Bioresource Potential and Safety Evaluations of Thai Zea mays L. Husk Waste Extracts

Corn husk, a prevalent agricultural byproduct, remains an underutilized source of bioactive compounds. This study investigated the influence of extraction solvents (water, 50% ethanol, and 95% ethanol) and techniques (maceration, reflux, ultrasound-assisted extraction) on the phytochemical profiles and biological activities of corn husk. The results revealed that water extraction produced the highest total phenolic content, whereas 95% ethanol extraction yielded the greatest total flavonoid content and the most potent antioxidant activity in DPPH testing. In contrast, ultrasound-assisted water extraction exhibited the most potent nitric oxide inhibition (94.62 ± 2.13%) and tyrosinase inhibition (IC₅₀ = 7.54 ± 0.27 mg/mL), indicating anti-inflammatory and skin-lightening potential. This extract showed anti-collagenase activity (91.49 ± 4.01%), outperforming ascorbic acid (29.79 ± 1.00%) and EGCG (82.27 ± 1.00%), though its anti-hyaluronidase activity was limited. Cytotoxicity testing revealed cytotoxicity at 10 mg/mL, while the HET-CAM assay confirmed non-irritation at the same level. These findings underscore that ultrasound-assisted water extraction is a safe and successful technique for obtaining bioactive-rich extracts. This study supports the transition of corn husk from agricultural waste to a high-value, safe, and multifunctional natural ingredient for the cosmetic, pharmaceutical, and functional food industries.