Novel Cinobufagin Oxime Ether Derivatives as Potential Na＋/K＋-ATPase Inhibitors： Synthesis, Biological Screening and Molecular Docking

Some cinobufagin oxime ether derivatives as potential Na＋/K＋-ATPase inkibitors were synthesized by following the side chain of istaroxime. These compounds inhibit Na＋/K＋-ATPase in a dose-dependent manner. Compound 3c with an oxyethylamine side chain that is the same as that of istaroxime showed the most potent inhibi- tion, which was stronger than compound 3a with only hydroxyoxime moiety at C3 and compound 3b with a methy-lated hydroxyoxime moiety. Molecular docking was used to explore the binding modes of the target compounds with Na＋/K＋-ATPase, which suggested that the longer ethyl amine group at C3 oxime moiety of compound 3c could make stronger interaction with Na＋/K＋-ATPase via intermolecular charge-charge and H-bond interaction as compared with other derivatives.

Chemical composition-based characterization of the anti-allergic effect of Guominkang Formula on IgE-mediated mast cells activation and passive cutaneous anaphylaxis

Guominkang(GMK),a Chinese medicine formula,has been used to treat allergic diseases in clinical settings for many years.To evaluate the antiallergic effect and molecular mechanism of action of GMK extract,RBL-2H3 cell models and passive cutaneous anaphylaxis(PCA)mouse models were established.High performance liquid chromatography(HPLC)and ultra-high performance liquid chromatography-mass spectrometry(UHPLC-MS)analyses were performed to characterize the chemical composition of GMK.A total of 94 compounds were identified or tentatively identified from GMK.Three of them,emodin,ursolic acid,and hamaudol,were identified for the first time as potential active compounds in GMK,since they inhibited the degranulation of mast cells.The anti-allergic effect of hamaudol was the first to be discovered.GMK could markedly mitigate the shade of Evans Blue extravasation and ear incrassation in PCA mouse models.Additionally,GMK significantly inhibited the degranulation of mast cells,suppressed mast cell degranulation by reducing Ca2+influx and the levels of TNF-α,IL-4,and histamine,and markedly inhibited the phosphorylation of Lyn,Syk,PLCγ1,IκBα,and NF-κB p65.Molecular docking results indicated that hamaudol and emodin had strong interaction with FcεRI and NF-κB related proteins,while ursolic acid only interacted with NF-κB associated proteins.These results suggest GMK suppresses the activation of MCs both in vivo and in vitro.The underlying mechanism of its anti-allergic activity is associated with the inhibition of FcεRI and NF-κB activation.

Synthesis of Camptothecin-lO-O-glucoside Using an Engineered Oleandomycin Glucosyltransferase

Oleandomycin glycosyltransferase variant P67T/S132F/A242V（ASP） was used to convert 10-hydroxycamptothecin into camptothecin-10-O-glucoside, which was confirmed by spectral analysis. Compared to the previously reported results, the present study reached the conversion rate up to 80% through the optimization of reaction conditions. In addition, compared with 10-hydroxycamptotheein（HCPT）, camptothecin-10-O-glucoside inhibited the proliferation of Huh7 cells in a concentration-dependent manner and showed stronger antineoplastic effect but lower toxicity. Furthermore, camptothecin-10-O-glucoside induced more apoptotic cells as compared with the parent compound.

Synthesis and Cytotoxic Activities of Spin-labeled Derivatives of Cinobufagin

Two series of novel spin-labeled derivatives of Cinobufagin（compounds 5 and 8a--8f in series 1 with five-membered ring nitroxyl free radical and compounds 6 and 9a-9f in series 2 with six-membered ring nitroxyl free radical） were synthesized. The cytotoxic activities in vitro against two tumor cell lines（HepG2 and HeLa） were evaluated, and the results indicate that all compounds display potent cytotoxicity against HepG2 and HeLa cells, and most compounds show better activities on HeLa cells than on HepG2 cells except for compounds 8a and 9d. Gene- rally, the compounds in series 2 have more potent cytotoxic activity against HepG2 than the compounds in series 1. Especially, compounds 6 and 9f in series 2 exhibit even more potent activities against the two tumor cell lines than Cinobufagin. Thus incorPoration of different L-amino acids as the linker changed the cytotoxic profile of the spin-labeled Cinobufagin. In addition, the representative compound 9f significantly changed the cell cycle distribution and led to HeLa cell cycle arrested at G2/M phase.