Introduction Type diabetes T D has

Introduction Type 2 diabetes (T2D) has been seriously affecting the health life of 415 million people and 193 million undiagnosed people [1]. Importantly, this disease was found to cause death at least 1.5 million annually, and has brought about an extensive health concern throughout the world [2,3]. Moreover, diabetes extremely increases complication of a lot other chronic disease, including stroke, kidney and cardiovascular health problems, which induce financial and health burden relative to diabetes [4]. Hyperglycemia, a dominant peculiarity of T2D, is most come from excess endogenous glucose production (EGP) by gluconeogenesis (GNG) pathway [5]. Thus, the most attractive strategy for the development of therapy diabetics is to block GNG pathway and control blood glucose [6]. Fructose-1,6-bisphosphatase (FBPase) is a rate-limiting enzyme in the hepatic GNG pathway, and has been acknowledged as a potential therapeutic target for the treatment of T2D. Recently, FBPase as a potential target has been received much attention, mainly because it could inhibit the GNG while avoid direct effects on glycogenolysis, glycolysis, and the tricarboxylic Dequalinium Chloride cycle [7]. FBPase inhibitors gained extensive interest because they are devoid of hypoglycemia associated with conventional T2D drug therapies and also combats with the key factor responsible for hyperglycemia [8]. FBPase is an allosteric enzyme and exists in two different conformational states (R and T) [9]. R state is an active state for catalysis, and T state go through 17° rotation of subunit pair with AMP binding the allosteric site, which is far away from the substrate catalysis site with 28 Å [10]. Furthermore, many efforts have been carried to explore AMP binding site inhibitors against FBPase by research institutes or pharmaceutical companies [[11], [12], [13], [14], [15], [16], [17], [18]]. The previous drug design of novel inhibitors target into AMP allosteric site were mainly focused on the imitation of AMP [19,20]. As shown in Fig. 1, the framework of tricyclic compound 2 and 3 originate from the phosphate and purine group of AMP, because the phosphate and purine group were regarded as the essential part for the binding of AMP [21]. In addition, the effective inhibitor 5 (CS-917), a prodrug of 4, was also similar to the AMP structure, and explored to clinical development [22]. The phosphate and purine group of compound 6 almost make no different with AMP [23]. However, AMP, an endogenous metabolite, participate in many critical physiological and biochemical process. For instance, AMP can bind to AMP-activated protein kinase, which is a central manager of metabolism and can control fatty acid oxidation, triglyceride biosynthesis and glucose translocation [24,25]. Another AMP binding enzyme is 6-phosphofructo-1-kinase, serving as key regulatory in glycolytic [26]. Therefore, the AMP analogues inhibitors could more or less inhibit others protein beside FBPase, and thus be associated with serious side effects [22,27]. Herein, using the pharmacophore-based virtual screening method, we expect to discovery some novel scaffolds inhibitors against FBPase. The in vitro inhibitions assays for these screened compounds were further carried out. Combining the DOX2.0 strategy [28] of our group and site-directed mutagenesis, the probable binding-mode of representative hit compound with FBPase was further identified.
Materials and methods
Results and discussion
Conclusion FBPase plays a gatekeeper role in gluconeogenesis pathway, and has been considered as a notably attractive target for control glucose level to improve T2D [42]. Actually, several of inhibitors against FBPase has been reported, but most of those inhibitors imitated the structure of the endogenous inhibitor AMP, which will result in some other side effects [8,27]. Therefore, efforts have been applied to find a novel scaffold for FBPase inhibitor through pharmacophore-based virtual screening, binding model predicted and structure optimization.