Unveiling the potential of xanthines, discovery of potential 7-benzyl-1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione derivatives with antifibrotic activity for liver injury.

A new series of xanthine-based derivatives were designed, synthesized, and investigated to achieve promising antifibrotic and antioxidant agents for management of liver injury. Structure-based optimizations of the methylxanthine-based KMUP-1 (IX) were performed for inhibiting NF-κB activation pathway. All the newly designed xanthine derivatives 3, 4, 5, 6a-d, 7a-d, and 9a-d were in vitro screened for the antioxidant activity using the DPPH method. Compounds 4 and 5 showed the highest antioxidant activity with an IC50 of 28.02 and 36.02 μM, respectively. Compounds 9c and 9d retained a promising interception of the NF-κB activation pathway in molecular docking simulations within I-κB kinase α (IKKα) crystal structure (PDB ID: 5EBZ). Subsequently, compounds 9c and 9d were evaluated for their in vivo antifibrotic and chemoprotective activity using CCl4-induced hepatic fibrosis rat model. Compounds 9c and 9d successfully ameliorated liver fibrosis, as evidenced by the improved liver histopathological examination and liver enzyme activity levels. Compounds 9c and 9d were evaluated for their effects on mRNA expression levels of key genes involved in liver fibrosis via real-time PCR assays. Compound 9c exhibited a greater inhibitory effect on the expression levels of NF-κB and HIF-1α and a more pronounced stimulation of Nrf2 than compound 9d. Moreover, all the new xanthine derivatives were screened for the cytotoxic activity against the NCI tumor cell lines. Compounds 9c and 9d revealed a non-significant cytotoxic activity against all the assayed tumor cell lines, which indicate their selectivity for the antifibrotic activity. While compounds 6a and 6c displayed promising selective activity against melanoma SK-MEL-5 cell line (GI = 125.6, 90.3 %, respectively), and breast T-47D cell line (GI =87.8, 80.6 %, respectively). The utilized design approach unveiled the versatility of xanthine scaffold to deliver potential antioxidant, liver antifibrotic and chemoprotective agents, along with anticancer candidates via structure modification and optimization.