FR429 from <i>Polygonum capitatum</i> Demonstrates Potential as an Anti-hepatic Injury Agent by Modulating PI3K/Akt Signaling Pathway

FR429, an ellagitannin isolated and purified from the whole herb Polygonum capitatum (P. capitatum), possesses a robust pharmacological profile, which is particularly noteworthy for its anti-inflammatory and anticancer properties. Despite these established effects, its potential in mitigating hepatic injury remains to be fully explored. The present investigation delineates the hepatoprotective efficacy of FR429 and unveils its underlying molecular mechanisms. Initially, of the tested compounds, 10 compounds (specifically, compounds 2, 4, 5, 6, 7, 8, 9, 12, 13, and 14) exhibited significant protective effects at a concentration of 10 μM, elevating HepG2 (human liver cancer cell) cell viability from 43.4 to 70% following carbon tetrachloride (CCl₄) exposure. Among them, compounds 2 (FR429, half-maximum effective concentration (EC₅₀) = 6.46 μM) and 6 (2"-O-galloylquercitrin, EC₅₀ = 5.36 μM) demonstrated the highest cytoprotective activities. In the murine model, FR429 dramatically attenuated serum levels of alanine transaminase, aspartate transaminase, and alkaline phosphatase, indicative of its hepatoprotective potential. Histopathological evaluation further substantiated these findings, as FR429 noticeably mitigated CCl₄-induced hepatic lesions, involving necrosis, ballooning degeneration, and neutrophil infiltration. Transcriptomic analysis unveiled 178 differentially expressed genes in FR429-treated mice liver tissue, with significant alterations indicative of a hepatoprotective response. Mechanistic investigations revealed that FR429's hepatoprotective effects involve modulation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway, evidenced by downregulation of toll-like receptor 2, phosphorylated PI3K, phosphorylated Akt, nuclear factor-kappa-B, interleukin-1 beta, and tumor necrosis factor-alpha expression. Furthermore, FR429 modulated the gene and protein expression levels of apoptotic markers (apoptotic protein (Bax) and B-lymphoblastoma-2 gene (Bcl2)), reinforcing its anti-hepatic damage efficacy. This study represents the first report establishing FR429 as an effective hepatoprotective compound, paving the way for further investigation into its therapeutic applications.