3VJM:
reference: Fused bicyclic heteroarylpiperazine-substituted l-prolylthiazolidines as highly potent DPP-4 inhibitors lacking the electrophilic nitrile group., Yoshida T, Akahoshi F, Sakashita H, Sonda S, Takeuchi M, Tanaka Y, Nabeno M, Kishida H, Miyaguchi I, Hayashi Y, Bioorg Med Chem. 2012 Aug 15;20(16):5033-41. Epub 2012 Jul 5. PMID: 22824762

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