Design, synthesis, and in vitro application of a two-photon fluorescent probe for fluorescent imaging and in vitro biological evaluation of ulcerative colitis.

The clinical diagnosis and management of ulcerative colitis (UC) face considerable challenges, including invasiveness, insufficient sensitivity for early detection, and significant side effects associated with current therapeutics. Based on the altered expression of the TGR5 receptor during UC progression and the anti-inflammatory potential of its endogenous agonists (bile acids), we designed and synthesized a bile acid-derived two-photon fluorescent probe, CATPF-1. Through molecular docking-based screening, CATPF-1 was obtained and exhibited excellent photophysical properties, including a fluorescence quantum yield of 0.53 and a two-photon absorption cross-section of 228 GM, as well as favorable biocompatibility and robust stability under varied pH and ionic conditions. Cellular assays suggested that the actions of CATPF-1 may involve TGR5-related signaling pathways; however, the current data do not establish direct or specific binding to TGR5. Meanwhile, under in vitro conditions, the probe demonstrated preliminary inflammation-modulating activity, significantly suppressing the release of pro-inflammatory cytokines (TNF-α and IL-6) in lipopolysaccharide (LPS)-stimulated macrophages and intestinal epithelial cells, enhancing superoxide dismutase (SOD) activity, and reducing lactate dehydrogenase (LDH) and reactive oxygen species (ROS) levels, thereby effectively reversing inflammatory and oxidative injury. Collectively, this study identifies CATPF-1 as a candidate cholic acid-derived fluorescent compound worthy of further biological evaluation, with important theoretical significance and translational potential.