•Efficient synthetic procedures for newly designed compounds were described.•CHEQ-2 efficiently inhibited the activities of CDC25A/B and the proliferation of different types of cancer cell lines.•The inhibition mechanisms of CHEQ-2 in cancer cells were elucidated.•Oral administration of CHEQ-2 (10 mg/kg) significantly inhibited xenografted human liver tumor growth in nude mice.•CHEQ-2 demonstrated extremely low toxicity (LD50 > 2000 mg/kg).Cell division cycle (CDC) 25 proteins are key phosphatases regulating cell cycle transition and proliferation via the interactions with CDK/Cyclin complexes. Overexpression of CDC25 proteins is frequently observed in cancer and is related to aggressiveness, high-grade tumors and poor prognosis. Thus, inhibiting CDC25 activity in cancer treatment appears a good therapeutic strategy. In this article, refinement of the initial hit XDW-1 by synthesis and screening of a focused compound library led to the identification of a novel set of imidazopyridine derivatives as potent CDC25 inhibitors. Among them, the most potent molecule was CHEQ-2, which could efficiently inhibit the activities of CDC25A/B enzymes as well as the proliferation of various different types of cancer cell lines in vitro assay. Moreover, CHEQ-2 triggered S-phase cell cycle arrest in MCF-7, HepG2 and HT-29 cell lines, accompanied by generation of ROS, mitochondrial dysfunction and apoptosis. Besides, oral administration of CHEQ-2 (10 mg/kg) significantly inhibited xenografted human liver tumor growth in nude mice, while demonstrated extremely low toxicity (LD50 > 2000 mg/kg). These findings make CHEQ-2 a good starting point for further investigation and structure modification.A potent CDC25 inhibitor and promising anticancer drug candidate.

Heparin is an effective competitive antagonist of inositol 1,4,5-trisphosphate receptors (IP3Rs). It binds to IP3Rs and affects calcium homeostasis. Ultra-low-molecular-weight heparin (ULMWH) is heparin's derivative, the present study was designed to test the effects of ULMWH on intracellular calcium concentration ([Ca2+]i) in primary cultured neurons. [Ca2+]i was measured by Multilabel Counter Victor-1420 using Fura-2/AM as the calcium fluorescent probe. The results indicated that ULMWH decreased the resting [Ca2+]i with or without extracellular Ca2+. They had no effects on high K+-induced elevation of intracellular Ca2+ level indicating that ULMWH had no effect on external Ca2+ influx mediated by voltage-dependent calcium channels. However, they partially reduced the increase in [Ca2+]i induced by glutamate. Furthermore, ULMWH significantly inhibited the inositol 1,4,5-trisphosphate (IP3)-induced increase in [Ca2+]i both in cellular and subcellular level. These results suggest that ULMWH may reduce [Ca2+]i in neurons through suppressing Ca2+ release from IP3-sensitive stores.Highlights► ULMWH seems to cross the BBB and causes lower risk of bleeding. ► It is the first study about the beneficial effects of ULMWH on [Ca2+]i. ► The mechanism involves in suppressing IP3-mediated Ca2+release. ► We isolated ER and mitochondria using subcellular fractionation. ► ULMWH might act as a useful agent in the prevention and treatment in AD.