hydroxyl groups drive antifungal action, while lactone structures boost insecticidal potency.

This work transforms agricultural waste into a treasure trove of multifunctional agrochemicals, offering a green, science-backed path toward sustainable farming. Cotton byproducts are no longer just waste—they're a resource waiting to be unlocked.

Key Points

• Pro-CA NADES boosts phenolic yield 2.2x, gossypol 4.8x vs ethanol
• Optimized extraction achieves 7x gossypol yield over ethanol
• 21 gossypol derivatives isolated, 2 novel, with strong pesticide activity