Valorization of Corn Silk as an Agricultural By-Product through the Optimization of Ultrasound-Assisted Extraction

Corn silk, derived from the stigmas of corn (Zea mays, Poaceae) flowers, possesses valuable bioactive compounds that can be harnessed for therapeutical, nutritional, and industrial purposes. This research aimed to optimize the extraction of bioactive compounds from corn silk, specifically flavonoids and total antioxidant capacity, by comparing it with classical extraction (infusion and maceration). The study identified significant factors influencing total flavonoid content (TFC) and antioxidant activity (assessed through an ABTS assay), including ethanol concentration, ultrasonic amplitude, and their quadratic interactions. This optimized combination of independent variables (37.89% ethanolic concentration, 48.58% ultrasound amplitude, and an extraction time of 38.72 min) yielded a balanced extraction, maximizing both TFC and antioxidant activity. Further analyses revealed significant total phenolic content, total flavonoid content (50.69 ± 0.36 mg GAE, 23.54 ± 0.01 mg QE, and 78.33 ± 0.94 mg TE/g extract, respectively), and potent in vitro antioxidant activity, affirming the efficacy of the optimized extraction. The study also explored the inhibitory effects on α-glucosidase (IC50 = 411.67 ± 25.39 µg/mL), acetylcholinesterase (IC50 = 1166.4 ± 399.38 µg/mL), and pancreatic lipase (IC50 = 1519.67 ± 209.04 µg/mL), showcasing potential antidiabetic and neuroprotective properties. While tyrosinase inhibition activity was not observed, the research emphasizes the nutraceutical potential of corn silk, offering valuable insights for its utilization and further exploration in the pharmaceutical and functional food industries.