Structural repurposing of SGLT2 inhibitor empagliflozin for strengthening anti-heart failure activity with lower glycosuria

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been reapproved for heart failure (HF) therapy in patients with and without diabetes. However, the initial glucose-lowering indication of SGLT2i has impeded their uses in cardiovascular clinical practice. A challenge of SGLT2i then becomes how to separate their anti-HF activity from glucose-lowering side-effect. To address this issue, we conducted structural repurposing of EMPA, a representative SGLT2 inhibitor, to strengthen anti-HF activity and reduce the SGLT2-inhibitory activity according to structural basis of inhibition of SGLT2. Compared to EMPA, the optimal derivative JX01, which was produced by methylation of C2-OH of the glucose ring, exhibited weaker SGLT2-inhibitory activity (IC50 > 100 nmol/L), and lower glycosuria and glucose-lowering side-effect, better NHE1-inhibitory activity and cardioprotective effect in HF mice. Furthermore, JX01 showed good safety profiles in respect of single-dose/repeat-dose toxicity and hERG activity, and good pharmacokinetic properties in both mouse and rat species. Collectively, the present study provided a paradigm of drug repurposing to discover novel anti-HF drugs, and indirectly demonstrated that SGLT2-independent molecular mechanisms play an important role in cardioprotective effects of SGLT2 inhibitors.

Amiloride slows down calpain-mediated ABCA1 degradation through in-hibition of hypoxia-induced NHE1 expression / 中国病理生理杂志

AIM:To examine the effects of hypoxia on sodium-hydrogen exchange 1 (NHE1) expression, in-tracellular Ca2+concentration ( [ Ca2+] i ) and calpain activity, and to explore the effect of amiloride on adenosine triphos-phate-binding cassette transporter A1 (ABCA1) degradation and its calpain-related mechanism.METHODS:RAW264.7 cells were exposed to hypoxia for 0 h, 12 h, 24 h and 48 h.The cell viability was measured by MTT assay and the expres-sion of NHE1 at mRNA and protein levels was detected by real-time PCR and Western blot.[ Ca2+] i was analyzed by flow cytometry.Calpain activity was assessed by the method of Suc-LLVY-aminoluciferin.Furthermore, the protein levels of ABCA1 in the RAW264.7 cells exposed to hypoxia for 24 h were determined after 6 h or 12 h treatment with NHE1 inhibi-tor amiloride in the presence of cycloheximide.ABCA1 protein levels and calpain activity were detected after 12 h incuba-tion with calpain inhibitor ALLN or intracellular calcium-chelating agent BAPTA.RESULTS: Hypoxia inhibited the cell viability in a time-dependent manner.Hypoxia up-regulated the mRNA and protein expression of NHE1, and increased [ Ca2+] i and calpain activity.Hypoxia increased the degradation of ABCA1 and amiloride slowed down the ABCA1 degra-dation.ALLN or BAPTA increased ABCA1 protein level and decreased calpain activity.CONCLUSION:NHE1 inhibitor amiloride attenuates the calpain-mediated degradation of ABCA1, indicating that hypoxia-induced NHE1 might, at least in part, participate in the ABCA1 degradation.