5T4B:
reference: Scaffold-hopping from xanthines to tricyclic guanines: A case study of dipeptidyl peptidase 4 (DPP4) inhibitors., Pissarnitski DA, Zhao Z, Cole D, Wu WL, Domalski M, Clader JW, Scapin G, Voigt J, Soriano A, Kelly T, Powles MA, Yao Z, Burnett DA, Bioorg Med Chem. 2016 Sep 4. pii: S0968-0896(16)30694-0. doi:, 10.1016/j.bmc.2016.09.007. PMID: 27670099

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).