This investigation aimed to determine the effect of high-power ultrasonic pulses on the antioxidant, antibacterial, and antiproliferative activity of sorghum (Sorghum bicolor) lignin. A lignin yield of 7.35% was obtained using the organosolv method. Additionally, the best conditions of the ultrasonic pulses were optimized to obtain a more significant increase in antioxidant capacity, resulting in 10 min for all treatments, with amplitudes of 20% for DPPH and FRAP, 18% for ABTS, and 14% for total phenols. The effect of ultrasonic pulses was mainly observed with FRAP (1694.88 µmol TE/g), indicating that the main antioxidant mechanism of lignin is through electron transport. Sorghum lignin with and without ultrasonic pulses showed high percentages of hemolysis inhibition (>80%) at concentrations of 0.003 to 0.33 mg/mL. The AB blood group and, in general, all Rh- groups are the most susceptible to hemolysis. Lignin showed high anti-inflammatory potential due to heat and hypotonicity (>82%). A higher antimicrobial activity of lignin on Escherichia coli bacteria was observed. The lignins evaluated without sonication and sonication presented higher activity in the cell line PC-3. No effect was observed on the lignin structure with the FT-IR technique between sonication and non-sonication; however, the organosolv method helped extract pure lignin according to HPLC.
Keywords: lignin; organosolv; sorghum; ultrasonic pulses.