Activities than ZYJ-34c and SAHA against all tested tumor cell lines. Meanwhile, it was notable that ZYJ-34c epimer and ZYJ-34c possessed lower toxicity to normal human lung fibroblast cell line (WI38) compared with SAHA. Encouraged by its great in vitro activity, ZYJ-34c epimer was progressed to an in vivo experiment. We applied the identical MDA-MB-231 xenograft mouse model as in our prior research8,9 with ZYJ-34c and SAHA as constructive control. The final dissected tumor volume, tumor growth inhibition (TGI) and relative increment ration (T/C) shown in Fig. 2 all indicated that ZYJ-34c epimer was one of the most potent compound, which was in line with its HDACs inhibitory activities and in vitro antiproliferative activities. The proposed binding modes of ZYJ-34c epimer and ZYJ-34c in the active web-site of HDAC2 were respectively navigated by molecular dynamic (MD) simulations to probe the reason why ZYJ-34c epimer was a lot more potent than its diastereomer. We chose HDAC2 for the following 3 motives. 1st, all Zn2+ dependant HDACs, especially isoforms belonging towards the same class bear a hugely conserved active web-site. Second, Class I HDACs, particularly HDAC1, HDAC2 and HDAC3 would be the most tumor-related HDACs isoforms.12 Third, the HDAC2 crystal structure has been reported (PDB ID: 3MAX). Just after 200 ps of simulation, both the complexes had converged and reached equilibrium (Fig. S8). Soon after MD simulation, MM-GBSA approach was used to calculate the Gibbs totally free power associated using the binding of inhibitors to HDAC2. The total binding energy ( Gb) of ZYJ-34c epimerNIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptRSC Adv. Author manuscript; offered in PMC 2014 November 21.Zhang et al.Page(-63.44 kJ/mol) was slightly lower than that of ZYJ-34c (-61.Bilobalide In Vivo 58 kJ/mol), which was in accordance with their HDACs inhibitory activity.Alicaforsen supplier To be able to investigate the influence of different chirality on protein-ligand interaction, MM-GBSA decomposition calculation was performed.PMID:23341580 Calculation benefits of two essential residues (PRO-23 and ASP-93, Table S1), which interacted with the chiral side chains of the two epimers, as well as the binding modes in HDAC2 (Fig. 3) indicated that compared with ZYJ-34c, its epimer could not only type an further -0.503 kcal/mol of hydrophobic interaction with PRO-23 (Fig. 3b) but in addition minimize three.579 kcal/mol of repulsive force against ASP-93 (Fig. 3a).NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptConclusionsIn conclusion, we successfully determined the precise absolute configurations on the earlier HDACi ZYJ-34c and its newly found epimer by a facile asymmetric synthetic method. It can be intriguing that ZYJ-34c epimer exhibited far more potent HDACs inhibition and antitumor activities than ZYJ-34c. Extra importantly, both diastereomers could be obtained on significant scale using our asymmetric synthetic approach, which laid a strong foundation for further research and improvement of ZYJ-34c epimer as a promising antitumor candidate. Additionally, the distinctive HDACs inhibitory activities of the two epimers may very well be rationalized by computational study, validating MD simulations and MM-GBSA as reliable approaches for HDACi discovery, at the least for rational style and screening of our tetrahydroisoquinoline-based HDACi.Supplementary MaterialRefer to Net version on PubMed Central for supplementary material.AcknowledgmentsThis work was supported by National Scientific and Technological Major Project of Ministry of Science and.