Unveiling the structural properties of water-soluble lignin from gramineous biomass by autohydrolysis and its functionality as a bioactivator (anti-inflammatory and antioxidative).

Due to its low molecular weight and abundant functional groups, water-soluble lignin (WSL) is considered as a more potent antioxidant than traditional industrial lignin in biofields. However, few studies have been conducted to evaluate its intracellular and endogenous reactive oxygen species (ROS)-scavenging ability, especially for the intervention of ROS-related disease in vivo. In this work, WSL in bamboo autohydrolysate (WSL-BM) and wheat stalk autohydrolysate (WSL-WS) were isolated and characterized to comparably analyze their bioactivities. The composition analysis and NMR characterization showed that both WSL-BM and WSL-WS contained relatively similar components and substructures, but WSL-BM contained higher contents of phenolic OH groups. Both WSL samples exhibited excellent biocompatibility with the concentration below 50 µg/mL, while WSL-BM exhibited superior ROS-scavenging ability and ROS-related ulcerative colitis treatment potential at same concentration. In addition, WSL-BM also showed better performance in ameliorating inflammation and oxidative stress in RAW 264.7 cells and colitis mice by activating Nrf2 and suppressing NFκB signaling, resulting in an overall improvement in both macroscopic and histological parameters. Overall, these results implied that WSL from gramineous biomass can be used as a novel anti-inflammatory and antioxidative agent in the biomedical field.